A validation study comparing accelerator MS and liquid scintillation counting for analysis of 14C-labelled drugs in plasma, urine and faecal extracts

J Pharm Biomed Anal. 2000 Dec 15;24(2):197-209. doi: 10.1016/s0731-7085(00)00397-6.


A comparison has been made between accelerator mass spectrometry (AMS) analysis and liquid scintillation counting (LSC) of plasma, urine and faecal samples containing 14C-labelled drugs. In an in vitro study in which human plasma was spiked (the term spiked is used in Section 2.6) with 14C-Fluconazole (14C-FL) over a concentration range of 0.1-2.5 dpm/ml, a correlation coefficient of 0.999 was determined for AMS analysis versus extrapolated LSC data. No significant day to day (or inter-day)variation was seen (P < 0.05 by ANOVA). Coefficients of variation for these analyses ranged from 2.68 to 6.50%. In vivo studies in which rats were given a high (11.5 microCi/kg) or low (18.1 nCi/kg) radioactive dose (to model an exposure of 0.9 microSievert to man) of 14C-Fluticasone propionate(14C-FP) showed that there was also a good correspondence between AMS and LSC data. A mass balance study in a single the faeces by 96 h; less than 1% of the administered dose was excreted in the urine. The limit of reliable measurement of drug related material, above background concentrations, by AMS analysis in this study was approximately 0.1 dpm/ml for plasma, 0.01 dpm/ml for urine without any sample extraction or concentration and 0.01 dpm/ml for faecal extracts. The data reported here demonstrate that AMS is an ultrasensitive and reliable method for analysing 14C-labelled drugs in human and animal body fluids.

Publication types

  • Validation Study

MeSH terms

  • Animals
  • Carbon Radioisotopes
  • Feces / chemistry*
  • Humans
  • Male
  • Mass Spectrometry / methods*
  • Pharmaceutical Preparations / analysis*
  • Pharmaceutical Preparations / blood
  • Pharmaceutical Preparations / urine
  • Rats
  • Rats, Wistar
  • Reproducibility of Results
  • Scintillation Counting / methods*
  • Sensitivity and Specificity


  • Carbon Radioisotopes
  • Pharmaceutical Preparations