共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
3.
4.
This paper addresses the calculation of detection limits (DLs) for ion-chromatographic data at low part-per-trillion (w/w) levels. The main objectives are: (1) to explain two statistical techniques (the EPA or “3σ” approach and the Hubaux-Vos method), (2) to calculate DLs using each procedure, (3) to discuss the strengths and weaknesses of each statistical approach and (4) to decide if the analytical method is appropriate for quantifying anions at the 50-ppt level in deionized water. The analytes of interest are: fluoride, chloride, nitrite, bromide, nitrate, sulfate and phosphate. All work was performed on a Dionex DX500 microbore unit, using an AS11 column. Results indicate that the H-V method gives a more realistic (and higher) DL than does the 3σ. Assuming false-negative and false-positives probabilities of 10% or less, this analytical method is not acceptable for quantifying anions at the desired level. 相似文献
5.
Summary A sensitive and rapid routine HPLC method is proposed for quantitative estimation of morphine hydrochloride and hydromorphone
hydrochloride in pharmaceutical dosage forms. The drugs were chromatographed on a C18 reversed-phase column; the mobile phase was acetonitrile-water, 35:65 (v/v), containing sodium dodecyl sulphate (0.5%, w/v),
as ion pairing reagent, and acetic acid (0.4% v/v). Detection was at 230 nm.
The optimized method was validated and linearity (r>0.999), precision, and accuracy were found to be acceptable within the concentration ranges 86–124 μg mL−1 for morphine hydroloride and 60–180 μg mL−1 for hydromorphone hydrochloride.
The method is being used to investigate the stability of morphine hydrochloride and hydromorphone hydrochloride in solution
used for intramuscular injection. 相似文献
6.
在玻璃碳 (GC)基底上电沉积Pd ,应用SEM观测Pd沉积层的表面形貌 ,用循环伏安法研究了Pd/GC电极上HCOOH在HClO4溶液中的电氧化行为 .结果表明 ,Pd的电沉积条件影响电极的催化性能 .在高电流密度下制得的Pd/GC电极对HCOOH的电氧化具有比纯Pd电极更高的催化活性 .当电极表面生成PdO时 ,HCOOH被电氧化的活性很低 ,而在PdO还原后生成的Pd表面 ,HCOOH的电氧化显示极高的活性 .本文还讨论了Pd(Ⅱ )离子对HCOOH电氧化过程的影响 . 相似文献
7.
8.
制备了以脲醛树脂、KCl粉末、Ag/ Ag Cl丝为材料的 Ag/ Ag Cl固体电极 ,然后以此固体电极分别作为内外参比电极、以含四苯硼酸雷尼替丁离子对缔合物的 PVC膜作为敏感元件 ,组装成一种全固态复合式雷尼替丁电极 ,并详细研究了其性能。结果表明该电极具有良好的稳定性 ,其 Nernst响应范围为 5× 1 0 - 4~ 1× 1 0 - 1 mol/ L,斜率为 58.7m V/pc,检测下限为 2 .5× 1 0 - 4 mol/ L,使用寿命不少于 6个月 ,能用于盐酸雷尼替丁制剂的含量测定。 相似文献
9.
Xuzhi Zhang Qianqian Yang Xuchang Zhang Pingping Wang Zhihui Hao Jun Zhao Keming Qu 《中国化学快报》2018,29(9):1391-1394
By employing a developed automatic eight-channel electrical titrator, ciprofloxacin, clomipramine and fexofenadine hydrochlorides are determined in batch, respectively, with satisfactory accuracy and precision. It shows a higher efficiency superior to traditional titration method, and maximally 30 measurements per minute can be completed. 相似文献
10.
研究了NH2 OH·HCl存在下测定阿托品的极谱动力波法。在 0 .1mol/LLiCl 4.4× 1 0 - 3 mol/LNH2 OH·HCl支持电解质溶液中 ,阿托品于 - 1 .90V(vs.SCE)处产生一个极谱动力波 ,其二阶导数峰电流与阿托品在 6.0× 1 0 - 5~ 4.0×1 0 - 4 mol/L浓度范围内呈线性关系 (r=0 .9992 ,n =5 )。与无NH2 OH·HCl存在时相应还原波相比 ,该动力波电流可提高分析灵敏度一个数量级。讨论了该动力波的产生机理 相似文献
11.
