Enantiomeric Separation and Quantitative Determination of Propranolol in Tablets by Chiral High-Performance Liquid Chromatography

This work reports an application of chiral high-performance liquid chromatography (HPLC) in the separation and quantitative determination of propranolol isomers in tablets. The isomers were separated using a Chiralcel OD® column (250 × 4.6 mm, 10 μm) with a mobile phase of hexane:ethanol (75:25 v/v) at a flow rate of 0.7 ml/min and ultraviolet detection at 280 nm. The coefficient of variation and average recovery of (R)-isomer for samples A, B, C, and D were 0.72% and 100.30%, 0.67% and 99.40%, 0.62% and 99.76%, and 0.70% and 99.68%, respectively. The coefficient of variation and average recovery of (S)-isomer for samples A, B, C, and D were 0.74% and 99.62%, 0.64% and 100.27%, 0.71% and 99.99%, and 0.70% and 99.72%, respectively.     

Enantiomeric Separation and Quantitative Determination of Atenolol in Tablets by Chiral High-Performance Liquid Chromatography

The separation and quantitative determination of atenolol isomers by chiral high-performance liquid chromatography (HPLC) are described. Atenolol isomers were separated using a Chiralcel OD® column (250 × 4.6 mm,10 μm); the mobile phase was hexane-ethanol-diethylamine (75:25:0.1 v/v/v); ultraviolet detection was at 276 nm; and flow rate was 0.7 ml/min. The coefficient of variation and average recovery of (R)-isomer were 0.60% and 100.37%, respectively, for sample A and 0.69% and 100.63%, respectively, for sample B. The coefficient of variation and average recovery of (S)-isomer were 0.59% and 100.33%, respectively, for sample A and 0.63% and 99.78%, respectively, for sample B.     

Enantiomeric separation and quantitative determination of atenolol in tablets by chiral high-performance liquid chromatography

The separation and quantitative determination of atenolol isomers by chiral high-performance liquid chromatography (HPLC) are described. Atenolol isomers were separated using a Chiralcel OD® column (250 × 4.6 mm,10 μm); the mobile phase was hexane-ethanol-diethylamine (75:25:0.1 v/v/v); ultraviolet detection was at 276 nm; and flow rate was 0.7 ml/min. The coefficient of variation and average recovery of (R)-isomer were 0.60% and 100.37%, respectively, for sample A and 0.69% and 100.63%, respectively, for sample B. The coefficient of variation and average recovery of (S)-isomer were 0.59% and 100.33%, respectively, for sample A and 0.63% and 99.78%, respectively, for sample B.     

Determination of Steroid Hormones in Oral Contraceptives by High-Performance Liquid Chromatography

ABSTRACT

The aim of this research was to standardize a high-performance liquid chromatographic method for quantitative determination of steroid hormones, like ethinylestradiol (ETE), levonorgestrel (LEVO), and gestodene (GEST), in commercially available oral contraceptives (OCs). The combination ETE– LEVO was analyzed using a LiChrospher® 100 RP-8 column (5 μm, 125×4 mm) in LiChroCART®, with a mobile phase constituted of acetonitrile: water (60:40 v/v). Using the same column, ETE–GEST was analyzed with a mobile phase constituted of acetonitrile:water (50:50 v/v) at pH 7.5 adjusted with 0.02 M ammonium hydroxide. For both methods, a flow rate of 0.8 mL/min was utilized and detection was carried out at 215 nm. All analyses were performed at room temperature (24±2°C).

Calibration curves for ETE–LEVO were obtained using solutions with concentration ranges from 2.40 to 60.0 μg/mL (ETE), and from 12.0 to 300.0 μg/mL (LEVO). Calibration curves for ETE–GEST were obtained using solutions with concentration ranges from 2.40 to 60.0 μg/mL (ETE), and from 9.0 to 160.0 μg/mL (GEST). Correlation coefficients obtained were from 0.9999 to 0.9990. Coefficients of variation for samples containing ETE–LEVO were 0.47% and 0.38%, respectively. For samples with ETE–GEST they were 0.39% and 0.44%, respectively. The average recovery for samples with ETE–LEVO was 103.46% and 100.78%, respectively. For samples containing ETE–GEST it was 100.89% and 101.03%, respectively.     

