ABSTRACT
The powder X-ray diffraction(PXRD) technique was used to investigate fourteen kinds of Ranunculaceae herbal decoction pieces(RHDP) recorded in Chinese Pharmacopoeia and to explore a novel PXRD quality control method for RHDP. The results indicated that only three RHDP-Paeoniae Radix Alba, Paeoniae Radix Rubra, and Moutan Cortex, contained calcium oxalate monodydrate(COM), whereas no COM existed in other eleven kinds of RHDP. The difference in PXRD for Paeoniae Radix Alba and Paeoniae Radix Rubra from different growing areas were investigated. The quantitative analysis method for COM was discussed by considering the water-boiling manufacturing process of herbal decoction pieces. The water-boiling experiments revealed that the PXRD peaks from COM crystals in RHDP were enhanced significantly after boiling. Paeoniae Radix Alba, Paeoniae Radix Rubra, Moutan Cortex, Aconiti Lateralis Radix Praeparata, Aconiti Radix, Aconiti Kusnezoffii Radix, and Anemone Raddeanae Rhizoma exhibited a similar series of broader peaks in the 2θ region of 15° to 35°, whose origins were discussed on the basis of chemical constituents RHDP reported by other researchers. These diffraction broader peaks most likely originated from periodic orientation of benzene ring in organic molecular crystals of aconitine-and paeonolum-based alkaloids and glycosides chemical constituents, subsequently, possibly from some other organic constituents. The PXRD technique can be used to rapidly identify Cimicifuga heracleifolia with an amorphous dispersion peak and C. dahurica with a sharp-peak feature. Climatidis Radix et Rhizoma exhibited a series of sharp PXRD peaks. The PXRD method can provide a valuable quality control method for RHDP.