Characterization of the 0-(2,3,4,5,6-Pentafluorobenzyl)- hydroxylamine Hydrochloride (PFBOA) Derivatives of Some Aliphatic Mono- and Dialdehydes and Quantitative Water Analysis of These Aldehydes

Abstract

Abstract A study was conducted to validate the use of O- (2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride (PFBOA) as an agent for the determination of formaldehyde, acetaldehyde, n-heptanal, n-decanal, and glyoxal, aldehydes commonly found as byproducts in drinking and other water after a prior ozonation step. The study involved synthesis and characterization of the pure PFBOA-oxime derivatives and their subsequent use in validation studies in various types of chemically defined waters. The yields of the synthesized PFBOA-oximes exceeded 80%. They were characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, ultraviolet (UV) and infrared (IR) spectrophotometry, and gas chromatography/electron impact positive ion mass spectrometry (GC/MS) to assess their purity and define the suitability of these techniques in aldehyde quantitation. The syn/anti isomers of the oximes were detected by GC/MS and both NMR techniques, but not by IR or UV. The most sensitive technique was selected ion monitoring GC/MS, which allowed picogram quantitation over a wide linear range. A high PFBOA concentration (10 mg/mL) with 3 hexane extractions, initial pH adjustment, and microwave heating proved superior (<80% recoveries) to a published method involving room temperature, low PFBOA concentration (1 mg/mL), and a single hexane extraction for many defined waters. The use of standard reference materials as defined matrixes for aldehyde spiking recovery experiments to account for matrix effects is novel, and demonstrates that the method is quantitative (<80% recoveries) in a wide variety of matrixes.