RP-HPLC method for the quantitative analysis of naturally occurring flavonoids in leaves of Blumea balsamifera DC

A selective and sensitive reversed-phase (RP) high-performance liquid chromatographic method is developed for the quantitative analysis of five naturally occurring flavonoids of Blumea balsamifera DC, namely dihydroquercetin-7,4'-dimethyl ether (DQDE), blumeatin (BL), quercetin (QN), 5,7,3',5'-tetrahydroxyflavanone (THFE), and dihydroquercetin-4'-methyl ether (DQME). These compounds have been isolated using various chromatographic methods. The five compounds are completely separated within 35 min using an RP C18, Nucleosil column and with an isocratic methanol-0.5% phosphoric acid (50:50, v/v) mobile phase at the flow rate of 0.9 mL/min. The separation of the compounds is monitored at 285 nm using UV detection. Identifications of specific flavonoids are made by comparing their retention times with those of the standards. Reproducibility of the method is good, with coefficients of variation of 1.48% for DQME, 2.25% for THFE, 2.31% for QN, 2.23% for DQDE, and 1.51% for BL. The average recoveries of pure flavonoids upon addition to lyophilized powder and subsequent extraction are 99.8% for DQME, 99.9% for THFE, 100.0% for BL, 100.6% for DQDE, and 97.4% for QN.     

Spectrophotometric determination of silicon in ferrophosphorus

A method is described for the spectrophotometric determination of 0-4% silicon in ferrophosphorus, following fusion with sodium peroxide in a zirconium crucible. Silicomolybdic acid is formed with sodium molybdate. The acidity is increased to 2N and the solution stood for 10 min to destroy phosphomolybdic and arsenomolybdic acids. The silicomolybdic acid is reduced with ascorbic acid and the absorbance measured at 810 nm. The colour is stable, and a standard deviation of 0.006% was achieved for 0.7% silicon. Results obtained for three samples with alternative procedures are compared.     

Development and validation of an HPLC method for the quantitation of 1,3-dihydroxy-2-methylxanthone in biodegradable nanoparticles

A rapid and simple high-performance liquid chromatographic method for the analysis of 1,3-dihydroxy-2-methylxanthone (DHMXAN) in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanosphere and nanocapsule formulations is developed and validated. The method does not require any complex sample extraction procedure. Chromatographic separation is made with a reversed-phase C18 column, using methanol-water (90:10, v/v) containing 1% (v/v) acetic acid as a mobile phase at a flow rate of 1 mL/min. Identification is made by UV detection at 237 nm. The isocratic system operates at ambient temperature and requires 7.5 min of chromatographic time. The developed method is statistically validated according to ICH guidelines and USP 29 for its specificity, linearity, accuracy, and precision. The assay method proposed in this study is specific for DHMXAN in the presence of nanosphere and nanocapsule excipients. Diode-array analyses confirm the purity of DHMXAN peak in stress conditions (> 99.0%). The method is shown to be linear (r > or = 0.999) over the concentration range of 0.25-3.0 microg/mL. Recovery ranges from 99.0% to 102.7% (RSD: 1.49%) and from 98.3% to 101.6% (RSD: 1.07%) for nanospheres and nanocapsules, respectively. Repeatability (intra-assay precision) and intermediate precision is acceptable with RSD values ranging from 0.6% to 1.9% and from 0.3% to 2.0%, respectively. The method is shown to be suitable for the evaluation of DHMXAN content entrapped in PLGA nanoparticles.     