Determination of steroid hormones in oral contraceptives by high-performance liquid chromatography

The aim of this research was to standardize a high-performance liquid chromatographic method for quantitative determination of steroid hormones, like ethinylestradiol (ETE), levonorgestrel (LEVO), and gestodene (GEST), in commercially available oral contraceptives (OCs). The combination ETE- LEVO was analyzed using a LiChrospher® 100 RP-8 column (5 μm, 125×4 mm) in LiChroCART®, with a mobile phase constituted of acetonitrile: water (60:40 v/v). Using the same column, ETE-GEST was analyzed with a mobile phase constituted of acetonitrile:water (50:50 v/v) at pH 7.5 adjusted with 0.02 M ammonium hydroxide. For both methods, a flow rate of 0.8 mL/min was utilized and detection was carried out at 215 nm. All analyses were performed at room temperature (24±2°C).

Calibration curves for ETE-LEVO were obtained using solutions with concentration ranges from 2.40 to 60.0 μg/mL (ETE), and from 12.0 to 300.0 μg/mL (LEVO). Calibration curves for ETE-GEST were obtained using solutions with concentration ranges from 2.40 to 60.0 μg/mL (ETE), and from 9.0 to 160.0 μg/mL (GEST). Correlation coefficients obtained were from 0.9999 to 0.9990. Coefficients of variation for samples containing ETE-LEVO were 0.47% and 0.38%, respectively. For samples with ETE-GEST they were 0.39% and 0.44%, respectively. The average recovery for samples with ETE-LEVO was 103.46% and 100.78%, respectively. For samples containing ETE-GEST it was 100.89% and 101.03%, respectively.     

Simultaneous determination of thiabendazole and mebendazole in tablets by high-performance liquid chromatography

Reversed-phase high performance liquid chromatography using an RP 18 column (4 × 125 mm), tetrahydrofuran-acetonitrile-0.5% formic acid (5:25:70, v/v/v) as mobile phase and UV detection at 254 nm enabled the simultaneous determination of thiabendazole (TZ) and mebendazole (MZ) in tablets. The method showed linearity over 4.0 to 40.0 μg TZ/ml and 6.0 to 60.0 μg MZ/ml. The correlation coefficient r was .9999 for both TZ and MZ. The coefficient of variation (CV) was 0.59-0.80% for TZ and 0.49-0.67% for MZ. The average recovery was 100.54-101.17% for TZ and 100.35-101.13% for MZ. The excipients of the tablets did not interfere in the proposed method. The developed method is precise, accurate, and selective for the determination of both benzimidazoles analyzed.     

Simultaneous Determination of Thiabendazole and Mebendazole in Tablets by High-Performance Liquid Chromatography

Reversed-phase high performance liquid chromatography using an RP 18 column (4 × 125 mm), tetrahydrofuran–acetonitrile–0.5% formic acid (5:25:70, v/v/v) as mobile phase and UV detection at 254 nm enabled the simultaneous determination of thiabendazole (TZ) and mebendazole (MZ) in tablets. The method showed linearity over 4.0 to 40.0 μg TZ/ml and 6.0 to 60.0 μg MZ/ml. The correlation coefficient r was. 9999 for both TZ and MZ. The coefficient of variation (CV) was 0.59–0.80% for TZ and 0.49–0.67% for MZ. The average recovery was 100.54–101.17% for TZ and 100.35–101.13% for MZ. The excipients of the tablets did not interfere in the proposed method. The developed method is precise, accurate, and selective for the determination of both benzimidazoles analyzed.     

Determination of hydroxytyrosol in plasma by HPLC

Hydroxytyrosol (2-(3,4-dihydroxyphenyl)ethanol), a phenolic compound present in extravirgin olive oil, has been reported to contribute to the prevention of cardiovascular disease. The present study describes an accurate and reproducible reversed-phase HPLC method to measure hydroxytyrosol in plasma. This compound was extracted from acidified plasma by solid-phase extraction using an Oasis HLB copolymer. The plasma sample was rinsed with water and methanol in water (5:95; v/v). Hydroxytyrosol was eluted with methanol, which was subsequently evaporated under a nitrogen stream. Analysis by HPLC with diode array-UV detection was carried out using a C18 column and a gradient elution with acidified water and methanol/acetonitrile (50:50; v/v). The method was validated by the analyses of plasma samples spiked with pure hydroxytyrosol, obtaining a linear correlation (0.9986) and precision with a coefficient of variation ranging from 0.79 to 6.66%. The recovery was approximately 100%, and the limit of detection was 37 ng/mL. The oral administration of hydroxytyrosol to rats and its subsequent detection in plasma showed that the method is suitable for pharmacokinetic studies.     

