Ether derivatives for the determination of phenols and phenol-generating pesticides by electron capture gas chromatography

Selective trace level analysis of phenolic compounds in water by flow injection analysis--membrane introduction mass spectrometry

Flow injection analysis coupled with membrane introduction mass spectrometry (FIA-MIMS) with on-line derivatization is shown to allow fast, accurate, nearly interference-free, and sensitive (low microgram/L) quantitation of phenolic compounds in water. On-line FIA derivatization of the phenolic compounds is performed by acetic anhydride acetylation in a K2CO3-buffered alkaline medium. The phenol acetates so formed efficiently permeate a silicone membrane and are directly transferred to the mass spectrometer, in which they are analyzed with selectivity and high sensitivity via selected ion monitoring. FIA-MIMS analysis was performed for aqueous solutions of phenol, 2-methylphenol, 4-chlorophenol, 4-chloro-3-methylphenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol, and detection limits in the 0.5-20 micrograms/L (ppb) range were observed for an analytical frequency of six samples/h. FIA-MIMS for phenolic compound analysis is considerably less time-consuming and labor intensive than most chromatographic methods based on liquid-liquid extraction and preconcentration procedures and is therefore applicable for on-line and in-situ monitoring of phenols in wastewaters and in the environment. FIA-MIMS employing acetic anhydride derivatization is also virtually free of interferences since it combines chemical, membrane, and enhanced MS selectivity; hence quantitation of phenolic compounds can be performed in the presence of congeners.

Application of a direct aqueous acetylation technique to the gas chromatographic quantitation of nitrophenols and 1-naphthol in environmental water samples

An improved method for the determination of low levels of nitrophenols in aqueous samples has been developed. The method is based on the gas chromatographic analysis of phenols as acetate derivatives which have been prepared directly in water. Recoveries of 97% or greater were obtained from aqueous solutions containing nitrophenols in concentrations ranging from 25 to 100 microgram/l. Concentrations as low as 1 microgram/l were easily detected. Nitrophenols appear to exhibit some resistance to degradation by microorganisms indigenous to the Athabasca River. Water samples to which 139 microgram/l each of o- and p-nitrophenol were added did not show evidence of microbial metabolism over a two week interval. Under identical conditions 100 microgram/l of m-cresol was metabolized within a 3-day period.

Gas-liquid chromatographic method with electron-capture detection for the determination of residues of some phenoxyacetic acid herbicides in water as their 2,2,2-trichloroethyl esters

A gas-liquid chromatographic method with electron-capture detection was developed for the determination of residues of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylpenoxyacetic acid (MCPA) in water as their 2,2,2-trichloroethyl esters, and the sensitivity was compared with that for 2-chloro- and 2,2,2-trifluoroethyl esters. The residue is isolated by sorption of the phenoxy acid on Amberlite XAD-4, eluted with benzene and then esterified with 20% (v/v) 2,2,2-trichloroethanol in trifluoroacetic anhydride in the presence of sulphuric acid. The recoveries at the 0.4 ppb level are 92.1 +/- 3.4% (2,4-D) and 87.8 +/- 2.1% (MCPA) and the detection limits for a 1-1 sample of water are 0.096 ppb (2,4-D) and 0.06 ppb (MCPA).