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Equipment OF clinical laboratories

 

Clinical laboratories are located in buildings and clinics are equipped with the latest technology with a high level of professionalism that makes possible the initial examination and follow-up of patients with any disease. The clinical laboratory performed all possible tests prescribed by the doctor, in sickness and in full accordance with the wishes of the patient. If necessary, the full survey can be produced with maximum speed and no quality is lost in just a couple of hours.

After passing the tests directly in the laboratory patient can get a brief description of the techniques and advice for further treatment or prevention.

The clinical laboratory has several main areas of examination: biochemistry, coagulation, bacteriology, hematology, general studies: hormonology, STI (sexually transmitted infections).

Biochemistry

This course deals with the study of organic and non-organic origin, biochemical processes in the body fluids of the human body and its pathologies.

Hematology

Hematology is researching blood cells and their pathologies. Related to hematology and general studies - consideration of cells in biological fluids and their pathologies. The clinical laboratory conducted a general analysis of blood. The results determine the number of blood platelets, reticulocytes. Set leukocyte formula. Ascertain the level of electrolytes in the blood. Under laboratory conditions, each indicator can be found and examined separately.

Coagulology

Involved in the processes of coagulation and their pathological disorders. For the analysis of coagulation components of hemostasis view.

Needed in this case is the following procedures: elektrokoahulohramma; hemokoahulohramma the definition clotting time, fibrinogen, prothrombin.

Bacteriology

This branch deals with the study of bacteria in human biological fluids. Clinical laboratory tests conducted on the micro-biome of biological fluids: blood, urine, breast milk, semen. In the study of microorganisms is possible to detect microorganisms that cause pathogenic effects on the body, identify them in quantitative terms.

Hormonology

Includes diagnose all types of hormones and tumor markers.

Clinical Laboratory conducts an assessment of the thyroid gland. For diagnosis of disease transmitting definition tireodnyh panel.

Clinical laboratory enables the evaluation of patients with the problem of infertility and reproductive functions.

Serology and diagnosis of STI

The clinical laboratory facilities STI - infections transmitted sexually. The most common of them - chlamydia, herpes type II, gonorrhea, candidiasis, syphilis, mycoplasmosis.

 

1.     Spectrophotometry

 

Spectrophotometry - methods of research and analysis of substances based on the measurement of the absorption spectrum in the optical region of the electromagnetic radiation. This method is the basis of many devices used in the clinical laboratory.

The main dependence is studied in spectrophotometry - dependence of absorption intensity of the incident light wavelength.

The basic principle of spectrophotometry measurements is as follows: if we consider properly chosen and fairly narrow band of the electromagnetic spectrum, the absorbing properties of the test material can be used to determine its concentration. In most cases these substances in the form in which they are normally present in samples obtained from patients (eg, serum, urine, or cerebrospinal fluid) does not have the required characteristics of the absorption of electromagnetic energy. In such cases, the samples are added reagents that cause chemical reaction. This reaction gives a product that already has the required characteristics. Then the reaction products is placed in the cuvette for analysis. Calibration procedures provide a possible account of the difference between the concentration of the reaction product and the starting number of the analyzed substance.

 

Fig. 1. Optical scheme spectrophotometer

 

1.     Light source.

2.     Entering slite.

3.     Reflecting mirror.

4.     Diffraction grating.

5.     Reflecting mirror.

6.     The stop slite.

7.     Lens.

8.     Cuvette with the sample.

9.     Silicon photodetector.

 

Interference of light waves

Interference - the addition of spacious two (or more) waves, which in its various exit point strengthening or weakening of the amplitude of the resultant wave.

Rack interference pattern given only coherent waves.

Coherent wave - a wave with the same frequency, constant phase difference, and oscillations occur in one plane.

 

Fig. 2. Blending light waves(interference)

 

Let the point A came two waves of equal frequency, the last before this different distances and from their sources.

The amplitude of the resulting oscillations depends on the magnitude of what is called the path difference of the waves.

- path difference, - the way waves, - optical path difference; - refractive index media.

If the path difference is an integer waves, the waves come to a point in phase. Consisting, the waves reinforce one another and provide twice the amplitude of the oscillations.

The condition of maximum

,

- wavelength, - any integer

If the path difference is an odd number of half-wave, the waves come to the point A in anti- phase. In this case, they canceled each other out, resulting oscillation amplitude is zero.

Conditions of minimum

,

- fuzzy numbers

At other points in space there is a partial strengthening or weakening of the resultant wave.

 

Diffraction on reflecting diffraction grating

 

Almost all studies used spectral diffraction in reflection. The effect of grating reflectivity can be easily understood, considered some interference of plane waves that are reflected on the faces of strokes grating.

 

Rice. 3. The phenomenon of reflection of light waves in the diffraction grating

 

Let edge touches grating composed of lattice plane angle , spacing , width edge . Light falls on the grid in one direction, making the normal to the plane of the grating angle and is reflected in the direction of 2, making the normal angle .

As can be seen from the figure, the geometric path difference between the beams diffracting from neighboring strokes equal: . Terms major highs for grating reflectivity is formula . At normal incidence rays on the grid and the condition for a maximum reflectivity grid looks like . In the case of reflecting neuro-filtering grating enegry distribution of light is the main maximum of the zero-order at an angle , equal to the angle of specular reflection . If a reflecting diffraction grating has profiled strokes , the main maximum occurs when . This angle corresponds to the mirror image of the edge groove (corner light).

Thus, depending on the angle of strokes and distances between diffraction grating may produce different orders of spectrum.

 

Law Bouguer - Lambert Beer

 

With the passage of radiation through a solution of light- absorbing substance flux weakening the stronger, the more energy absorbing particles of the substance. Lowering the intensity depends on the concentration of the absorbing substance and length of the path traversed by a stream. This relationship is expressed by the law Bouguer - Lambert - Beer.

To account for the loss of light that has passed through the solution, the reflection and scattering, compared to the intensity of light passing through the test solution and the solvent.

For the same thickness of the same material cuvettes containing the same solvent loss on reflection and scattering of light are approximately the same in both beams of light and reduce the intensity depends on the concentration of the substance.

 

Fig. 4. The passage of light through the test liquid

 

The ratio of the intensity of the incident and outgoing light by passing the name or transmittance:

 

 

where - the intensity of the incident light, - intensity of light flux that has passed through the solution.

Skip expressed as a percentage. To completely clear solution for completely , opaque . Taken with the opposite sign logarithm called optical density :

 

 

For a completely transparent solution , for completely opaque .

Reducing the intensity of radiation as it passes through the solution obeys the Bouguer - Lambert - Beer:

 

or or

 

where - the molar absorption coefficient; - the thickness of the absorbing layer deterioration (cm); - solution concentration (mol / l).