高效液相色谱测定福龙口服液中的腺苷

本文介绍了等度反相高效液相色谱(HPLC)测定福龙口服液中腺苷的方法,采用μBondapak C_(18)色谱柱,以甲醇:磷酸二氢钠(0.01mol/L)=13:87(v/v)为流动相。流速为1 mL/分,在254nm波长处检测。在0.17～10.2mg/mL测定范围内腺苷的峰面积与质量浓度的线性关系良好,相关系数为0.9997;腺苷的回收率97.18%;日内测定相对标准偏差(n=6)在1.35%～2.01%之间,隔5天测定结果基本无变化,该法已成功应用于福龙口服液中腺苷的日常测定。     

一种新型铸型——磷酸盐石墨铸型的研究

用正交试验对磷酸盐石墨铸型进行了成分设计 ,并应用数理统计原理对各因素的影响程度进行了分析 ,确定了磷酸盐石墨铸型的较佳制作工艺。结果表明 ,w (磷酸 ) :w (高铝粉 ) :w (石墨 ) =0 .3 0 :0 .3 0 :0 .70时 ,混制造型后于 60 0℃烘干 40min左右 ,磷酸铝盐石墨铸型具有较好的力学性能 ,其干拉伸强度可达4.67× 10 5Pa、干压缩强度可达 2 2 .2 1× 10 5Pa。高铝粉、磷酸之比的较佳范围值为 0 .8～ 1.0。干拉伸强度(σt)、压缩强度 (σc)与各种因素之间的一次关系分别为 :σc(10 5Pa) =0 .71A(% ) + 0 .47B(% ) + 0 .0 2 2C(℃ ) -0 .11D(min) -2 3 .49,σt(10 5Pa) =0 .165A(% ) + 0 .13 5B(% ) + 0 .0 0 5 1C(℃ ) -0 .0 0 63D(min) -7.419。磷酸盐石墨铸型的耐激冷能力较强     

A Validated Stability Indicating LC Method for Nateglinide

ABSTRACT

A simple, isocratic, rapid and accurate reverse phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of Nateglinide. The developed method is also applicable for determination of related substance in bulk drugs. The chromatographic separation was achieved on a Hypersil C18 (250 × 4.6 mm 5 μm) column using aqueous mixture of 0.025 M potassium hydrogen phosphate and 0.1% triethyl amine, v/v (pH 3.0 with dilute phosphoric acid)—methanol (25:75, v/v) as a mobile phase. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The chromatographic resolutions between Nateglinide and its potential impurities A and B were found to be greater than four. Forced degradation studies were performed for Nateglinide using acid (0.5 N hydrochloric acid), base (0.5 N sodium hydroxide), oxidation (3% hydrogen peroxide) heat (60°C) and UV light (254 nm). The limit of detection and limit of quantification of Nateglinide, impurities A and B were found to be 0.05 and 0.15 μg /mL, respectively for 20 μL injection volume. The percentage recovery of Nateglinide was ranged from 98.4 to 100.9. The percentage recovery of impurities in Nateglinide sample was ranged from 96.8 to 103.5. The developed RP-HPLC method was validated with respect to linearity, accuracy, precision, robustness, and forced degradation studies prove the stability indicating power of the method.     

