Liquid chromatographic methods for assay of carbamazepine, 10,11-dihydrocarbamazepine, and related compounds in carbamazepine drug substance and tablets

Liquid chromatographic (LC) methods have been developed for the determination of carbamazepine, the impurity 10,11-dihydrocarbamazepine, and related compounds in carbamazepine drug substance and tablets. The LC methods specify a 5 micron diol column and a mobile phase of acetonitrile-methanol-0.05% aqueous acetic acid (5 + 5 + 90). Iminodibenzyl and iminostilbene, starting materials for some routes of synthesis, elute late in the LC system; therefore, a thin-layer chromatographic method for their detection at the 0.05% level has been developed. Eight tablet and 13 raw material samples from several sources were examined. The impurities most frequently found were 10, 11-dihydrocarbamazepine and a compound identified as 10-bromocarbamazepine at levels up to 1.3 and 0.5%, respectively; minimum detectable amounts were about 0.01 and 0.03%, respectively.     

Liquid chromatographic determination of pindolol and related compounds in raw materials

A liquid chromatographic method for the assay of pindolol and related compounds in the bulk drug has been developed. The method resolves 6 known and several unknown impurities from the drug and each other by using a nitrile column, an acetonitrile-sodium acetate buffer (35 + 65), and a UV detector set at 219 nm. Minimum quantifiable amounts of impurities are 0.02% or less relative to the drug. Ten lots of pindolol raw material were evaluated for purity and drug content. Total levels of impurities in these samples, quantitated against pindolol, ranged from about 0.03 to 0.24%. Assay results were within the range of 98.5 to 101.5%.     

Analysis of USP epinephrine injections for potency, impurities, degradation products, and d-enantiomer by liquid chromatography, using ultraviolet and electrochemical detectors

A liquid chromatographic (LC) method was adapted for the determination of epinephrine and related impurities in intravenous and cardiac injections; ultraviolet (UV) and electrochemical detectors (EC) were used in series. Epinephrine was determined and related impurities, i.e., adrenalone, epinephrine sulfonic acid, and norepinephrine, were detected directly in a small portion of the injection solution. Diastereoisomers of the epinephrine enantiomers were prepared by derivatization and determined by LC with a UV detector. The recovery of epinephrine added to epinephrine injection was 100%. The recovery of d-enantiomer from a d, l mixture was 100%. Impurities at levels less than 1% were easily detected. The LC method with UV detection is faster and more convenient than the USP XX method. In addition, impurities can be detected in the same portion of sample. The procedure is stability-indicating.     

基于机器视觉的水稻杂质及破碎籽粒在线识别方法

为了解决目前国内联合收获机缺乏针对含杂率、破碎率的在线监测装置的问题,该文提出基于机器视觉的水稻图像采集,杂质与破碎籽粒分类识别方法。采用带色彩恢复的多尺度Retinex算法增强原始图像,对HSV颜色模型的色调、饱和度两个通道分别设定阈值进行图像分割,并结合形状特征得到分类识别结果。采用综合评价指标对试验结果进行量化评价,研究表明,茎秆杂质识别的综合评价指标值达到了86.92%,细小枝梗杂质识别的综合评价指标值为85.07%,破碎籽粒识别的综合评价指标值为84.74%,平均识别一幅图像的时间为3.24 s。结果表明,所提出的算法能够快速有效识别出水稻图像中的杂质以及破碎籽粒,为水稻含杂率、破碎率的在线监测提供技术支撑。     

Liquid chromatographic determination of morphine sulfate and some contaminants in injections and bulk drug material

A liquid chromatographic (LC) procedure is described for the assay of morphine sulfate in bulk drug material and injection solutions. The bulk drug and injection samples are prepared by direct dilution with LC mobile solvent. The average bulk drug purity (5 manufacturers) determined by the LC method was 99.9% with a difference of 0.1% from the average purity (anhydrous) found by the official USP XX procedure. The average LC recovery (19 studies) of morphine sulfate added to injection samples was 99.4% with a coefficient of variation (CV) of 1.14%. Morphine sulfate content was determined in triplicate for 53 injection samples (1-15 mg morphine sulfate/mL) formulated by 6 manufacturers, using the proposed LC procedure. Individual sample CV (n = 3) averaged 1.14%. The LC method is simple and specific for morphine sulfate. Major degradation products, preservatives, and some contaminants and related compounds are separated during LC.     