Amr L. Saber 《Electroanalysis》2010,22(24):2997-3002
Simple, selective and accurate sensors were developed for the determination of melatonin and oxomemazine in biological samples (urine) and in pharmaceutical preparations. Potentiometric measurements were based on bismus tetraiodate‐drug ion‐pair as novel electroactive materials incorporating a plasticized PVC membrane with o‐nitrophenyl octyl ether or dioctyl phthalate. Each sensor was conditioned for at least two days in 0.1 M drug solution before use. It exhibited fast and stable Nernstian response for melatonin and oxomemazine over the concentration range of 1.0×10?6–1.0×10?2 M and 1.0×10?5–1.0×10?2 M, pH range of 3.0–6.5 and 3.5–6.0 for melatonin and oxomemazine sensors, respectively. Results with an average recovery not more than 101 % and a mean standard deviation less than 1.0 % of the nominal were obtained for the four sensors. The sensors showed reasonable selectivity towards investigated drugs in presence of many cations. 相似文献
12.
The effect of matrix contents on the detection limit of total reflection X-ray fluorescence analysis was experimentally investigated using a set of multielement standard solutions (500 ng/mL of each element) in variable concentrations of NH4NO3. It was found that high matrix concentration, i.e. 0.1–10% NH4NO3, had a strong effect on the detection limits for all investigated elements, whereas no effect was observed at lower matrix concentration, i.e. 0–0.1% NH4NO3. 相似文献
13.
14.
15.
作者研制一种微机化光离子化气相色谱仪,其灵敏度和检出限优于FID两个数量级(苯)可用于有机挥发物痕量分析。 相似文献
16.
Francisco Wirley P. Ribeiro Amanda S. Cardoso Rafael R. Portela Janete E. S. Lima Sergio A. S. Machado Pedro de Lima‐Neto Djenaine De Souza Adriana N. Correia 《Electroanalysis》2008,20(18):2031-2039
The electrochemical oxidation of promethazine hydrochloride was made on highly boron‐doped diamond electrodes. Cyclic voltammetry experiments showed that the oxidation mechanisms involved the formation of an adsorbed product that is more readily oxidized, producing a new peak with lower potential values whose intensity can be increased by applying the accumulation potential for given times. The parameters were optimized and the highest current intensities were obtained by applying +0.78 V for 30 seconds. The square‐wave adsorptive voltammetry results obtained in BR buffer showed two well‐defined peaks, dependent on the pH and on the voltammetric parameters. The best responses were obtained at pH 4.0, frequency of 50 s?1, step of 2 mV, and amplitude of 50 mV. Under these conditions, linear responses were obtained for concentrations from 5.96×10?7 to 4.76×10?6 mol L?1, and calculated detection limits of 2.66×10?8 mol L?1 (8.51 μg L?1) for peak 1 and of 4.61×10?8 mol L?1 (14.77 μg L?1) for peak 2. The precision and accuracy were evaluated by repeatability and reproducibility experiments, which yielded values of less than 5.00% for both voltammetric peaks. The applicability of this procedure was tested on commercial formulations of promethazine hydrochloride by observing the stability, specificity, recovery and precision of the procedure in complex samples. All results obtained were compared to recommended procedure by British Pharmacopeia. The voltammetric results indicate that the proposed procedure is stable and sensitive, with good reproducibility even when the accumulation steps involve short times. It is therefore very suitable for the development of the electroanalytical procedure, providing adequate sensitivity and a reliable method. 相似文献
17.