A validated stability indicating LC method for Nateglinide

A simple, isocratic, rapid and accurate reverse phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of Nateglinide. The developed method is also applicable for determination of related substance in bulk drugs. The chromatographic separation was achieved on a Hypersil C18 (250 × 4.6 mm 5 μm) column using aqueous mixture of 0.025 M potassium hydrogen phosphate and 0.1% triethyl amine, v/v (pH 3.0 with dilute phosphoric acid)—methanol (25:75, v/v) as a mobile phase. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The chromatographic resolutions between Nateglinide and its potential impurities A and B were found to be greater than four. Forced degradation studies were performed for Nateglinide using acid (0.5 N hydrochloric acid), base (0.5 N sodium hydroxide), oxidation (3% hydrogen peroxide) heat (60°C) and UV light (254 nm). The limit of detection and limit of quantification of Nateglinide, impurities A and B were found to be 0.05 and 0.15 μg /mL, respectively for 20 μL injection volume. The percentage recovery of Nateglinide was ranged from 98.4 to 100.9. The percentage recovery of impurities in Nateglinide sample was ranged from 96.8 to 103.5. The developed RP-HPLC method was validated with respect to linearity, accuracy, precision, robustness, and forced degradation studies prove the stability indicating power of the method.     

Determination of nitrite in drinking water and environmental samples by ion exclusion chromatography with electrochemical detection

An extremely sensitive determination of nitrite in drinking water (tap water and underground water) and environmental samples (rain, lake water, and soil) was achieved by ion exclusion chromatography (IEC) with electrochemical (EC) detection. Potential interferences in the determination of nitrite by the standard spectrophotometric method or by the ion exchange chromatographic method with either conductivity detection or UV detection were eliminated. The detection limit was 0.1 ppb without preconcentration. No nitrite was observed from tap water or underground drinking water. The recoveries of nitrite added to tap water at 0.02, 0.1, and 1 ppm levels were between 96 and 104.5%. The average coefficient of variation was 4.7%. The recovery results were in good agreement with those obtained by the standard spectrophotometric method. Nitrite concentrations between 0.068 and 0.19 ppm were observed in rain within a week period. A greater variation, between 0.015 and 0.26 ppm, was observed in lake water. Amounts of 19.1 ppm and 0.50 ppm nitrite were observed from fertilized and unfertilized soil, respectively.     

HPLC测定食品中脂溶性维生素A、D、E

本文讨论了用反相液相色谱法测定食品中脂溶性维生素A、D、E的方法。样品经皂化处理,乙醚抽提后,经μBondapak C_(18)柱分离,流动相为甲醇-水(98:2),样品中维生素A、D、E完全分离并定量测定。回收率为82.3～100.9％,相对标准偏差小于3.1％,线性相关系数优于0.9977。方法简便,用途广泛。     

The role of oxygen and nitrogen in the recovery process of niobium

Electrical resistivity and Vickers hardness were measured in order to clarify the role of oxygen and nitrogen atoms in the stage III recovery of niobium. Defects were introduced mainly by means of cold-rolling. Specimens were prepared from the material A (O + N<50 ppm), B (O + N 210 ppm) or C (O + N 850 ppm). All specimens showed recovery in the temperature range 100 to 200° C; an additional recovery stage was observed in the material C and nitrogen-doped B.The values of activation energy for A and B were 0.7 eV. The order of reaction was second for A, while it was first for B. For C, activation energy and the reaction order were 1.2 eV and first, respectively. For the additional stage of C, the value of 3.4 eV was obtained, but the reaction was not simple. From these results and other results concerning the change in hardness, irradiation and quenching experiments, the dominant mechanism for recovery was considered. It was believed that point defects, probably the interstitial atoms, played a very important role in the recovery process of A and B, while in C recovery seemed to be due to migration of oxygen atoms.     

Determination of 2-(4-Morpholinyl)benzothiazole in Environmental Samples by a Gas Chromatograph Equipped with a Flame Photometric Detector

2-(4-Morpholinyl)benzothiazole (24MoBT) exists in automobile tire rubber as an impurity of a vulcanization accelerator and has been proposed as a potential molecular marker of street runoff (Spies, R. B.; Andresen, B. D.; Rice, D. W., Jr. Nature 1987, 327, 697-699). The present paper describes an analytical method for 24MoBT in environmental samples (e.g., street dusts and river sediments) by gas chromatography. The method relies upon extraction with a 6:4 (v/v) mixture of benzene and methanol, purification by acid extraction, and adsorption column chromatography, followed by determination using capillary GC equipped with a sulfur-selective detector (i.e., FPD). The recovery of 24MoBT for the entire procedure was 85%, and the relative standard deviation for four replicated analyses was 1.5%. The detection limit was 0.08 ng injected 24MoBT, corresponding to 0.20 ng/g of dry sample. The selectivity and sensitivity of the present method permit the determination of 24MoBT at the trace levels (e.g., ～ng/g) encountered in environmental samples. 24MoBT concentrations in various environmental samples are also reported.     