Liquid chromatographic determination of prednisolone in tablets and bulk drugs: interlaboratory study

A normal phase liquid chromatographic (LC) method for the determination of prednisolone in tablets and bulk drugs was studied by 7 analysts. An LC system, consisting of a methanol-water-ethylene dichloride-acetic acid mobile phase and a silica column, was used to analyze bulk drugs, individual tablets, and composite samples. Analysts were supplied with 16 samples, including simulated formulations, composites of commercial tablets, intact tablets, and bulk drug substances. Results agreed with those obtained by the author. The coefficients of variation of the analysts' results ranged from 1.34% for bulk drugs to 2.14% for tablet composites. The LC method is suggested as an alternative to the official AOAC and USP XX blue tetrazolium colorimetric methods.     

Quantitative nuclear magnetic resonance (QNMR) spectroscopy for assessing the purity of technical grade agrochemicals: 2,4-dichlorophenoxyacetic acid (2,4-D) and sodium 2,2-dichloropropionate (Dalapon sodium)

Comparison of quantitative NMR spectroscopy (QNMR) with chromatographic methods such as gas chromatography (GC) or high-pressure liquid chromatography (HPLC) for the determination of the purity of and impurities in technical grade agrochemicals, 2,4-dichlorophenoxyacetic acid (2,4-D), 1, and Dalapon sodium (sodium 2,2-dichloropropionate), 10, has revealed that QNMR is more precise and accurate than the chromatographic methods. Quantitative impurity profiling of technical grade 1 is rapid and accurate using 600 MHz (1)H NMR. Extra dispersion at the relatively high frequency allowed full assignment of the NMR spectrum of 1 and its related organic impurities in technical samples. The percentage purity of 1 was measured by the difference QNMR method, which involves summing the amounts of impurities and subtracting from 100%. Results are superior in consistency to those obtained by chromatographic methods. The percentage purity of Dalapon sodium, 10, in technical grade batches is readily obtained by (1)H QNMR, using either the difference method or the internal standard method, using dimethyl sulfone (DMSO2) internally as a reference material, that is chemically unrelated to the analyte. The latter method also allows the simultaneous identification and quantification of impurities, many of which are either not accessible to or detectable by the chromatographic methods. Uncertainty budgets for the QNMR method are presented and demonstrate that the major contributors to uncertainty lie in the weighing of the chemicals and in purity of the standard reference material prior to the QNMR experiment.     

Liquid chromatographic determination of primidone in tablets: collaborative study

Six laboratories collaboratively studied a liquid chromatographic (LC) method for the quantitative determination of primidone in tablets. Two lots each of commercially prepared 50 and 250 mg tablets and 2 authentic mixtures, at 50 and 250 mg levels, were sent to each collaborator. Samples were dissolved in the mobile phase, filtered, and injected into the chromatograph. Average recoveries for the 8 samples ranged from 97.5 to 101.2%, and coefficients of variation ranged from 0.53 to 3.01%. The LC method has been adopted interim official first action.     

Liquid chromatographic determination of aflatoxin M1 in milk

The official AOAC method for aflatoxin M1 in milk was modified by replacing cellulose column chromatography with cartridge chromatographic cleanup and replacing thin layer chromatographic (TLC) determination with liquid chromatographic (LC) quantitation to yield a new method for bovine and porcine milk. An acetone extract of milk is treated with lead acetate and defatted with hexane, and M1 is partitioned into chloroform as in the AOAC method. Chloroform is removed by evaporation under a stream of nitrogen at 50 degrees C. The residue is dissolved in chloroform, the vessel is rinsed with hexane, and the 2 solutions are applied in sequence to a hexane-activated silica Sep-Pak cartridge. Less polar impurities are removed with hexane-ethyl ether, and M1 is eluted with chloroform-methanol, and determined by C18 reverse phase LC using fluorescence detection. Recoveries of M1 added to bovine milk at 0.25, 0.50, and 1.0 ng/mL were 90.8, 93.4, and 94.1%, respectively. The limit of detection was less than 0.1 ng M1/mL for both bovine and porcine milk.     

