title: Selected ion monitoring in quantitative gas-liquid chromatographic-mass spectrometric detection of fatty acid methyl esters from environmental samples.
abstract: To calculate selected ion monitoring (SIM) gas-liquid chromatography (GLC)-mass spectrometry (MS) results of phospholipid fatty acids (PLFAs) from environmental samples, coefficients were calculated for each fatty acid by dividing the sum of ion intensities in SCAN with that of ions followed in SIM. The SIM chromatogram areas were multiplied with the coefficients, and then processed as in SCAN. The results were compared to those obtained using calibration curves and SCAN. The calibration curve and coefficient based results had the greatest errors of 7.8 and 6.7%, respectively, outside standard deviations of SCAN percentages. The PLFA contents calculated using calibration curves and coefficients were 104.9+/-7.3% and 101.5+/-8.6%, respectively, of SCAN values. SIM increased sensitivity approximately 10-fold from SCAN, and the smallest detectable injected amount was approximately 50 ng (0.18 nmol) for 20 fatty acids, corresponding to 4 x 10(6) cells.
authors.affiliation: National Public Health Institute, Department of Environmental Health, P.O. Box 95, FIN-70701 Kuopio, Finland. merjakontro@hotmail.com
authors.forename: Merja
authors.initials: M
authors.lastname: Kontro
authors.forename: Leena
authors.initials: L
authors.lastname: Korhonen
authors.forename: Terttu
authors.initials: T
authors.lastname: Vartiainen
authors.forename: Päivi
authors.initials: P
authors.lastname: Pellikka
authors.forename: Pertti J
authors.initials: PJ
authors.lastname: Martikainen
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D004952:Esters / Q000032:analysis*; D005227:Fatty Acids / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D019015:Geologic Sediments; D006017:Glycolipids / Q000032:analysis; D010743:Phospholipids / Q000032:analysis; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D004952:Esters; D005227:Fatty Acids; D006017:Glycolipids; D010743:Phospholipids; D014874:Water Pollutants, Chemical