Spectrophotometer

An electronic device that determines the composition of substances and their compounds in emulsions, suspensions and solutions is called a medical spectrophotometer. The device has two most well-known names: photoelectric photometer and photoelectric colorimeter. Spectrophotometers are used in various fields, but most of all they have found their application in medicine and pharmaceuticals. The devices are highly accurate and allow you to save reagents and time for research.

Features of spectrophotometers

The very first photometers needed the participation of a medical professional to conduct the study. The specialist had to compare and record the indicators received from the device. The data were compared with generally accepted standards. These devices were replaced by automated photoelectric colorimeters.

Spectrophotometers are modern medical equipment designed to study and analyze the properties of objects or substances using electromagnetic radiation. Light rays pass through the sample or are reflected from it. The device compares the flow of light that is initially directed to the biomaterial with radiation passing through the sample or reflecting from its surface.

For analysis, a wide range of waves is scanned: from 160 nm (ultraviolet) to 3300 nm (infrared), with the help of which the most accurate information about the substance is obtained.

The spectrophotometric technique is based on the fact that each object has special spectral characteristics. That is why during the analysis the temperature regime and the state of aggregation of the sample do not play a role. A feature of the spectrophotometer is the possibility of conducting qualitative and quantitative studies.

The main advantage of a photoelectric photometer is the output of the received information to the display (the laboratory assistant can see the composition of the sample, the presence and amount of impurities). With the help of special light filters, the device determines at least 3-5 constituent components in the sample.

Applications

Spectrophotometers are used for research in biochemistry (lipids, electrolytes, substrates, enzymes are analyzed), immunochemistry (lambda, ferritin, myoglobin, microalbumin, haptoglobin are analyzed), bacteriology. A photoelectric colorimeter is used to analyze the quality of food and water (waste, natural and drinking). When determining the quality characteristics of water, the turbidity and color of the liquid, the presence of heavy metals and surface-active components, the content of nitrites, phosphates, phenols and sulfates are determined.

The spectrophotometer is useful for scientific, hormonal, environmental and special studies. In the departments of sanitary and epidemiological supervision, the presence of this device is mandatory. In addition to medicine, the equipment is used in agriculture and industry.

A photoelectric photometer is needed for:

• identifying the purity of the studied samples and finding impurities;
• measurements in liquids of optical density and its changes;
• determining the concentration of the sample (the study is carried out in medical institutions);
• study, analysis of the composition and chemical structure of substances, samples and reagents;
• spectral diagnostics.

A photoelectric colorimeter is a device that is used to conduct various studies: medical; biological; pharmaceutical; chemical. Thanks to the accurate results that appear on the screen of the equipment, the doctor can find out the characteristics of the reagents and prescribe an effective treatment for the patient.

How is the device arranged?

Absolutely all automated photoelectric colorimeters consist of: light source (tungsten, deuterium or halogen-deuterium lamp); signal amplifier; photodetector; monochromator; optical components (light guides, mirrors, prisms and glasses); reagent compartment.

A monochromator contains a diffraction grating or prism that emits radiation of a certain wavelength. Various models have from one to four sample compartments. With the help of photodetectors, the spectrophotometer captures the level of light radiation that passes through the biological material.

The most modern devices are equipped with a photodiode matrix, which includes a built-in sensor. The chip converts the light signal into an electrical signal, this is recorded by the microcontroller and displayed on the equipment monitor. Not powerful enough devices process waves with different lengths gradually, and only then display the results on the display. The performance and information content of the spectrophotometer depends on the number of photodiode sensors.

With the help of devices with a photodiode matrix, it is possible to carry out operational research without leaving production or during the occurrence of a chemical reaction. This allows a detailed analysis of the state of the reaction substances.

Features of the device

The spectrophotometric technique is based on measuring the degree of reflection or absorption of monochromatic light rays. During the study, extraneous factors cannot influence the effectiveness of the analysis. All devices operate on two types of circuits. In the first case, a monochromatic light beam with a certain wavelength hits the sample, which, after passing through the sample, is directed to a photodetector that measures the difference between the fluxes.

The essence of the second scheme is that the reagent receives a light flux directly from the lamp, then the monochromator selects a small beam and directs it to the photodetector.

Spectrophotometers are single beam and double beam. In instruments with a single beam, correction factors are applied for measurement. In the case of two-beam diagnostics, one beam hits the sample, and the second one hits the reference value. Equipment with two beams is more accurate, informative and less sensitive to environmental factors.

Rules for choosing a spectrophotometer

When selecting a device, it is necessary to take into account the scope of its application and the tasks performed. Photoelectric photometers are portable and stationary. Portable devices are lightweight, compact and easy to use. Stationary devices are installed in medical institutions and diagnostic centers. With the help of these devices, more complex measurements are carried out. Such spectrophotometers can be connected to a personal computer with a cable, and the data obtained are subject to archiving, processing and printing on a printer.

When choosing a medical device, you need to consider: the spectrum of action (range); wavelength; versatility of the device; dimensions; price; the likelihood of conducting certain studies; number of sections for reagents; way to get results. It is also necessary to pay attention to the standard equipment of the spectrometer model, because almost all modern instruments are sold with a cuvette and a Petri dish.