Investigation of chromatographic conditions for the separation of ofloxacin and its degradation products

A sensitive, precise, and accurate reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for simultaneous determination of fluoroquinolone antibacterial ofloxacin and its degradation products: decarboxy ofloxacin, 9-piperazino ofloxacin, des-methyl ofloxacin, and ofloxacin-N-oxide. The proposed RP-HPLC method allowed separation of all five compounds simultaneously with the total time of the analysis not more than 15 min. The relative standard deviation (RSD) values for quantification of DOF, POF, MOF, OF, and NOF were of 0.77, 0.58, 0.51, 0.10, and 0.70%, respectively, indicating a good precision of the method. The limits of detection for DOF, POF, MOF, OF, and NOF were 0.10, 0.13, 0.06, 0.03, and 0.03 microg mL(-1), respectively. The described method can be used for simultaneous identification and quantification of all analysed compounds in different pharmaceutical formulations.     

Development and application of a validated stability-indicating high-performance liquid chromatographic method using photodiode array detection for simultaneous determination of granisetron, methylparaben, propylparaben, sodium benzoate, and their main degradation products in oral pharmaceutical preparations

A simple, rapid, and sensitive RP-HPLC method using photodiode array detection was developed and validated for the simultaneous determination of granisetron hydrochloride, 1-methyl-1H-indazole-3-carboxylic acid (the main degradation product of granisetron), sodium benzoate, methylparaben, propylparaben, and 4-hydroxybenzoic acid (the main degradation product of parabens) in granisetron oral drops and solutions. The separation of the compounds was achieved within 8 min on a SymmetryShield RP18 column (100 x 4.6 mm id, 3.5 microm particle size) using the mobile phase acetonitrile--0.05 M KH2PO4 buffered to pH 3 using H3PO4 (3+7, v/v). The photodiode array detector was used to test the purity of the peaks, and the chromatograms were extracted at 240 nm. The method was validated, and validation acceptance criteria were met in all cases. The robust method was successfully applied to the determination of granisetron and preservatives, as well as their degradation products in different batches of granisetron oral drops and solutions. The method proved to be sensitive for determination down to 0.04% (w/w) of granisetron degradation product relative to granisetron and 0.03% (w/w) 4-hydroxybenzoic acid relative to total parabens.     

多贝斯在纳米金修饰玻碳电极上的电化学行为与测定

采用循环伏安法将纳米金电沉积于玻碳电极表面,制备了纳米金修饰玻碳电极(NG/GCE).在0.05 mol/L H2SO4溶液中,用循环伏安法研究了多贝斯在NG/GCE上的电化学行为.结果表明,NG/GCE对多贝斯的氧化还原反应有明显的电催化作用.建立了测定多贝斯的新方法,用方波伏安法测得多贝斯的氧化峰电流与其浓度在4....     

Simultaneous determination of chlorogenic acid, caffeic acid, ferulic acid, protocatechuic acid and protocatechuic aldehyde in Chinese herbal preparation by RP-HPLC

In the present study, a reversed phase high performance liquid chromatographic (RP-HPLC) method was established for simultaneous determination of chlorogenic acid, caffeic acid, ferulic acid, protocatechuic acid and protocatechuic aldehyde in a Chinese herbal preparation (Fufang-Pugongying-Mixture). The separation was performed on a Hypersil ODS-2 column by isocratic elution with methanol and 0.2 M acetate buffer (pH 3.6) (15 : 85, v/v) as the mobile phase at the flow-rate of 1.0 ml/min with operating temperature of 30 degrees C, and detection wavelength of 300 nm. A good linear regression relationship between peak-areas and concentrations was obtained over the range of 2-200 microg/ml for the five marker compounds mentioned above. The spike recoveries were within 96.72-104.07%. The variation coefficient (CV) values of the precision were in the range of 0.89-4.50%. Moreover the developed method has reference value for quantitative analysis of Taraxacum, Lonicera and Angelica.     

