Separation and identification of illicit heroin samples by liquid chromatography using an alumina and C18 coupled column system and photodiode array detection.

The analysis of illicit heroin and opium samples on a coupled alumina and C18 column system is described. The compounds to be analysed can be divided into two groups: those with low pKa values, such as caffeine, papaverine and noscapine, and those with high pKa values, such as heroin, acetylcodeine, O6-monoacetylmorphine, procaine, codeine, morphine and strychnine. The first group can best be separated on a C18 column, whereas alumina is more suitable for the second group. Previously reported criteria for choosing proper buffer systems for ion-exchange separations on alumina were used together with an iterative regressive optimization procedure developed in our laboratory. The system can be used with and without valve-switching, depending on the sample type. The peak purity of the judicially important components heroin and O6-monoacetylmorphine has been checked with a photodiode array detector and by use of advanced software.