Aim: To establish an HPLC method for the determination of secnidazole and its related substances, and to elucidate the structure of the main related substances. Methods: HPLC was performed on an Agilent C_(18) (150 mm × 4. 6 mm, 5 μm) column. The mobile phase consisted of acetonitrile and 0. 1% formic acid solution( 10 : 90). The detection wavelength was set at 320 nm and the column oven was maintained at 30 ℃. The mass spec-trometry detector was equipped with an ESI source with a temperature of 350 ℃, and set at positive ion monito-ring model The spray chamber pressure was 0. 34 MPa. The drying gas flow rate was 10 L/min. Results: Sec-nidazole was completely separated from the impurities. The calibration curve of secnidazole was linear over the range of 0. 10-1 500. 0 μg/mL with the correlation coefficient of 0. 999 9. The contents of secnidazole in the sam-ples were 100.5%, 100.3% and 100.7%, respectively, and those of the related substances were 0.463%, 0. 488% and 0.465%, respectively. The three related substances were identified by HPLC-UV-MS~n as 2-methyl-5-nitroimida-zole and the isomerides of secnidazole, respectively. Conclusion: The developed method is reliable for the quality control and determination of related substances of secnidazole.

An RP-HPLC method was established to separate the related substances of benzyl hydroxybenzoate.The separation was carried out on a Agilent ZORBAX Eclipse Plus Phenyl-Hexyl column.The mobile phase was methonal-0.1％ glacial acetic acid,using linear gradient elution,and the detection wavelength was 254 nm.There was a good linear relationship between 0.051-101.88 μg/mL (r =1.00) and 0.050-99.48 μg/mL(r =0.999 8) for benzyl hydroxybenzoate and p-hydroxybenzoic acid,repectively.The average recovery of p-hydroxybenzoic acid was 100.3％ and the RSD was 0.95％.The LOQ of p-hydroxybenzoic acid was 0.24 ng.The detected impurities were also identified by UPLC-Q-TOF.The established method is accurate and reproducible,and could be used for the quality control of benzyl hydroxybenzoate.

Due to the complex components of polysorbate 80, analysis is time-consuming and labor-intensive, so there is an urgent need to find a method for rapid analysis of polysorbate 80 components.In this study, 10 batches of samples collected from 3 domestic and foreign enterprises were analyzed by UHPLC-HRMS, with the being further results were analyzed by the ExcipientProfiler software and supplemented by the extended database.The results showed that the ExcipientProfiler software could quickly identify the [M+Na]+ peak in the mass spectrogram, and obtain the information of component distribution, the numbers of components and the degree of polymerization of the sample.Meanwhile, the numbers of components obtained by the ExcipientProfiler software could be used to distinguish the injection grade samples from the ordinary grade samples by systematic clustering analysis.In addition, it was found through further supplement that the sample contained other fatty acid ester components by manually searching the relevant extended database.The polyoxyethylene sorbitan tetraoleate components were found in the sample according to the analysis of mass spectrum data.Therefore, although this method is fast and simple, it is necessary to add polyoxyethylene sorbitan tetraoleate components and other fatty acid ester components to further supplement the information in the ExcipientProfiler software, so that it can be better used for the analysis of polysorbate 80.

This study was to evaluate quality consistency of domestic generic and reference preparations. Content and related substances of domestic generic preparations and reference preparation were inspected according to Chinese Pharmacopeia 2015. Then the basic solution for determining dissolution curve was established through preliminary experiment and validation for determination. The dissolution curves of domestic rifampicin capsules and reference preparation were compared in four dissolution mediums: HCl(pH 1. 2), PBS(pH 4. 0), PBS(pH 6. 8)and pure water, respectively. Results showed that the content and related substances of domestic generic and reference preparations complied with the quality standard, but impurity profile displayed that impurities in domestic generic preparations were less than those in the reference preparation, with the content of rifampin quinine being especially less. Furthermore, dissolution of domestic generic and reference preparations were compared, and their dissolution curves were not similar. It is suggested that consistency between domestic rifampicin capsules and reference preparation should be evaluated by bioequivalence test.

