Liquid‐phase microextraction by solidification of floating organic microdrop and GC‐MS detection of trihalomethanes in drinking water

A simple and sensitive methodology based on liquid‐phase microextraction (LPME) followed by GC‐MS, was developed for the determination of trihalomethanes (THMs) in drinking water. A microdrop of organic solvent was floated on the surface of the aqueous sample and it was agitated for a desired time. Then, the sample vial was cooled by inserting it into an ice bath for 4 min. The solidified solvent was transferred into a suitable vial and immediately melted. The extract was directly injected into the GC. Microextraction efficiency factors were investigated and optimized: 7 μL 1‐undecanol microdrop exposed for 15 min floated on the surface of a 10.0 mL aqueous sample with the temperature of 60°C containing 3 M of NaCl and stirred at 750 rpm. Under the selected conditions, enrichment factors (EFs) up to 482‐fold, LOD of 0.03–0.08 μg/L (S/N = 3) and dynamic linear ranges of 0.10–100 μg/L were obtained. A reasonable repeatability (RSD < 8.6%, n = 8) with satisfactory linearity ( r 2 ⪈ 0.9947) of results illustrated a good performance of the present method. The protocol proved to be rapid, cost‐effective, and is a green procedure for the screening purposes.