Impurities, adulterants and diluents of illicit heroin. Changes during a 12-year period.

Changes in the content of impurities, adulterants and diluents are described for 383 samples of illicit heroin seized in the western part of Denmark during the 12-year period 1981 through 1992. A wide range in purity was found within each year, whereas the average purity did not vary much from one year to another. The average purity of wholesale samples (45%) was only slightly higher than the purity of retail samples (36%). The SW Asian type of heroin, containing high concentrations of noscapine, predominated from the mid-eighties. Heroin base and heroin hydrochloride each accounted for approximately half of the samples during the eighties. However, in recent years the base form has become predominant. During the early eighties caffeine and procaine were the most frequent additives next to sugars. During the middle and late eighties an increasing number of heroin samples were cut with phenobarbital and methaqualone. During the early nineties the occurrence of phenobarbital and methaqualone has decreased, whereas paracetamol in combination with caffeine has become predominant. Re-analyses of samples which had been kept in storage for several years showed that most samples had not changed after being stored in the dark for a couple of years at room temperature. However, storage for more than 5 years often resulted in decomposition, particularly in samples consisting of the SW Asian type of heroin.