To establish a RP-HPLC method for the determination of content of sisomicin sulfate and sodium chloride injection. Thermo Aminoglycoside RP 18(4. 6 mm ×150 mm, 3 μm)column was used. The mobile phase consisted of Sodium heptane sulfonate solution(take 6 g of sodium heptane sulfonate, add 0. 1 mol/L potassium dihydrogen phosphate solution and dilute to 1 000 mL, adjust the pH to 1. 5 with phosphoric acid)- acetonitrile(77∶23). The detection wavelength was 205 nm, the flow rate was 1. 0 mL/min. and the column temperature was 35 °C. The separation of sisomicin peaks with related substances and the degradation products was good. The linear range of the peak area with sisomicin was 0. 010 024-1. 002 4 mg/mL(Y=4. 210 2×106 X+9. 107 0×103, r=0. 999 9, n=7), the detection limit was 0. 6 ng, the limit of quantification was 2 ng, and the recovery rate was at 99. 1%-100. 9%(RSD< 1. 0%, n=9). The method is sensitive, exclusive, accurate and suitable for the determination of sisomicin. Compared with the antibiotic microbiological test method, the specificity is better, the confidence interval of the result is narrowed, and the test time is saved.

The UPLC fingerprint of colistimethate sodium was established for the study of quality consistency.The chromatographic column was Acquity UPLC? Peptide CSH C18 (2.1 mm × 150 mm, 1.7 μm).The mobile phase A was phosphate buffer-acetonitrile (19∶1), and the mobile phase B was phosphate buffer-acetonitrile (1∶1).The mobile phase was in gradient elution at a flow rate of 0.3 mL/min.The column temperature was set at 30 °C and the detection wavelength was 210 nm.The similarity of the fingerprints was analyzed with the Similarity Evaluation System for Chromatographic Fingerprint of Tradition Chinese Medicine (Version 2012) in combination with content determination of multiple index components to evaluate the quality consistency of imported and domestic bulk drugs.The result showed that both the original and generic bulk drugs met the specified limit requirements in the European Pharmacopoeia standards, and that their UPLC fingerprints were highly similar, indicating that the quality of the two substances was consistent.Establishing a fingerprint for similarity evaluation and combining it with the results of indicator component content determination as a comprehensive evaluation method for the study of drug quality consistency of complex components has the characteristics of fast, accurate, and comprehensive, which is helpful for drug quality evaluation and provides ideas for the evaluation of antibiotic quality consistency of complex components.

Abstract: This study aims to find out the causes for the dissolution of unqualified samples found during evaluation sampling of lansoprazole enteric-coated preparations by the laser infrared imaging system and orbitrap high resolution mass spectrometry, with suggestions for improvement. Lansoprazole enteric-coated preparations were tested by current standard, the dissolution of a batch of samples was below the limit and other items were in line with the standard. Considering that this product is unstable to acid and alkali, the following exploratory experiments were designed from different dimensions, based on the conclusion of the unannounced inspection of the company, to explore the reasons for the unqualified batch, including the influence of high-temperature and high-humidity storage environment on the key quality properties of the sample, the influence of 2-hour acid resistance test on dissolution result, the imaging of the core and the measure of coating layer thickness, the optimization of chromatographic conditions of related substances, and the analysis of the source of impurities. It was found that improper storage in circulation and poor coating process caused the low dissolution of this batch: the high-temperature and high-humidity storage environment possible in the circulation process led to the decreasing efficacy of disintegrating agent in the samples and thus the difficulty to release the active pharmaceutical ingredient fully; the coating solution could not be uniformly sprayed on the core, resulting in thin isolation layer and different thickness, which then affected the protection of the main drug against acid degradation. The above two reasons together resulted in unqualified dissolution of this batch. The overall quality of lansoprazole enteric-soluble preparation is good, but the formulation and process in some companies need to be optimized; and the temperature and humidity in the circulation process need to be controlled in strict accordance with the regulations.

A novel method was developed for the content assay and related substances determination of neomycin sulfate by high performance liquid chromatography combined with pulsed amperometric detection(HPLC-PAD). The HPLC was performed on Thermo AcclaimTMAmG C18(4. 6 mm×150 mm, 3 μm). The mobile phase consisted of aqueous solution with 2% trifluoroacetic acid containing 0. 01% pentafluoropropionic acid and 0. 6%NaOH. The pulsed amperometric detector was operated with aquadruple-potential waveform for the detection. Neomycin B, Neomycin C and thirteen related substances were adequately separated by the established HPLC conditions. The limits of detection(LOD)and quantification(LOQ)of neomycin B and neomycin C were both 1. 75 ng and 3. 5 ng, respectively. Good linearities of neomycin B and neomycin C were found in their respective ranges which their correlation coefficients were greater than 0. 998 5. The established method is characterized by high specificity, sensitivity and wide range of linearity which has a good application prospect and provides the basis for improving the standard and quality control of neomycin sulfate.

