Development of Method Determining Tetramethylammonium Hydroxide and Tetramethylammonium Salts in Industrial Wastewater by LC-MS/MS

In this study, we developed a method of determining tetramethylammonium hydroxide and tetramethylammonium salts, present in industrial wastewater as tetramethylammonium ions (TMA) , by liquid chromatography-tandem mass spectrometry (LC-MS/MS) . Tetramethylammonium hydroxide was used as a standard solution. The lower limit of quantification for TMA analysis by solid-phase extraction (SPE) using a weak cation exchange resin (Oasis WCX) was 0.00034 mg L-1, and the recovery of surrogate standards ranged from 50 to 120%. We investigated 30 industrial wastewater samples from Fukuoka Prefecture by the developed TMA analysis method. TMA was detected in two samples, H and X, with concentrations of 0.0014 and 2.5 mg L-1, respectively. In sample X, the immobilization of Daphnia magna was observed even at 50% dilution, and the 48 h-EC50 was 62%. The toxicity removal test indicated reduced toxicity for sample X after SPE-WCX.