Simple and efficient high performance liquid chromatography (HPLC) with photodiode array (PDA) and fluorescence (FLD) detection methods have been validated for determination of taurine in energy drinks. These methods are based on pre-column derivatization of taurine with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) at alkaline medium to form colored fluorescent product. In the both validated HPLC methods, the derivatization product is separated on Intersil ODS-3 analytical column with acetonitrile and 0.1% trichloroacetic acid (30:70, v:v) as mobile phase. The eluted derivative is detected at 472 nm for HPLC-PDA and 472 nm/530 nm (Ex/Em) for HPLC-FLD. The methods were validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), precision and accuracy (recovery). Good linearities were achieved for taurine (r 2 > 0.9998 and 0.9993) in the concentration range of 5-50 mg L-1 and 5-50 µg L-1 for HPLC-PDA and HPLC-FLD respectively. The LODs were 0.296 and 0.616 × 10-3 mg L-1 for HPLC-PDA and HPLC-FLD respectively. The precision for peak area were 0.78 and 0.61% for HPLC-PDA and HPLC-FLD respectively. Recoveries of taurine ranging from 92-103.3%), (n = 3) were obtained. The validated method was successfully applied for the determination of taurine in some selected energy drinks available in local markets.

Rapid and efficient high-performance liquid chromatographic and UV-Vis spectrophotometric methods have been optimized and validated for taurine determination in energy drinks. Taurine was derivatized with o-phthalaldehyde and sodium sulfite in alkaline media prior to analysis. The optimum derivatization parameters were found to be 0.1 M borate buffer at pH 9.5, reaction time 5.0 min, o-phthalaldehyde concentration of 60 mg L-1 , sodium sulfite concentration of 202 mg L-1 and water as diluting solvent. The analytical parameters such as linearity, limit of detection (LOD), limit of quantification (LOQ), precision and accuracy were investigated. The methods were linear in range 0.5-20 mg L-1 and 0.5-15 mg L-1 with correlation coefficient (r 2) of 0.9998 and 0.9996 for HPLC-PDA and spectrophotometer respectively. The LODs were 0.109 mg L-1 and 0.141 mg L-1 for HPLC-PDA and spectrophotometer respectively. The precision (RSD%) of intra-day and inter-day of the methods were 1.816-1.278% and 2.858-2.236% respectively, for HPLC-PDA and spectrophotometer respectively. Recoveries of taurine ranging from 90% to 105%, (n = 3) were obtained. The methods were successfully applied for determination of taurine in energy drink samples.