注入热焓法测定萃取磷酸中三氧化硫

以钡离子与硫酸根离子沉淀反应的热效应为基础，通过测定孤立体系中的温度变化，建立了测定萃取磷酸中三氧化硫的注入热焓法，该法在４．０－３２．０ｇ／Ｌ范围内可准确测定ＳＯ３的含量，相对标准偏差为１．８％；标准加入回收率为９８％－１０３％。     

离子色谱法同时测定湿法磷酸中氯离子、硝酸根和硫酸根的含量

正湿法磷酸是指用硫酸分解磷矿粉,分离出粗磷酸,再经净化后制得磷酸产品,湿法磷酸技术的应用大幅度降低了能源消耗,提高了经济效益,产品用途广泛。湿法磷酸中阴离子含量的控制和检测一直是产品质量控制的重要组成部分,但目前测定化工和食品添加剂中杂质阴离子的标准方法大多采用比浊法和分光光度法[1],这些传统方法干扰大、准确度低,不适合低含量阴离子的测定,而离子色谱法具有快速、准确、选择性好和多组分同时测定的优点[2],     

流动注射热焓法测定浸取磷酸中三氧化硫

以测量钡离子与硫酸根离子沉淀反应热效应的热焓法为基础,采用合并带流路建立了测定浸取磷酸中三氧化硫的流动注射热焓法。该法在４．０－４２．０ｇ／Ｌ范围内可准确测定了ＳＯ３的含量。相对标准偏差为１．６％,标准加入回怍率为９６％－１０４％;测样速度为６０样／ｈ。     

湿法磷酸生产过程中控制稀土走向的研究

采用稀土含量0．55％REO磷矿为原料在间歇实验装置中进行二水物湿法磷酸模拟生产,研究了湿法磷酸生产中工艺条件及活性添加剂对磷矿中稀土走向的影响。研究结果表明：较低的体系温度、高的磷酸浓度及较大的液固比均有利于稀土在磷酸中的富集;控制合适的SO^2-4浓度有利于硫酸钙晶体的成长,可减少磷酸稀土的共晶和吸附作用,从而提高稀土的浸出率,在硫酸与磷矿的化学计量比为1.1时可形成易于洗涤和过滤的类球状聚晶;通过添加活性添加剂控制硫酸钙的结晶速度和结晶形貌,从而减少磷酸稀土和硫酸钙的共晶和吸附作用,以提高稀土在磷酸中的富集;添加不同活性添加剂,稀土在磷酸中的富集程度不同,其中以NS-2,NS-1及IA-1对稀土在磷酸中的富集影响尤著,稀土总浸出率可达75％以上。     

湿法磷酸中钾、钠、钙、镁的原子吸收光谱法测定

在湿法磷酸生产过程中,为了对生产流程和产品质量进行控制,有必要对湿法磷酸中微量的钾、钠、钙、镁含量进行分析。用火焰原子吸收光谱法测定湿法磷酸中钾、钠、钙、镁受基体和背景以及溶液粘度的影响很大,特别是对钙含量的测定,干扰最严重[1]。为此本文提出用离子交换树脂分离     

还原浊度法测定溴化锂－铬酸锂混合液中的硫酸根

还原浊度法测定溴化锂－铬酸锂混合液中的硫酸根谢家理，冯易君，王劲榕（四川大学化学系成都６１００６４）关键词硫酸根，溴化锂，铬酸锂，比浊法由于溴化锂致冷剂不污染环境将得到推广应用，以取代氟里昂。因此控制微量杂质硫酸根的测定是必要的。若用离子色谱法测定，...     

离子色谱法测定高山红景天多糖硫酸酯中硫酸根含量的研究

从高山红景天、平菇、红缘层孔菌中分别分离出多糖ＲＳＡ,ＡＴ,ＦＰ用氯磺酸吡啶法对多糖进行硫酸化修饰分别得到ＲＳＡＳＬ,ＡＴＳＬ,ＦＰＳＬ,多糖硫酸酯的生物活性与硫酸根的含量密切相关,用离子色谱法测定多糖硫酸酯中硫酸根的含量,ＲＳＡＳＬ为２７．７％,ＡＴＳＬ为３６．９２％,ＦＰＳＬ为３７．５％,与紫外比浊法相比,离子色７谱法具有准确、简便、重复性好等优点。     

硅钼蓝分光光度法测定湿法磷酸中的二氧化硅

采用硅钼蓝分光光度法直接测定湿法磷酸中的可溶性二氧化硅。显色时,利用草酸消除大量磷酸根的干扰。方法操作简单,稀酸和浓酸中可溶性二氧化硅测定结果的相对标准偏差分别为1.6%、6.2%,加标回收率均在96%~103%,测定结果的准确度及精密度均能满足工业分析的要求。     

