Study on Rhizoma Chuanxiong based on capillary electrophoresis with amperometric detection

A high-performance capillary electrophoresis with amperometric detection(CE-AD) method has been developed for the analysis of seven bioactive ingredients,namely ferulic acid(FA),vanillin,vanillic acid,p-hydroxybenzoic acid,caffeic acid,gallic acid and protocatechuic acid,in Rhizoma Chuanxiong.The effects of several factors such as the acidity and concentration of running buffer,the separation voltage,the applied potential to working electrode and the injection time were investigated.Under the optimum condit...

Studies of Active Ingredients in Cough Syrup by Capillary Zone Electrophoresis with Amperometric Detection

The present paper covers a simple, reliable and reproducible method, based on capillary zone electrophoresis(CZE) with amperometric detection(AD), for the separation and the determination of ephedrine hydrochloride, promethazine hydrochloride and codeine phosphate. Under the optimal conditions, the three analytes were base-line separated completely within 16 min. Good linear relationships between the peak heights and the concentrations of the three analytes were obtained with the correlation coefficients better than 0 9993. The method was directly applied to the determination of the active ingredients in pharmaceutical preparations and the assay results were satisfactory.

Amperometric Detection of Histamine and Amino Acid Neurotransmitters in Capillary Electrophoresis with Copper Microelectrodes

Copper microelectrodes were used in microvoltammetry to detect histamine and several amino acid neurotransmitters. High sensitivity was obtained through the use of copper microelectrodes, and detection limits of 50 nmol/L and 90 nmol/L were obtained for histamine and histidine, respectively. Furthermore, histamine and several amino acids neurotransmitters were firstly separated and detected by capillary electrophoresis with amperometric detection on copper microelectrodes. Mass limits of 490 amol and 440 amol were achieved for histamine and histidine, respectively, by using this mothod.

Determination of neomycin in water samples by high performance anion chromatography with pulsed amperometric detection

A simple, fast and reliable method, using high performance anion chromatography with pulsed amperometric detection, had been developed for the analysis of neomycin in water samples. The elution and separation were carried out with an isocratic mobile phase, containing 10 mmol/L NaOH. The influence of the concentration and pH of the mobile phase on the separation and detection was investigated. A quadruple-potential waveform used for the detection was optimized. The detection limit of neomycin was down to 0.027 μg/mL. The linearity of neomycin calibration curve ranged from 0.050 to 0.505 μg/mL with correlation coefficient of 0.9997. R.S.D. (n = 11) was 4.0%.

Determination of Roxithromycin Tablets by Capillary Electrophoresis Employing Non-aqueous Media with Square-wave Amperometric Detection

A new method of determination for roxithromycin tablets by non-aqueous capillary electrophoresis (NACE) with square-wave amperometric detection was carried out. Several parameters affecting the NACE-AD determination were studied. The data was modified by spline wavelet least square (SWLS). The method is simple, rapid and highly reliable for routine analysis.

Detection of Catecholic Compounds with Field-ampilfied CZE-Amperometry

On-column sample stacking technique has been used extensively in capillary zone electrophoresis (CZE) to enhance the sensitivity of the measurements with UV-Vis detection. However, the detection limits for CZE-separation are still limit- ed due to the poor sensitivity of a UV-Vis detector. We incorporated field-amplified sample stacking technique into CZE with amperometric detection. Compared with the conventional electromigration injection , a negative peak of water was observed and a great enhancement of signals was obtained. The results in phosphate buffer with sodium dodecyl sulfate (SDS ) and 2-N-(morpholino) ethane sulphonic acid ( MES ) buffer were compared. Subnanomolar concentration limits for cate- cholamine neurotransmitters (dopamine, norepinephrine , epinephriine) and isopro- terenol were achieved in the 25 um capillary with two or three orders of magnitude lower than those with amperometric detection reported previously.

Electrocatalytic Oxidation and Ion Chromatography Detection of S_2O^(2-)_3, SO^(2-)_3, I^- and SCN^- at Glassy Carbon Electrode with Functionalized Multi-Wall Carbon Nanotubes Film

In this research, a glassy carbon electrode modified with the functionalized multi-wall carbon nanotubes(MWNT-COOHs) film was used as an amperometric sensor for the determination of S_2O^(2-)_3, SO^(2-)_3, I^- and SCN^-. The electrochemical behavior of those oxidizable inorganic anions at this modified electrode was studied by means of cyclic voltammetry(CV). The experimental results indicate that the modified electrode exhibits a high electrocatalytic activity towards the oxidation of those anions with a relatively high sensitivity, a good stability and a long-life. Separated by ion chromatography(IC) with 1.25 mmol/L H_2SO_4 as an eluent, those oxidizable anions can be determined by the MWNT-COOHs modified electrode successfully. Under the optimal chromatographic conditions, the detection limits are 1.5×10^(-7) mol/L for S_2O^(2-)_3, 2.5×10^(-7) mol/L for SO^(2-)_3, 1.2×10^(-7) mol/L for I^- and 2.0×10^(-7) mol/L for SCN^-, respectively. The method was applied successfully to the determination of those anions in environmental water

