A Reliable Gas Capillary Chromatographic Determination of Lactulose in Dairy Samples

The rhizome of Polygonum cuspidatum is an important Chinese medicine used against infectious hepatitis, leucorrhagia, pruritus vulvae of the dampness-heat type, burns, snake bite, carbunculosis, amenorrhea, dysmenorrhea, trauma with blood stasis, and rheumatism, etc. Emodin, resveratrol, and polydatin are main active components of the rhizome. We report a simple densitometric HPTLC method for quantification of these compounds. The method was validated for precision, repeatability, and accuracy. The method was found to be precise, with RSD of 0.23, 0.25, and 0.32 (interday) and 0.45, 0.57, and 0.48 (intraday) for different concentrations of emodin, resveratrol, and polydatin, respectively. Instrument precision was 0.25, 0.23, and 0.34 (%CV) for emodin, resveratrol, and polydatin, respectively. The accuracy of the method was checked by measuring the recovery of the three compounds at three different levels; the average recoveries were 102.56%, 100.21%, and 100.27%, respectively. The amounts of emodin, resveratrol and polydatin in Polygonum cuspidatum, as estimated by the proposed method, were 4.96 mg g^–1, 1.81 mg g^–1, and 13.02 mg g^–1. The HPTLC method proposed for estimation of emodin, resveratrol and polydatin was found to be simple, precise, specific, sensitive, and accurate and can be used for quality control of Polygonum cuspidatum.