Molar absorption coefficient - individual characteristics matter, it depends on the nature of the substance and the wavelength and does not depend on the concentration and length cuvette.

The value reflects the ability of a substance to absorb light. This ability is not unlimited and is determined by the structure of the molecule, the maximum possible value is ~ 105 l cm -1 mol -1.

 

Spectrophotometer

A spectrophotometer designed to measure the transmittance and optical density of liquids (including biological) to determine the concentration of dissolved components in them, and measuring the transmittance and optical density of solid and liquid samples of different origin. Used in ecological and analytical epidemiological and sanitary laboratories, medical facilities, as well as chemical, optical, biological laboratories, industry, research and educational institutions.

The spectrometer consists of four main parts:

1.     Halogen or deuterium lamp as the light source.

2.     Monochromator to separate the desired wavelength and remove unwanted second order radiation.

3.     Cuvette department for placing the investigated models.

4.     Detector to register a missed light and converting it into an electrical signal and displayed on the screen.

 

Fig. 5. The main part of a spectrophotometer

 

In Fig. 5 is a block diagram of the device spectrophotometric type. The source produces a stream of radiant energy that is used to analyze the sample. Monochromator transmits energy in a limited frequency band. The cuvette containing the analyzed sample is based on the way the energy of the beam. The detector produces an electrical signal proportional to the amount of energy received by and the indicator shows the numerical value of the received energy flow or some function of it (for example, by analyzing the concentration of substances in the sample).

Power Sources. Hydrogen or deuterium discharge lamps are used to provide power in the 200-to-360 nm range, and tungsten filament lamps are used for the 360-to-800 nm range. Hydrogen and deuterium lamps both produce a continuous spectrum; but a problem with these power sources is that they produce about 90% of their power in the infrared range. The output in the ultraviolet and visible ranges can be increased by operating the lamp at voltages above the rated value, but this stratagem significantly reduces the expected life of the lamp. Another problem with tungsten lamps is that, during operation, the tungsten progressively vaporizes from the filaments and condenses on the glass envelope. This coating, which is generally uneven, alters the spectral characteristics of the lamp and can cause errors in determinations.

Monochromators are devices that utilize prisms and diffraction gratings. They provide very narrow bandwidths and have adjustable nominal wavelengths. The basic principle of operation of these devices is that they disperse the input beam spatially as a function of wavelength. A mechanical device is then used to allow wavelengths in the band of interest to pass through a slit.

Prisms are constructed from glass and quartz. Quartz is required for wavelengths below 350 nm. A convergent lens system is used to direct the light from the source through an entrance slit. The prism bends the light as a function of wavelength. The smaller wavelengths (ultraviolet) are bent the most. This produces an output beam in which the wavelength band of interest can be selectively passed by placing in the light path an opaque substance with a slit in it. The wavelength spectrum of the power passing through the slit is nominally triangle shaped. In prisms, as in filters, the wavelength at which maximal transmittance occurs is the nominal central wavelength. Bandwidths of 0.5 nm can be obtained with this type of device. Prisms have been used over the wavelength range of 220 to 950 nm. The nonlinear spatial distribution of the power emerging from a prism requires relatively complex mechanical devices for control of the slit position to select different nominal wavelengths.

Diffraction gratings are constructed by inscribing a large number of closely spaced parallel lines on glass or metal. A grating exploits the fact that rays of light bend around sharp corners. The degree of bending is a function of wavelength. This results in separation of the light into a spectrum at each line. As these wave fronts move and interact, reinforcement and cancellation occur. The light emerging from a grating is resolved spatially in a linear fashion, unlike the light from a prism, in which the separation of wavelengths is less at longer wavelengths. As in the case of the prism, a slit is used to select the desired bandwidth. The mechanics of the slit-positioning mechanism of a grating are less complicated than those of a prism because of the linearity of the spatial separation of the wavelengths. Gratings can achieve bandwidths down to 0.5 nm and can operate over the range of 200 to 800 nm.

Cuvette. The cuvette (Figure 5) holds the substance being analyzed. Its optical characteristics must be such that it does not significantly alter the spectral characteristics of the light as that light enters or leaves the cuvette. The degree of care and expense involved in cuvette design is a function of the overall accuracy required of the spectrophotometer.

Sample. The sample (actually, in most cases, the substances resulting from the interaction of the patient specimen and appropriate reagents) absorbs light selectively according to the laws of Lambert, Bouguer, Bunsen, Roscoe, and Beer. The principles stated in these laws are usually grouped together and called Beer's law.

Spectrophotometer made ​​so as to preserve the value of and as a constant, so that in each case the value of depends on . According unknown concentration of a substance can be defined as follows. First, there is an unknown substance absorption , for a standard sample containing a known concentration of test material . More determined absorption , sample of unknown concentration of the test substance. Finally, the unknown quantity of the test substance concentration calculated by the following formula:

 

 

Figure 6 shows the description of spectrophotometer model 101.

 

Fig. 6. Main parts of spectrophotometer model 101

 

1.     Cover of cuvette department.

2.     Cuvette office - holder with a ditch.

3.     Handle switch cuvette - holder.

4.     Control Panel.

5.     Adjusting knob wavelength.

6.     USB port.

7.     Parallel port.

8.     Hood fan.

9.     Rosier cable for power supply.

10.                       Power supply.

(a)

(b)

Fig. 7. View of the lamp, the source of light (a) and digital display spectrophotometer (b)

 

Appearance control panel is shown in Figure 7, where 1) Keyboard 2) LCD screen.

- (Mode) transition in photometric mode

- (Input) proof / print

- Increase the value / set 0

- Increase the value / set 100 % T.

Examples of modern spectrophotometers are presented in Figure 8.

 

(a)

(b)

Fig. 8. Modern examples of spectrophotometers:

Spectrophotometer CM-5 (a), Spectrophotometer UV-vis (b).

 

2. Flame photometers

 

Flame photometry is one option and emission spectral analysis is based on measuring the intensity of light emitted by excited particles (atoms or molecules) with the introduction of substances into the flame.

Flaming photometers are used to determine the concentration of alkali, alkaline earth metals in solution, drinking, mineral, waste water, wines, beverages, biological substances, pharmaceuticals. The device is widely used in medical, biological and educational laboratories.

Flaming photometers are three important differences from the device discussed above. Firstly, the energy function and the device containing the sample is placed in a flame. Second, in most applications, flame photometry goal is to measure the light emission pattern, rather than the absorption of light by him, although we will also discuss photometers flames atomic absorption type. Third, fire photometers can only determine the concentration of pure metals.

When normal power levels used in the fiery photometer, only about 1% of the atoms moving in an excited state. In addition, only some elements emit enough radiation power at a wavelength in the transition from high-to low-energy orbitals. These two factors limit the use of atomic emission flame photometry definition, mainly ions , and . A device that can carry out determination of other elements such as but they need much more complicated optical scheme.

