Salt-induced homogenous solid phase extraction of hydroxylated metabolites of polycyclic aromatic hydrocarbons from urine samples using a deep eutectic solvent as an elution solvent prior to HPLC-FLD analysis

A novel solid phase extraction approach named homogenous dispersive solid phase extraction was introduced for the simultaneous extraction/preconcentration of four polycyclic aromatic hydrocarbons hydroxylated metabolites from urine samples. The method was done by dissolving a water-miscible organic polymer in urine and a homogenous phase was obtained. Then, by adding NaCl the sorbent was re-precipitated in the solution bulk as tiny particles and the analytes are adsorbed onto the sorbent. Hence, the sorbent was separated and the analytes on the surface of particles were separated by choline chloride: butyric acid deep eutectic solvent and determined by HPLC-FLD. The effective parameters were optimized by central composite design and the following conditions were obtained: sample solution pH, 4; polyvinylpyrrolidone amount, 63 mg; sodium chloride concentration, 20% w/v; and choline chloride:butyric acid deep eutectic solvent volume, 87 µL. After optimization, the method was validated and broad linear ranges and low limits of detection (14–28 ng/L) and quantification (49–96 ng/L) were obtained. Acceptable enrichment factors (85–109), extraction recoveries (74–96%), and adequate percision (RSDs ≤ 6.2%) were obtained. Finally, the introduced method was effectively applied for measurement of the studied chemical compounds in urine samples obtained from tobacco smokers.