Rapid, inexpensive, and convenient methods for quantifying elemental sulfur (S0) with low or sub-μgg-1 limits of detection would be useful for a range of applications where S0 can act as a precursor for noxious off-aromas, e.g., S0 in pesticide residues on winegrapes or as a contaminant in drywall. However, existing quantification methods rely on toxic reagents, expensive and cumbersome equipment, or demonstrate poor selectivity. We have developed and optimized an inexpensive, rapid method (∼15min per sample) for quantifying S0 in complex matrices. Following dispersion of the sample in PEG-400 and buffering, S0 is quantitatively reduced to H2S in situ by dithiothreitol and simultaneously quantified by commercially available colorimetric H2S detection tubes. By employing multiple tubes, the method demonstrated linearity from 0.03 to 100μgS0g-1 for a 5g sample (R2=0.994, mean CV=6.4%), and the methodological detection limit was 0.01μgS0g-1. Interferences from sulfite or sulfate were not observed. Mean recovery of an S0 containing sulfur fungicide in grape macerate was 84.7% with a mean CV of 10.4%. Mean recovery of S0 in a colloidal sulfur preparation from a drywall matrix was 106.6% with a mean CV of 6.9%. Comparable methodological detection limits, sensitivity, and recoveries were achieved in grape juice, grape macerate and with 1g drywall samples, indicating that the methodology should be robust across a range of complex matrices.
All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Environmental Chemistry