The following table provides detailed information about the measurements of atomic emission flame alkali, alkaline earth metals in terms of the wavelength and color.

 

Table 1

Elements

Wavelength (nm)

Color flame

sodium

589

yellow

potassium

766

violet

barium

554

lime green

calcium

622*

orange

lithium

670

red

*Calcium is measured by using the calcium hydroxide band emission at 622 nm as the Calcium main atomic emission occurs at 423 nm.

 

A simple flame photometer consists of the following basic components:

a)                      The burner: a flame that can be maintained in a constant form and at a constant temperature.

b)                     Sprayer and mixing chamber: a means of transporting a homogeneous solution into the flame at a steady rate.

c)                      Simple colour filters (interference type): a means of isolating light of the wavelength to be measured from that of extraneous emissions.

d)                     Photo-detector: a means of measuring the intensity of radiation emitted by the flame.

Figure 9 shows the sequential arrangement of major components.

Fig. 9. The main part of the fierce photometer

 

A simple optical scheme that includes only the filter and lens focusing the filtered light beam detector, commonly used in determining and . For other measurements require more sophisticated optical circuit comprising monochromator.

Detailed structure flaming photometer is presented in figure 9.

 

Fig. 10. Flame photometer

1 - compressor 2 - cup with sample solution, 3 - sprayer, 4 - valve, regulating the flow of gas, 5 - pressure gauge, 6 washing, 7 - burner, 8 - concave mirror, 9 - lens, 10 - filter (monochromator) 11 - photocell (photoelectonical multiplier), 12 - amp, 13 - pointer galvanometer.

As shown in Fig. 10, the sample with the solvent is fed into the atomizer that turns the liquid into a finely dispersed spray that is injected into the flame. In fiery photometer using multiple fuel types. At present, the commonly used mixture of propane or natural gas with compressed air. The solvent is evaporated in the flame, leaving a microscopic sample. These particles break down into atoms. As already noted, only a small fraction of atoms moving in an excited state. When the atoms return to the ground state, they release energy in the form of electromagnetic waves at characteristic frequencies.

Many modern atomic emission fiery photometers designed for the use of an internal standard, designed to compensate for variations in the rate of flow of the solution, aerosol and efficiency of education in the characteristics of the flame. For this purpose, the lithium ions ().These ions are normally absent in biological samples with high intensity radiation, and their line emission is significantly different wavelength lines of sodium and potassium. In the attached sample accurately laid salt . A separate optical channel is provided for measuring the intensity of radiation , and this value, together with the known concentration value is used to enter the amendments instrument compensates for deviations in the definition and . In fact, in most cases the definition of , , carried out in parallel.

When using the as an internal standard having some problems. First, although the compensation of small variations in the characteristics of the device and can not manage to compensate for the large deviation. Secondly salt are increasingly used for the treatment of essential mental disorder - manic-depressive psychosis. If patients are treated with salt not specifically identified in the clinical laboratory, the definition and may be due to large errors. Unfortunately, in clinical laboratories rarely reported any patient information that can be used to ensure the reliability of measurements.

Examples of modern fiery photometers are presented in Figure 11.

 

(a)

(b)

Fig. 11. Modern examples of fiery photometers:

) Cole-Parmer 2655-00/10/15; b) Jenway PFP-7

 

3. Fluorescence spectroscopy

 

Fluorescence spectroscopy - photometric analysis method based on measuring the intensity of the secondary radiation produced by the interaction of radiant energy with crucial matter. One of the objectives of fluorescent analysis is to determine the chemical composition and structure of substances on the basis of study of their fluorescent properties.

Fluorescence usually determined in solutions with a concentration of a substance that does not exceed 10-4 10-6 g / ml. Increasing the concentration of fluorescent substances leads to a decrease or complete disappearance of fluorescence (the so-called concentration quenching of fluorescence). When the temperature is also usually reduced fluorescence intensity.

The physical effect of fluorescence is that the molecule of the substance absorbs a quantum of excitation light while moving in a new, more energy rich state, some micro period of time it emits the excess energy as a photon fluorescence (emission).

 

Fig. 12. Scheme of the mechanism of spontaneous fluorescence

 

Figure 12 shows a diagram of two electronic energy levels of a molecule or ion - basic (unexcited) and first excited 1. Each of these energy levels is oscillatory system (converging) sublevels of the vibrational quantum numbers v''=0; 1; 2; ; - Basic electronic state and v'=0; 1; 2; ; - First excited state. If the molecule (or ion) is situated in the gaseous state, the cutaneous vibrational levels corresponding to the rotational system (divergent) sublevels. However, because intelligence is used primarily fluorescence of molecules or ions in solution when their free spins tend to suppression by interaction with surrounding particles, the rotational sublevels in the circuit in Figure 12 are not taken into account. At ordinary temperatures the molecules and ions are in the ground (unexcited) state, when v''=0. Absorption particles (molecules or ion) of a quantum of electromagnetic energy abc=hvabc, where h Planck's constant, vabc frequency of the absorbed light particle increases its energy (excited) and enters the upper electron-vibrational state 1 for a vibrational level of the vibrational quantum number v ', for example, the level of v'=3, as shown in Figure 12, that carried the energy transition v''=0 → v'=3.

Fluorescence has been applied in analytical practice for identifying substances in color lyuminestsyruyuscheho radiation and quantitative analysis for determining the intensity of fluorescence. Table 2 shows the values ​​of the maxima wavelength of the exciting light and fluorescence for some pharmaceuticals.

 

Table 2

Fluorescence maxima of some pharmaceuticals

 

Preparation

λmax

 

Preparation

λmax

excitation

fluorescence

excitation

fluorescence

Adrenaline

410

520

Procainamide 

295

385

Mepacrine

285, 420

500

Norepinephrine 

395

505

Chlorpromazine 

350

480

Tetracyclines 

390

520

y-Aminobutyric  acid 

375

485

Riboflavin

450

535

n-aminosalicylic acid

300

405

 

Salicylic acid

310

 

435

 

Amytal

265

410

Tetracycline

390

515

Vitamin

325, 327

470, 510

Thiamine 

365

450

Vitamin D2

390

480

Thiopentalum

315

530

Vitamin D3

390

480

Phenobarbital 

300

440

Harmine 

300, 365

400

Physostigmine

300

360

griseofulvin

295, 335

450

Folic acid

290

450

diethylstilbestrol

410

510

Chlortetracycline 

355

445

Menadione 

335

410

Quinidine 

250, 350

450

Pentobarbital 

265

440

Quinine 

350

450

 

Fluorimeter

 

Used when performing photometric, and chemiluminescence fluorymetrychnoho method of measuring the mass concentration of organic and inorganic chemicals, and pharmaceutical analysis.