机采籽棉收购环节含杂率快速检测系统研制

籽棉收购过程中含杂率检测工序繁杂、劳动强度大、效率低,不利于籽棉的快速检测分级,严重影响籽棉收购效率。该研究开发了一种适于收购环节的机采籽棉含杂率快速检测系统。系统由驱动传输单元、压棉单元、传感单元、机器视觉系统、PLC控制系统组成。首先利用大杂清理机清除籽棉中的棉杆和铃壳等大密度杂质(大杂),对去大杂后的籽棉进行称量后送至机器视觉系统,采用RGB双面成像方法获取籽棉样本图像,分析计算图像中的杂质面积,预测去除大杂的籽棉含杂率和小杂质量,最后结合计算的大杂质量预测籽棉样本总含杂率。其中,RGB图像处理中使用同态滤波、主成分分析(Principal Component Analysis,PCA)变换和局部自适应阈值方法提升图像的可分割性;比较了线性回归(Linear Regression,LR)和支持向量机回归(Support Vector Regression,SVR)2种回归模型的准确率,确定较优的回归模型为LR,总含杂率决定系数R~2为0.95,均方根误差RMSE为0.58%,最后利用100个籽棉样品对系统性能进行验证,实测值与预测值之间平均绝对误差为0.36个百分点,单个样本含杂率检测程序处理时间为48.38 s。结果表明该系统具有较高的预测准确率和效率。     

Liquid chromatographic determination of sulfasalazine in tablets and bulk powder

A liquid chromatographic method has been developed that determines the amount of sulfasalazine in tablets and bulk powder in the presence of residual synthesis by-products and excipients. The method was tested on crude product containing large amounts of impurities. A C-18 reverse phase column with water-acetonitrile-acetic acid mobile phase was found to effectively separate the drug on the column. Six different commercial samples of 500 mg tablets were assayed. The results varied from 92.6 to 101.8% of the declared amount. Spectrophotometric determinations, which do not discriminate between the drug and impurities, gave 95.4-101.8% of declared. One commercial sample of bulk powder was assayed.     

Liquid chromatographic determination of spiramycin residues in chicken tissues

A liquid chromatographic (LC) method is described for determination of spiramycin residues in chicken muscles. The drug is extracted from muscles with acetonitrile, the extract is concentrated to 3-4 mL and rinsed with n-hexane followed by ethyl ether, and the drug is extracted with chloroform. LC analysis is carried out on a Zorbax BP-C8 column, and spiramycin is detected spectrophotometrically at 231 nm. Recoveries of spiramycin added to chicken muscles at 0.2 and 0.1 ppm were 93.9 and 89.0%, respectively. The detection limit was 5 ng for spiramycin standard, and 0.05 ppm in chicken muscles.     

Determination of diclofenac sodium and related compounds in raw materials and formulations

A liquid chromatographic method has been developed for determination of drug and related compounds in diclofenac sodium raw material, slow-release, and enteric coated tablets. The method specifies a 5 microns octadecylsilane bonded phase column, a mobile phase of tetrahydrofuran-acetonitrile-buffer, pH 5 (1 + 4 + 8.3), and detection at 229 nm. The method resolves 10 known related compounds with limits of quantitation of 0.2% or less. Seventeen drug raw material samples were evaluated. Total impurity levels ranged from 0.1 to 0.9%. The method has also been used for determination of drug content in raw materials and formulations. Mean assay levels in drug raw materials ranged between 98.3% and 101.8%.     

Liquid chromatographic method for analysis of elemental sulfur in pesticide formulations

A nonaqueous reverse-phase liquid chromatographic (LC) method has been developed to determine elemental sulfur in pesticide formulations. Samples were extracted in 50 mL of stabilized tetrahydrofuran (THF) by gentle swirling while sonicating for 1 min. A 5 microL aliquot was injected into the LC instrument equipped with a Vydac 218 TP 54 column. The mobile phase was methanol-acetonitrile-stabilized tetrahydrofuran (58.5 + 40 + 1.5). Sulfur was monitored at 280 nm. Retention time was approximately 5 min with total analysis time of 7 min. For 6 different products analyzed 12 times each, the coefficients of variations were all less than 3.5%. Purity of each sulfur peak was checked by using a photodiode array detector in the spectrum and absorbance ratio modes. No impurities were observed at the monitoring wavelength.     

Determination of ampicillin residues in fish tissues by liquid chromatography

A liquid chromatographic (LC) method is described for determination of ampicillin residues in fish tissues. The drug is extracted from tissues with methanol, and the extract is evaporated to dryness. This residue is cleaned up by Florisil cartridge chromatography. LC analysis is carried out on a Nucleosil C18 column, and ampicillin is quantitated by ultraviolet detection at 222 nm. Recoveries of ampicillin added to tissues at levels of 0.2 and 0.1 ppm were 73.2 and 61.5%, respectively. The detection limit was 3 ng for ampicillin standard, and 0.03 ppm in tissues.     

