A high-performance liquid-chromatographic method for routine simultaneous determination of nicotine and cotinine in plasma.
We describe a rapid, sensitive method for the routine simultaneous determination of nicotine and cotinine in 1 mL of plasma. Extraction in 10-mL screw-capped Teflon tubes with methylene chloride after deproteinization with trichloroacetic acid eliminated emulsion formation. The extract, after evaporation and reconstitution in 30 microL of mobile phase, is injected into a reversed-phase C-18 ion-pair column of an isocratic high-performance liquid-chromatographic unit. Absorbance is monitored at 256 nm. The mobile phase is a citrate-phosphate (30 mmol each per liter) buffer mixture containing 50 mL of acetonitrile and 1 mmol of sodium heptanesulfonate per liter. 2-Phenylimidazole is the internal standard. The detection limit is 1 microgram/L for nicotine and 3 micrograms/L for cotinine. The standard curve is linear from 0 to 700 micrograms/L for both compounds. The average CV for nicotine in the concentration range 0-100 micrograms/L is 6.5%, and that for cotinine in the concentration range 50-700 micrograms/L is 4%.
Hariharan
M
M
Department of Psychiatry, University of Michigan Medical School, Ann Arbor 48109-0656.
VanNoord
T
T
Greden
J F
JF
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003367:Cotinine / Q000097:blood*; D006801:Humans; D009538:Nicotine / Q000097:blood*; D011760:Pyrrolidinones / Q000097:blood*; D012907:Smoking
D011760:Pyrrolidinones; D009538:Nicotine; D003367:Cotinine