ICP-AES法测定钢中的铈

建立了离子体发射光谱仪测定钢中铈元素的方法。为消除共存元素对铈分析游线的光谱干扰,选择Ce413．380nm作为分析线,铈含量在0．005％-0．50％之间工作曲线线性良好。对于含量范围在0．005％-0．10％的铈元素,回收率为85．6％-12．5％,测定结果的相对标准偏差小于9．74％（n=8）;对于含量范围在0．10％-0．50％的铈元素,回收率为99．5％-103．0％,测定结果的相对标准偏差小于3．52％（n=8）。该方法适宜钢中含量范围在O．005％-0．50％的铈元素的测定。     

基于黑体辐射提高自由定标激光诱导击穿光谱(CF-LIBS)定量精度的方法

自由定标激光诱导击穿光谱(Calibration-Free LIBS,CF-LIBS)技术是定量分析行业发展的主要趋势之一。该技术可直接基于局部热力学平衡等离子体模型,通过LIBS光谱数据和谱线参数计算出等离子体参数和各元素含量。且无需使用标准样品建立定标曲线,该技术不受基体效应的影响,非常适合实时、在线和多元素同时分析。但由光学厚而引起的自吸收效应是影响定量分析的重要因素。通过对比实验光谱数据与黑体辐射强度,研究等离子体温度,提高光学系统收集效率,抑制自吸收效应对CF-LIBS定量结果的影响。经过黑体辐射校正后,基体元素Fe的测定含量从88.700%提升到94.575%,相对误差(RE)从8.072%降低到1.984%。微量元素Cr、Mo和V的测定含量分别从0.635%、0.096%和0.023%降低至0.698%、0.143%和0.022%,相对误差(RE)从13.723%、45.455%和21.053%降低至5.163%、18.75%和15.789%。整体的平均绝对误差(MAE)从1.994%降低至0.497%。玻尔兹曼图拟合回归曲线有了更高的线性度。拟合系数R²     

ICP–AES法测定金属钼中微量Fe,Ni

采用ICP–AES法测定金属钼中Fe,Ni含量,以盐酸–硝酸–氢氟酸溶解样品,试验了基体元素和共存元素对Fe,Ni的光谱干扰,Fe,Ni的分析谱线分别为238.204 nm,341.477 nm。测定Fe,Ni的线性范围均为0.001%~0.01%,线性相关系数分别为0.999 4,0 999 8,检出限分别为0.000 01%,0.000 04%。方法的加标回收率为95.7%~115.0%,测定结果的相对标准偏差为2.36%~17.82%(n=8)。该方法快速、简便,能够满足金属钼中含量范围为0.001%~0.01%的Fe,Ni元素的检测要求。     

纺织品中残留氯酚的毛细管气相色谱测定法

采用稀硫酸浸湿样品,正己烷提取,乙酸酐衍生后以毛细管气相色谱分离测定的方法对纺织品中五氯酚、三氯酚残留量进行了同时测定,探讨了提取、净化及色谱分析条件。方法回收率范围三氯酚84.8％～98.1％,五氯酚88.0％～100.2％。相对标准偏差三氯酚1.54％～2.33％,五氯酚3.48％。方法的检出限（质量分数）分别为2,4,6-三氯酚1.0×10     

Quantitative determination of octadecenedioic acid in human skin and transdermal perfusates by gas chromatography-mass spectrometry

A gas chromatographic (GC) method with mass spectrometric (MS) detection is developed and validated for the accurate and precise determination of octadecenedioic acid (C18:1 DIOIC) in human skin samples and transdermal perfusates. C18:1 DIOIC is extracted using methanol. The saturated analogue 1,18-octadecanedioic acid (C18:0 DIOIC) is added as internal standard. Prior to analysis, both compounds are converted to their trimethylsilylated derivatives using N,O-bis(trimethylsilyl)trifluoroacetamide with 15% trimethylchlorosilane. Quantitation is performed in selected ion monitoring mode with a limit of quantitation of 250 ng/mL. Linearity with a correlation coefficient of 0.998 is obtained over a concentration range of 250-2000 ng/mL. Values for within-day accuracy range from 94.5% to 102.4%, and from 97.5% to 105.8% for between-day accuracy. Within- and between-day precision values are better than 5% and 7%, respectively. The recovery values from the various matrices vary from 92.6% to 104.0%. The GC-MS method is employed for the determination of C18:1 DIOIC after application of an emulsion containing the active ingredient onto human skin in vitro. The results demonstrate that the method is suitable for the determination of C18:1 DIOIC in human skin samples and transdermal perfusates.     

