A rapid HPLC with evaporative light scattering method for quantification of forskolin in multi-herbal weight-loss solid oral dosage forms

A rapid reverse-phase HPLC method with evaporative light scattering detection (ELSD) was developed for the determination of forskolin in weight loss multi-herbals products. The analysis was performed by water-acetonitrile gradient elution at a temperature of 40°C and a flow rate of 1.0 mL/min. The evaporator tube temperature of ELSD was set at 35°C, and with the nebulizing gas flow-rate (pressure) of 3.0 bar. The method was validated for linearity, accuracy, precision and limits of detection (LOD) and quantification (LOQ). Good linear relationships were obtained with correlation coefficients exceeding 0.9995. The average recovery of forskolin ranged from 99.4% to 100.4% with RSDs below 3%. The percent relative standard deviations (%RSD) of intra- and inter-day precision varied by less than 2.1%. LOD and LOQ were 0.95 μg/ml and 3.21 μg/ml, respectively. The validated ELSD method permits a shorter determination time without compromising accuracy and demonstrates that it can be used for quantification of forskolin incorporated in multi-herbal solid oral dosage forms.