Experience in using high matrix introduction (HMI) technology for the analysis of lead by inductively coupled plasma mass-spectrometry (ICP-MS)

Abstract

The impurities contained in lead and lead-based alloys, which are widely used in various branches of industry, i.e., nuclear, medical, electrical engineering, etc., affect their physicochemical properties which necessitates developing of the reliable method for the impurity determination. Photometric, spectral, and chemical — spectral methods used to address this problem are labor-intensive and do not always have the required sensitivity. A method of inductively coupled plasma mass spectrometry (ICP-MS) coupled with High Matrix Introduction (HMI) technology has been proposed as alternative easy to use procedure designed to be more sensitive. The Agilent HMI Sample Injection System provides inline dilution of the sample aerosol (supplied from the spray chamber to the burner) with pure argon. This method of sample introduction provides for analysis of the solutions with a solute content of up to 1% and higher. The aerosol dilution reduces concentration of the matrix and solvent at the inductively coupled plasma interface without conventional dilution. In this case, the matrix suppression of impurities is almost eliminated and CeO+/Ce+ is reduced to 0.2%, while the typical CeO+/Ce+ ratio for the Agilent 7500 mass spectrometers is 1 – 2%, but no more than 3%. We present application of this method to the analysis of Mg, Ca, Fe, Cu, As, Ag, Sn, Sb, Bi in lead by an Agilent 7500cx ICP-MS with preliminary acid digestion of lead samples in a microwave autoclave. The use of the HMI system made it possible to exclude the stage of sample dilution, reducing the possibility of sample contamination with a diluent, and to determine the content of impurities in a highly concentrated matrix at a level of 10–4 – 10–5 %. The efficiency of the method, as well as the possibility of using multi-element standard solutions prepared with 1% nitric acid for analysis of the samples with high lead content is shown.