Determination of alkylphenol ethoxylates in water-based adhesives by high performance liquid chromatography-tandem mass spectrometry combined with dispersive solid phase extraction

To determine the alkylphenol ethoxylate levels in water-based adhesives accurately, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method combined with dispersive solid phase extraction to quantify octylphenol ethoxylate (OP_nEO) and nonylphenol ethoxylate (NP_nEO) in water-based adhesives was developed. Water-based adhesive samples were extracted with methanol, and then purified by C₁₈ dispersive solid phase extraction. The extract solution was separated bygradient elution on an Inspire HILIC chromatographic column using 5 mmol/L ammonium acetate solution and acetonitrile as the mobile phases. MS/MS analysis was performed in multiple reaction monitoring mode (MRM). The results showed that: 1) Baseline separation was realized for all OP_nEO and NP_nEO with different polymerization degrees within 25 minutes. 2)Under optimized conditions, the spiked recoveries for all the analytes were in the range of 79.8%-93.8% with relative standard deviations(RSDs)less than 7.0% at the addition levels of 10, 50 and 100 mg/kg. Good determination coefficients(R²≥0.998 7)were achieved for all the analytes in the given concentration ranges. The LODs and LOQs were in the range of 6.64-7.42 and 22.6-24.9 μg/kg respectively. 3) Ten actual water-based adhesive samples were tested with the developed method. NP_nEO was detected only in 2 samples and OP_nEO was not detected in all the samples. This method is stable and accurate with strong specificity, and can be used to determine the OP_nEO and NP_nEO in water-based adhesives.