Simultaneous determination of potassium nitrate and sodium monofluorophosphate in dentifrices by single column ion chromatography

The simultaneous determination of potassium nitrate and sodium monofluorophosphate in dentifrices by single column ion chromatography is described. Nitrate and monofluorophosphate are extracted from the dentifrice with deionized water and separated by a low capacity anion separator column with 0.2% sodium benzoate (adjusted to pH 5.8 +/- 0.1 with formic acid) as the mobile phase. A conductivity meter is used for concentration measurements. The method has been applied to commercial dentifrices containing both potassium nitrate and sodium monofluorophosphate. The mean recoveries for potassium nitrate and monofluorophosphate from spiked samples were 99.0% and 99.2%, respectively, with corresponding standard deviations of 1.73% and 2.55%. The minimum detectable concentration is 5 micrograms/ml for both nitrate and monofluorophosphate.     

Validation of high-performance liquid chromatographic-mass spectrometric method for the analysis of lidocaine in human plasma

A sensitive and simple liquid chromatography-tandem mass spectrometry method is developed and validated for the determination of lidocaine in human plasma. Bupivacaine is used as an internal standard, and the plasma extraction is performed by a simple liquid-liquid extraction. The limit of quantitation (LOQ) is 0.5 ng/mL with a signal-to-noise ratio greater than 5. The calibration curve is linear from 0.5 to 250 ng/mL with an r2 greater than 0.99. The coefficients of variation for within- and between-assay imprecision, including LOQ, are < or = 13% and < or = 8%, respectively. The percentage of inaccuracy for within- and between-assay, including LOQ, are < or = 9% and < or = 5%, respectively. The absolute recovery of lidocaine and bupivacaine are greater than 84% and 82%, respectively. The higher sensitivity and accuracy of this method allow the measurement of low concentrations of lidocaine in plasma from a clinical study of topically applied lidocaine in healthy subjects.     

Separation and determination of ephedrine and pseudoephedrine by combination of flow injection with capillary electrophoresis

A simple, rapid, and accurate method for the separation and determination of ephedrine and pseudoephedrine using direct UV absorbance detection has been developed by the combination of flow injection with capillary electrophoresis for the first time. The buffer solution used is a 40 mM borate solution with the pH adjusted to 9.5 using a 2 M NaOH solution. The linear calibration range is 50 to 1000 microg/mL (r = 0.9996) for both analytes, and the recoveries are 91.2-108.2% for ephedrine and 92.6-107.3% for pseudoephedrine, respectively. The relative standard deviation of the peak area is 1.6% for ephedrine and 1.3% for pseudoephedrine (n = 6) at a concentration of 500 microg/mL, respectively. A series of samples is injected repeatedly without current interruption and subsequent rinsing, and the contents of these two alkaloids in three marketed drugs and the medical plant, Ephedra sinica, are determined with satisfactory results by this method.     

痰热清的不良反应分析与用药指导

目的对痰热清药品不良反应监测报告的结果进行分析,为临床合理用药提供参考依据。方法对赣州市妇幼保健院2012—2014年使用痰热清后出现不良反应的288例患者进行分类统计,分析患者性别、年龄、联合用药情况、用药观察时间与不良反应的发生率和临床症状的关联性。结果在所有不良反应患者当中,男性患者占55.56%,女性患者占44.44%,年龄小于10岁占38.9%,年龄大于60岁占33.3%。在联用药物中,抗菌药的不良反应发生率占90%以上。用药后30 min内出现的不良反应占50%,用药后1 d内出现不良反应占22.2%;不良反应症状中,过敏反应占33.3%。结论痰热清的不良反应与患者的年龄、性别和联合用药情况有关,且发生时间多集中在30 min以内。不良反应的临床症状以过敏反应为主。     

Description of a Method for Automated Determination of Organic Pollutants in Water

Abstract

A method for automated determination of 73 organic pollutants in water is described. The compounds, which are key representatives for different types of pollutants are determined in two chromatographic runs. 11 halogenated aliphatic hydrocarbons are determined using capillary GC equipped with electron capture detector. The remaining pollutants, representing both basic/neutral and acidic compounds are determined by using GC/MS combined with an automated search computer program. The majority of the compounds have a limit of quantitation at 1 ig/1 or lower. The precision of the GC method is in the range of 1.8% to 4.3%, with an average of 3.2%. The precision for compounds determined by GC/MS is in the range of 1% to 38%, with an average of 14%.