This study aimed to isolate and prepare highly purified impurity C from doxycycline hyclate by a preparative HPLC method and to inspect the toxicity and in vitro antimicrobial activity of the impurity C of doxycycline hyclate. The solution of doxycycline hyclate treated with heat produced a solution containing 10% of impurity C which was firstly separated by the Sapphire C18(21. 2 mm×250 mm, 5 μm)column with 0. 1% acetic acid-acetonitrile(83 ∶17)as the mobile phase at 20 mL/min. Secondly, rotary evaporation of the eluted solution at the time of 8. 4 min was performed at 50 °C to remove organic solvent. Then the target product was prepared after freeze drying of evaporated solution adjusting pH to 1. 8 with formic acid. The target product was identified with ultraviolet absorbance(UV), infrared(IR), mass spectrometry(MS)and nuclear magnetic resonance(NMR), and its purity was be determined by HPLC. Meanwhile, cytotoxicity and genotoxicity in the Chinese hamster lung cells, toxicity on the development of zebrafish embryos and in vitro antimicrobial activity were compared among impurity C of doxycycline hyclate, doxycycline, metacycline and β-doxycycline. Results showed that prepared product was confirmed to be the impurity C of doxycycline hyclate. Its purity was 90. 1%, which had been the highest so far. In the cellular toxic tests and genetic toxic tests of Chinese hamster lung cells, impurity C of doxycycline hyclate, doxycycline, metacycline and β-doxycycline were somewhat toxic to Chinese hamster lung cells. Toxicity gradually decreased from doxycycline, impurity C of doxycycline hyclate, β-doxycycline to metacycline from -S9mix test results; toxicity gradually decreased from doxycycline, β-doxycycline, impurity C of doxycycline hyclate to metacycline from +S9mix test results; the aberration rate of all the tested related substances was less than 5%, and no obvious genotoxicity was found. According to test results of the development of zebrafish embryos, impurity C of doxycycline hyclate showed the strongest teratogenicity and lethality. Invitro antimicrobial tests revealed that impurity C of doxycycline hyclate had a weaker antimicrobial activity, and invitro antimicrobial activity potential of the tested compounds followed the order: metacycline, doxycycline, impurity C of doxycycline hyclate, β-doxycycline. Studies on safety and effectiveness indicated that impurity C of doxycycline hyclate belonged to toxic and ineffective impurity and need to be controlled individually in quality standard. A useful suggestion was given to revise the quality standard of doxycycline hyclate and its preparation in the current Pharmacopoeia of the People′s Republic of China.

Using high performance liquid chromatography and high resolution orbital trap mass spectrometry, a two-dimensional online desalting detection method was established to determine the structure of the impurities detected under the official testing conditions of lansoprazole enteric solution preparation, and a chromatographic method compatible with mass spectrometry was established to determine and presume the structure of the impurities that could not be separated by the the official testing method.The identification of impurity was to presume its structure according to the presence of impurity reference product, so as to investigate the difference of impurity spectrum of products from different manufacturers.The one-dimensional chromatographic conditions for the 2D online desalting method were the same as those in China Pharmacopoeia (2020) under relevant substances.Two-dimensional chromatography was performed on a Waters C18 T3 column (2.1 mm × 100 mm, 1.7 μm) with 0.1% formic acid in water-acetonitrile mobile phase and gradient elution.The chromatographic conditions for the compatible mass spectra were based on an Agilent Extend C18 (4.6 mm × 150 mm, 5 μm) column with mobile phase A: 25 mmol/L ammonium acetate and B: 25 mmol/L ammonium acetate-acetonitrile (1∶4) [pH adjusted to 6.5 with glacial acetic acid], with gradient elution. Nine impurities were detected by two-dimensional online desalting method, with 5 known impurities (A-E) and 4 unknown ones.14 impurities were detected by the compatible mass spectrometry method, with 9 unknown impurities (4 consistent with the results of two-dimensional online desalting method, and 5 newly detected).The structures and sources of the unknown impurities were deduced.The two detection methods of lansoprazole preparation by high-performance liquid chromatography-high resolution orbital trap mass spectrometry have guiding significance for quality control and process evaluation.