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??OBJECTIVE To establish a gradient elution method for determination of related substances of azithromycin for injection. METHODS Gradient elution was used for the analysis. A C₁₈ (CAPCELL PAK MG??, 4.6 mm??250 mm,5 ??m)column was used. The mobile phase A consisted of 0.05 mol??L^-1 K₂HPO₄ solution (pH 8.2, adjusted with 20% phosphoric acid)-acetonitrile (45??55), and the mobile phase B was methanol. The flow rate was 1.2 mL??min^-1, and the detection wavelength was set at 210 nm. The column temperature was maintained at 30 ??. The gradient elution program was as follows: 0-35 min, A:75%??95%; 35-64 min, A:75%; 64-65 min, A:95%??75%; 65-71 min, A:75%. RESULTS Azithromycin, near peaks and known impurities were well separated from each other. All acid radicals of azithromycin for injection did not influence the determination of related substances of azithromycin. CONCLUSION This method is more specific than the exising method for determination of related substances of azithromycin, which can more effectively control the quality of the drug.     

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??OBJECTIVE To establish a qualitative and quantitative HPLC method for the determination of impurity ??in tebutaline sulfate.METHODS The Kromasil C₁₈column(4.6 mm??150 mm,5 ??m)was used as the analysis column;buffer solution [dissolving 4.23 g of sodium hexanesulfonate in 770 mL of 0.050 mol??L^-1 ammonium formate solution (pH 3)]-methanol (77:23) was used as the mobile phase. The flow rate was 1.0 mL??min^-1, the column temperature was maitained at 30 ??, the detection wavelength was set at 276 nm,and the injectiong volume was 20 ??L.Area normalization method with correction factor was used for the quantitative analysis of the impurity ??. RESULTS Under the separation condition,the impurity ?? was completely separated from the principal components. The calibration curve showed good linearity in the concentration range of 0.10-579 ??g??mL^-1(r??1.000 0). The correction factor was 3.6.CONCLUSION The area normalization method with correction factor developed in the paper can be used for the qualitative and quantitative analysis of the impurity ??in terbutaline sulfate,which can not only solve the problem of the availability of impurity reference standards,but also reflect the actual contents of impurity.The method provides an efficient and convenient method for quality control of terbutaline sulfate.     

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??OBJECTIVE To establish a quantitative method for determining the contents of uracil, cytidine, hypoxanthine, xanthine, uridine, inosine, and guanosine in Holotrichia diomphalia Larvae by HPLC. METHODS The HPLC analysis was performed on Waters HSS T3 column(4.6 mm??250 mm, 5 ??m). The mobile phase was composed of acetonitrile(A) and water(B), and gradient elution was carried out. The flow rate was 1.0 mL??min^-1. The column temperature was maintained at 30 ??. The detection wavelength was 260 nm. RESULTS The correlation coefficients of the seven components ranged from 0.999 1 to 1.000 0. The average recovery rates(n=6) were between 91.2% and 97.4%, and the RSDs were between 1.5% and 2.3%. CONCLUSION The proposed method is simple, accurate and reliable, thus providing basis for comprehensive quality control of Holotrichia diomphalia Larvae.     

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??OBJECTIVE To establish an HPLC-MS/MS method to identify the unknown impurities in polymyxin B sulfate. METHODS The analysis was performed on Agilent 1260-6550 Q/TOF-MS with a Diamonsil Plus C₁₈ column(4.6 mm??250 mm, 5 ??m). Mobile phase A was 0.01 mol??L^-1 trifluoroacetic acid-acetonitrile(95??5), and mobile phase B was acetonitrile containing 0.1% formic acid. Mobile phase A and B were set at the volume ratio of 79??21 at a flow rate of 1 mL??min^-1 under isocratic elution. The detection wavelength was set at 254 nm. ESI source was used. Positive ion scanning was conducted in the range of m/z 50-1 700 for MS and MS/MS. The unknown components were identified by comparing the MS and MS/MS with the known reference standards like polymyxin B₁ and B₂. The photochemical Paterno-B??chi reaction was performed using a low-pressure mercury lamp as the light source at emission wavelength of 254 nm with acetone/water(50/50, V/V) as the reaction solvent. RESULTS The structures of seven unknown related substances in polymyxin B sulfate were identified. The most abundant impurity was identified to be vinyl polymyxin B₁, for which the double bond was at the end of the fatty acyl residue. CONCLUSION Vinyl polymyxin B₁ is reported for the first time. The method provides a good idea for the identification of related substances in drugs.     

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??OBJECTIVE To establish an HPLC-UV-ESI-MSⁿ method for the study of impurity profile of amoxicillin and clavulanate potassium tablets. METHODS Agilent 1100 LC/MSD Trap liquid chromatography-mass spectrometry was used, and the column was Shim pack CLC-ODS RP18(4.6 mm??250 mm, 5 ??m). The mobile phase A was 20 mmol??L^-1 ammonium acetate (pH adjusted to 6.0), and the mobile phase B was 20 mmol??L^-1 ammonium acetate-acetonitrile (20??80) (pH adjusted to 6.0). Gradient elution was performed at a flow rate of 1.0 mL??min^-1. ESI source was used. Positive and negative ion scan was conducted with a scanning range of m/z 100-1 500. The nebulizing pressure was 275.8 kPa, dry gas flow was 9 L??min^-1, and post-column diversion ratio was 1??5. Some related substances were identified by comparing the retention time in the chromatography, [M+H]⁺ spectrum and MS² spectrum with those of the reference substances, while the others which do not have reference substances were deduced or speculated by analyzing the MS² or MSⁿ fragmentation with the help of a rule summarized from the MS² fragmentation of amoxicillin, clavulanic acid and system suitability impurity reference substances. RESULTS A total of 15 related substances were separated and characterized including nine known impurities like amoxicilloic acid, amoxicillin dimer, etc. and six unknown impurities. CONCLUSION The method can be applied in the identification and qualitative analysis of the related substances in amoxicillin and clavulanate potassium tablets and is helpful for the quality control and optimization of the synthetic process.     