《Journal of Saudi Chemical Society》2014,18(2):107-114
The present study describes two simple, rapid, selective and cost-effective spectrophotometric methods for the determination of dothiepin hydrochloride (DOTH), an antidepressant drug, in bulk drug and pharmaceutical formulations. The first method (method A) is based on the formation of yellow colored ion-pair complex between DOTH and alizarin red S (ARS) in acid medium which was extracted into dichloromethane and the absorbance was measured at 445 nm. The second method (method B) is based on the breaking of the yellow DOTH–ARS ion-pair complex in alkaline medium followed by the measurement of the violet color free dye at 570 nm. Under the optimized conditions, Beer’s law is obeyed over the concentration ranges of 2.50–55.0 and 1.00–35.0 μg ml−1 DOTH for method A and method B, respectively. The molar absorptivity, Sandell’s sensitivity, detection and quantification limits are also calculated. The methods were validated for intra-day and inter-day accuracy and precision; selectivity and robustness and ruggedness. The proposed methods were applied successfully to the determination of DOTH in pure drug and commercial formulations. The accuracy and reliability of the proposed methods were further established by parallel determination by the official method and also by recovery studies via standard addition technique. 相似文献
18.
Rongbin Wei Zhongjie Fei Yanrong Liu Bangwen Fu Ling Chen Liu Wang Pengfeng Xiao 《Electrophoresis》2021,42(11):1262-1269
In the present study, we developed a novel digital coding combination analysis (DCCA) to analyze the gene mutation based on the sample combination principle. The principle is that any numerically named sample is divided into two groups, any two samples are not grouped in the same two groups, and any sample can be tested within the detection limit. Therefore, we proposed a specific combination that N samples were divided into M groups. Then N samples were analyzed, which could obtain the mutation results of M mixed groups. If only two groups showed positive (mutant type) signals, the same sample number from two positive signal groups would be the positive sample, and the remaining samples were negative (wild type). If three groups or more exhibited positive results, the same sample number from three positive signal groups would be the positive sample. If some samples remained uncertain, individual samples could be analyzed on a small scale. In the present study, we used the two genotypes of a mutation site (A5301G) to verify whether it was a useful and promising method. The results showed that we could quantitatively detect mutations and demonstrate 100% consistent results against a panel of defined mixtures with the detection limit using pyrosequencing. This method was suitable, sensitive, and reproducible for screening and analyzing low-frequency mutation samples, which could reduce reagent consumption and cost by approximately 70–80% compared with conventional clinical methods. 相似文献
19.
Simple, reliable, sensitive and accurate kinetic spectrophotometric and spectrofluorimetric methods were proposed for the determination of ciprofloxacin hydrochloride (CPX) and norfloxacin (NRX) in pure form and in pharmaceuticals. The methods are based on coupling the studied drugs with 4‐chloro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl) in the presence of alkaline borate buffer. Spectrophotometric measurement was achieved by recording the absorbance at 477 nm after a fixed time of 20 and 15 min on a water bath adjusted at 70 ± 1 °C for CPX and NRX, respectively. The same product exhibited emission peaks at 540 nm. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The absorbance concentration plots were linear over the ranges 3‐18 and 2.5‐15.0 μg/mL for CPX and NRX, respectively, while the fluorescence concentration plots were linear over the ranges 0.06‐0.36 and 0.05‐0.30 μg/mL for CPX and NRX, respectively. The limit of detection of the kinetic method was about 0.2 μg/mL for both drugs while the fluorescence measurement enabled their detection at a concentration of about 0.012 μg/mL. The proposed methods were successfully applied for the assay of the two drugs in their commercial products. The results obtained were statistically compared with those obtained by reference HPLC and spectrophotometric methods. The stoichiometry of the reaction was determined and the reaction pathway was postulated. 相似文献
20.
《Electroanalysis》2017,29(4):975-982
Sensitive disposable sensors have been constructed for potentiometric determination of Biperiden hydrochloride (BPHCl) based on multi‐walled carbon nanotubes–polyvinylchloride (MWNTs–PVC) composite in presence of dibenzo 24‐crown‐8‐ ether as a molecular receptor. Electrode matrix composition was optimized on the basis of the nature of the electroactive material, ionic sites, membrane plasticizer, and nanomaterial. The fabricated sensors showed improved selectivity and sensitivity towards biperiden hydrochloride with Nernstian cationic compliance of 59.8±1.1 mV decade−1 in the concentration range from 10−6 to 10−2 mol L−1. Modification with carbon nanotubes promote electron‐transfer processes and enhanced the stability of potential reading, response time and shelf lifetime of sensors. The proposed method was applied for potentiometric assay of BPHCl in dosage formulation and biological fluids under batch and flow injection analysis (FIA) with average recoveries agreeable with the reported official methods. 相似文献