Palmatine is an isoquinoline alkaloid that has been widely used in China for the treatment of various inflammatory diseases such as gynecological inflammation, bacillary dysentery, enteritis, respiratory tract infection, urinary infection, etc. In the study reported in this paper, a simple and rapid high-performance liquid chromatography/electrospray ionization (ESI) tandem mass spectrometric method (MS/MS) was developed for elucidation of the structures of metabolites of palmatine in rat urine after administration of a single dose (20 mg/kg). The rat urine samples were collected and purified through C18 solid-phase extraction cartridges, and then injected onto a reversed-phase C18 column with 60:40 (v/v) methanol/0.01% triethylamine solution (2 mM, adjusted to pH 3.5 with formic acid) as mobile phase and detected by on-line MS/MS. Identification of the metabolites and elucidation of their structures were performed by comparing changes in molecular masses (DeltaM), retention times and spectral patterns of product ions with those of the parent drug. As a result, six phase I metabolites, the parent drug palmatine and two phase II metabolites were identified in rat urine for the first time.

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A method based on a reversed-phase HPLC method was established, optimized, and validated for the separation and quantitation of 10 polyphenols extracted from the peel of apple species. A bidentate reversed-phase C18 column was used as stationary phase, and an acidified water buffer and methanol were used as mobile phase. The polyphenols were well separated and detected using UV at 280 and 320 nm. Validation parameters, such as linearity, LOD, LOQ, accuracy, and precision, were acceptable for all 10 polyphenols. The proposed method has enough linearity with correlation coefficient >0.99 within the investigated range for all tested polyphenols. The LOD was 0.24 μg/mL for ellagic acid and <0.2 μg/mL for all other polyphenols. The LOQ was 9.39 × 10(-2) μg/mL for chlorogenic acid, and ellagic acid, 2.82 × 10(-2) μg/mL for caffeic acid and >0.1 μg/mL for all other polyphenols. Recovery was within the acceptable range from 98.38 to 100.39% for all polyphenols standards. Satisfactory precision was achieved for both intra- and interday assay, with RSD <2%. The method was successfully applied for simultaneous analysis of polyphenols from apple peel.

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