Sensitive determination of ethopabate residues in chicken tissues by liquid chromatography with fluorometric detection

A liquid chromatographic (LC) method is described for determination of ethopabate residues in chicken tissues. The drug is extracted from tissues with acetonitrile, and the extract is concentrated to 2-3 mL. This aqueous solution is rinsed with ethyl acetate and cleaned up by Florisil column chromatography. LC analysis is carried out on a Zorbax ODS column, and ethopabate is quantitated by using a fluorometric detector set at 306 nm (excitation) and 350 nm (emission). Recoveries of ethopabate added to chicken tissues at levels of 0.01 and 0.05 ppm were 87.8 and 92.7%, respectively. The detection limit was 100 pg for ethopabate standard, and 0.5 ppb in chicken tissues.     

Determination of olaquindox residues in swine tissues by liquid chromatography

A liquid chromatographic (LC) method is described for determination of olaquindox residues in swine tissues. The drug is extracted from tissues with acetonitrile, and the extract is evaporated to dryness. This residue is cleaned up by alumina column chromatography. LC analysis is carried out on a Nucleosil C18 column, and olaquindox is quantitated by ultraviolet detection at 350 nm. The average recoveries of olaquindox added to tissues at levels of 0.2, 0.1, and 0.05 ppm were 74.0, 68.6, and 66.3%, respectively. The detection limit was 2 ng for olaquindox standard and 0.02 ppm in tissues.     

Liquid chromatographic determination and identification tests for dexamethasone in bulk drugs and elixirs: collaborative study

A normal phase liquid chromatographic method for the determination of dexamethasone in bulk drugs and elixirs was collaboratively studied by 6 laboratories. The method uses a silica column, water-modified acetic acid-methanol-methylene chloride mobile phase, cortisone internal standard, and photometric detection at 254 nm. Collaborators were supplied blind duplicate samples of 3 bulk drugs, 2 commercial elixirs, and 1 authentic elixir. Dexamethasone elixir dosage level is 0.5 mg/5 mL. Mean recovery of dexamethasone from the authentic elixir formulated to contain 0.471 mg/5 mL was 94.5%. (Authentic elixirs were found to stabilize about 6% below the theoretical concentration.) Mean recovery for the bulk drugs was between 97.1 and 100.1%. Mean coefficients of variation for bulk drug and elixir samples were less than 0.8% and 3.6%, respectively. Identification tests for dexamethasone by thin-layer chromatography, infrared spectroscopy, and relative LC retention times, as well as the gas chromatographic determination of alcohol in the elixirs were also collaboratively studied. Mean recovery of alcohol from the synthetic elixir was 98.6%. The mean coefficient of variation for alcohol for all samples analyzed was less than 1.4%. The LC method for dexamethasone in drug substance and elixirs, the identification tests, and the GC method for alcohol in dexamethasone elixirs have been adopted official first action.     

Gas chromatographic methods for determination of gamma-BHC in technical emulsifiable concentrates and water-dispersible powder formulations and in lindane shampoo and lotion: collaborative study

Although the gas chromatographic separation of the isomers of BHC was demonstrated two decades ago, the present AOAC method of analysis of BHC for gamma-isomer (lindane) content is based on a separation carried out on a liquid chromatographic partition column. A method of analysis has been developed that uses an OV-210 column for separation of the gamma-isomer from the other isomers and impurities in technical BHC. Di-n-propyl phthalate was chosen as an internal standard. The same system allows quantitation of lindane in lotion and shampoo after these products are extracted with ethyl acetate-isooctane (1 + 4). The analytical methods were subjected to a collaborative trial with 10 laboratories. The coefficient of variation for technical BHC was 2.83%. For the water-dispersible powder and emulsifiable concentrate, the coefficients of variation were 2.89% and 4.62%, respectively. Coefficients of variation for 1% lindane lotion and shampoo were 4.36% and 11.92%, respectively. The method has been adopted official first action.     

Identification of a propantheline analog in propantheline bromide tablets

A major impurity in a sample of propantheline bromide tablets has been identified as 9-hydroxypropantheline on the basis of the proton magnetic resonance (PMR) and mass spectra (MS). This identification was confirmed by methanolysis of the tablet extract, which yielded a mixture of methyl xanthanoate and methyl 9-hydroxyxanthanoate. A liquid chromatographic (LC) procedure is described which will permit quantitation of 9-hydroxypropantheline bromide in the presence of propantheline bromide, xanthone, and xanthanoic acid.