多贝斯在石墨烯修饰玻碳电极上的电化学行为及其测定

制备了石墨烯修饰玻碳电极（GN/GCE）。 在0.05 mol/L H2SO4溶液中,用循环伏安法研究了多贝斯在GN/GCE上的电化学行为。 结果表明,GN/GCE对多贝斯的氧化还原反应有明显的电催化作用。 建立了测定多贝斯的新方法,用微分脉冲伏安法测得多贝斯的氧化峰电流与其浓度在2.0×10-9~1.2×10-6 mol/L范围内呈线性关系,检出限为1.0×10-9 mol/L(S/N=3)。 该法可用于胶囊中多贝斯的测定,修饰电极有较好的稳定性和重新性。     

Determination of some phenolic compounds in red wine by RP-HPLC: method development and validation

A methodology employing reversed-phase high-performance liquid chromatography (RP-HPLC) was developed and validated for simultaneous determination of five phenolic compounds in red wine. The chromatographic separation was carried out in a C(18) column with water acidify with acetic acid (pH 2.6) (solvent A) and 20% solvent A and 80% acetonitrile (solvent B) as the mobile phase. The validation parameters included: selectivity, linearity, range, limits of detection and quantitation, precision and accuracy, using an internal standard. All calibration curves were linear (R(2) > 0.999) within the range, and good precision (RSD < 2.6%) and recovery (80-120%) was obtained for all compounds. This method was applied to quantify phenolics in red wine samples from Santa Catarina State, Brazil, and good separation peaks for phenolic compounds in these wines were observed.     

等离子炬-质谱技术测定白菜、萝卜、大豆、土壤中的痕量锰、钴、镍、铜、锌、砷、钼和锶

营养学家们已经确定了锰、钻、镍、铜、锌、砷、钼和锶等10多种人体所必需的痕量元素,它们对于维持人体的健康和长寿起着重要的生理作用。本文首次应用等离子炬-质谱技术测定了白菜、萝卜、大豆和土壤中这八种痕量元素的含量,并报告了它们的测定结果和标准偏差,其中土壤样品的测定值与参考值相比较,经 T 检验,两者之间在统计学上,没有显著性差异。实验证明该方法可对多种痕量元素同时定性、定量分析。操作简便、快速,灵敏度高;方法准确可靠,重现性好。为开展食品卫生学、营养学的研究,提供了更为先进的测试技术。     

基于纳米银/碳纳米纤维复合材料的增强效应电化学测定多贝斯

将银纳米粒子(AgNPs)电沉积在碳纳米纤维(CNFs)修饰玻碳电极表面制备纳米银/碳纳米纤维修饰玻碳电极(AgNPs/CNFs/GCE).采用扫描电镜考察其表面形态,在K3[Fe(CN)6]-K4[Fe(CN)6]体系中用循环伏安法和电化学阻抗法研究AgNPs/CNFs/GCE的电化学行为.采用循环伏安法和方波伏安法...     

Simultaneous reversed-phase high-performance liquid chromatographic separation of mono-, di-and trichloroanilines through a gradient elution optimised by experimental design

A new RP-HPLC method for the simultaneous determination of the 13 mono-, di- and trichloroanilines has been developed. In order to obtain the analyte resolution within an acceptable analysis time, a gradient elution program has been optimised through the use of an experimental design and a grid search algorithm. The optimized conditions provided the resolution of all the analytes in less than 80 min. The primary validation of the analytical method gave limit of detection values ranging between 0.02 and 0.06 mg/l and very good linearity of the calibration curves.     

三种长春碱类化合物的反相高效液相色谱同时测定及其定量构效关系的研究

本文在模拟植物生理浓度条件下,建立了反相-高效液相色谱(RP-HPLC)同时测定文多灵碱、酒石酸长春质碱和硫酸长春碱3种生物碱的方法;在此基础上,用启发式计算法(Heuristic Method,HM)筛选出与量子化学相关的3个描述符参数,应用多元线性回归方法建立了23种生物碱类化合物对保留时间值的定量结构-性质关系(Quan-titative Structure-Property relationship,QSPR)模型,模型的相关系数R2为0.9160,F值为69.08,s2方差为47.7217,结果表明此模型具有比较好的预测能力。     

