Optimization of a pre-concentration method for the analysis of mercury isotopes in low-concentration foliar samples

Anal Bioanal Chem. 2024 Jan 9. doi: 10.1007/s00216-023-05116-5. Online ahead of print.ABSTRACTHg isotope analysis in samples from background regions is constrained by the presence of low Hg concentration and therefore requires a pre-concentration method. Existing Hg pre-concentration methods are constrained by long sample processing time and limited sample loading capacity. Using foliar samples as a test case, an optimized Hg pre-concentration method is presented that involves the microwave-assisted digestion of samples for Hg isotope analysis with the addition of a pre-digestion step. Microwave-digested foliar samples and CRMs were transferred to an impinger, reduced with SnCl2, and collected in a 2.25 mL concentrated inverse aqua regia (3:1 HNO3:HCl, v/v). This resulted in an optimal acid concentration in the solution ideal for analysis on MC-ICP-MS. The time for purging with Hg-free N2 was optimized to 30 min and the efficiency of the pre-concentration method was tested using a combination of approaches. Tests performed on pure reagents and matrix of foliar samples spiked with 197Hg radiotracer showed recoveries averaging 99 ± 1.7% and 100 ± 3.0%, respectively. Mercury at concentrations as low as 1.83 ng g-1 was pre-concentrated by digesting aliquots of foliage samples in individual digestion vessels. Recoveries following their pre-concentration averaged 99 ± 6.0%, whereas recoveries of 95 ± 4.7% and 95 ± 2.5% were achieved for NIST SRM 1575a (pine needle) and reagent...

Source: Analytical and Bioanalytical Chemistry - January 9, 2024 Category: Chemistry Authors: Saeed Waqar Ali Dominik Bo žič Sreekanth Vijayakumaran Nair Igor Živković Jan Ga čnik Teodor-Daniel Andron Marta Jagodic Hudobivnik David Kocman Milena Horvat Source Type: research