Synthesis and determination of dicarboxylic degradation products of nonylphenol polyethoxylates by gas chromatography-mass spectrometry

The synthesis and determination of persistent dicarboxylic metabolites of alkylphenol polyethoxylates (NPEOs), carboxyalkyl phenoxy ethoxy carboxylates (CAPECs), are investigated. The synthesized CAPECs have three and four carbon atoms and a carboxyl group in the alkyl chain side, and a carboxymethoxy acid group in its para-position (expressed as CA₃P1EC and CA₄P1EC in their abbreviation). The synthesis was successfully accomplished via a four-step reaction sequence that started from 4-fluoroanisole. After propylation by a propanol/acetyl chloride procedure, the derivatives of synthesized CA₃P1EC and CA₄P1EC were separated and identified by GC-MS with electron impact ionization (EI). The most abundant characteristic ions were produced by benzylic cleavages of carboxyalkyl chain to yield [M-87]⁺, corresponding to ions of m/z 235 for CA₃P1EC and m/z 249 for CA₄P1EC. Recoveries of synthesized CA₃P1EC and CA₄P1EC in various spiked water samples ranged from 82 to 92% with relative standard deviations (RSD) lesser than 7%. The limits of quantitation (LOQ) of CA₃P1EC and CA₄P1EC were estimated to be 0.005 and 0.01 μg/l in 100 ml of water samples, respectively. The concentrations of CA₄P1EC residues were detected in the aquatic environment ranging from n.d. to 3.24 μg/l. The results show that the synthesized CA₄P1EC has been successfully applied to more accurately determine the concentrations of CA₄P1EC residues in water samples.