RP-HPTLC densitometric determination and validation of vanillin and related phenolic compounds in accelerated solvent extract of Vanilla planifolia*

A simple, fast and sensitive RP-HPTLC method is developed for simultaneous quantitative determination of vanillin and related phenolic compounds in ethanolic extracts of Vanilla planifolia pods. In addition to this, the applicability of accelerated solvent extraction (ASE) as an alternative to microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and Soxhlet extraction was also explored for the rapid extraction of phenolic compounds in vanilla pods. Good separation was achieved on aluminium plates precoated with silica gel RP-18 F(254S) in the mobile phase of methanol/water/isopropanol/acetic acid (30:65:2:3, by volume). The method showed good linearity, high precision and good recovery of compounds of interest. ASE showed good extraction efficiency in less time as compared to other techniques for all the phenolic compounds. The present method would be useful for analytical research and for routine analysis of vanilla extracts for their quality control.     

An ionic liquid-type carbon paste electrode for electrochemical investigation and determination of calcium dobesilate

An ionic liquid-type carbon paste electrode (IL-CPE) had been fabricated by replacing non-conductive organic binders with a conductive room temperature ionic liquid, 1-pentyl-3-methylimidazolium hexafluorophosphate (PMIMPF₆). The electrochemical responses of calcium dobesilate were investigated at the IL-CPE and the traditional carbon paste electrode (T-CPE) in 0.05 mol L⁻¹ H₂SO₄, respectively. The results showed the superiority of IL-CPE to T-CPE in terms of provision of higher sensitivity, faster electron transfer and better reversibility. A novel method for determination of calcium dobesilate was proposed. The oxidation peak current was rectilinear with calcium dobesilate concentration in the range of 8.0 × 10⁻⁷ to 1.0 × 10⁻⁴ mol L⁻¹, with a detection limit of 4.0 × 10⁻⁷ mol L⁻¹(S/N = 3) by differential pulse voltammetry. The proposed method was applied to directly determine calcium dobesilate in capsule and urine samples.     

Simultaneous determination of a ternary mixture of doxylamine succinate, pyridoxine hydrochloride, and folic acid by the ratio spectra-zero-crossing, double divisor-ratio spectra derivative, and column high-performance liquid chromatographic methods

Three simple, rapid, and accurate methods, i.e., the derivative ratio spectra-zero-crossing method (method I), double divisor-ratio spectra derivative method (method II), and column reversed-phase high-performance liquid chromatographic (RP-HPLC) method (method III) were developed for the simultaneous determination of doxylamine succinate (DOX), pyridoxine hydrochloride (PYR), and folic acid (FA) in their ternary mixtures and in tablets. In methods I and II, the calibration graphs were linear in the range of 2.5-80, 1.0-40, and 1.0-30 microg/mL for DOX, PYR, and FA, respectively. In the HPLC method, the separation of these compounds was performed using mobile phase consisting of 0.05 M phosphate buffer (pH 6.3)-methanol-acetonitrile (50 + 20 + 30, v/v/v), and UV detection was performed at 263 nm. Linearity was observed between the concentrations of the analytes and peak areas [correlation coefficient (r) > or =0.9998] in the concentration range of 1.0-200, 4.0-600, and 4.0-600 microg/mL for DOX, PYR, and FA, respectively. The standard deviation of retention time in method III was 0.011, 0.015, and 0.016 for DOX, PYR, and FA, respectively. The precision studies for all of the methods gave relative standard deviation values of <2%. The results obtained from the methods were statistically compared by means of Student's t-test and the variance ratio F-test. It was concluded that all of the developed methods were equally accurate, sensitive, and precise. These methods could be applied to determine DOX, PYR, and FA in their combined dosage forms.     

