Monitoring strychnine and brucine in biochemical samples using direct injection micellar liquid chromatography

Abstract

Nux-vomica is a tropical plant that contains two ergot alkaloids i.e. strychnine and brucine which have pharmaceutical and toxic properties. In some places, for example in India, Nux-vomica is used in ayurvedic preparations in homeopathic medicine. As both compounds are toxic monitoring is required. In this work a method for the chromatographic determination of strychnine and brucine in various herbal/ayurvedic sample preparations, homeopathic medicines, containing Nux-vomica, seeds of Nux-vomica as well as in spiked serum and real urine samples are described. The method involves a direct injection micellar liquid chromatography technique that was optimised under ICH guidelines. Optimum conditions are a mobile phase composed by 0.10 M SDS-pentanol 4% (v/v)-NaH₂PO₄ buffered at pH 3 with UV detection at 258 nm, flow rate of 1 mL min⁻¹, and temperature 25 °C. Under these conditions strychnine and brucine were analyzed in 15 and 11 min, respectively. Validation studies using ICH guidelines were performed to show that the proposed method was linear (r² > 0.9997), with LODs (0.18 and 0.09) and LOQs (0.69 and 0.35), for strycnine and brucine, respectively. Repeatability intra- and inter-day was below of 2.50. The developed method can be useful for analyzing strychnine and brucine for quality control and other related forensic and clinical cases.