EA019087B1 - Method of atomic-absorption measurements - Google Patents

Abstract

The invention relates to the sphere of atomic absorption spectrophotometry and is suitable for use in atomic absorption analysis and spectral instrument engineering. The object of the invention is to improve the accuracy of measurements under the conditions of non-selective absorption. The objective is solved by means of that in the method for atomic absorption measurements the emission from the sources of a continuous or discontinuous spectrum is alternatively passed through the work sample atomic vapor for the measurement of the atomic vapor optical density. Furthermore, samples with different concentrations of material providing the origination of non-selective absorption are previously put into the atomizer, and the optical density of non-selective absorption Dof each of the samples is determined from the expressionwhere Jis the emission intensity of the continuous spectrum source before the atomizer; Jis the emission intensity of the continuous spectrum source after the atomizer, and uncompensated value of the optical density of the non-selective absorption Dof each of the samples is determined from the expressionwhere Jis the emission intensity of the continuous spectrum source after the atomizer; Jis the emission intensity of the discontinuous spectrum source after the atomizer, measurements are repeated to obtain the dependence D=F(D), Dof the work sample, and in accordance with said dependence - Dof the work sample are determined, the value of which is used for the correction of the result of measurement of the optical density of the work sample atomic vapor.

Description

The invention relates to the field of atomic absorption spectrophotometry and is intended for use in atomic absorption analysis and spectral instrumentation.

A known method of atomic absorption measurements, which is characterized in that the radiation of the line spectrum source is alternately passed through the atomic vapor generated in the atomizer and through the reference optical channel [1].

A known method of atomic absorption measurements, selected as a prototype, including alternating transmission through the atomic vapor radiation of a continuous spectrum source and a working determination of the optical density of the atomic vapor [2]. The data obtained are then used to calculate the concentration of the determined element.

The fundamental disadvantage of the methods is the low accuracy of the measurements, since it is impossible to precisely combine the image of the radiation sources in the atomization plane due to the design features of the radiation sources and the lighting system used for these purposes. This disadvantage is typical when using an additional source of continuous spectrum radiation in order to correct non-selective absorption.

As a result of this, the result of a working determination of the optical density of atomic vapor is characterized by the uncompensated component of the optical density of non-selective absorption _{Ό ά1 £} and the working optical density of the atoms being determined _{атомов Ο ΌΓ] ί} , which reduces the measurement accuracy.

B ~ Β, Ιίί + ϋ »οι Ιί (1)

The present invention is to improve the accuracy of measurements under conditions of non-selective absorption.

The problem is achieved in that in the method of atomic absorption measurements, in which radiation is alternately passed through the atomic vapor of a working sample from sources of continuous and line spectra to measure the optical density of atomic vapor. In this case, samples with various concentrations of a substance providing the occurrence of non-selective absorption are first introduced into the atomizer, and the optical density of non-selective absorption is determined _. each sample from the expression

In _PL ^- (2) where 1 _{o <} and ₈ is the radiation intensity of the continuous spectrum source to the atomizer;

C * is the radiation intensity of the continuous spectrum source after the atomizer, and the uncompensated value of the optical density of non-selective absorption Ό _{41 £ of} each sample from the expression

ΟΰπΜοσΙΙ ^ -Ιοοχ.Ιΐρκ), (3) where Hn is the radiation intensity of the continuous spectrum source after the atomizer;

A1 _pk - the intensity of the radiation source line spectrum atomizer after repeated measurements to obtain depending _{ϋ ^ ί £ = Ρ (ϋ} η8), E ,,, define a working sample and said depending - ϋ _{£ 4} Working sample whose value is used to correct the result of measuring the optical density of the atomic vapor of the working sample.

Such measurements are made with different values of the optical density of non-selective absorption, thus obtaining the dependence _{Ό ά1} £ = Ε ( _{Ό η8} ). For example, you can measure the optical density of non-selective absorption in the range of 0.001-0.01-0.1-1 B and get uncompensated values of Ό _{41 £} for the specified range. The dependence _{Ό ά1ί} = Ρ (Ό _η ,) is then used to correct the measurement result during working measurements. This dependence can be approximated, for example, by the method of least squares and thus obtained intermediate values of the correction measure O <11 £ ^and

The specified method implements an atomic absorption spectrophotometer, a diagram of which is shown in the drawing of the figure.

The spectrophotometer contains optically coupled sources of radiation of a continuous 1 and line spectrum 2, a lighting system 3, an atomizer 4, a monochromator 5, a photodetector 6, and a measurement device 7, which is based on a personal computer coupled to an analog-to-digital converter 8.

The method is implemented as follows.

After calibrating the device by measuring several standard solutions, several samples with different concentrations of No. 1C1 are fed into atomizer 4. which causes the appearance of non-selective absorption in the atomizer. The measuring device operates in accordance with formulas (2) and (3) and stores the obtained values _{Ό ά1} £ = Ρ ( _{Ό η8} ).

Now, working samples are supplied to the atomizer 4 and Ό is measured by the formula (1) and Ό _η , by the formula (2). In accordance with the value of E _{| k} , the value of E _{41 £ is} chosen and subtracted from the result obtained by the formula (1).

Therefore, as a result of measuring the working sample, the uncompensated value of the optical density of non-selective absorption will be corrected. The result of measuring the optical density of the working samples will be more accurate in this case, which ensures the presence of a positive effect.

- 1 019087

Thus, the claimed combination of features is not known from the existing level of technology, should not be obvious to a person skilled in this field, gives a new positive result and is technically feasible.

Information sources

1. Atomic absorption spectrophotometer ηονΑΑ-400. Technical instruction manual. 2005 year

2. K.P. Kureichik. Pulse atomic spectrophotometry. Measurement Methods. Equipment. - Mn. Universitetskoye, 1989, p. 77 (prototype).

Claims (1)

CLAIM A method of atomic absorption measurements, in which radiation from continuous and line spectral sources is passed through atomic steam of a working sample alternately to measure the optical density of atomic vapor, characterized in that samples with different concentrations of a substance providing nonselective absorption are introduced into the atomizer and determine non-selective absorption optical density of each sample Ό _η8 from expression ϋ _η3 wherein aa 1 _{0 8} - intensity continuous spectrum radiation source to the atomic mizatora; Ι _άά8 - radiation intensity of the continuous spectrum source after the atomizer, and uncompensated value of the non-selective absorption optical density ϋ _άίί · each sample from the expression θ θδΡάάδΗοδΡίρίΑ where 1аа ₈ - radiation intensity of the source of the continuous spectrum after the atomizer; 11 _P c - radiation intensity of the source of the line spectrum after the atomizer, repeat the measurements to obtain the dependence _{Ό ώί} = _Ό ( _{Ό η8} ), determine _{Ό η8 of the} working sample, and according to the mentioned dependence - _{Ό рабочей} · working sample, the value of which is used to correct the measurement result of the optical atomic vapor density working sample.