Simultaneous determination of the herbicides isoproturon, dichlorprop-p, and bifenox in soils using RP-HPLC

Summary A simple and fast analytical method for the simultaneous determination of the herbicides isoproturon (N-(4-isopropylphenyl)-N'N'-dimethyl-urea), dichlorprop-p ((+)-2-(2,4-dichlorophenoxy)-propionic acid), bifenox (methyl-5-(2,4-dichlorophenoxy)-2-nitro-benzoate), and its main metabolite bifenox acid (5-(2,4-dichloro-phenoxy)-2-nitro-benzoic acid) in soils is described. The herbicides differ substantially in their physical and chemical properties. The soil extraction with a mixture of CH₂Cl₂, C₂H₅OH, and acetone, followed by an isocratic RP-HPLC determination yields high, reproducible recoveries for all compounds. The method can be used for different soil moisture and pH conditions. The detection limits range from 0.01 to 0.03 mg active compound/kg dry soil. An additional clean-up using size exclusion techniques can improve the detection limits to 0.003 to 0.007 mg active compound/kg dry soil. The method is suitable for routine residue analyses and applicable to other herbicides as well.     

Isolation and characterization of process related impurities of olanzapine using HPLC and ESI-MS/MS

An RP-HPLC method for the simultaneous separation and determination of olanzapine (OLZ) and its process impurities in bulk drugs and pharmaceutical formulations was developed. The separation was accomplished on Inertsil ODS 3V (4.6 mm x 250 mm; particle size 5 microm) column using 0.2 M ammonium acetate (pH = 4.50) and ACN as mobile phase in gradient elution mode. The analytes were monitored by a photo diode array (PDA) detector set at 254 nm and the flow rate was kept at 1.0 mL/min. The chromatographic behavior of all the compounds was examined under variable compositions of different solvents, buffer concentrations, and pH. The method was validated in terms of accuracy, precision, and linearity. Four unknown process impurities observed consistently during the analysis of different batches of OLZ were isolated and characterized by ESI-MS/MS, (1)H NMR, and FT-IR. The proposed RP-HPLC method was successfully applied to the analysis of commercial formulations. The method could be of use not only for rapid and routine evaluation of the quality of OLZ in bulk drug manufacturing units but also for the detection of its impurities in pharmaceutical formulations.     

Simultaneous separation and quantitation of the major bovine whey proteins including proteose peptone and caseinomacropeptide by reversed-phase high-performance liquid chromatography on polystyrene-divinylbenzene

A precise, sensitive and reliable RP-HPLC method was developed to enable not only unequivocal determination of alpha-lactalbumin and beta-lactoglobulin in bovine whey samples, but also simultaneous measurement of proteose peptone, caseinomacropeptide, bovine serum albumin and immunoglobulin G. The optimised method on the Resource RPC column allowed separation of the proteins in 30 min and could be applied to the analysis of soluble proteins in a variety of commercial and laboratory whey products. Furthermore, some qualitative information on protein heterogeneity and quality could be derived from the RP-HPLC analyses with additional data available from on-line electrospray mass spectrometry. Within- and between-day repeatability over a wide range of concentrations was excellent (RSD< or =5%) for all proteins except immunoglobulin G and bovine serum albumin where RSD was 7-10%. Analysis of grouped data from whey protein concentrate and whey protein isolate samples gave a limit of detection of < or =0.3% powder mass and a limit of quantitation of < or =1.0% powder mass for all proteins except immunoglobulin G. Limits of detection and quantitation were 0.6% and 2.0%, respectively, for this protein. Quantitative data obtained by the RP-HPLC method compared very favourably with data obtained by alternative methods of whey protein analysis.     

Flow injection chemiluninescence for detecting picogram amounts of dobesilate in human urine

A sensitive method for the determination of dobesilate in pharmaceutical preparations and human urine is described by using controlled-reagent-release technology. The method entailed the use of luminol and periodate, which are immobilized on anion exchange resin and react in alkaline medium, giving chemiluminescence (CL) at 425 nm. Dobesilate was detected by measuring the decrease of CL intensity, and which was observed linear over the dobesilate concentration range of 10-600 pg ml(-1), and the limit of detection was 3.5 pg ml(-1) (3sigma) and a relative standard deviation of less than 3.0%. At a flow rate of 2.0 ml min(-1), the determination of dobesilate, including sampling and washing, could be performed in 0.5 min, giving a throughput of about 120 times per hour. The proposed method has an extremely low limit of detection down to 3.5 pg ml(-1), thus it can be applied directly in the assay of human urine without any pre-treatment. It was also found that the dobesilate concentration reached its maximum after orally administrated for 3.5h, and the excretion ratio in 24h was 58.8% in the body of volunteers.     