So far 30 water samples representing both polluted fjord areas as well as effluents from municipal treatment plants, refineries, petrochemical industries and metallurgic industries have been analysed. The method has been found to be an interesting alternative to traditional methods for monitoring water quality, and has demonstrated its potential both as a screening method for detecting “hot spots” as well as for routine monitoring of specific hazardous compounds.     

Liquid chromatographic method for the simultaneous determination of imipenem and sulbactam in mouse plasma

The first analytical method is developed and validated for the simultaneous determination of imipenem and sulbactam in mouse plasma. Sample treatment is based on plasma stabilization with 4-(2-hydroxyethyl)piperazine-ethanesulfonic acid (HEPES) (0.5 mol/L; pH 7.0)-water-ethylene glycol (2:1:1, v/v/v), precipitation of plasma proteins with acetonitrile, centrifugation, evaporation, and reconstitution with borate buffer. Analytical determination is carried out by high-performance liquid chromatography with diode-array detection. Chromatographic separation is achieved within 11 min on a C(18) column by gradient elution with borate buffer (0.1 mol/L, pH 7.2) and methanol. Imipenem and sulbactam are monitored at 295 and 230 nm, respectively. The overall interday accuracy is in the range of 95% to 100% and from 98% and 101% for imipenem and sulbactam, respectively. Interday precision is below 8% and 4% for imipenem and sulbactam, respectively. Limits of quantitation of imipenem and sulbactam are 0.05 and 1.0 microg/mL, respectively. The mean extraction recoveries are 94.5% and 94.2% for imipenem and sulbactam, respectively. The described method allows an accurate, simple, and rapid identification and quantitation of imipenem and sulbactam in mouse plasma. This method is applied to the analysis of imipenem and sulbactam in mouse plasma after drug administration.     

Rapid polarographic method for determination of arsenic in ferrotungsten

A simple and sensitive method for determining arsenic in ferrotungsten is presented. The alloy is dissolved in aqua regia and the arsenic reduced with K(2)S(2)O(5). The polarographic wave is recorded for an electrolyte at pH 3.0 and containing Fe(II), Mn(II), citric acid and ascorbic acid. Levels of 0.2%, and 0.003% As can be determined with errors of +/- 8 and +/- 20% respectively. The limit of detection is 0.003%.     

A sensitive high-throughput HPLC assay for simultaneous determination of everolimus and clobetasol propionate

A novel sensitive high-throughput high-performance liquid chromatography assay is developed and validated for the simultaneous determination of everolimus and clobetasol propionate in pharmaceutical formulations. The chromatographic separation is achieved on a Zorbax Eclipse XDB-C18 reversed-phase column using a gradient elution, with solvent A: ammonium acetate (pH 6.8; 0.01 M) and solvent B: acetonitrile. The mean recovery ranges from 95.1% to 100.0% for clobetasol propionate and from 97.9% to 103.7% for everolimus. The limit of quantitation for each analyte is 0.02 microg/mL. The percent relative standard deviations are less than 3% for intra- and inter-day analyses. The proposed method can be used for the routine quality control of everolimus and clobetasol propionate in complex pharmaceutical formulations, especially the drug-delivery systems with a low total drug-load.     

