Determination, Isolation, and Identification of Related Impurities in Erdosteine Bulk Drug.

BACKGROUND: Erdosteine is a mucolytic drug and has antioxidant activity. OBJECTIVE: The study aimed to develop an HPLC method for determination of erdosteine and its impurities in erdosteine bulk drug and to identify the main impurities to help improve the quality of erdosteine bulk drug. METHOD: The chromatographic separations were performed on a CAPCELL PAK C18 column (250 mm × 4.6 mm id, 5 µm). Acetonitrile-0.01 mol/L citric acid solution (13 + 87, by volume) pumped at a flow rate of 1.0 mL/min was used as the mobile phase. The detection wavelength was 254 nm. Two main impurities in erdosteine bulk drug were enriched by an ODS column chromatography and oxidative degradation, respectively, and then both were purified by semipreparative HPLC. Finally, their structures were identified by a variety of spectral data (MS, 1H NMR and 13C NMR). RESULTS: Good separations of erdosteine and its related impurities were observed. A new impurity was confirmed as ethyl ({2-oxo-2-[(2-oxotetrahydro-3-thiophenyl) amino] ethyl} sulfanyl)acetate, which was erdosteine ethyl ester, and was produced in the refining process of erdosteine bulk drug when using ethanol as a refining solvent. Another impurity was confirmed as ({2-oxo-2-[(2-oxotetrahydro-3-thiophenyl)amino]ethyl}sulfinyl) acetic acid, which was an erdosteine oxide. CONCLUSIONS: An HPLC method for determination of erdosteine and its related impurities was developed and validated. Two main impurities in erdosteine bulk drug were isolated and identified. Avoiding ethanol as the refining solvent can improve the purity of erdosteine bulk drug. HIGHLIGHTS: A new process-related impurity and an oxidative degradation impurity in erdosteine bulk drug were isolated and identified.

Development and Validation of a Sensitive GC-MS/MS Method for the Determination of Five Potential Genotoxic Impurities in Abiraterone Acetate.

A sensitive and selective gas chromatography-tandem mass spectrometry method was developed for the identification and quantification of five potential genotoxic impurities (PGIs), i.e., chloromethane, 2-chloropropane, 2-bromopropane, 4-chloro-1-butanol and diethyl sulfate, in abiraterone acetate. The method was validated according to the International Council for Harmonisation (ICH) guidelines. The linearity was established for the concentration range of 30-480 ng/mL (2-chloropropane, 2-bromopropane, 4-chloro-1-butanol and diethyl sulfate) and 90-1440 ng/mL (chloromethane). The correlation coefficient of each PGIs was >0.995. The extraction recoveries ranged from 90.49 to 106.79% for the five PGIs. The quantitation limit, detection limit, accuracy, precision, repeatability and stability of the method demonstrated that the method was an adequate quality control tool for quantitation and identification of chloromethane, 2-chloropropane, 2-bromopropane, 4-chloro-1-butanol and diethyl sulfate at trace levels in drug substances and drug products.

Identification and quantification of five impurities in cloperastine hydrochloride.

Cloperastine hydrochloride, a piperidine derivative, is a drug substance with a central antitussive effect and widely used in cough treatment; and its impurities have not been reported. Herein we isolated and identified five impurities (named as impurity A, B, C, D and E) in cloperastine hydrochloride bulk drug and developed a quantitative HPLC method. First, impurity A, B, C were enriched by ODS column chromatography and isolated by semi-preparative HPLC, at the same time, impurity D was purified by ODS column chromatography. Then, impurity E was enriched by strong acid degradation and purified by semi-preparative HPLC. At last, their structures were characterized by a variety of spectral data (MS, 1H NMR, 13C NMR, HSQC, HMBC and 1H-1H COSY). Impurity A was confirmed as 1-[2-(diphenylmethoxy)ethyl]piperidine, which having one less chloro-substituent compared with cloperastine. Impurity B was confirmed as 1-[2-[(2-chlorophenyl)(phenyl)methoxy]ethyl]piperidine, which was the isomer of cloperastine with 2-chloro-substituent. Impurity C was confirmed as 1-[2-[(3-chlorophenyl)(phenyl)methoxy]ethyl]piperidine, which was the isomer of cloperastine with 3-chloro-substituent. Impurity D was confirmed as (4-chlorophenyl)(phenyl)methanone, which was the raw material for the synthesis of cloperastine. Impurity E was confirmed as (4-chlorophenyl)(phenyl)methanol, which was an intermediate in the synthesis of cloperastine, and it was also a hydrolysate of cloperastine. Finally, the developed method was validated in terms of specificity, linearity, sensitivity, precision and accuracy.

Structural Identification and Conversion Analysis of Malonyl Isoflavonoid Glycosides in Astragali Radix by HPLC Coupled with ESI-Q TOF/MS.

In this study, four malonyl isoflavonoid glycosides (MIGs), a type of isoflavonoid with poor structural stability, were efficiently isolated and purified from Astragali Radix by a medium pressure ODS C18 column chromatography. The structures of the four compounds were determined on the basis of NMR and literature analysis. Their major diagnostic fragment ions and fragmentation pathways were proposed in ESI/Q-TOF/MS positive mode. Using a target precursor ions scan, a total of 26 isoflavonoid compounds, including eleven malonyl isoflavonoid glycosides coupled with eight related isoflavonoid glycosides and seven aglycones were characterized from the methanolic extract of Astragali Radix. To clarify the relationship of MIGs and the ratio of transformation in Astragali Radix under different extraction conditions, two MIGs (calycosin-7-O-glycoside-6″-O-malonate and formononetin-7-O-glycoside-6″-O-malonate) coupled with related glycosides (calycosin-7-O-glycoside and formononetin-7-O-glycoside) and aglycones (calycosin and formononetin) were detected by a comprehensive HPLC-UV method. Results showed that MIGs could convert into related glycosides under elevated temperature conditions, which was further confirmed by the conversion experiment of MIGs reference compounds. Moreover, the total contents of MIGs and related glycosides displayed no obvious change during the long-duration extraction. These findings indicated that the quality of Astragali Radix could be evaluated efficiently and accurately by using the total content of MIGs and related glycosides as the quality index.