Determination of Tin in Soil by Hydride Generation-Atomic Fluorescence Spectrometry with Microwave Assisted Digestion in Alkaline Solution

The soil sample should be dried preliminarily at (102±3)℃ in an oven. 0.10 g of the dried sample was taken and digested with 2 mL of 500 g·L^-1 sodium hydroxide solution in the PTFE vessel in the microwave digestor under programmed temperature elevation mode. At the end of digestion, the solution obtained was diluted to 25.0 mL with re-deionized water, and used as sample solution for atom fluorescence spectrometry analysis. The sample solution was introduced into the atom fluorescence spectrometry instrument by the carrier of 1 mol·L^-1 sodium hydroxide solution and through the 3-way valve. 5% (volum fraction) sulfuric acid solution, as introduced also through the 3-way valve, was used for online neutralization of the alkaline sample solution, and then the acidic sample solution was reacted with potessium borohydride, delivered by the wriggling pump, to have the Sn(Ⅱ) reacted to form tin hydride which was atomized in the atomizer. By the action ofthe high performance hollow cathode lamp, fluorescence of tin atom was emitted and its intensity as shown by its peak area was measured by the detector. Linearity range of the standard curve of tin was found within 100 μg·L^-1. Value of detection limit (3s) found was 0.062 μg·g^-1. Seven GBW standard materials of soil were analyzed by the present method, giving relative errors between the results found by this method and the certified values of the CRMs in the range of -1.61%-3.07%. Values of RSDs (n=7) obtained were ranged from 1.8%-3.2%.