In this article, we will consider the concept of an atomic absorption spectrometer and the field of study in which this device is used. We will also pay attention to the general definition of an analytical tool, various historical data and the principles of the device used.
Introduction
Before embarking on the study of atomic absorption spectrometers, it will be important to familiarize yourself with the very concept of this spectrometry - AAS. It is common in the fields of analytical chemistry as a methodological tool for analyzing elemental components, based on atomic spectral absorption (absorption) for specific metal contents in the salt solutions that these metals form. This is the same for natural and wastewater, as well as mineralized solutions and other types of process fluids.
The device by which AAS indicators are determined is called an atomic absorption spectrometer. Its main elements are presented in the form of: a light source, an atomizer, a spectral device and an electronic system. To determine the content of an element in various samples, it is necessary to use experimentally established data on functional subordination between a signal containing analytical data and an indicator of the concentration of an element in a solution in a graduated form.
History of methodology
The first to discover the phenomenon of spectral lines absorbed by atoms was William Wollanston, a physician and chemist from England. His work was based on the analysis of radiation from the solar spectrum. The discovery was made in the early nineteenth century. After some time, the same phenomenon was discovered by the German physicist I. Fraunhofer. The relationship between the emitted and absorbed spectrum and the chemical composition of the heated gases was discovered by scientists from Germany - R. Bunsen and G. Kirchhoff - in the period from 1859 to 1861.
As an analytical measure, spectral atomic absorption began to be used from 1930 to 1940 in order to identify various chemical elementary components in the stellar atmosphere. In the same way, the amount of mercury in a diverse sample set and indoor atmosphere is also determined. Their inconvenience was due to the lack of highly sensitive devices.
The work of Alan Walsh
In 1955, Alan Walsh proposed an easily implemented method for determining the quantitative indicator of a specific type of element in a solution that is sprayed over a flame of acetylene burning in air. Here we used the definition of the absorbed radiation of the atomic series of lines that emitted selective lamps. A. Walsh became the founder of Techtron, which in 1962 launched the production of the world's first mass-produced atomic absorption spectrometers. Later, the technology of a graphite furnace, created by Boris Lvov and Hans Massman, was introduced into the industry.
Means of implementation
The instruments used for this analysis are presented in the form of precision highly automated devices that are capable of reproducing a number of measurement conditions, as well as automatically entering samples and recording measurement results. The atomic absorption spectrometer device consists of the following set of components:
- A light emitting source that characterizes a narrow spectral line characteristic of the compound being analyzed.
- An atomizer is a means of converting a specific substance into atomic pairs.
- A spectrometer is part of a mechanism that distinguishes characteristic analytical lines of substances.
- An electronic system that is used to detect, enhance, and process a signal that carries analytic absorption data.
Currently, there are many devices of this type in the market for sale. The atomic absorption spectrometer MGA has become very widely used and widespread. Currently, there are many generations of this equipment, each of which has a set of improved characteristics and high performance, accuracy. For example, in the territory of the Russian Federation you can often see the model MGA-1000.
Radiation sources
Among the main requirements for the radiation source, a special place is given to their narrow-band, high stability with respect to the indicators of frequency and intensity. It is also important to take into account the high intensity of the resonance lines, the low value of the noise level, the absence of various overlays of the spectral nature on the resonance line and its self-absorbing ability, the minimum amount of time it takes to establish the operating mode, and the ability to detect luminescence bodies of minimum size.
Among the list of light sources, the most significant are: full cathode bulbs, electrodeless cathode tubes and lasers.
One of the devices analyzing the radiation of such sources is the Kvant-Z atomic absorption spectrometer. One of its varieties is AAS QUANT-Z.ETA. It finds its application in various fields of human activity. For example, in geology, biological and chemical research, petrochemistry, medicine and pharmacology, scientific research, etc.
QUANTUM-2AT
Currently, there are a considerable number of devices of this type. Consider the example of one of them.
One of the tools for analyzing radiation is the Kvant-2AT atomic absorption spectrometer. Most often it is used for: monitoring the state of environmental objects, analyzing the food range of products, raw materials, metallurgical products, etc.
Among the main modes distinguish:
- Direct absorption with automation on fire.
- Automation in quantum ditches.
- Atomic absorption with flow-injection concentration.
- Atomic emission.
As a radiation source, he uses spectral type lamps with hollow cathodes. The lamp power is pulse-periodic. Flame types may include: air + propane, air + acetylene, nitrous oxide + acetylene. The spectrometer itself belongs to the group of ultrafast, single-beam devices that correct non-selective absorption through the use of deuterium.
Installation requirements briefly
The QUANT atomic absorption spectrometer should be installed in a closed type room with heating. It must be dry and located away from heating devices and sources with sharp air currents. The area of the premises should not be lower than 10 meters squared, and the volume should be at least 30 cubic meters.
Supply and exhaust ventilation is required, and an umbrella must be placed above the burner relative to the spectrometer and equipped with a gate for regulation. It is important to pay attention to the minimum level of requirements for such problems as dust and smoke.
The ceiling, floors and walls must be covered in accordance with the requirements of technological hygiene. It is necessary that the air be free of impurities of substances with chemical activity. It is undesirable to install the device near sources of vibration. It is also desirable to have a sink and sewage system in the room where the analyst chemist works.
About the manufacturer QUANT-2AT
The manufacturer of the quantum-absorption spectrometer KVANT-2AT is the company "KORTEK". This is a very reliable supplier of such products, which has been operating on the market for more than a dozen years, and since 1988 it has been recognized as a leader in its field. The company has many branches, one of which is located in Moscow at the address: st. Nikulinskaya, d. 27, box. 2. In addition to spectrometers, they also develop various additional equipment, deal with software and manufacture spectral lamps, complete and consumables, and also do not bypass phototherapy. Very popular atomic absorption spectrometer KVANT-2AT (manufacturer "KORTEK"). When choosing a device, it should be remembered that to this day, this company remains a leader in the production of quality products.
MGA-915MD
Earlier, we mentioned a specific model of the apparatus, namely, the atomic absorption spectrometer MGA-915MD.
Speaking about it in more detail, we can note some of its features that set it apart from other models.
MGA-915MD has high selectivity associated with the operation of highly efficient options for selective analysis of the atomic absorption type. The MGA-915MD analyzer system is highly selective and allows one to determine the amount of a wide range of elements contained in a sample with any type of composition. The Zeeman corrective non-selective absorption method and AAS are “reference methods” with respect to the determination of even a small amount of elements contained in a sample with a complex composition.
The presence of high sensitivity allows us to increase the maximum detection capabilities to the level of the best spectrometers that we can offer on the market.
This model is an absolutely automated mechanism with a change in the radiation source and the establishment of specifically necessary resonance lines in an independent mode. She has a six-lamp turret. The 55-cell autosampler is a sample injection system in the MGA-915MD. Data can be continuously transferred to the ACS system for subsequent control of the technology process. Air is analyzed by applying the method of electrostatic deposition of air aerosols directly in a graphite type atomizer.