离子色谱法测定土壤提取液中的磷酸根、硝酸根和硫酸根

用离子色谱(以下简称IC)测定水和大气等环境样品中的阴离子已有不少报导,但用IC测定土壤样品中的阴离子到目前为止报导极少,用该法测定土壤中的磷酸根还未见报导。我们选择了六种土壤提取液,讨论了定量提取磷酸根、硝酸根和硫酸根的条件,并对测定磷酸根的淋洗液进行了较系统研究,找出在复杂的土壤提取液中离子色谱测定磷酸根的条件。鉴于在我们以前的工作中,硝酸根、硫酸根的IC法已与化学法作过对照,此文不再重复,仅就磷酸根的数据与化学法对比,并用两种淋洗液测定,结果颇为一致。     

溴化十六烷基三甲铵浊度法测定磷化液中硫酸根

磷化液中硫酸根的测定,以往采用在盐酸介质中与氯化钡生成硫酸钡沉淀,经灼烧后称重换算出硫酸根的含量。浊度法测定磷化液中硫酸根尚未见有报道。本人根据浊度法测定镀铬溶液中硫酸根报道经过多年的实践,发现反应能在高酸度条件下测定磷化液中的硫酸根。反应灵敏度并不高,但许多常见离子几毫克乃至20多毫克都不干扰测定。我们认为用本法分析磷化液中硫酸根数据准确、速度快、成本低,用此法分析标准溶液、磷化槽液中硫酸根的含量与硫酸钡重量法所测得结果对照,都得到了满意结果。可分析硫酸根<3g·L~(-1)的磷化液中硫酸根的含量。 1 试验部分1.1 试剂与仪器 硫酸根标准溶液:2mg· ml~(-1),称取已于 110℃烘干的无水硫酸钠2.9583g,用水稀释至1L。 氯化钡-CTMAB溶液:称取氯化钡25g溶于热     

一种简易同时蒸馏萃取方法用于八角茴香挥发油提取及其GC-MS分析

设计了一种简易同时蒸馏萃取(SSDE)装置并用于八角茴香挥发油提取及其气相色谱-质谱法(GC-MS)分析。 该装置由圆底烧瓶、恒压滴液漏斗和回流冷凝管构成。 通过对八角茴香挥发油组分的GC-MS分析,比较SSDE法和水蒸汽蒸馏提取法(HD)提取植物源挥发油的效果。 结果表明,SSDE法所得挥发油相对含量在0.1%以上的19种化合物占挥发油总量的98.84%(相对标准偏差(RSD)(n=3)均不大于5.59%,其中RSD﹤5%的17种化合物占鉴定组分89.5%。SSDE法和HD法挥发油平均收率分别为7.30%(RSD=2.37%(n=5))和6.67%(RSD=5.26%(n=5))。 SSDE法简便、快速,适用于八角茴香挥发油的提取。     

反相高效液相色谱中流动相线性梯度洗脱条件下溶质保留时间预测的新方法

 在计算溶质的梯度保留时间时 ,根据流动相在色谱柱内的分布规律 ,对溶质在色谱柱内的迁移距离和流动相梯度同时进行校正 ,从而建立了一种预测溶质线性梯度洗脱条件下保留时间的新方法。该方法在不同的仪器系统中 ,对于弱保留和强保留溶质在不同线性梯度洗脱条件下保留时间的预测 ,都具有良好的准确度。以 15种氨基酸和 8种苯的同系物为例 ,该方法对于弱保留溶质保留时间的预测 ,相对平均误差分别为 3 70 %和 4 90 % ,远小于文献方法得到的结果 (2 3 6 1%和 31 16 % ) ;对于强保留溶质保留时间的预测 ,相对平均误差分别为 0 2 1%和6 0 1% ,略小于文献 。     

ICP-AES测定钼铁中杂质元素

研究了用ICP-AES测定钼铁中硅、磷和铜的方法,建立了最佳工作条件,采用基体匹配方法,应用软件中谱线干扰校正程序消除了干扰,检出限小于0．005％,回收率在93％-108%之间,RSD小于1．0％。方法简便、快速、准确。     

Improved tribenzylamine-silver bromide extraction/atomic-absorption spectrophotometric method for the determination of silver in ores, related materials and zinc process solutions

An improved tribenzylamine extraction/atomic-absorption method for the determination of silver in ores, related materials and zinc process solutions is described. The method, which involves the separation of silver by a single methyl isobutyl ketone extraction of the tribenzylamine-silver bromide ion-association complex from ~ 0.5-2M sulphuric acid-0.14M potassium bromide, is simpler and more rapid than a previous method based on a triple chloroform extraction of the complex. Silver is stripped with 12M hydrochloric acid containing 1% thiourea as a complexing agent. Thiourea is destroyed with nitric and perchloric acids and silver is ultimately determined by atomic-absorption spectrophotometry in an air-acetylene flame, at 328.1 nm, in a 10% v v hydrochloric acid-1% v v diethylenetriamine medium. Cadmium and bismuth are partly co-extracted but do not interfere. Results obtained by this method are compared with those obtained previously by the tribenzylamine/chloroform extraction method and with those obtained by a direct acid-decomposition/atomic-absorption method.     

