硫酸肼比浊法测定微量硒

依据硒(Ⅳ)在以甘油为稳定剂,盐酸为反应介质的条件下,被过量硫酸肼还原,使体系形成稳定悬浊液的原理,建立了比浊法测定硒的方法。探讨了盐酸用量、甘油用量、反应温度和反应时间以及硫酸肼用量等5个关键因素的影响,确定了最佳测定条件。实验结果表明:大量的共存物质不干扰测定。在选定的实验条件下,线性方程为:ΔA750nm=12.725ρ+0.0076,在2.0×10-4~3.2×10-2mg·m L-1范围内线性关系良好,相关系数(R2)=0.9911,方法的检出限为1.2×10-4mg·m L-1。方法用于测定强化营养盐中总硒,回收率在97.0~103.5%之间,RSD为1.8%。     

硫酸钡比浊法测定食盐中硫酸根

用硫酸钡比浊法测定硫酸盐,大多采用甘油、明胶或乙醇作稳定剂,为保证分析结果的再现性,均需严格控制电磁搅拌时间、搅拌速度、固体氯化钡的粒度和试剂加入顺序。本试验改用吐温-80作稳定剂,使方法对操作条件无苟刻要求,手续较简便,结果再现性好,相对标准偏差1.8％;方法加标回收率为99.5％～102％。 1 试验部分 1.1 试剂与仪器 BaCl_2-吐温溶液:BaCl_2·2H_2O溶液(12％)80ml和吐温-80 20ml混合。 硫酸盐标准液:经105℃干燥的优级纯K_2SO_41.8141g或Na_2SO_41.4787g,水溶解后定容于1000ml量瓶中,分液,准确稀释10倍得SO_4~(2-)0.1mg·ml~(-1)工作液。 53W型紫外可见分光光度计(上海光学仪器厂) 1.2 试验方法 准确称取食盐样品2g于烧杯中,加水约50ml,加热溶解,滤入200ml量瓶中,洗涤后,以水定容至200ml。准确分液5～50ml于50ml具塞比色管中,加水至50ml,加HCl(1+1)和BaCl_(2-)-吐温溶液各2.5ml,倒转数次混匀,10min,在720nm处,用3cm比色皿,以水作参比,测吸光度。 标准曲线绘制:分别取SO_4~(2-)0、0.4、0.6……1.5mg于一组50ml比色管中,加水至50ml后,按上述样品分析操作。     

比浊法测定铅锌精矿中的微量氯

本文应用比浊法测定铅锌精矿中的微量氯，通过溶样方法，表面活性剂等条件的选择，使方法的稳定性，精密度得到了提高，获得了比较满意的分析结果。     

比浊法测定酸性镀铜液中微量氯离子

以乙二醇为增溶剂,硝酸银作沉淀剂,采用氯化银比浊法,在不分离硫酸铜的条件下,直接测定酸性镀铜液中微量氯离子。测定波长为440 nm,线形范围为0~50μg/25 mL,其表观摩尔吸光系数ε=1.3×105,方法检出限为0.035μg/mL,该法用于测定酸性镀铜液中微量氯离子在不同水平的加标回收率为95.4%~104.5%。结果表明,该法准确,快速,简便,其它的常见离子无干扰。     

氯化银比浊法测定铜箔镀液中微量氯

采用氯化银比浊法,在不分离硫酸铜的条件下,直接测定镀铜电解液中微量氯离子。对试验条件和可能存在的干扰进行了研究,榈的加标回收率在９８．７％￣１０７．０％之间,相对标准偏差在２．７％￣８．８％之间。方法快速简单,结果满意。     

垂直光路光电比浊法测定尿微量蛋白的研究

垂直光路光度法具有待测溶液分层、溶剂分子蒸发及试剂（标准及样品除外）的吸量误差对吸光度测量结果影响较小等许多水平光路光度法（即常规光度法）所不具备的优点。我们根据蛋白质与磺基水杨酸（SSA）发生灵敏的沉淀反应，且聚乙烯吡咯啉酮K30（PVPK30)对该反应有增敏作用，提出了以SSA为沉淀剂、PVPK30为增敏剂，用垂直光路光电比浊法测定尿液中微量蛋白质的新方法。该法应用于尿液总蛋白测定，其结果与考马斯亮蓝光度法相吻合。     

