Spent tea leaves as an adsorbent for micro-solid-phase extraction of polycyclic aromatic hydrocarbons (PAHs) from water and food samples prior to GC-FID analysis

Abstract

Spent tea leaves (STL) which is a waste from brewed tea leaves, Camellia sinensis is utilized as micro-solid phase extraction (µ-SPE) sorbent for the extraction of hazardous polycyclic aromatic hydrocarbons (PAHs) from water and food samples for the first time. STL contains lignin, cellulose, hemicellulose, polyphenols, and aliphatic carbon which enable the adsorption of PAHs. Tea filter bag is used as a porous membrane to reduce the cost. In this work, STL-µ-SPE coupled with GC-FID was successfully applied to extract 5 types of PAHs, namely fluorene, fluoranthene, pyrene, chrysene, and benzo[a]pyrene in real samples though it is challenging as PAHs usually exist in complex matrices and trace level. STL and its interaction with PAHs were then characterized by FT-IR, FESEM, and EDX analyses. The µ-SPE method was optimized by several parameters such as eluent type and volume, dosage of sorbent, extraction time, desorption time and volume of sample. Under the optimized conditions, the linear calibration curves were in the range of 50 ng mL−1 to 1000 ng mL−1 with the R2 ranged between 0.9952 and 0.9983 in the water sample. The recoveries in the real samples ranged from 88.0 to 111.4% with the RSDs (n = 3) ranged at 1.0 to 9.8%. The present method found to be fast, sensitive, cost-effective, reproducible and feasible as a new application of using low-cost adsorbent for the determination of PAHs in the water and food samples.