Analysis of bisphenol A and its chlorinated derivatives in sewage sludge samples. Comparison of the efficiency of three extraction techniques.

This paper presents a comparison of three extraction techniques--ultrasound-assisted extraction, microwave-assisted extraction and pressurized liquid extraction--in order to evaluate their efficiency in the determination of bisphenol A and its chlorinated derivatives in sewage sludge samples. Extraction parameters for each technique were accurately optimized to achieve the highest recoveries. The selected compounds were detected and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS), operating in negative atmospheric pressure chemical ionization (APCI) and in multiple reaction monitoring (MRM) mode. The analytes were separated in less than 6 min. BPA-d₁₆ was used as internal standard. Three selective, sensitive, robust and accurate analytical methods were developed. The limits of detection (LODs) of the methods ranged from 2 to 9 ng g⁻¹ and the limits of quantification (LOQs) from 8 to 26 ng g⁻¹, while inter- and intra-day variability was under 6% in all cases. Given the absence of certified reference materials (CRMs), the methods were validated separately by using matrix-matched calibration and recovery assays with spiked samples. Recovery rates ranged from 97.7% to 103.1%. The sewage sludge samples used for experiments were collected from two different wastewater treatments plants (WWTPs) located in the province of Granada (South-East Spain). The statistical comparison of the methods demonstrated no statistically significant differences between the extraction techniques for the determination of BPA and chlorinated derivatives in sludge samples.