比浊法快速测定电解锌废液中微量氯

电解锌生产流程是封闭循环系统,从锌矿至电解废液,氯离子的检测必不可少。氯离子主要源于矿石及辅料中可溶性氯化物,并不断累积,当流程中氯离子超过100mg·L-1时,就会引起烧极板锌片剥离困难等生产不利因素,废液中的锰(Ⅶ)则来自净化工序,含量一般在10～20g·L-1。用比浊法测定氯离子时产生严重背景干扰,导致氯离子结果偏高。消除锰(Ⅶ)的背景干扰,是采用比浊法快速测定电解锌废液中微量氯的关键。经试验用硫酸亚铁将七价锰还原至无色低价锰,不仅空白值低,还原效果好,30g·L-1硫酸亚铁溶液0.3ml,可还原100mg七价锰至低价,试样加标回收…     

氯化银比浊法测定邻苯二甲醇中微量氯离子

邻苯二甲醇是合成药物体的中间体,对其氯离子的含量有严格要求。因此,准确测定合成产物邻苯二甲醇中的氯离子含量十分重要。测定微量氯离子的含量常用光度法^[1-3]。本文用氯化银比浊法直接测定合成产物邻苯二甲醇中的微量氯离子,对待测定条件进行了研究。通过对样品的分析表明,本法简便快速,准确度高,能满足生产分析的需要。     

目视比浊法测定三氧化二砷中氯离子

出口三氧化二砷中常要求检测氯离子含量。但在国家标准及行业标准中均未列入此项目的测定方法。目前有不少试验室采用氯化银沉淀比浊法测定氯离子 ,试样用氢氧化钠溶液 ( 1 0 0 g· L- 1 )溶解后加硝酸 ( 1 1 )酸化。此时试样中的大量 As( )又重复以三氧化二砷的形式析出 ,必须过滤除去后方能加入硝酸银进行比浊测定其含氯 ( Cl- )量。此方法不仅因过滤等手续使分析手续繁杂 ,而且由于沉淀对氯离子的吸附 ,造成结果偏低。为此 ,本文提出用硝酸溶样并加过氧化氢将 As( )氧化至 As( ) ,从而避免了氧化砷沉淀的析出[1 ] 。按改进后的方法…     

光电比浊法测定钙离子的分析方法研究

测定盐及盐化工产品中钙离子的方法有EDTA络合滴定法、吸光光度法、原子吸收分光光度法.后两种方法只能用作分析微量钙离子的测定,操作较繁琐,因而目前大多采用EDTA络合滴定法作常规分析.此法操作简便,但人为误差较大.因为在进行终点滴定分析时,溶液的颜色、滴定管的读数,在很大程度上由操作人员的经验和习惯来判断,同一试样的分析结果都往往因人而异,特别是对于低含量钙的产品,误差较大.本文使用草酸钙比浊法测定钙离子,获得了满意结果.其分析原理是在含有被测钙离子的水样中,加入适当过量的草酸铵细末,生成草酸钙白色沉淀(Ca~(2+)+C_2O_4~(2-)+H_2O→CaC_2O_4·H_2O↓),使水溶液浑浊,其浑浊程度与水作中钙含量成正比关系.     

Spectrophotometric determination of osmium with ammonium thiocyanate

Summary A spectrophotometric method for the determination of osmium using ammonium thiocyanate is described. A stable reddish brown colour with an absorption maximum at 440 nm is produced when osmium tetroxide is heated for 30 min at a p_H between 1 to 4 over a boiling water bath with excess reagent. The recommended concentration range is from 3 to 15 ppm of osmium in aqueous medium and from 0.6 to 1.5 ppm when the brown colour (which turns blue) is extracted into isoamyl alcohol. Errors are about ± 1.5%.

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Zusammenfassung Zur spektrophotometrischen Bestimmung von Osmium wird als Reagens Ammoniumthiocyanat empfohlen. Bei Erwärmung von Osmiumtetroxid bei p_H 1–4 mit überschüssigem Reagens (30 min) wird eine beständige rötlich-braune Färbung mit einem Absorptionsmaximum bei 440 nm gebildet. Der günstigste Konzentrationsbereich ist 3–15 ppm in wä\rigem Medium bzw. 0,6–1,5 ppm, wenn mit Isoamylalkohol extrahiert wird (wobei die Farbe nach Blau umschlägt). Die Fehler betragen etwa ± 1,5%.