凉垫、凉枕降温性能检测方法研究

通过模拟实际使用环境,对降温凉垫、凉枕的降温性能进行了研究。结果表明:大多数凉垫、凉枕使用后最低温度在20~25℃之间。当降温时间大于2 h、平均温差>5℃时,可认为该凉垫、凉枕具有持续降温性能,凉垫、凉枕在炎热的夏季可以起到凉爽降温的作用。该检测方法可为相关生产企业控制产品质量提供参考。

反相离子对色谱法测定辅助生殖培养液中庆大霉素含量

目的建立测定辅助生殖培养液中庆大霉素含量的反相离子对色谱法。方法辅助生殖培养液样品采用WCX固相萃取小柱富集、净化法进行前处理。色谱柱为Apollo C_(18)柱(250 mm×4.6 mm,5μm),淋洗液为水(含0.7%三氟乙酸、0.025%五氟丙酸、0.2%NaOH,pH为2.6)-乙腈(50∶3,V/V),检测器为柱后加碱-脉冲安培检测器,以外标法定量。结果庆大霉素C^(1),C_(1a),C_(2),C_(2a)的质量浓度分别在0.550~10.996μg/mL、0.526~10.512μg/mL、0.584~11.688μg/mL、0.356~7.124μg/mL范围内与峰面积线性关系良好(r>0.9995,n=6);检测限为0.2016μg/mL,定量限为0.6722μg/mL;回收率为92.66%~99.82%,RSD<5%(n=6)。精子冷冻液中未检出庆大霉素,颗粒细胞去除液、玻璃化解冻液、全程培养液、精子密度梯度分离液、精子制动液中庆大霉素的含量分别为17.54,12.60,15.08,9.26,11.12μg/mL(n=6)。结论该方法前处理简单,无须衍生化处理,简便高效,灵敏度高,重复性好,可用于多种辅助生殖培养液中庆大霉素的检测。

IC-IPAD同时测定运动饮料中20种氨基酸和6种糖

建立了梯度淋洗-离子色谱-积分脉冲安培检测法同时测定运动饮料中20种氨基酸和6种糖的分析方法。通过对梯度淋洗条件、色谱柱温度、p H以及前处理条件等实验影响因素的考察,优化出适合同时检测26种组分的分析方法。结果表明,样品经调节pH沉淀蛋白后,再由RP净化柱处理,采用多级梯度淋洗模式,在35℃的色谱柱温度和样品溶液pH值为5.2~6.7条件下进行分离检测,26种组分在0.5~50.0 mg/L质量浓度范围内线性良好,相关系数(R2)为0.990~0.999,检出限为0.001~0.060 mg/L,定量限为0.003~0.200 mg/L。加标试验分别添加1 mg/L,10 mg/L和50 mg/L 3个水平,加标回收率达到86.2%~105.0%(n=5),相对标准偏差(RSD)为1.9%~5.3%。该方法高效、简便、灵敏、准确,可用于运动饮料中多种氨基酸和糖的同时测定分析。

HPLC-PAD外标法及UPLC-MS/MS内标法测定乳及乳制品中三聚氰胺的含量

分别建立高效液相色谱-二极管阵列法(HPLC-PAD)、超高压液相色谱-串联质谱法(UPLC-MS/MS)测定乳及乳制品中三聚氰胺含量的方法。利用HPLC-PAD外标法进行样品中三聚氰胺的初筛,利用UPLC-MS/MS法进行确证,以13C315N3-三聚氰胺为同位素内标定量。乳制品经乙腈、乙酸锌、盐酸溶液提取,质谱检测时,样品再经MCX固相萃取柱富集净化。HPLC-PAD法的定量限为4mg/kg,UPLC-MS/MS的定量限为0.05mg/kg;HPLC-PAD的添加回收率为95.7%～102.3%,UPLC-MS/MS的添加回收率为91.3%～95.7%(基质匹配曲线校正),两种方法的相对标准偏差(RSD)分别为1.98%～4.51%,1.60%～3.27%。