Underlying fluometrychnyh measurements is the fact that some molecules emit light characteristic spectrum (emission spectrum) immediately after the absorption of electromagnetic energy and the transition to an excited state (fluorescence phenomenon). The extent to which the molecules are excited depends on the amplitude and wavelength of the radiation energy in the excitation spectrum. In this process, a small portion of the energy is lost, which results in the emission spectrum as a whole is in a long-wave region than the excitation spectrum.

Each fluorymetr or spectral fluorymetr contains three main blocks (Figure 13):

1) light source to excite the fluorescence of the sample.

2) sample holder (cuvette).

3) detector for fluorescence observation or measurement.

 

Fig. 13. The main part of fluorimeter

 

Fluorimeter is a different sensitivity using various sources of radiation, wave selectors and recording schemes. As a source of radiation commonly used mercury arc lamp. They give line spectrum with maxima at 365, 405, 436 and 546 nm. As commonly used photomultiplier detectors. A unique feature of these devices is the need to choose the working frequency band for the two spectra - excitation and emission.

One advantage is fluorymetriyi higher sensitivity, which may not exceed four orders of magnitude sensitivity photometric methods. This is because of photometric methods for determining the unknown concentration of the test substance in the sample is measured difference in absorption between the solution containing zero concentration of test material (% = 100) and the analyzed sample. In the case of highly diluted samples (which, for example, % = 98), small deviations in the measurement process can lead to large relative errors in the measurement results. If fluorymetriyi, however, carried out a direct measurement of the fluorescence of the sample to determine the unknown concentration it contains test material.

 

Fig. 14. Block diagram of the fluorimeter

 

Fig. 15. Optical scheme fluorimeter

1.     Light source - monochromatic LED.

2.     UVC filter.

3.     Collecting lens.

4.     Emitting light output.

5.     The cuvette.

6.     Emission flow and diffused into the cell from the light source.

7.     Collimator.

8.     Selective mirror.

9.     Optical filters.

10.           Photomultiplier tube.

 

Photomultiplier tube, vacuum devices in which the flow of electrons emitted photocathode under the action of optical radiation (photocurrent), increased as a result of secondary electron emission, the current in the circuit anode (collector of secondary electrons) is much higher than the initial photocurrent. The device is used to detect very weak signals.

The principle of these detectors is the multiplication of electrons released under photocathode photon flux.

 

Fig. 16. Photomultiplier tube

Photomultipliers acquire light through a glass or quartz window that covers a photosensitive surface, called a photocathode, which then releases electrons that are multiplied by electrodes known as metal channel dynodes. At the end of the dynode chain is an anode or collection electrode. Over a very large range, the current flowing from the anode to ground is directly proportional to the photoelectron flux generated by the photocathode.

The spectral response, quantum efficiency, sensitivity, and dark current of a photomultiplier tube are determined by the composition of the photocathode. The best photocathodes capable of responding to visible light are less than 30 percent quantum efficient, meaning that 70 percent of the photons impacting on the photocathode do not produce a photoelectron and are therefore not detected. Photocathode thickness is an important variable that must be monitored to ensure the proper response from absorbed photons. If the photocathode is too thick, more photons will be absorbed but fewer electrons will be emitted from the back surface, but if it is too thin, too many photons will pass through without being absorbed. The photomultiplier used in this tutorial is a side-on design, which uses an opaque and relatively thick photocathode. Photoelectrons are ejected from the front face of the photocathode and angled toward the first dynode.

Electrons emitted by the photocathode are accelerated toward the dynode chain, which may contain up to 14 elements. Focusing electrodes are usually present to ensure that photoelectrons emitted near the edges of the photocathode will be likely to land on the first dynode. Upon impacting the first dynode, a photoelectron will invoke the release of additional electron that are accelerated toward the next dynode, and so on. The surface composition and geometry of the dynodes determines their ability to serve as electron multipliers. Because gain varies with the voltage across the dynodes and the total number of dynodes, electron gains of 10 million are possible if 12-14 dynode stages are employed.

  Confocal microscopes, spectrophotometers, and many high-end automatic camera exposure bodies utilize photomultipliers to gauge light intensity. Spectral sensitivity of the photomultiplier depends on the chemical composition of the photocathode with the best devices having gallium-arsenide elements, which are sensitive from 300 to 800 nanometers. Photomultiplier photocathodes are not uniformly sensitive and typically the photons are spread over the entire entrance window rather than on one region. Because photomultipliers do not store charge and respond to changes in input light fluxes within a few nanoseconds, they can be used for the detection and recording of extremely fast events. Finally, the signal to noise ratio is very high in scientific grade photomultipliers because the dark current is extremely low (it can be further reduced by cooling) and the gain may be greater than one million.

 

Fig. 17. Cuvette detector assembly

 

Fig. 18. A view of the front panel of the detector

 

1.     LED "Power".

2.     Button 'the zero'.

3.     Transshipment LED solar cells.

4.     Handle switch ranges RFU (sensuality).

5.     Scale factor ranges sensuality.

6.     Button "label."

7.     Incoming fitting detector elements of the cell attachment.

8.     Incoming fitting detector.

Fig. 19. View back panel detector

 

1.     Earth wire with screw.

2.     Positive contact analog output connector RCA.

3.     Positive terminal of analog input connector RCA.

4.     Positive contact auxiliary output connector RCA.

5.     Voltage switcher auxiliary input.

6.     Switcher time constant.

Time constant - value filtering (averaging) of the analog signal. The higher the value of time constant, the better the filter, the smoother baseline.

7.     The negative effect of auxiliary input jack RCA.

8.     Switches voltage 220-110V.

9.     Fuse.

10.                       Connector cable tension.

11.                       On / off.

12.                       Number plate detector.

 

Examples of modern fluorimeters presented in Figure 20.

 

(a)

(b)

Fig. 20. Modern examples fluorometer:

) Varioskan Flash; b) -02-B-

 

4. Hematology

 

The blood consists of formed elements, substances in solution, and water. This section covers only devices that measure characteristics of the formed elements: red blood cells (RBCs), white blood cells (WBCs), and platelets.

The primary functions of the RBCs are to carry oxygen from the lungs to the various organs and to carry carbon dioxide back from these organs to the lungs for excretion. The primary function of the WBCs is to help defend the body against infections.

Platelets perform two main functions:

1) formation of platelet aggregate, primary stopper, closing the vessel injury site;

2) providing the surface to accelerate key reactions of plasma coagulation.

Complete blood count - drug analysis, enabling to assess the degree of hemoglobin in the red blood system, the number of erythrocyte, white blood cells, platelets, hemoglobin count in one erythrocyte and erythrocyte sedimentation rate.

