Sensitive and rapid determination of elemental nanosulfur/sulfur by liquid chromatography

Abstract

In order to identify the most suitable method for the estimation of nanosulfur for studying its residue dynamics, the present work was taken up. HPLC and GC methods were explored for its analysis. A comparative study of the existing analytical methods for the quality control of nanosulfur was undertaken. UV spectrophotometry and HPLC methods were superior with lower LOD when compared to GC-MS, which was not satisfactory due to breakage of catenated S20 into S6 and S8 . The method has been validated by analyzing various nanosulfur formulations of known concentrations. The recovery of the UV and HPLC methods ranged from 80.71 to 109.51% and 82.31 to 109.84%, respectively. The LOD of UV, GC-MS, and HPLC is 4, 20, and 1 ppm, respectively. The retention time of sulfur was 13.77 (HPLC), 2.89 (ultra high performance liquid chromatography), and 12.715 + 21.524 min (GC-MS). The method was successfully utilized for estimating sulfur in natural samples such as water from a sulfur hot spring and wastewater. The method has been validated by following the method recommended by the American Society for Testing and Materials. The HPLC method emerged as the best analytical method for the estimation of elemental sulfur.

Environmental behavior and analysis of agricultural sulfur

“…43 As in studies previously discussed, 22,39 the authors found multiple peaks for GC-MS in standard solutions, where there was a large S 8 peak, a smaller (by almost one-third) S 6 peak and many peaks of other S allotropes, leading to its relatively high LOD. 43 HPLC, therefore, was found to be the better tool owing to its high sensitivity and selectivity compared with GC-MS and UV spectrophotometry. UV spectrophotometry may lead to a higher estimated sulfur content on account of its inability to be selective between organic and inorganic sulfur at the wavelength used.…”

“…HPLC, therefore, was found to be the better tool owing to its high sensitivity and selectivity compared with GC‐MS and UV spectrophotometry. UV spectrophotometry may lead to a higher estimated sulfur content on account of its inability to be selective between organic and inorganic sulfur at the wavelength used . Figure shows the LC‐MS/MS mass spectra of a nanosulfur formulation with a parent ion peak at m / z 989.3 which implied about 30 S catenated together .…”

“…A limit of detection (LOD) of 20 ppm for GC‐MS, 4 ppm for UV spectrophotometry and 1 ppm for HPLC was determined . As in studies previously discussed, the authors found multiple peaks for GC‐MS in standard solutions, where there was a large S 8 peak, a smaller (by almost one‐third) S 6 peak and many peaks of other S allotropes, leading to its relatively high LOD . HPLC, therefore, was found to be the better tool owing to its high sensitivity and selectivity compared with GC‐MS and UV spectrophotometry.…”

“…UV spectrophotometry may lead to a higher estimated sulfur content on account of its inability to be selective between organic and inorganic sulfur at the wavelength used . Figure shows the LC‐MS/MS mass spectra of a nanosulfur formulation with a parent ion peak at m / z 989.3 which implied about 30 S catenated together . The authors also found an LOD and limit of quantitation (LOQ) of 0.04 and 0.1 ppm respectively for nanosulfur and elemental sulfur, using their UHPLC method, as opposed to the 4 ppm in previous HPLC methods described …”

“…LC‐MS/MS mass spectra of nanosulfur, showing a parent ion peak at m / z 989.3. Reprinted from Nair et al with kind permission from the Wiley Online Library.…”