Determination of individual nonylphenol isomers in water samples by using relative response factor method

Abstract

Because technical nonylphenol (NP) preparations are constituted by complex isomers and impurities, wide varieties of isomer composition were found in the environmental matrix. Since there is not sufficient information concerning isomer specific quantification, the currently available analytical method (e.g. JIS K 0450-20-10, 2002) of NP is applicable to determine only the total concentration, which is calculated by summing three to eight peaks in a gas-chromatogram. Hence, reliable analytical methods for each isomer are necessary for a risk assessment and source determination of NP, which is one of the most important endocrine disruptors. In this study, we developed an isomer-specific quantification method of thirteen individual NP isomers based on relative response factor (RRF) quantification by gas-chromatograph mass spectrometry in combination with steam distillation extraction of non-filtered water (SD-RRF method). The remarkable points concerning the SD-RRF method are that the extraction efficiencies of chemicals using steam distillation correspond to their boiling point, not only polarity. This method enables a reliable identification/quantification of thirteen isomers of NP by using RRF (by using a suitable ion to quantify; m/z 107, 121, 135, 149, 163, 177, 191 and 220). We validated the SD-RRF method for selected water samples in Arakawa River and Hanamigawa River around Tokyo Bay; a significant variation (3.8 to 15%) of the isomer composition was found in environment water samples.