The basic attribute of the formed elements in the blood that is measured is the number of elements of each type per microliter (ml). The normal range of content ERTS adult males is 4.6-6.2 x 107 ml, and for adult female 4.2-5.4 x 106 / ml. The normal range of the RBC count in an adult male is 4.6 to 6.2 x 106/ml and, in an adult female, 4.2to5.4 x 106/ml. The normal ranges of WBCs and platelet counts are the same for men and women. The normal range of the WBC count is 4,500 to 11,000/ml; that for the platelet count is 150,000 to 400,000/ml. The hematocrit (HCT) is the ratio of the volume of all the formed elements in a sample of blood to the total volume of the blood sample. Hematocrit is expressed as a percentage, and his normal range for an adult is 40-54 %, and 35-47 % of adult women. Hemoglobin (Hb) is a conjugated protein within the RBCs that transports most of the O2 and a portion of the CO2 that is carried in the blood. It is reported in grams per deciliter. The normal range in adult men is 13.5 to 18 g/dl, and that in adult women is 12 to 16 g/dl.

A second group of measurements is made to characterize the RBC volume and Hb concentration. These measurements include the mean corpuscular volume (MCV) in cubic micrometers, the mean corpuscular hemoglobin (MCH) content in picograms, and the mean corpuscular hemoglobin concentration (MCHC) in percent. These values are called the RBC indices. Normal ranges for these parameters are as follows:

 

MCV = 82-98 mm3

MCH = 27-31 pg

MCHC = 32-36 %

 

The RBC count (in millions per microliter), HCT (in percent), MCV (in cubic micrometers), Hb (in grams per deciliter), MCH (in picograms), and MCHC (in percent) are related as follows:

 

MCV = 10 HCT / RBC count

MCH = 10 Hb / RBC count

MCHC = 100 Hb / HCT

 

The units for RBC count, Hb, and HCT that are employed in these calculations are such that the units for MCV, MCH, and MCHC are those given above.

EXAMPLE 1. Calculate the RBC indices from the following data.

 

RBC = 5 milion / ml

Hb = 15 g / dl

HCT = 45 %

 

ANSWER:

MCV = 10 HCT / RBC count = 450 / 5 = 90 ml3

= 10 Hb / RBC count = 150 / 5 = 30 pg

= 100 Hb / HCT = 1500 / 45 = 33,3 %

 

Hematology analyzers

 

Hematology analyzers are used to diagnose diseases of the hematopoietic system as well as of the human body, and are designed to monitor tests in clinical diagnostic laboratories. Examples of such analyzers is Cobas Micros, Hemocomp-10, Hemoscrin.

 

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()

(b)

Fig. 21. Modern examples of hematology analyzers:

) Cobas Micros; b) HOSPITEX HEMASCREEN

All hematology diversity of devices can be divided into 3 classes:

Grade 1 - Semi-automatic blood cell counters that define commonly 4 to 10 parameters (leukocytes, erythrocytes, hemoglobin, hematocrit, mean erythrocyte volume, mean erythrocyte hemoglobin in the average concentration of hemoglobin in the red blood cell mass, platelets, mean platelet volume). These devices are mostly used in the pre- diluted blood. The basis of the calculation and analysis of cells in the counters is conductometric method.

Grade 2 - automatic analyzers that conduct analysis of whole blood and determine the 20 parameters, including the estimated values ​​of red blood cells and platelets in volume, as well as carry out the partial differentiation of WBC 3 parameters (granulocytes, lymphocytes and " secondary cell " that consisting mainly of eosinophils and basophils). At the core count and cell differentiation analysis- this class is the conductometric method, which is complemented by a system of internal quality control.

Grade 3 - High-tech hematology analyzers that allow for a detailed analysis of the blood, including full differentiation of leukocytes to 5 parameters (neutrophils, eosinophils, basophils, monocytes and lymphocytes), histogram distribution of leukocytes, erythrocytes and platelets by volume sketohrammy. The operation of devices of this class is a combination of conductometric method with other methods (scattering of the laser beam, RF, tsytohymycheskyy use different differentiating lysates, etc.).

The most modern and most widespread use is hemametr Coulter (Coulter STKS).

 

Fig. 22. Hematology Analyzer Coulter (Coulter STKS)

The analyzed sample is blood that has been anticoagulated, with ethylene- diaminetetraacetic acid (EDTA). Anticoagulants are substances that interfere with the normal clot-forming mechanism of the blood. They keep the formed elements from clumping together, which would prevent them from being counted accurately. Ethylenediaminetetraacetic acid does this by removing calcium from the blood. The initial step in the analysis procedure is the automatic aspiration of a carefully measured portion of the specimen. Next the specimen is diluted to 1:224 with a solution of approximately the same osmolality as the plasma in Diluter I, Figure 23. The diluted specimen is then split, part going to the mixing and lyzing chamber and part to Diluter II.

Fig. 23. Block diagram of the hematology analyzer Coulter

 

The function of the diluting and lyzing chamber is to prepare the specimen for the measurement of its hemoglobin content and WBC count. The lyzing agent causes the cell membranes of the RBCs to rupture and release their hemoglobin into the solution. The WBCs are not lyzed by this agent. Adding the volume of lyzing agent increases the dilution to 1:250. A second substance, Drabkin's solution, is present; it converts hemoglobin to cyanmethemoglobin. This is done to conform to the accepted standard method for determining hemoglobin concentration. The advantage of this method is that it includes essentially all forms of hemoglobin found in the blood. The specimen is next passed through the WBC bath, which functions as a cuvette for the spectrophotometric determination of the hemoglobin content. The final step in this process is measurement of the WBC count.

Figure 23 outlines the method that is used in making this determination. The same method is used for counting RBCs. A vacuum pump draws a carefully controlled volume of fluid from the WBC-counting bath through the aperture. A constant current passes from the electrode in the WBC- counting bath through the aperture to the second electrode in the aperture tube. As each WBC passes through the aperture, it displaces a volume of the solution equal to its own volume. The resistance of the WBC is much greater than that of the fluid, so a voltage pulse is created in the circuit connecting the two electrodes. The magnitude of that voltage pulse is related to the volume of the WBC (Zhanf, 2006).

To increase the accuracy of the measurement, the system uses three parallel counting units. They share the common WBC-counting-bath electrode and have individual aperture-tube electrodes. The output of each of these circuits is connected to a preamplifier. The amplified voltage pulses pass through a threshold circuit. The threshold voltage is selected as part of the calibration procedure. Specimens whose WBC count values have been determined by reference methods are processed, and the threshold is set to give counts that agree with the reference values.

Fig. 24. Coulter STKS aperture bath.

 

Pulses that exceed the threshold enter a pulse-integrator circuit, which produces a dc voltage proportional to the WBC count. The outputs of the three pulse-integrator circuits are sent to a voting circuit. If the three outputs agree within a specified range, they are averaged. If one output disagrees with the other two by more than the specified range, it is not used in computing the average. If all three outputs disagree by more than the specified range, an error indicator is set, and a zero value is produced.

