A Study on the Development of Analytical Method for Trimethyl (octadecyl) Ammonium and it’s Salts in Sediment by LC-MS/MS, and the Change of its Concentrations Over the Years

Abstract

Trimethyl (octadecyl) ammonium and it's salts is widely used as a cationic surfactant. In this study, an analytical method for trimethyl (octadecyl) ammonium and it's salts in sediment by liquid chromatography tandem-mass spectrometry (LC-MS/MS) was developed. In this method, trimethyl (octadecyl) ammonium and it's salts in sediment is measured as trimethyl (octadecyl) ammonium chloride. The method detection limit (MDL) and method quantification limit (MQL) were 0.00026 μg/g-dry and 0.00069 μg/g-dry, respectively. This method was able to measure the trimethyl (octadecyl) ammonium and it's salts in organic or inorganic-rich sediments, which had been difficult with conventional methods. In addition to the hydrophobic adsorption of trimethyl (octadecyl) ammonium and it's salts on organic matter, electrostatic adsorption on inorganic matter was also observed. It was also detected in the sediments at Yamagata Prefecture, which is considered to be relatively less polluted by chemical substances. The substances were detected in both rivers and sea areas in sediments at Nagoya City, and was found to be at higher concentrations than that detected in sediments at Yamagata Prefecture. Trimethyl (octadecyl) ammonium and it's salts was detected in all sediments at Nagoya City after 2003, which means its continuous pollution in sediments at Nagoya City.