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??OBJECTIVE To establish the HPLC fingerprints of Fructus Aristolochiae and honey-fried products from different habitats, compare and analyze their difference in chemical components. METHODS Using an Agilent ZORBAX SB-C₁₈ column (4.6 mm??250 mm, 5 ??m), HPLC method was performed to collect the fingerprints. The mobile phase A and B were acetonitrile and 1% acetic acid, respectively. Gradient elution was performed at the flow rate of 1.0 mL??min^-1 and column temperature of 30 ??. The detection was carried out at 250 nm. Similarity Evaluation System for Chromatographic Fingerprint of TCMs (Ver. 2012) and SPSS22.0 was used in cluster analysis and principal component analysis (PCA). RESULTS The fingerprints of 14 batches of Fructus Aristolochiae samples, before and after process, were established by HPLC. The reduction rate of AA I, a poisonous component, was over 36%. Except for S4 (0.822), S18 (0.771) and S19 (0.639), the similarities of Fructus Aristolochiae and processed products were over 0.9. The non-processing samples were classified into four groups by cluster analysis. As PCA shown, the five principal components including AA I had a contributing rate of 84.914% to cumulative sum of squares, illustrating the chemical similarity and difference of samples from different areas. CONCLUSION The results may provide reference for Fructus Aristolochiae processing and standardization of its detoxification technology.     

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??OBJECTIVE To develop a method for simultaneous determination of six iridoid glycosides from Cymbaria dahurica.METHODS Cymbaria dahurica collected from different regions were determined by HPLC. The separation was performed on Inertsil ODS-SP column (4.6 mm??250 mm,5 ??m) at 30 ?? by gradient elution with CH₃OH-H₂O as the mobile phase, with the detection wavelength set at 210 nm.RESULTS Under the chromatographic conditions adopted in this study, all the calibration curves exhibited good linearity (r>0.999 4) in a relatively wide concentration range. The recovery of the method was within the range of 95.0%-98.0%, and the RSD was less than 3%. The contents of all the compounds (S1-S6) in samples from different habitats varied significantly.CONCLUSION The quantitative method for evaluating the quality of Cymbaria dahurica is established and can be used for the quality control of Cymbaria dahurica.     

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??OBJECTIVE To establish an HPLC method to determine the related substances of vortioxetine hydrobromide and identify the degradation products of vortioxetine hydrobromide by HPLC-MS. METHODS An HPLC method was developed by using a CN column(Agilent Zorbax SB-CN,4.6 mm??250 mm, 5 ??m),the mobile phase consisted of CH₃CN-HCOONH₄(50??50, pH adjusted to 5.0 with phosphoric acid),the flow rate was 1.0 mL??min^-1, and the detection wavelength was set at 228 nm. The column temperature was maintained at 25 ??, and the injection volume was 20 ??L. RESULTS Vortioxetine hydrobromide was well separated from the related substances. The detection sensitivity of vortioxetine hydrobromide and its related substances met the determination requirements. The calibration curves of vortioxetine hydrobromide and related substances had good linearity. The repeatability of the method was good(RSD=6.89%, n=6). The average recoveries of the sample were all within 95%-105%. The degradation product produced by oxidation was identified by mass spectrometry as related substance D. CONCLUSION The developed method proves to be simple,accurate,specific and reliable. It can be applied to the determination of vortioxetine hydrobromide and its related substances.     

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??OBJECTIVE To establish a method for quantitative analysis of the impurities in vardenafil hydrochloride orally disintegrating tablets.METHODS Gradient elution at the flow rate of 1.0 mL??min^-1 was used for the determination of known impurities A-E and the unknown impurities simultaneously. The separation was performed on Athena C₁₈-WP column (4.6 mm??250 mm,5 ??m) with acetate solution containing 0.8 g ammonium acetate in 900 mL of water-acetonitrile (90??10) as mobile phase A and acetate solution containing 0.8 g ammonium acetate in 100 mL of water-acetonitrile (10??90) as mobile phase B. The UV detection was carried out at 245 nm, and the column temperature was maintained at 40 ??. RESULTS After being treated with oxidation, heat, and light, vardenafil underwent more or less degradation. The degradation products were effectively separated and detected using this method.Meanwhile, the method showed good specificity, linearity, and ruggedness. CONCLUSION The method is selective, sensitive, and accurate, and it is suitable for the quality control of vardenafil hydrochloride orally disintegrating tablets.     

氟康唑原料药有关物质的研究

 目的 建立高效液相色谱梯度法测定氟康唑原料药的有关物质。方法 采用十八烷基硅烷键合硅胶为填充剂,流动相A为0.01 mol·L^-1甲酸铵,流动相B为乙腈,梯度洗脱,流速为0.5 mL·min^-1, 检测波长为261 nm, 进样量为20 μL。结果 降解产物和杂质在该色谱条件分离良好, 氟康唑与杂质Ｂ～Ｄ在2.632～21.06、2.688～53.76、0.853 6～21.34、2.595～20.76 μg·mL^-1之间线性关系良好,检测限分别为0.20、0.005 2、0.007 3、0.13 μg·mL^-1,对来自9个厂家17批氟康唑原料药（含国外5批）进行了测定,各杂质能有效检出。结论 该方法简便、快速、灵敏、准确,可用于测定氟康唑原料药的有关物质。