ICP-AES测定南红玛瑙中剧毒元素As、Cd、Cr、Pb、Sb含量的研究

文章研究报道了电感耦合等离子体发射光谱法测定南红玛瑙中As、Cd、Cr、Pb、Sb元素含量的分析方法。通过对前处理方法的确定、分析线的选择、基体干扰方面的研究,确定了分析条件,并对比研究了标准曲线法与标准加入法在测定方面的异同。标准加入法与标准曲线法的测定结果相近,但标准曲线法的测定结果总是比标准加入法的测定结果小。在标准加入法中,各元素加标回收率在93.6％～103％之间,测定值的相对标准偏差(RSD_n=6)小于10％;在标准曲线法中,各元素加标回收率在90.2％～103％之间,各元素的相对标准偏差(RSD _n=6)也均小于10％。基体效应对标准曲线法测定存在一定的影响,但不十分明显。标准加入法可以很好地减轻基体效应的干扰,但不可大批量测定样品。因此,在分析控制质量要求允许范围内,可采用标准曲线法对南红玛瑙中剧毒元素As、Cd、Cr、Pb、Sb的含量进行测定。     

Determination of water by flow-injection analysis with the karl fischer reagent

A method for the determination of water in organic solvents by flow-injection analysis (f.i.a.) is described. The method, which is based on the reaction between water and the Karl Fischer reagent, is capable of 120 determinations per hour. The concentration range 0.01–5% (v/v) of water can be covered by using a single Karl Fischer reagent solution. The results obtained with a specially constructed potentiometric detector showed a relative standard deviation of less than 0.5% (v/v). This value was about 3 times less than that obtained with a spectrophotometric detector. The f.i.a. technique is shown to offer some unique possibilities in minimizing interferences associated with the standard Karl Fischer batch titration method.     

Determination of Four Nitrofuran Metabolites and Chloramphenicolin Biological Samples Using Enzyme-Linked Immunosorbent Assay

A pretreatment method was developed for the determination of four nitrofuran metabolites and chloramphenicol in pork, chicken, fish, and shrimp. Homogenized samples were hydrolyzed and derivatized with 2-nitrobenzaldehyde. Extraction was performed using ethyl acetate followed by purification of the extract by hexane. Lastly, the ethyl acetate was dried under nitrogen and the residue was redissolved for analysis. The performance of the method was satisfactory for all drugs tested at contamination levels close to or below the relevant European Union maximum levels permitted. The limits of detection (LODs) of the method were 0.025–0.13 ng/g. Recoveries higher than 72.0% were obtained for all drugs tested, and the coefficient of variation was less than 15%. Results from analysis of unknown samples by the developed ELISA were similar to those obtained by a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.     

Validation of a confirmatory method for the determination of macrolides in liver and kidney animal tissues in accordance with the European Union regulation 2002/657/EC

This study proposes a simple multiresidue liquid chromatography-diode array detector (LC-DAD) method capable of determining seven macrolide antibiotics in samples of liver and kidney animals at concentrations lower than those allowed by current legislation. Samples were prepared by homogenizing the tissue with EDTA-McIlvaine's buffer and extracted with an Oasis HLB cartridge. The consumption of organic solvent during extraction was minimum. The analytes were detected by LC-DAD and also by liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The method was specific, stable and robust enough for the required purposes. The DAD method was validated in accordance with the European Commission Decision 657/2002. Recovery data were also satisfactory with values higher than 67% for most macrolide antibiotics extracted from liver and kidney samples spiked at 200 microg/kg, the lowest MRL established for the macrolides studied. The relative standard deviations (RSD (%), (n=3)) were lower than 13% and 15% for intra-day and inter-day assays. The method was applied to investigate the occurrence of the studied macrolides in 31 beef and kidney animal samples. The results obtained by LC-DAD for positive samples were compared to those obtained by LC-(ESI)MS. Therefore, the method with simpler instrumentation than a LC-(ESI)MS can be used as a control method and the results of the validation process demonstrate that this method is suitable for application in a European Union program for monitoring residues of veterinary drugs.     

Automated development of analytical chemical methods : The determination of senun calcium by the cresolphthalein complexone method

The cresolphthalein complexone method for serum calcium determination was investigated by means of a modified Technicon Autoanalyzer II under computer control. Simplex optimization of reagent concentrations, followed by response-surface mapping in the region of the optimum produced a method yielding 8.5% greater calcium sensitivity and 15% lower baseline absorbance than the standard method, with comparable insensitivity to interferences, and only a very slight sacrifice in linearity; a comprehensive operational understanding of the chemical system was also obtained.     

Electrochemical detection for microscale analytical systems: a review

This paper describes the development of an electrophoretic method used to analyse diuretics, and its use in the analysis of pharmaceutical formulations. Chlorthalidone, furosemide, hydrochlorothiazide and triamterene were separated in 5 min by micellar electrokinetic capillary chromatography using a carrier containing sodium dodecylsulphate as surfactant, and were subsequently detected spectrophotometrically using a diode-array detector. The limits of detection (S/N=3) were in all cases less than 1.2 mugml(-1) for all compounds. Satisfactory repeatability was obtained for migration times (<1.6%) and corrected peak areas (<5.3%) in the analysis of pharmaceutical formulations. The reproducibility was less than 4% for all samples tested. The average recoveries obtained, which ranged between 97 and 100%, testify to the accuracy of the proposed method.