The next step in the signal processing is to correct the average-count signal for coincidence. Coincidence is the passage of two or more WBCs through the aperture at the same time. Statistical analysis is used to estimate the average level of coincidence for the aperture size and any uncorrected count level. An analog circuit makes this conversion. The digital WBC count value is displayed and also recorded on a printer.

We will now examine the right side of Figure 24. The first step is the further dilution of the specimen to 1:224 in Diluter II. This second dilution is required because of the much greater concentration of RBC than of WBC in the blood. A system identical to the one described for the WBC count is used to obtain the RBC count.

Cells with volumes greater than 35.9 fl are classified as RBCs. A 256- channel RBC size histogram is prepared. The MCV and RDW are computed from this histogram. The RDW is the coefficient of variation of the RBC volume distribution.

Cells whose volumes are in the 2 to 20 fl range are classified as platelets. The volumes of these cells from each aperture are transformed into a 64- channel histogram. These histograms are statistically processed to yield a platelet count along with a mean platelet volume (MPV) and platelet distribution width (PDW) from each channel. A voting process similar to that described for the WBC count is used to determine the final values for these parameters. The MPV and PDW values are primarily used for quality control functions at this time.

The RBC count, Hb and MCV are input to a special-purpose computer circuit that calculates the values of HCT, MCH, and MCHC

 

5. Chromatography

 

Chromatography - is the own group of methods designed to separate compounds substances components. In this method, the mobile phase is a gas (carrier gas) and fixed - solid or liquid that is deposited on a solid inert carrier or evenly cover the inner walls of the column (stationary phase placed in a column.).

This process is characterized by a constant distribution , which is the ratio of the concentration of substances in the stationary phase to the concentration in the mobile phase .

 

Concentration - depends on the nature of matter, the nature of mobile and stationary phase, temperature, etc etc.

In terms of application in clinical laboratory data techniques are used to detect heavy substances such as drugs and hormones. For example by using gas-liquid chromatography easily find where power is a drug used in the case of an overdose. Having this information is vital to the doctor who must choose the following therapeutic procedures.

For separation of components using different speeds of movement in the mobile phase that dictated by the interaction of these substances from stationary phase.

Gas chromatography is based on the mechanisms of absorption and distribution. The equipment consists of a feed gas, the device input samples, the chromatographic column, detector and recording device. Speakers are usually made from glass or stainless steel and filled with stationary phase. Carrier gas passes through a given speed device input sample column, and then - through the detector. Determination is carried out at a constant temperature or according to a predetermined temperature program. Detector gas chromatography (flame ionization by thermal conductivity termoionnyy, mass spectrometry by electron capture, etc.), the most versatile and sensitive as other chromatographic methods. Column, device input sample and detector termostatuyut at the specified temperature. Prepare the solution is tested and the solution (s) of comparison, as described in a separate article. Using the reference solution, establishing device and selects the sample volume entered and allow you to obtain the necessary signal. Perform repeated administration to check the match. Enter solutions and recording the results of chromatography. Specifies the height (in an isothermal determining if the symmetry factor is 0.8-1.2) or peak area of ​​the analyzed components. To calculate the content of the test component methods using external or internal standard. To calculate the impurity content can be used, where appropriate, the method of internal normalization. In these cases, recommend the use of wide-range amplifier and automatic integrator. In pharmaceutical analysis gas chromatography are used to control residual amounts of organic solvents in substance identification and quantification of solvents and other compounds.

Figure 25 is represented by gas-liquid chromatograph working principle.

 

Fig. 25. Schematic diagram of the gas-liquid chromatograph

1 - bulb with an inert gas, 2 - a device for introducing samples into column (dispenser) 3 chromatography column 4 - Thermostat 5 - Detector 6 - Signal Converters, 7 - recorder.

 

An apparatus for introducing samples into the chromatograph is a steel cylinder with a channel closed a rubber gasket. The sample is injected through micro-squirt (Fig.26), which is pierced elastic membrane. On the tube that goes to the chromatographic column is the dispenser.

 

Fig. 26. Micro-squirt for inputing samples

 

Dispenser - a device for quantitative sampling and putting it into the chromatography column.

 

(a)

1 - elastic membrane

2 - heating element

(b)

Fig. 27. Diagram of input samples in chromatography column (a) and process input (b)

The device is heated in order to test after the introduction of the chronograph quickly evaporated. Couples caught bearing gas begins to move through the column. The gas sample is introduced through another device which is a double tap of the dispenser tube bundle. In the first position the crane through the tube flushed atmosphere analyzing a gas mixture. Then turn the tap cover dispenser tube and the next turn is introduced into the carrier gas stream it.

 

(a)

(b)

Fig. 28. Inlet valve: a - filling loop tap gas samples ; b) input samples in a stream of carrier gas

 

Chromatographic column - a means for separating components of a mixture by adsorption. It is packed solid supportive matrix, which caused the liquid phase. Column placed in a thermostat, which continuously monitored the temperature level. Programmer temperature gradually increases the temperature of the column in the sequence matched for maximum efficiency allocation of that same substance that is analyzed. Speakers come in different lengths and shapes, but usually it has a length of 1 m and a diameter less than 7 mm.

Capillary columns are capillary with an inner diameter of 0.1-0.5 mm and a length of several meters. Capillary walls act as a carrier, the carrier liquid phase is applied directly to it. Reduces resistance to gas flow, so you can make big column length, reducing the efficiency of separation.

 

Fig. 29. Capillary Column for Gas Chromatography

 

Detector - a device for finding changes in the composition of the carrier gas passed through the column. Fashion detector are converted into an electrical signal and transmitted device that is a record, such as a computer.

Fig. 30. Gas-liquid chromatograph detector

 

Options delays characterize sorption property of the analyzed compounds.

 

Fig. 31. Parameters analyzed delay compounds in chromatographic column.

time from input samples into the column to the output of the maximum peak.

time molecules in the gas form of communication

time molecules adsorbed state due to

 

The registrar on the axis represents time, and the axis - intensity of the output signal of the detector. So chromatograph shows the number of elements present, and future maintenance with which these substances evaporate from the column. Based on this information, there are elements can be identified by their delay or by comparison with chromatogram, obtained by gas-liquid chronograph analysis of substances known structure. Examples of chromatograms are presented in Fig. 32.

 

Fig. 32. Example chromatogram analysis of alcohol that is in the blood: X axis - time delay (min), Y - signal detector (Matthew)

 

Fig. 33. Example chromatogram analysis of fluid located in the gastric juice

 

Modern gas-liquid chromatographs

Gas chromatograph "Krystallyuks 4000m" fully automated, from sample introduction and ending with chromatographic data processing, including the functions of automatic temperature control thermostats, flow and pressure of the carrier gas (EUPH system), auxiliary gas, automatic setting fire detectors, control burning flame in the process, measuring the detector signal using a 24-bit ADC.

