Highly sensitive immuno-assays for the determination of cotinine in serum and saliva. Comparison between RIA and an avidin-biotin ELISA

Eur J Clin Chem Clin Biochem. 1991 Jun;29(6):405-10. doi: 10.1515/cclm.1991.29.6.405.


Two immuno-assay methods (RIA and ELISA) have been developed for the accurate and sensitive measurement of cotinine in human body fluids (serum, saliva). RIA uses [3H]cotinine as antigen and charcoal/dextran for separating cotinine-bound antibodies from the free derivative. Another technique (ELISA) was developed to avoid the use of radio-labelled compounds and to determine cotinine in large populations, including passive or non-smokers who usually present very low concentrations. The two techniques were analytically validated. The detection limit was similar (0.1 micrograms/l) and the precision was better than 10% for both techniques. Non-smoker values ranged from 0.1 to 17 micrograms/l by ELISA and 0.1 to 27.5 micrograms/l by RIA, whereas smoker values ranged from 50 to 1000 micrograms/l (ELISA) and from 70 to 800 micrograms/l (RIA). The comparative analysis of cotinine in 96 human sera revealed a good correlation between the two methods (r = 0.97) and a reliable discrimination between the populations of non-smokers and smokers. As usual, the ELISA is more rapid (4 h 30 min) than the RIA (longer than 48 h). ELISA is proposed for use in the epidemiological investigation of the human tobacco risk.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Avidin
  • Biotin
  • Cotinine / analysis*
  • Cotinine / blood
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Indicators and Reagents
  • Radioimmunoassay / methods
  • Reference Values
  • Saliva / chemistry*


  • Indicators and Reagents
  • Avidin
  • Biotin
  • Cotinine