Surfactant-modified Zn/Al-layered double hydroxides for efficient extraction of alkyl phenols from aqueous samples

Zn/Al-layered double hydroxides (LDHs) modified by sodium dodecylsulfate (SDS) were synthesized as a hydrophobic organic sorbent via urea hydrolysis. LDHs were applied as adsorbent for solid phase extraction (SPE) analysis to determine three alkylphenols (namely, p-tert-amylphenol (PTAP), p-cumylphenol (PCP), and p-n-octylphenol (POP)) in water samples using gas chromatography-mass spectrometry. The extraction efficiency was optimized by adjusting key variables of eluent volume, eluent type, sample flow rate, adsorbent amount, pH, and the effect of salt addition. Under the optimal conditions, APs showed excellent linearity (1-250 ng/mL: R-2 > 0.99) and reproducibility (relative standard deviation: < 5%). The detection limits for PTAP, PCP, and POP were 19, 16, and 33 pg/mL, respectively. LDHs based SPE method offered high recovery for aqueous samples (e.g., 83.2-99.46%) with enhanced reusability (e.g., up to 10 cycles). The feasibility of the developed method has thus been validated for quantitation of three alkyl phenols (i.e., PTAP, PCP, and POP) in aqueous environmental samples with high sensitivity and good stability.