 

Fig. 34. Gas chromatograph "Krystallyuks 4000m"

 

Gas chromatograph 430-GC (Fig. 23) is an ideal instrument for routine studies in areas such as clinical analysis, identification of impurities in alcohol products, determining the composition of fatty acids, forensic examination, petroleum refining industry. The device is compact (½ of space required to install conventional laboratory gas chromatograph), has a moderate cost.

 

Fig. 35. Gas chromatograph 430-GC and its digital screen

 

Gas-liquid chromatography offers several important advantages in the analysis of heavy compounds: speed, the ability to work with small amounts of models and high sensitivity. Most devices can perform an analysis of clinically significant substance less than 1 hour, and often less than 15 min, and the analysis requires only 1 mm. model. Sensitivity means depends on the type of detector used.

 

6. Equipment using electrophoresis

 

Devices based on electrophoretic principles are used in the clinical laboratory to measure quantities of the various types of proteins in plasma, urine, and CSF; to separate enzymes into their component isoenzymes; to identify antibodies; and to serve in a variety of other applications.

Electrophoresis may in general be defined as the movement of a solid phase with respect to a liquid (the buffer solution). The main functions of the buffer solution are to carry the current and to keep the pH of the solution constant during the migration. The buffer solution is supported by a solid substance called the medium.

 

Zone electrophoresis

In this technique, the sample is applied to the medium; and under the effect of the electric field, groups of particles that are similar in charge, size, and shape migrate at similar rates. This results in separation of the particles into zones. The factors that affect the speed of migration of the particles in the field are discussed in the following paragraphs.

Magnitude of Charge. The mobility of a given particle is directly related to the net magnitude of the particle's charge. Mobility is defined as ''the distance in centimeters a particle moves in unit time per unit field strength, expressed as voltage drop per centimeter'' [mobility = cm2/(V-s)].

Ionic Strength of Buffer. The more concentrated the buffer, the slower the rate of migration of the particles. This is because the greater the proportion of buffer ions present, the greater the proportion of the current they carry. It is also due to interaction between the buffer ions and the particles.

Temperature. Mobility is directly related to temperature. The flow of current through the resistance of the medium produces heat. This heat has two important effects on the electrophoresis. First, it causes the temperature of the medium to increase, which decreases its resistance and thereby causes the rate of migration to increase. Second, the heat causes water to evaporate from the surface of the medium. This increases the concentration of the particles and further boosts the rate of migration. Because of these effects, either the applied voltage or the current must be held constant in order to maintain acceptable reproducibility of the procedures. For short runs at relatively low voltage levels, either can be held constant. However, when a gel is used as the medium, heating is a significant problem. With this type of medium, constant-current sources are normally used to minimize the production of heat.

Time. The distance of migration is directly related to the time the electrophoresis takes. Other factors that influence migration include electro endosmosis, chromatography, particle shape, "barrier" effect, ''wick flow,'' and streaming potential.

Types of Support Media. A large variety of support media have been used in various electrophoretic applications. They include paper, cellulose acetate, starch gel, agar gel, acrylamide gel, and sucrose. We discuss cellulose acetate electrophoresis here, because it is used extensively in clinical laboratories and because the same general method is used with other media.

Cellulose acetate has a number of desirable properties compared with the paper that was the medium first used in electrophoresis.

Figure 35 illustrates the basic process of cellulose acetate electrophoresis. The cellulose acetate strip is saturated with the buffer solution and placed in the membrane holder (the ''bridge''). The bridge is placed in the ''cell'' with both ends of the strip in the buffer wells.

 

Fig. 36. An apparatus for electrophoresis

1 - medium (cellulose acetate), 2 - cap 3 - electrodes, 4 - buffer solution, 5 - isolator, 6 - flammable wick.

 

Separation of charged particles spend in any homogeneous medium. This paper chromatography, thin layer of silicon oxide (IV), or aluminum, or other starch gels. All media material distributed in an electric field in a zone that can be detected and identified as a method called zonal electrophoresis.

General Laws electrophoresis following:

1) the mobility of the particles increases with the total charge ;

2) the greater the size of the molecules, the lower their mobility ;

3) globular and fibrous proteins have different mobility caused by the friction force when moving ;

4) the speed of movement of substances directly proportional to the current strength and the length of the path traveled by the particles is directly proportional to the current time of transmission ;

5) the greater the resistance, the lower the speed of moving particles in an electric field ;

6) the mobility of the particles affects the composition of the solvent, its concentration and pH;

7) the rate of movement depends on the chemical composition of the medium and its relation to the separation of the particles.

The result of the analysis are displayed as elektroforehrammy presented in Figure 37.

 

(a) (b)

Fig. 37. Examples of patterns of blood: a - in normal B - in nephritis (kidney disease), where albumin; - globulins.

 

Examples of modern devices electrophoresis is SAS-1 Plus, Experion, MINICAP, CAPILLARYS-2. These systems are fully automated, multi-functional and can simultaneously analyze up to 28 samples.

 

(a)

(b)

Fig. 38. Modern devices for electrophoresis: SAS-1 Plus () MINICAP (b)

 

7. Automated chemical analyzers

Automated chemical analyzers significantly improve the efficiency of clinical laboratories. These devices are characterized by great versatility, and simplify and speed up the results.

Consider an automatic chemical analyzer Synchron CX4 (manufacturer Beckman), as shown in Figure 39:

 

Fig. 39. Synchron CX4

 

System Synchron CX4

 

Synchron CX4 system of biochemical analyzer ideal for small and medium-sized laboratories performing the entire range of tests, including medication monitoring and determination of drugs. Maximum Performance 225 tests per hour. The possibility of determining in a sample 24 different parameters.

The performance characteristics. The operator controls the operation of the device SH4 using the monitor and keyboard. There are five main functions: programming models, downloads reagents, calibration, special functions and system parameters.

1. Programming models. With this feature, the operator can set the material contained in a particular dish, as analyzed and the reference sample, enter the information to identify the material. and indicate which tests the material should be subjected to. There are special procedures that allow for the analysis of emergency samples. By using the system printer can get a list of types of material to be placed in each of the cups in the sector models (download list). Features sector samples will be discussed below. This list is used when placing the sector obtained from the patient and control samples.

2. Download reagents. This procedure allows the operator to insert, delete and replace cartridges with reagents at 24 nests on the drum reagents. Each cartridge reagent has a label with a bar code that contains full information about it. including the type of test, in which it is used, and its expiration date. Reader takes information from the bar code when you install or extract the cartridge from the drum, and this information is transmitted to the main processor system.

3. Calibration. To ensure the accuracy and reliability of measurements using materials with known concentrations of test material (standard samples). Calibration is carried out both at the time of loading of reagents into the system, and at regular intervals.

