Immunogen preparation purity

Although 1-nicotine is the predominant natural isomer, the occurrence of some d-nicotine makes it of interest to develop enantioselective assays for this compound. A review of nicotine and cotinine assays has been given (42). An early report of an RIA for 1-nicotine described an immunogen prepared from 6-aminonicotine. This compound was converted to 6-(p-aminobenzamido)nicotine and conjugated to albumin (Fig. 4 [8b]) by diazotization (43). The enantiomeric purity of the 6-aminonicotine was not discussed, and the synthesis of 6-aminonicotine is reported to cause racemization (44). However, the antiserum eventually obtained showed only 6% cross-reaction with d-nicotine (43). 

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