Single-step microwave assisted headspace liquid-phase microextraction of trihalomethanes and haloketones in biological samples

• For the first time, a single-step microwave assisted headspace liquid-phase microextraction method was developed.
• Rapid method for screening volatile and semi volatile analytes.
• Suitable micro-extraction method for disinfection by-products in complex sample matrix.

A single-step microwave assisted headspace liquid-phase microextraction (MA-HS-LPME) method was developed for determination of trihalomethanes (THMs) and haloketones (HKs) in biological samples. In this method, a porous membrane envelope was filled with few microliters of extraction solvent and then placed inside the microwave extraction vial. A PTFE ring was designed to support the membrane envelope over a certain height inside the vial. An optimum amount of biological sample was placed in the vial equipped with magnetic stirrer. After that nitric acid was added to the vial for digestion of biological sample. The sample was digested and the volatile THMs and HKs were extracted at headspace in the solvent containing porous membrane. After simultaneous digestion and extraction, the extract was injected to gas chromatography/mass spectrometry for analysis. Factors affecting the extraction efficiency were optimized to achieve higher extraction performance. Quantification was carried out over a concentration range of 0.3–100 ng g−1 for brominated compounds while for the chlorinated ones linear range was between 0.5–100 ng g−1. Limit of detections (LODs) were ranged from 0.051 to 0.110 ng g−1 while limit of quantification (LOQ) were in the range of 0.175–0.351 ng g−1. The relative standard deviations (RSDs) of the calibrations were ranged between 1.1 and 6.8%. The MA-HS-LPME was applied for the determination of trace level THMs and HKs in fish tissue and green alga samples.