High-performance liquid chromatography-based determination of total isothiocyanate levels in human plasma: application to studies with 2-phenethyl isothiocyanate

Anal Biochem. 2001 Apr 15;291(2):279-89. doi: 10.1006/abio.2001.5030.


Dietary and pharmacologic isothiocyanates (ITCs) may play a role in reducing the risk of certain cancers. The quantification of ITCs in humans is important both for epidemiological and pharmacokinetic studies. We describe a modification of an HPLC-based assay of urinary ITCs for use with human plasma. The assay utilizes the cyclocondensation reaction of 1,2-benzenedithiol with ITCs present in human plasma, followed by a two-step hexane extraction and analysis by HPLC using UV detection at 365 nm. The method shows linearity and reproducibility with human plasma over a range of 49-3003 nM phenethyl isothiocyanate (PEITC) (r(2) = 0.996 +/- 0.003). A similar degree of linearity was seen with two other biologically occurring conjugates of PEITC: PEITC--N-acetylcysteine (PEITC--NAC) and PEITC--glutathione (PEITC--GSH). The recovery of PEITC assessed on multiple days was 96.6 +/- 1.5% and was 100% for PEITC--GSH and PEITC--NAC. The reproducibility of the assay on multiday samplings showed a mean %CV of 6.5 +/- 0.3% for PEITC, 6.4 +/- 4.3 for PEITC--NAC and 12.3 +/- 3.9 for PEITC--GSH. In clinical studies, mean plasma ITC level of 413 +/- 193 nM PEITC equivalents was determined for a non-dietary-controlled group of 23 subjects. Multiday analysis data from pharmacokinetic plasma sets of 3 subjects taking a single dose of PEITC at 40 mg showed a good CV (range: 16-21%). The applicability of the methodology to pharmacokinetic studies of PEITC in humans is demonstrated.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Chromatography, High Pressure Liquid
  • Clinical Trials, Phase I as Topic
  • Diet
  • Humans
  • Isothiocyanates / blood*
  • Isothiocyanates / chemistry
  • Isothiocyanates / pharmacokinetics
  • Regression Analysis
  • Reproducibility of Results
  • Sensitivity and Specificity


  • Isothiocyanates
  • isothiocyanic acid
  • phenethyl isothiocyanate