Coupling of chromatographic analyses with pretreatment for the determination of bioactive compounds in Emblica officinalis juice

A simple and new method for the simultaneous detection and quantification of vitamin C (ascorbic acid), phenolic acids (gallic acid and ellagic acid), hydroxycinnamic acid (chlorogenic acid) and flavonoids (myricetin, quercetin and kaempferol) in Emblica juice is developed. The compounds are separated in 18 minutes by an intangible curved gradient of 0.1% ortho-phosphoric acid in water (v/v) and acetonitrile, as mobile phase A and B, respectively, using Zorbax SB RP C-18 column at a wavelength of 254 nm. The assay was optimized by varying the mobile phase, gradient type, pretreatment method (thermal and non-thermal) and detection wavelength. The method was validated in terms of linearity, precision, detection limits and quantification limits. Good linear response was observed over the range specified for all the analytes, as confirmed by the correlation coefficient which ranged from 0.991 and 0.995. The limit of detection (LOD) and limit of quantification (LOQ) were found to be in the range of 0.129–0.685 μg ml−1 and 0.43–2.883 μg ml−1 respectively. Pulsed electric field (PEF) was used as the non-thermal pretreatment sample technique. HPLC-PDA showed increased levels of phenolic acids, as gallic and ellagic acid, and flavonoid, as quercetin, in PEF treated Emblica juice with respect to the untreated and thermally treated juice samples (p < 0.05). The overall precision values obtained for standards and samples were within the range 0.01–0.2 and 0.15–0.23 respectively. Further, total polyphenolic content and free radical scavenging capacity of the untreated, thermally and PEF treated Emblica juice were corroborated by HPLC.