Evaluation of peroxyoxalate chemiluminescence for the sensitive determination of hallucinogenic alkaloids

The continuous addition of reagent technique was used for the determination of hallucinogenic alkaloids such as harmaline, harmalol, harmine, harmol and harmane by measuring the chemiluminescence (CL) produced in the reaction with the bis(2,4-dinitrophenyl) oxalate/hydrogen peroxide system; this was the first reported use of peroxyoxalate chemiluminescence for these hallucinogens. The ability of this technique to reduce background emission in peroxyoxalate CL determinations was exploited to develop a sensitive method for the determination of the above mentioned hallucinogens. The method features linear responses over 2 orders of magnitude, relative standard deviations of ca. 3% and detection limits in the picomole range, in addition to a high selectivity. Also it compares favourably in terms of sensitivity with that based on another well-known peroxyoxalate reagent, viz. bis(2,4,6-trichlorophenyl) oxalate. It also excels other alternatives based on different techniques in terms of sensitivity. The proposed method was validated for analysis of real samples by applying it to the determination of harmaline in plasma samples.