Detection of pharmaceuticals in "dirty sprite" using gas chromatography and mass spectrometry

Dirty Sprite, also known as "lean" or "purple drank", is a preparation associated with the presence of codeine and promethazine. These drinks, predominantly used by young people, are mixtures of, for example, soft drinks, prescription medicines, and prescription cough syrups. The use of these illicit preparations started in Texas in the 1960s and become popularized in the 1990s. However, the misuse of these cocktails has become more common in other countries to date, for example, in Thailand. Given the illicit nature of these preparations and the lack of information available on the composition of these products, there is a need to identify and quantify the drugs that may be present. Three samples of Dirty Sprite were analyzed using GC-MS after liquid/liquid-extraction under acidic and basic conditions. Since the acidic extraction did not show the detection of relevant substances, samples were alkalized to pH ≥ 9, followed by extraction with 1-chlorobutane. GC-MS screening revealed the identification of codeine, dihydrocodeine, promethazine and impurities of cocaine. A selected ion monitoring method was developed for the quantification of these compounds using lemonade as a calibration matrix. Quantitative analysis showed concentrations of 130-mg/L codeine, 75-mg/L promethazine, and 3.4-mg/L cocaine in sample 1; 74-mg/L promethazine and 91-mg/L dihydrocodeine in sample 2; and 130-mg/L codeine combined with 68-mg/L promethazine in sample 3. The results also illustrate that the consumption of drugs detected in Dirty Sprite samples could lead to health risks given that these prescription medicines are consumed outside the medical environment.