On-line solid-phase extraction-ion-pair liquid chromatography-electrospray mass spectrometry for the trace determination of naphthalene monosulphonates in water.

This paper presents an HPLC-MS method for the fully automated determination of a group of naphthalene monosulphonates in environmental water samples. The analytical procedure consisted of on-line ion-pair solid-phase extraction using a PLRP-S precolumn and ion-pair LC separation with triethylamine as ion-pair reagent in both cases. A mass spectrometric detector, coupled to LC through an electrospray interface and operated in negative ion mode, was used. Diagnostic ions usually corresponded to [SO3]- and/or [M-SO2H]- together with [M-H] and/or [M-2H+Na]-. The method was applied to the trace determination of several sulphonates present in tap water, seawater and water from the Ebro river. The analytes were determined at a concentration level between 0.05 and 1 microg l(-1) under selected ion monitoring acquisition by preconcentrating just 15 ml of sample. Naphthalene-1-sulphonate and naphthalene-2-sulphonate were identified and quantified in one of the samples of seawater.