Use of quadrupole GC-MS and ion trap GC-MS-MS for determining 3-hydroxy fatty acids in settled house dust: relation to endotoxin activity

Abstract

Gas chromatography-mass spectrometry (GC-MS) using a quadrupole instrument and GC-tandem MS (GC-MS-MS) using an ion trap instrument were applied to determine 3-hydroxy fatty acids (3-OH FAs) with 10-18 carbon chain lengths, specific components of the endotoxin (lipopolysaccharide, LPS) of Gram-negative bacteria, in 30 house dust samples. The two methods provided similar detection sensitivity for methyl ester/trimethylsilyl derivatives of the 3-OH FAs and allowed these acids to be distinguished from co-eluting 2-OH FA derivatives. The correlation coefficients between endotoxin activity (Limulus test) and the combined amounts of 3-OH C10, 3-OH C12, and 3-OH C14 were 0.60 and 0.61 when using GC-MS and GC-MS-MS, respectively. The superior selectivity of GC-MS-MS was illustrated in analyses of sub-milligram amounts of dust, where the chromatograms achieved by GC-MS were difficult to interpret due to a high background and several closely eluting compounds. GC-MS-MS is therefore preferable to GC-MS for determining 3-OH FAs in minute (sub-milligram) amounts of dust.

Heterogeneity in microbial exposure in schools in Sweden, Poland and Jordan revealed by analysis of chemical markers

“…Ergosterol was determined according to Saraf et al (1999). Briefly, dust (7-10 mg) was heated in 1 ml of 10% methanolic KOH (801C, 90 min).…”

“…Similarly, muramic acid (a unique peptidoglycan component) is used to measure peptidoglycan and bacterial biomass, whereas ergosterol represents a marker of fungal biomass. We have previously applied this type of analysis to characterize the microbiological community in indoor environments (Saraf et al, 1997(Saraf et al, , 1999Bal and Larsson, 2000;Hines et al, 2000).…”

Chemical markers for bacteria in extraterrestrial samples

“…However, viable bacteria were not detected (using classical microbiological culture) in the lunar material when it was first brought by the Apollo missions (Oyama et al, 1970). Unfortunately, chemical methods that detect dead bacterial remnants, or non-culturable bacteria, were in a primitive stage of development at that time (Maitra et al, 1978;Fox et al, 1980Fox et al, , 1993Fox et al, , 1995Fox et al, , 1996Findlay et al, 1983;Saraf and Larsson, 1996;Saraf et al, 1999;Bal and Larsson, 2000;Kozar et al, 2000).…”

“…The LC-fluor, GC-MS, and GC-MS/MS methods alternatively detect both viable bacteria and their nonviable cell wall remnants. The most unconventional technique, GC-MS/MS, has proven capable of detecting terrestrial bacterial markers at minute concentrations (Ͻ100 ppb) in a variety of complex environmental and clinical matrices (Fox et al, 1996;Krahmer et al, 1998Krahmer et al, , 1999Saraf et al, 1999;Kozar et al, 2000;Liu et al, 2000). However, GC-MS/MS has been used in only one extraterrestrial study to date (Kozar et al, 2001).…”

“…Analytical microbiology techniques (primarily GC-MS) detect not only viable bacteria, but also their nonviable cell envelope remnants when present in complex biological matrices (Maitra et al, 1978;Fox et al, 1980;Findlay et al, 1983;). More recently, gas chromatography tandem mass spectrometry (GC-MS/MS) has been proven to be capable of detecting terrestrial bacterial markers at minute concentrations in environmental and clinical samples (Fox et al, 1995(Fox et al, , 1996Saraf and Larsson, 1996;Saraf et al, 1999;Bal and Larsson, 2000;Kozar et al, 2000). GC-MS/MS was only recently used for the first time in studies of material of extraterrestrial origin (Kozar and Fox, 2001).…”