Simultaneous determination of paracetamol, chlorzoxazone, and related impurities 4-aminophenol, 4'-chloroacetanilide, and p-chlorophenol in pharmaceutical preparations by high-performance liquid chromatography

This paper presents a simple, specific, and precise high-performance liquid chromatographic method for the simultaneous determination of paracetamol (PCM), chlorzoxazone (CXZ), and their related impurities in bulk raw materials and solid dosage forms. The mobile phase consisted of water-methanol-glacial acetic acid (60 + 40 + 2, v/v/v). A column containing octadecylsilane chemically bonded to porous silica particles (Spherisorb ODS 1, 25 cm x 4.6 mm, 5 microm) was used as stationary phase. Detection was performed using a variable wavelength ultraviolet-visible detector set at 272 nm for all compounds. Solutions were injected into the chromatograph under isocratic condition at a constant flow rate of 1.2 mL/min. The method was validated according to International Conference on Harmonization requirements and demonstrates good accuracy and precision and a wide linearity range. The method separates PCM, CXZ, and 3 major impurities [4-aminophenol (4AP), 4'-chloracetanilide (4CA), and p-chlorophenol (PCP)] with fair resolution in less than 15 min. The developed method is rapid and sensitive (limit of detection for 4AP, 4CA, and PCP established at 31.25, 39.06, and 65.16 ng/mL, respectively) and, therefore, suitable for quality control and stability studies of these compounds in dosage forms.     

离子色谱-积分脉冲安培法测定肉类产品中鹅肌肽、高肌肽及肌肽

建立了一种离子色谱-积分脉冲安培（IC-IPAD）同时测定肉类样品中鹅肌肽、高肌肽及肌肽的分析方法。方法采用高效阴离子交换色谱柱AminoPac PA10（250 mm×2 mm）分离,以100 mmol/L NaOH为淋洗液,流速为0.2 mL/min,柱温为30℃。结果表明,3种目标化合物在15 min内可实现完全分离,且17种氨基酸对3种目标化合物不存在干扰。在最佳色谱条件下,鹅肌肽、高肌肽及肌肽在0.05~5.0 mg/L范围内呈良好的线性关系,线性相关系数（r）>0.99。3种目标化合物的检出限和定量限分别为8.9~22.1 μg/L和29.6~73.6 μg/L。对鸭胸及鹅胸样品进行分析,加标回收率为92.4%~104.5%。该方法简单方便,无需衍生化,灵敏度高,可用于肉类产品中相关营养成分的测定。     

Fingerprint analysis and multi‐ingredient quantitative analysis for quality evaluation of Xiaoyanlidan tablets by ultra high performance liquid chromatography with diode array detection

A rapid and sensitive ultra high performance liquid chromatography method with diode array detection was developed for the fingerprint analysis and simultaneous determination of seven active compounds in Xiaoyanlidan (XYLD) tablets. The chromatographic separations were obtained on an Agilent Eclipse plus C₁₈ column (50 × 2.1 mm id, 1.8 μm) using gradient elution with water/formic acid (1%) and acetonitrile at a flow rate of 0.4 mL/min. Within 63 min, 36 peaks could be selected as the common peaks for fingerprint analysis to evaluate the similarities among several samples of XYLD tablets collected from different manufacturers. In quantitative analysis, seven compounds showed good regression (R > 0.9990) within test ranges and the recovery of the method was within the range of 95.9–104.3%. The method was successfully applied to the simultaneous determination of seven compounds in six batches of XYLD tablets. These results demonstrate that the combination of chromatographic fingerprint analysis and simultaneous multi‐ingredient quantification using the ultra high performance liquid chromatography method with diode array detection offers a rapid, efficient, and reliable approach for quality evaluation of XYLD tablets.