| Abstract
| - The toxic nitrogen alkaloids nicotine, strychnine, and aconitine were quantitated in whole milk, skimmilk, and cream using solid-phase extraction cleanup and HPLC-UV with dual wavelength detection.Samples were extracted in McIlvaine's buffer with EDTA and then partitioned with aqueous acetonitrileand hexane. The aqueous phase was concentrated and passed through an OASIS HLB column.The column was eluted with methylene chloride/ammonium hydroxide, 1 mL/1 μL, v/v. The eluentwas acidified with hydrochloric acid and evaporated. The sample was diluted for HPLC with acetonitrile/phosphate buffer pH 7.4. Chromatography was performed on an Xterra RP-18 column using a gradientof acetonitrile and ammonium bicarbonate buffer at pH 9.8. Nicotine and strychnine were monitoredat 260 nm; aconitine was monitored at 232 nm. Calibration curves were generated from externalstandards in the range 0.2−10 μg/mL using 1/x weighting. Mean recoveries in whole milk spikedbetween 0.1 and 10 ppm were the following: nicotine 89.2%, strychnine 75.7%, and aconitine 85.1%.Mean recoveries in skim milk spiked between 0.1 and 10 ppm were the following: nicotine 72.1%,strychnine 78.2%, and aconitine 82.9%. Mean recoveries in cream spiked between 0.2 and 20 ppmwere the following: nicotine 87.9%, strychnine 76.9%, and aconitine 82.0%. Relative standarddeviations of recovery were less than 20% in each case. Keywords: Nicotine; strychnine; aconitine; milk; skim milk; cream; HPLC; solid-phase extraction;partitioning.
|
