Comparison of continuous‐flow microextraction and static liquid‐phase microextraction for the determination of p ‐toluidine in Chlamydomonas reinhardtii

In this study, two microextraction methods, viz. continuous‐flow microextraction (CFME) and static liquid‐phase microextraction (s‐LPME), were optimized and compared for the determination of p ‐toluidine in water and Chlamydomonas reinhardtii samples. The calibration curve for p ‐toluidine was linear in the concentration range of 0.01–5 μg/mL, and the squared regression coefficients ( r 2 ) for the lines were up to 0.999 for both CFME and s‐LPME treatments. Detection limits in CFME and s‐LPME were 8.2 ng/mL and 4.9 ng/mL, based on a signal‐to‐noise ( S/N ) ratio of 3, respectively. The precision was tested, in five replicates, by analysis of a 100‐ng/mL standard solution of p ‐toluidine and the relative standard deviations were 5.43 and 3.08% for CFME and s‐LPME, respectively. The concentration factors were 5.5 and 14.4 for CFME and s‐LPME, respectively. s‐LPME has a higher extraction efficiency, lower detection limit, and higher concentration factor than that of CFME. Additionally, the s‐LPME method is precise and reproducible, and requires only a 3.0‐μL microdrop of extraction solvent. Therefore, this procedure is more convenient in use, and viable for qualitative and quantitative analysis of p ‐toluidine in water and biota samples.