电感耦合等离子体质谱法快速测定苦荞茶中铜、铅、镉、钴、镍

建立了用硝酸-高氯酸消解样品,电感耦合等离子体质谱法(ICP-MS)测定苦荞茶中铜、铅、镉、钴、镍的方法.方法具有灵敏度高、检出限低、精密度好、基体干扰少、准确可靠、快捷、简便的特点.各元素方法检出限(3SD,μg/L)分别为:铜0.009、铅0.023、镉0.015、钴0.022、镍0.035;方法精密度(RSD,n=12)分别为:铜2.5%～3.0%、铅2.1%～2.3%、镉3.0%～3.8%、钴2.5%～2.6%、镍1.5%～1.9%;各元素加标回收率分别为:铜95.0%～105.0%、铅95.0%～105.0%、镉98.0%～105.0%、钴95.0%～105.0%、镍95.0%～105.0%.在线用铑作为内标95.0%～105.0%.方法经国家一级标准物质验证,测定值与标准值吻合.应用于实际样品测定,结果满意.     

Surfactant assisted dispersion of MWCNT's in epoxy nanocomposites and adhesion with aluminum

This article presents an experimental investigation into the adhesion between aluminum and epoxy nanocomposites reinforced with multi-walled carbon nanotubes (MWCNT's). The nanotubes are dispersed in epoxy chemically with the aid of a surfactant, rather than mechanically via high shear mixing or ultrasonication. Four MWCNT weight fractions are considered viz. 0%, 0.1%, 0.5% and 1%. The adhesion with aluminum is tested via end-notched flexure tests conducted on specimens consisting of Aluminum strips adhered together with various epoxy nanocomposite glues. The best results are obtained for 1% MWCNT, where the tests show a notable increase in adhesion, evidenced by an intact bond despite considerable plastic deformation of Aluminum. However, the peak load capacity is seen to be not enhanced. The higher adhesion with 1% MWCNT addition is seen to successfully suppress the brittle debonding failures even at very high levels of adherend plasticity. For this weight fraction the overall response is highly ductile involving shearing of the glue and is desirable for engineering applications. Despite promising results, the surfactant itself is seen to be not very effective as a dispersing agent for the epoxy resin considered here.     

Determination of niobium in zirconium-niobium alloys

A rapid control determination of niobium in 50% zirconium/50% niobium master-alloy is described; it is a direct spectrophotometric procedure, based on the reaction of niobium ions with hydrogen peroxide in concentrated sulphuric acid. The procedure is suitable for the examination of zirconium alloys containing niobium in the range 0.1 to about 60%. At least 1% of chromium, cobalt, copper, manganese, nickel or tantalum, does not interfere. Interference due to optical absorption by the peroxy-complexes of titanium, tungsten, molybdenum and vanadium is not significant in the determination of niobium above about 1%, provided that these metals are not in excess of about 0.5%, 0.25%, 0.1% and 0.02%, respectively. To compensate for optical absorption due to iron(III), a solution of the sample, not treated with peroxide, is used.     

Determination of vitamin E isomers of grape seeds by high-performance liquid chromatography-UV detection

A simple analytical method for the determination of vitamin E isomers in grape seeds by reversed-phase high-performance liquid chromatography with UV detection is described. The method is based on a solid-liquid extraction separation on an ODS column, and the analytes are monitored at 295 nm with a UV detector. Tocopherols are extracted in n-hexane and directly injected onto the column without using any purification step, such as saponification, prior to the separation and determination. The chromatographic separation of tocopherols is achieved in 12 min with a mobile phase that consists of n-hexane and isopropyl alcohol (99.99:0.01, v/v). The method is reproducible and accurate, with respect to demonstrating a relative standard deviation between 2.57% and 3.30% (n = 10, for 500 ng/mL) and a relative error between 0.84% and 6.54% (n = 10, for 500 ng/mL), respectively. The theoretical limits are estimated as 25 ng/mL for α-tocopherol, 43 ng/mL for γ-tocopherol, and 83 ng/mL for δ-tocopherols. The method is then applied for the determination of tocopherols in grape seeds grown in Turkey. The amounts of tocopherols are calculated by using the standard addition method.