4. Special functions. These features include the installation and configuration of the system, system diagnostics and procedures for system maintenance.

5. System Settings. In this mode, the operator can monitor the current operating status of the device, the current configuration of the system (eg, types of active tests), and indications of different sensor device (eg, temperature and liquid level).

Description of the system. SH4 The system includes three main subsystems: a block of samples, reagents and reaction block system.

1. Block samples. Block sample consists of five modules: the sectors of samples (up to eight), automatic loading, turntable samples, sampler, mixer, and a cup of washing - sampler mixer. Sector designs can carry up to ten cups with samples obtained from patients or from control samples. The operator enters information identifying material in each of the cups, using computer control system (above). Automatic load transports sectors of samples on drum samples running microcomputer. This process uses a stepper motor and Pneumohydraulic system. Upon completion of the test cycle sector similarly removed from the drum. Rotary table for samples consisting of drum samples and optical reading device. The drum samples are rotary device with discrete provisions, and driven by a stepper motor. Management turns performed microcomputer so that the test material was available for sampler. Sampler has a liquid level sensor, allowing it to dip the needle probe to the correct depth, thus providing an opportunity to select the correct amount of test material. Once the test material enters the sampler, sampler crane system returns to a position of the needle probe was over in the reaction cuvette drum. And after the material is discharged into a ditch.

2. Block reagents. Block reagent includes a reagent cartridges, drum reagents and reagent dispenser. Cartridges are disposable reagent containers which contain the reagents needed for a test. They have a label with a bar code that indicates a test in which they are used. The drum rotates reagents microcomputer running, giving the desired reagent to the dispenser. The drum has 24 reagent cartridges.

3. The reaction system. The reaction system includes a reaction drum and photometric unit. The reaction drum has 80 cells, in which chemical reactions take place to ditch the constant temperature of 30 º C or 37 º C. Photometric unit consists of a xenon lamp, sights systems, optical filters and photodiode detectors. Xenon lamp produces light flash every time the cell passes through the optical unit. Because the outbreaks have variable intensity, uses a system correction outbreaks. This system is based on the conduct of absorption measurements at frequencies other than the fundamental frequency of measurement. The light passing through the cuvette with sample enters the sights system that divides it into beams directed through each of the ten filters (340. 380, 410, 470, 320, 560, 600, 650, 670 and 700 nm) for ten photodiode detectors. Each detector produces a signal proportional to the intensity of light falling on it. The signals pass through the logarithmic amplification circuit and fed to the input switch. Switch, microcomputer controlled, at some point do metering signal and transmits an analog signal to the analog-to- digital converter. Absorption measurements are transmitted in a digital representation of the central processing system.

Fig. 40. Structure automatic chemical analyzer

 

1. Multifunctional sampler reagent.

2. Multifunctional sampler samples.

3. Mixer.

4. Block loading ditch.

5. Block reagents.

6. Block for samples.

7. The reaction block.

 

Test results are printed out in a report that can be included in the medical record of the patient and give it to a doctor.

 

Automatic Clinical Analyzer

Automatic Clinical Analyzer (ACA), produced by DuPont different from high-performance devices (Figure 41), similar sync SH4, its versatility, not peak performance. It performs measurements sequentially, not simultaneously, but each biological sample can automatically make any set of 40 tests.

Fig. 41. Clinical analyzers ACA

 

The principle of operation is based on the concept ACA automatic manipulation of biological samples cassettes (CBS) and a cluster of chemicals (COC). For each biochemical test using separate COC. In operation, the device COC moves from block to block on the conveyor, and for this sample, you can select any sequence COC. The time required for any determination using ACA, is a 7-minute interval between the definitions is 37 seconds. This means that the analyzer can carry out any analysis as an emergency. This feature represents a significant clinical laboratories extra features, but it also leads to an increase in the cost analysis as compared to other automated methods. A functional block diagram shown in Fig AKA 32.

Consider the basic characteristics of ACA. The sample obtained from the patient is placed in CBS, which is attached patient ID card. COC corresponding tests, which are expected to hold for a given sample set on the conveyor belt behind the CBS. COC design shown in Fig. 34. The latest COC on the line followed by a special tape that completes the work cycle. Each of the subsystems of the device performs the following functions:

Identification of the patient. When CBS is set in the ACA for the first time. it passes through the unit that reads and prints the information manually recorded on the patient's ID card attached to the CBS.

 

Fig. 42. Block diagram of automatic clinical analyzer (ACA). CBS - cassette biological samples. COC- cassette of chemicals. Rose. - Diluent. H. - Heater. OM = opener mixer. SD = station delays. CP = code of the patient.

 

Block filling. Box filling of the sample aliquot taken (metered volume of fluid) and mixed with diluents which may be different for different definitions. Then each packet COC introduced 5 ml. mixed solution. Binary codes printed on each COC, read electronic devices fill the block to determine which solvent to use for this package COC. After filling COC mixed for heaters and CBS is put in the output tray.

Fig. 43. Cassette biological samples (CBS) and a cassette of chemicals (COC) automatic clinical analyzer (ACA).

 

Heaters. In the heater package COC heated to 37 º C. and this temperature is maintained until the end of the process.

Openers mixer 1. This unit destroyed four plastic capsule with reagents that are mixed with the diluted sample (Fig. 43).

Stations delay. As soon as a package COC sequentially through five stations waiting, there occur chemical reaction between the first four reagents, diluting the solution and example.

Openers - mixer 2. In this block revealed three remaining capsules reagents and their contents added into the reaction mixture. For some tests at this stage assumed a certain delay, allowing chemical reactions pass through before it gets to COC photometric unit. This delay is determined by the binary code that indicates the type of test that can be read by filling in the block.

Photometer. In photometric unit with a special press plastic envelope COC converted into a ditch. In the plastic bag from the measured pressure and the result of measurement is used to determine whether the correct amount of sample and diluent was introduced in COC ​​. If the pressure is very small, the test results are indicated by "P" (from the word pressure). Binary code COC read again, and then the control circuit selects the photometer measurement method, filter type and parameters of the ADC.

AKA uses one of three methods of measurement: kinetic, and two-filtering two-cassettes (two COC). To determine the concentration of a test substance on the kinetic method, the absorption of light in the cell is measured twice. In this case, the time interval between measurements is strictly fixed, within two-filtering method of measuring the absorption is carried out with two different filters. The concentration of a test substance is proportional to the difference between the values ​​obtained by absorption of light. When working on two-cassettes method on the same wavelength is determined by the difference of light absorption by a mixture of substances and reagents analyzed two different COC. Photometer output signal is converted to digital form, set the controller photometer, and sent to the printer.

Printer. The printer makes a report that includes the identity of the patient, read off the block and fill photometric measurement results for each batch COC filled with sample data.