Immunoturbidlmetry for Albumin Measurement In Plasma or Serum of Patients wfth Renal Failure

To evaluate precision we used one sample from a smoker and one sample indicating passiveinhalation. The calculated within-assay CV of 10 replicates(80-L volumes)was 4.5% at 5.2 g’L and 1.4% at 220 g/L. The reagents and assay standards proved stable over a 3-month period. However, as with commercially prepared reagents, recalibration was desirable every week or so. Although the antiserum was previously found to have negligible crossreactivity with nicotine and the metabolites 1-N-oxide,isonicotinic acid, pyridylacetic acid, nicotinic acid, and nicotinamide (4), other metabolites, such as the glucuronic acid conjugates, were unavailable for testing. As with any hapten immunoassay (whether polyclonal or monoclonal antisera are used), interactions with other small molecules may only become apparent after extensive practical application. Large-scale epidemiological studies on smoking require a simple, automated process for the assay of cotinine, and we believe that the Abbott TDx used with saliva samples would fulifill this role. The greater sensitivity attainable with saliva gives a much clearer differentiation between smokers and nonsmokers than the urine assay reported previously (5) and may be useful in the study of passive inhalation.