2-methoxy-4-(2-phthalimidinyl)phenylsulfonyl chloride as a fluorescent labeling reagent for determination of phenols in high-performance liquid chromatography and application for determination of urinary phenol and p-cresol

Highly sensitive fluorescent labeling reagents, 2-(alkyloxy)-4-(2-phthalimi dinyl)phenylsulfonyl chlorides (alkyloxy = methoxy, ethoxy, and propoxy; MP S-Cl, EPS-Cl, and PPS-Cl, respectively), for determination of phenols by hi gh-performance liquid chromatography (HPLC) have been developed. These reag ents react with phenols in basic medium to produce the corresponding fluore scent sulfonyl esters. The maximum fluorescence wavelengths of the derivati ves were 308 nm for excitation and 410 nm for emission. The peaks due to ph enol labeled with MPS-CI, EPS-CL, and PPS-CI eluted at 6.3, 8.8, and 12.8 m in, respectively, on a reversed-phase column with isocratic elution of meth anol/water (2:1, v/v), and the detection limits (signal-to-noise = 3) of th e derivatives were 10, 12, and 17 fmol per injection, respectively. Among t hese reagents, MPS-Cl was advantageous because its derivatives had shorter retention times and higher sensitivities in HPLC. The efficiency of convert ing phenol to the fluorescent derivative by MPS-Cl was about 100%. When MPS -Cl was applied to the determination of urinary phenol and p-cresol by HPLC using p-ethylphenol as an internal standard, the derivatives were separate d at retention times of 6.3, 8.7, and 12.3 min, respectively, under the HPL C conditions described above. The concentrations of phenol and p-cresol in normal human urine were 11.9-293.5 and 8.2-346.1 nmol/mg creatinine, respec tively. (C) 2000 Academic Press.