Statistical Optimization of Hollow Fiber Liquid Phase Microextraction for Preconcentration and Determination of Strychnine

A sensitive and reliable extraction method based on the two-phase hollow fiber liquid phase microextraction followed by gas chromatography–mass spectrometry has been developed for determination of strychnine as an extremely poisonous alkaloid . Strychnine is obtained from Nux Vomica and its fatal dose is in the range of ۳۰–۹۰ mg [۱,۲]. A Box Behnken design (BBD) with three variables including the extraction time (۳۰, ۶۰, ۹۰ min), pH (۹, ۱۰, ۱۱) and ionic strength (۱, ۲, ۳ mol L-۱) was used to optimize the extraction process. The results were satisfactorily fitted to a quadratic response surface model with R۲=۰.۹۷۹۲ and F=۳۴.۳۶ which predicted the optimum conditions of operation (extraction time of ۸۹ min, pH=۱۱ and ionic strength of ۳). Based on the results, the ionic strength, extraction time and pH had significant effects on the extraction process. The method detection limit and limit of quantitation were obtained as ۵ and ۱۰ μg L-۱, respectively. The calibration curve was linear in the range of ۱۰-۱۰۰۰ μg L-۱ with a correlation coefficient of ۰.۹۹۴۷. The results suggested the proposed method as an environmentally friendly analytical method with a total consumption of ۴۰ μL of the organic solvent for each extraction, for highly efficient preconcentration and trace determination of strychnine in the biological fluids and environmental aqueous samples.

Keywords:

Hollow fiber liquid phase microextraction , Gas chromatography-mass spectrometry , Strychnine , Response surface methodology , Box Benken design