HPLC-PAD法测定硫酸新霉素含量及其有关物质

建立反相高效液相色谱-脉冲安培检测法(RP-HPLC-PAD)测定硫酸新霉素含量及有关物质方法。采用Thermo Acclaim^(TM) AmG C_(18)(4.6 mm×150 mm,3μm)色谱柱,以2%三氟乙酸溶液[含0.01%五氟丙酸+0.6%氢氧化钠]为流动相,采用积分脉冲安培电化学检测器四电位波形做为检测波形进行检测。测得新霉素B和新霉素C及13个杂质分离良好,新霉素B和新霉素C的检出限均为1.75 ng,定量限均为3.5 ng,新霉素B在0.14～27.89μg/mL内线性关系良好(r=0.998 5),新霉素C在0.14～4.69μg/mL内线性关系良好(r=0.999 6)。该HPLC-PAD法专属性强、灵敏度高、线性范围宽,具有良好的应用前景,为硫酸新霉素标准制定和质量控制提供了依据。

Milk Spoilage: Methods and Practices of Detecting Milk Quality

Milk spoilage is an indefinite term and difficult to measure with accuracy. This uncertainty can cause suffering for both milk manufacturers and consumers. Consumers who have been misled by ambiguous expiration dates on milk cartons waste resources by disposing of unspoiled milk or experience discomfort from drinking spoiled milk. Consumers are often unwilling to purchase products close to their inaccurate expiration dates. This consumer behavior has a negative financial impact on milk producers. Inaccurate milk spoilage detection methods also force milk producers to use overly conservative expiration dates in an effort to avoid the legal and economic consequences of consumers experiencing illness from drinking spoiled milk. Over the last decade, new methods have been researched with the purpose of developing more accurate and efficient means of detecting milk spoilage. These methods include indicators based on pH bacteria counts and gas-sensor arrays. This article explores various methods of spoilage detection designed to prevent such consequences. The respective level of effectiveness of each method is discussed, as well as several further approaches to contain freshness regardless of detection.

Determination of phenolic whitening agents in cosmetics by micellar electrokinetic capillary chromatography with amperometric detection

A sensitive method for simultaneous determination of six phenolic whitening agents, including arbutin, phenol, resorcinol, hydroquinone, kojic acid, and salicylic acid in cosmetics has been developed using micellar electrokinetic capillary chromatography with amperometric detection （MECC-AD）. Effects of several factors, such as the pH value and concentration of running buffer, potential applied to the working electrode, separation voltage, and injection time were investigated to obtain optimum conditions for separation and detection. With a 75 cm long fused-silica capillary tube, well-defined separation of six phenolic compounds was achieved in 10 mmol/L SDS/40 mmol/L H3BO3-Na2B407 running buffer （pH 9.0）. Good linear relationship was obtained for each analyte over three orders of magnitude with correlation coefficients （r2） between 0.9985 and 0.9994, and the detection limit （S/N = 3） ranged from 0.04 p^g/mL to 0.45 p^g/mL. The proposed method has been successfully applied for the determination of phenolic whitening agents in real cosmetic samples with satisfactory results, providing an alternative monitoring method for cosmetics safety regulation.

Simultaneous Determination of Catecholamines and Related Metabolites by Capillary Electrophoresis with Amperometric Detection

An electrophoretic method was developed for the determination of several important catecholamine markers, namely norepinephrine, epinephrine, dopamine, metanephrine, vanillylmandelic acid and homovanillic acid in urine samples. Under the optimum conditions, the six marker compounds could be well separated with the major coexisting interference compound uric acid within 24 rain at a separation voltage of 16 kV in a borate running buffer （80 mmol/L, pH=9.48）. Highly linear response can be obtained over three orders of magnitude for the above markers with the low limits of detection ranging from 1.0 ng/mL to 5.0 ng/mL（S/N=3）. The proposed capillary electrophoresis with amperometric detection（CE-AD） method has been used to simultaneously determine the six catecholamine markers in urine samples of healthy volunteers and patients suffering from different diseases avoiding redundant measurements and high assay cost; and the electrochemical profiles can suggest more diagnostic information of multiple diseases, which provides a promising and convenient entry into primary diagnoses of several clinical diseases.

Determination of Four Active Ingredients in Vc Yinqiao Tablets by Capillary Zone Electrophoresis with Amperometric Detection

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection （CZE-AD）, has been developed for simultaneous determination of four active ingredients in Vc Yinqiao tablets including paracetamol, vitamin C, caffeic acid and chlorogenic acid. A carbon-disk electrode was used as working electrode and 0.95 V （versus SCE） was selected as detection potential. The optimal conditions of CZE experiment were 30 mmol·L^-1 borate solution （pH 9.5） as running buffer, 14 kV as separation voltage and 8 s （14 kV） as electro-kinetic sampling time. Under the selected optimum conditions, paracetamol, vitamin C, caffeic acid and chlorogenic acid could be perfectly separated within 22 min, and their detection limits （S/N=3） ranged from 5×10^-7 to 1 ×10^-6 mol·L^-1. This proposed method demonstrated good reproducibility with relative standard deviations of less than 3% for both migration time and peak current （n=7）. The utility of this method was demonstrated by monitoring a kind of compound medicine named Vc Yinqiao tablets and the assay results were satisfactory.