     

Spectrophotometric determination of trace amounts of selenium with 4,5,6-triaminopyrimidine

4,5,6-Triaminopyrimidine reacts in acidic aqueous media with selenium (IV) to give a piazselenol which has an absorption maximum at 362 nm with a molar absorptivity of 1.72 x 10(4) 1.mole(-1).cm(-1). The compound is stable but not extractable into non-polar solvents. The calibration graph is linear up to 10 ppm of selenium, with a detection limit of 0.1 ppm in the sample solutions. Of the many different ions tested only iron (III) (in the presence of chloride) and tin (II) interfere. The method has good reproducibility, with a relative standard deviation of 1.5% for pure solutions. The application of this method to analysis of water and electrolytic copper is described.     

Indirect determination of thiocyanate with ammonium sulfate and ethanol by extraction-flotation of copper

A new method for the indirect determination of thiocyanate with ammonium sulfate and ethanol by extraction-flotation of copper in the presence of ascorbic acid is described. A small amount of Cu(II) is reduced to Cu(I) by ascorbic acid, then Cu(I) is precipitated with SCN-. In the course of phase separation of ethanol from water, the precipitated CuSCN stays in the interface of ethanol and water. A good linear relationship is observed between the flotation yield of Cu(II) and the amount of SCN-. Using 1.0 ml of 1 x 10(-3) M ascorbic acid solution, 50 micrograms of Cu(II), 3.5 g of (NH4)2SO4 and 3.0 ml of ethanol with a total volume of 10 ml, the concentration of thiocyanate could then be determined by determining the flotation yield of Cu(II). The detection limit for thiocyanate is 5 x 10(-5) M. Every parameter was optimized and the reaction mechanism was studied. The method is simple and rapid and it was successfully applied to the determination of thiocyanate in urine and saliva of smokers and non-smokers and in venous blood of patients infused with sodium nitroprusside.     

表面活性剂增敏动力学光度法测定尿液中的微量SCN-

在pH 11.4的NH3-NH4Cl缓冲溶液中,阳离子表面活性剂溴代十四烷基吡啶(TPB)对硫氰酸根阻抑高碘酸钾氧化间甲酚紫的褪色反应具有明显的增敏作用,据此建立了动力学光度法测定微量SCN-的新方法,该方法的线性范围为0.04～0.72 μg/mL,检出限6.74×10-3 μg/mL.可用于测定吸烟和非吸烟者的尿液中的微量SCN-.     

Nephelometric determination of gold with di-2-thienyl-ketoxime

A nephelometric method for the determination of microgram quantities of gold with di-2-thienylketoxime is described. The yellow gold complex, which has the empirical formula Au(C₉H₆NOS₂)₂OH, forms a stable suspension when gelatin is added as protective colloid. Many foreign ions do not interfere in 5-fold amounts. If necessary, a preliminary isopropyl ether extraction of gold can be used.     

Photometric determination of trace selenium in aqueous media

A new procedure is developed for the photometric determination of trace selenium in aqueous solutions. The selection of 2-(p-nitrophenyl)-3,5-diphenyltetrazolium chloride as a reagent for selenium is justified. The proposed sample preparation procedure involves gas extraction of selenium as hydrogen selenide followed by its liquid-adsorption extraction from the gas phase to an aqueous reagent solution with the formation of a water-insoluble formazan. Formazan formed upon the absorption of hydrogen selenide is extracted with isoamyl alcohol. The concentration of selenium is determined from the absorbance of the formazan extract in the isoamyl alcohol. The procedure allows the determination of 10–120 μg/L selenium.     

溶剂浮选缔合物光度法测定痕量硒

根据亚硒酸 ( H2 Se O3)氧化 I-生成 I2 ,I2 与 I-配阴离子 ,I-3 ,配阴离子I-3 与孔雀绿阳离子 ( MG+ )发生离子缔合反应 ,用 N2 气将此缔合物浮选的三元缔合物用光度法测定硒。方法的 ε为 2 .2× 1 0 6L· mol-1· cm-1,RSD为2 .7% ,检出限为 4.7× 1 0 -10 g· m L-1     

Flow injection spectrophotometric determination of trace amounts of selenium

A simple, rapid and sensitive flow injection spectrophotometric method for determination of selenium (0.005-1.5 mug ml(-1)) is described. The method is based on the catalytic effect of Se(IV) on the reduction reaction of thionine (TN) with sulphide ion, monitored spectrophotometrically at 598 nm. The detection limit is 5 ng ml(-1) the relative standard deviation for eight replicate measurements is 1.1% for 1 mug ml(-1) of selenium. The sampling rate is 25-30 samples h(-1). The procedure was applied successfully to the determination of selenium in real samples.