The determination of non-ionic surfactants in surface waters by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

Matrix-assisted time-of-flight mass spectrometry (MALDI-TOFMS) has been shown to be a useful tool for the analysis of a wide range of biological and synthetic polymers. This has included the analysis of some commercial formulations of some non-ionic surfactants. But, as yet, no one has reported the use of MALDI-TOFMS for the analysis of surfactants in environmental matrices. Here we report the use of MALDI-TOFMS for the qualitative and quantitative determination of nonylphenol ethoxylate surfactants in environmental surface waters. Following extraction/preconcentration by C18 solid phase extraction, the sample is mixed with a standard MALDI matrix (2,5-dihydroxybenzoic acid). The mixture is then crystallised on a stainless steel target for introduction into the mass spectrometer. The limit of detection is 40 µg/L based on a 250 mL sample.