微波水解-HPAEC-PAD法快速测定乳粉中的皮革水解蛋白

L-羟脯胺酸是皮革水解蛋白的特征氨基酸。样品经微波酸水解使氨基酸游离,水解液过C18柱和0.22μm水系膜净化过滤,以AminoPacTMPA10阴离子交换柱为分离柱,采用NaOH/NaOAc/HOAc梯度洗脱,脉冲安培检测,建立了脉冲安培检测-离子色谱法(HPAEC-PAD)测定乳粉中的皮革水解蛋白。结果表明,L-羟脯氨酸在0.05～0.20mg/L内线性良好,线性相关系数r2为0.999,阴性样品加标回收率为92.8%～101.7%,检出限(LOD)为0.015mg/L,定量限(LOQ)为0.050mg/L。相较国家标准方法准确、快速、简便,可以大致反映乳粉中皮革水解蛋白的添加量。

Fast Determination of Clenbuterol and Salbutamol in Feed and Meat Products Based on Miniaturized Capillary Electrophoresis with Amperometric Detection

The fast separation capability of a novel miniaturized capillary electrophoresis with an amperometric detection （μCE-AD） system was demonstrated by determining clenbuterol and salbutamol in real samples. The effects of several factors such as the acidity and concentration of the running buffer, the separation voltage, the applied potential and the injection time on CE-AD were examined and optimized. Under the optimum conditions, the two β-agonists could be baseline separated within 60 s at a separation voltage of 2 kV in a 90 mmol/L H3BO3-Na2B4O7 running buffer （pH 7.4）, which was not interfered by ascorbic acid and uric acid. Highly linear response was obtained for above compounds over three orders of magnitude with detection limits ranging from 1.20×10^-7 to 6.50×10^-8 mol/L （S/N=3）. This method was successfully used in the analysis of feed and meat products with relatively simple extraction procedures.

HPLC-PAD法测定硫酸依替米星注射液有关物质及含量

目的:建立硫酸依替米星注射液有关物质及含量的反相高效液相色谱-脉冲安培电化学(HPLC-PAD)法。方法:采用十八烷基硅烷键合硅胶为填充剂(4.6 mm×250 mm,5μm或效能相当的色谱柱),柱温35℃。以0.2 mol·L^-1三氟乙酸溶液(含0.05%五氟丙酸,1.5 g·L^-1无水硫酸钠,0.8%(V/V)的50%氢氧化钠溶液,用50%氢氧化钠溶液调节pH值至3.5)-乙腈(95∶5)为流动相,流速为每分钟1.0 mL。柱后加碱(50%氢氧化钠溶液1→25,流速每分钟0.5 mL)。用积分脉冲安培电化学检测器检测。结果:依替米星在0.075~50μg·mL^-1(r=0.9996)内线性关系良好;单个最大杂质的重复性试验的RSD(n=6)为1.4%,总杂质的重复性试验的RSD(n=6)为1.7%,含量测定的重复性试验的RSD(n=6)为0.8%;方法的检测限(S/N=3)为75 ng·mL^-1,定量限(S/N=10)为250 ng·mL^-1;供试品溶液在12 h内稳定性良好。9批样品用药典方法(反相高效液相色谱-蒸发光散射法)和HPLC-PAD法测定,HPLC-PAD法的总杂和杂质个数结果偏高,其中6批样品HPLC-PAD法的含量结果偏低。结论:经方法学验证,该方法可以用于硫酸依替米星注射液有关物质及含量的测定。

Construction and evaluation of a novel end-column amperometric detection system for electrophoresis microchips

A set of integrated end-column amperometric detection system has been developed,onto which an electrophoresis microchip can be conveniently integrated.Finely machined by a piece of transparent organic glass,the system consists of an electrophoresis microchip platform and an amperometric detection reservoir,in which the microchip can be fixed onto the platform by microchip grooves and with stainless steel fixture.Each detection electrode can be directly fixed in the amperometric detection reservoir by screws and nuts.With dopamine as the model analyte,we take platinum disc electrodes with different diameters of 100 μm,300 μm and 500 μm and a carbon fiber electrode with the diameter of 240 μm as the working electrode,all of which accomplish sensitive detection.The detection parameters of the system are optimized with the carbon fiber electrode.The detection results show that in the electrochemical cleaning procedure,the relative deviations of 3.2% and 0.5% for the peak current and retention time,respectively,can be obtained for the successive detections of 100 μM dopamine,and the limit of detection for dopamine can reach 0.4 μM(S/N = 3).This system is small,but its performance of detection is stable and sensitive,and the replacement of its working electrodes is convenient,so it is very suitable as a universal platform of end-column amperometric detection for electrophoresis microchips.