ICP-AES ANALYSIS OF HIGH-PURITY ARSENIC

The arc discharge atomic emission spectrometry method with pre-concentration of impurities is mainly used for multi-element analysis of high-purity arsenic. Spark ionization mass-spectrometry and neutron activation analysis are applied less often. The use of spark ionization mass-spectrometry and neutron activation analysis is quite problematic at the present time. Arc discharge atomic emission spectrometry in combination with pre-concentration of impurities makes it possible to determine the impurities at the level of 10−8-10−4 % mass. At the same time the number of the determined impurities is reduced (e.g., P, S, Sb, Se, Te are getting lost during concentration by matrix sublimation) with the increase in the duration of the analysis.Thus, at the present time the express multi-element techniques of analysis of arsenic which can provide the determination of wide range of impurities at the level of 10−7-10−5 % mass. (according to the modern requirements), including the elements P, S, Sb, Se and Te (with volatility close to that of the matrix) are actually absent. In the present paper the capabilities of available and widely used method of inductively-coupled plasma atomic emission spectrometry are estimated for analysis of high-purity arsenic. The matrix interference was investigated in the process of spraying the solutions with arsenic concentration up to 150 mg/mL into inductively-coupled plasma. It was found that in order to attain low limits of quantification of impurities it is expedient to analyze sample solutions with arsenic concentration ~100 mg/mL. It does not present a problem technically. Preparation of samples in chemically resistant vials of PFA (PerFluoroAlkoxy polymer) and the use of additionally purified reagents (water, nitric acid) made it possible to decrease the effect of contaminations on the limits of quantification of most impurities. A technique for determination of 39 elements in high-purity arsenic has been developed. The diapason of determined impurities includes the most abundant metals (Al, Ca, Cu, Mg, Fe) and Si, as well as the elements usually getting lost during concentration by matrix sublimation (B, P, S, Sb, Se, Te). The limits of quantification (as well as the limits of detection) of impurities in arsenic are equal ~10−7-10−5 % mass. If necessary, the range of impurities can be widened in view of the possibilities of inductively-coupled plasma atomic emission spectrometry, the possibilities of the suggested sample preparation technique and the availability of the corresponding standard solutions of the determined elements.Key words: high-purity arsenic, determination of impurities, inductively coupled plasma atomic emission spectrometry(Russian)DOI:http://dx.doi.org/10.15826/analitika.2015.19.1.006I.I. Evdokimov1,2, V.G. Pimenov1,2, D.A. Fadeeva21Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russian Federation2G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences,Nizhny Novgorod, Russian FederationThe arc discharge atomic emission spectrometry method with pre-concentration of impurities is mainly used for multi-element analysis of high-purity arsenic. Spark ionization mass-spectrometry and neutron activation analysis are applied less often. The use of spark ionization mass-spectrometry and neutron activation analysis is quite problematic at the present time. Arc discharge atomic emission spectrometry in combination with pre-concentration of impurities makes it possible to determine the impurities at the level of 10−8-10−4 % mass. At the same time the number of the determined impurities is reduced (e.g., P, S, Sb, Se, Te are getting lost during concentration by matrix sublimation) with the increase in the duration of the analysis.Thus, at the present time the express multi-element techniques of analysis of arsenic which can provide the determination of wide range of impurities at the level of 10−7-10−5 % mass. (according to the modern requirements), including the elements P, S, Sb, Se and Te (with volatility close to that of the matrix) are actually absent. In the present paper the capabilities of available and widely used method of inductively-coupled plasma atomic emission spectrometry are estimated for analysis of high-purity arsenic. The matrix interference was investigated in the process of spraying the solutions with arsenic concentration up to 150 mg/mL into inductively-coupled plasma. It was found that in order to attain low limits of quantification of impurities it is expedient to analyze sample solutions with arsenic concentration ~100 mg/mL. It does not present a problem technically. Preparation of samples in chemically resistant vials of PFA (PerFluoroAlkoxy polymer) and the use of additionally purified reagents (water, nitric acid) made it possible to decrease the effect of contaminations on the limits of quantification of most impurities. A technique for determination of 39 elements in high-purity arsenic has been developed. The diapason of determined impurities includes the most abundant metals (Al, Ca, Cu, Mg, Fe) and Si, as well as the elements usually getting lost during concentration by matrix sublimation (B, P, S, Sb, Se, Te). The limits of quantification (as well as the limits of detection) of impurities in arsenic are equal ~10−7-10−5 % mass. If necessary, the range of impurities can be widened in view of the possibilities of inductively-coupled plasma atomic emission spectrometry, the possibilities of the suggested sample preparation technique and the availability of the corresponding standard solutions of the determined elements.Key words: high-purity arsenic, determination of impurities, inductively coupled plasma atomic emission spectrometry.DOI:http://dx.doi.org/10.15826/analitika.2015.19.1.00

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