仿蟋蟀切齿叶减阻灭茬刀片设计与试验

为了降低切茬装置切割粉碎玉米根茬所需的功耗,以蟋蟀切齿叶为仿生原型设计了2种仿生灭茬刀片。应用MATLAB软件提取切齿叶部分的轮廓特征,分析其优良的减阻特性,并将此轮廓特征应用于灭茬刀片正刀刃的设计,设计出仿生刀片A;考虑到加工难易程度和经济成本,以二次函数为轮廓特征设计出仿生刀片B。在同等工作参数（前进速度为1 m/s,刀辊转速为420 r/min,耕深为50 mm）前提下,利用ANSYS/LS-DYNA软件仿真和田间试验的方法对2种仿生刀片和原型刀片的载荷状况进行对比分析。仿真结果表明：仿生刀片A和B的最大切削力（分别为881 N和908 N）较原型刀片的最大切削力（1 079 N）分别降低18.35%和15.85%;田间试验结果表明：仿生灭茬刀片A和B的平均扭矩和变异系数分别为267.894 N·m,2.31%和275.843 N·m,2.11%,原型灭茬刀片平均扭矩和变异系数为299.712 N·m和2.33%,且3种灭茬刀片的作业质量（灭茬深度和根茬粉碎率）均可达到相关国家标准。研究结果可为灭茬刀片的减阻降耗设计提供理论指导。     

Direct chromatographic separation of racemates on the basis of isotopic chirality

Direct separation was achieved between two isomers which are enantiomeric to each other by virtue of the presence of hydrogen/deuterium isotopes. A racemic mixture of the R- and S-isomers of phenyl(phenyl-d(5))methanol was separated by high-performance liquid chromatography using cellulose tribenzoate-coated silica as a stationary phase and a 2-propanol/hexane (5/95) mixture as a mobile phase, and the absolute configuration of each separated isomer was identified. The cellulose derivative showed preferential retention of (R)-(-)-phenyl(phenyl-d(5))methanol compared to the (S)-(+)-isomer, with a separation factor of 1.0080 based on the preferential binding of a C(6)D(5) group over a C(6)H(5) group to the primary binding site.     

Determination of alkylbenzyldimethylammonium chlorides in river water and sewage effluent by solid-phase extraction and gas chromatography/mass spectrometry

This study presents a modified method to analyze alkylbenzyldimethylammonium chlorides (ABDACs) in river water and sewage effluent. The method involves mixed samples with linear alkylbenzenesulfonates (LAS) as a counterion to enhance the extraction of ABDAC residues from an RP-18 solid-phase cartridge by formation of hydrophobic ion-pair complexes. The ABDACs were then eluted with methanol-ethyl acetate (1:1, v/v) and formed to their corresponding alkyldimethylamines by the Hofmann degradation with potassium tert-butoxide. The alkyldimethylamines were then identified and quantitated by gas chromatograph/mass spectrometry (GC/MS). The results indicate that, in the presence of LAS, debenzylation of ABDACs occurs selectively at a temperature higher than 90 degrees C to produce the corresponding nonionic alkyldimethylamines. The method proposed herein provides a high precision and sensitivity for ABDACs, to quantitation at < or =0.1 microg/L in 500 mL of the water samples. The average recovery of ABDAC spiked water samples was 95% with relative standard deviations (RSD, n = 7) of 9%. The RSDs of three replicate environmental sample analyses ranged from 5 to 11%. Direct HPLC method was applied to evaluate the GC/MS method, and compatible results were observed.     

荧光法测定医用维生素B_2片剂中维生素B_2的含量

研究了荧光分光光度计测定医用维生素B2片剂中维生素B2的含量。其荧光的激发波长为Ex;457 nm,发射波长为Em:528 nm。回收率为96.8%-100.0%,变易系数为2.03%。