Determination of alkyltrimethylammonium chlorides in river water by gas chromatography/ion trap mass spectrometry with electron impact and chemical ionization.
This work describes a modified method to analyze alkyltrimethylammonium chlorides (ATMACs) in river water samples. The proposed method involves adding solid potassium iodide to water sample (pH adjusted to 10.0) as a counterion to enhance the extraction of ATMAC residues by dichloromethane liquid-liquid extraction. The iodide-ATMA+ ion pairs were demethylated to their corresponding nonionic alkyldimethylamines (ADMAs) by thermal decomposition in a GC injection port. The corresponding ADMAs were then identified and quantitated by gas chromatography/ion trap mass spectrometry (GC/MS) in electron impact and low-pressure positive ion chemical ionization (PICI) modes. A relatively high abundance of ADMAs was detected at a demethylation temperature above 300 degrees C in the injection port. Experimental results indicate that the proposed method is precise and sensitive in ATMACs analysis and allows quantitation at < or = 0.01 microg/L in 500 mL of the water samples. The enhanced selectivity of quasi-molecular ion chromatograms of C12-C18-ADMA, obtained using methanol PICI-MS, enables ATMAC residues to be identified at trace levels in environmental samples. Recovery of the ATMACs in various spiked water samples ranged from 70 to 94% while RSD ranged from 3 to 12%. The concentrations of total measured ATMAC residues in river water samples ranged from nondetectable to 1.24 microg/L.
Ding
Wang-Hsien
WH
Department of Chemistry, National Central University, Chung-Li, 32054, Taiwan. wding@cc.ncu.edu.tw
Tsai
Pei-Chuan
PC
D005591:Chemical Fractionation; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis
D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical