One-step conversion of to its using salts for GC-MSdetection of bacterial endospores

Aaron N Nackos; Tai V Truong; Trenton C Pulsipher; Jon A Kimball; H Dennis Tolley; Richard A Robison; Calvin H Bartholomew; Milton L Lee

doi:10.1039/c0ay00270d

One-step conversion of to its using salts for GC-MSdetection of bacterial endospores

Anal Methods. 2011 Feb 1;3(2):245-258. doi: 10.1039/c0ay00270d.

Authors

Aaron N Nackos¹, Tai V Truong², Trenton C Pulsipher³, Jon A Kimball², H Dennis Tolley³, Richard A Robison⁴, Calvin H Bartholomew¹, Milton L Lee²

Affiliations

¹ Department of Chemical Engineering, Brigham Young University, Provo, UT 84602, USA. calb@byu.edu.
² Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA. milton_lee@byu.edu.
³ Department of Statistics, Brigham Young University, Provo, UT 84602, USA.
⁴ Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602, USA.

PMID: 32938021
DOI: 10.1039/c0ay00270d

Abstract

Methyl sulfate (MeSO4-) salts were explored as thermochemolysis-methylation (TCM) reagents for gas chromatographic (GC) analysis of dipicolinic acid (DPA) as its dimethyl ester (Me2DPA) from bacterial endospores. The reaction was carried out under non-pyrolytic conditions by inserting a small coiled wire filament coated with the sample and reagents directly inside a GC injection port at 290 °C. Above 10 : 1 methyl donor/DPA ratios, alkali metal salts of MeSO4- effected 80-90% conversion of DPA to Me2DPA, which was 10-20 times more active than the same amount of tetramethylammonium hydroxide (TMA-OH) at this temperature. A quaternary salt mixture consisting of 1 : 3 : 1 : 3 TMA+/Na+/OH-/MeSO4- methylated spore DPA with an average conversion of 86% (mean conversion by TMA-OH under the same conditions was 4%). Therefore, the sensitivity for detection of bacterial endospores was increased over 20-fold compared to that observed with the more commonly employed TMA-OH methylating reagent. The limit of detection by this method was 9 × 104 total spores. Mechanisms describing the observed behavior are proposed and discussed. This is the first use of MeSO4- as a TCM reagent for GC.