Trace-level determination of 1,4-dioxane in water by isotopic dilution GC and GC-MS.
The volatile and polar solvent 1,4-dioxane has recently been reported as a contaminant of ground and surface waters, establishing the need to determine this substance in drinking water. This investigation established that 1,4-dioxane can be determined in water by various techniques including direct aqueous injection (DAI) gas chromatography (GC) and purge and trap GC-mass spectrometry (MS). Purge and trap GC-MS is limited by 1,4-dioxane's poor purge efficiency, resulting in detection limits up to 100 times greater than the efficiently purged volatile organic compounds. To attain the sensitivity required for drinking water monitoring, a method based on continuous liquid-liquid extraction with dichloromethane was developed. Isotope dilution was more accurate and reproducible than quantification with external standards, and the improvement in precision led to a lower method detection limit, 0.2 microgram L-1, using a quadrupole ion trap instrument in the electron ionization mode. Isotope dilution accuracy approached 100% in ppb determinations. Isotopic dilution quantification was also possible using a non-selective GC detector owing to the high efficiency of capillary GC columns that resolve the deuterium-labeled solvent from the natural isotopes.
Draper
W M
WM
Sanitation and Radiation Laboratory Branch, California Department of Health Services, Berkeley 94704, USA.
Dhoot
J S
JS
Remoy
J W
JW
Perera
S K
SK
D002849:Chromatography, Gas; D004146:Dioxanes / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D011865:Radioisotope Dilution Technique; D012680:Sensitivity and Specificity; D014874:Water Pollutants, Chemical / Q000032:analysis*
D004146:Dioxanes; D014874:Water Pollutants, Chemical; C025223:1,4-dioxane