磷钼钨三元杂多酸光度法测定药物中的抗坏血酸

研究了抗坏血酸与磷钼钨三元杂多酸的显色反应,提出了借磷钼钨杂多蓝测定抗坏血酸的分光光度法.最大吸收波长为730nm,抗坏血酸在0.08～10mg/L范围内线性良好.回归方程为A=1.05×10⁴C+0.017,线性相关系数γ=0.9995,表观摩尔吸光系数ξ₇₃₀=1.05×10⁴L·mol^-1·cm^-1,方法检出限为0.04mg/L,回收率为94～102%,相对标准偏差≤1.5%(n=8).本方法由于钨钼的混合配位增强了氧化能力,较之二元杂多酸的方法,省去了水浴加热等操作,只需在室温下反应30min,吸光值至少可稳定6h.过量的黄色杂多酸可加入适量的氢氧化钠溶液分解,从而获得色泽纯正的高灵敏度显色体系.     

用氯丙嗪-磷钼杂多酸分光光度法测定烟叶中的磷

在１－５ ｍｏｌ／ＬＨＣｌ 介质中及聚乙烯醇（ＰＶＡ） 存在的条件下,氯丙嗪能与磷钼杂多酸形成摩尔比１∶１ 的离子缔合物, 可稳定１－５ ｈ 以上, 其最大吸收波长在３４５ ｎｍ 处, 磷在０ ～０－４８ ｍｇ／Ｌ 范围内符合Ｂｅｅｒ 定律, 表观摩尔吸光系数为６－０５ ×１０４ Ｌ·ｍｏｌ－ １ ·ｃｍ － １ 。 该法用于烟叶中磷的测定, 操作简便, 选择性好, 灵敏度高, 结果令人满意。     

磷钼杂多酸光度法测定吲哚乙酸

研究了吲哚乙酸与磷钼杂多酸在浓度为 0 .0 3 mol/L的硫酸介质中发生氧化还原反应 ,形成的还原产物 (钼蓝 )在 NH3-NH4Cl缓冲溶液 (p H8.4)中最大吸收波长为 314 nm,表观摩尔吸光系数 ε值为 3.5 4× 10 4L· mol-1·cm-1 ,吲哚乙酸含量在 5 .0× 10 -7～ 5 .0× 10 -5 mol/L范围内符合比尔定律 ,检出限为 1.0× 10 -7mol/L,对 2 .0 0× 10 -5 mol/L吲哚乙酸测定 10次的相对标准偏差为 6 .42 % ,加标回收率为 94.2 %～ 10 0 .1%     

磷钼钒杂多酸光度法测定钒

磷钼钒杂多酸早已用于磷的光度分析,其它应用尚未见报道。本文提出利用磷钼钒杂多酸光度测定高速钢中常量的钒,共存元素中铬、钴的影响以试样空白扣除,钨的负干扰可采用经验系数补正,样中1％Si和1％Nb不干扰测定。方法简便、快速、准确。本文还提出了在一定条件下形成磷钼钒酸、磷钨钒酸和磷钨钼酸的经验规律。 1 试剂与仪器 钼酸铵溶液:53g·L~(-1) 盐磷混酸:1.19g·ml~(-1)盐酸+1.74g·ml~(-1)磷酸=3+2 钒标准溶液:0.900mg·ml~(-1)(里偏钒酸铵配制并以滴定法标定) 721型分光光度计 2 分析方法称取试样0.1000g于200ml锥形瓶中(同时称一份不含钒的钢样作试剂空白A_0),加盐磷混酸1.5ml,硫酸(1+1)8ml,加热溶解,滴加浓硝酸助溶,继续加热     

对苯二酚—磷钼杂多酸光度法测定比色钢中的磷

研究了对苯二酚-氟化钠-氯化亚锡联合还原磷钼蓝光度法测定钢铁中的磷含量,使磷钼蓝的吸光度值能够稳定在40 min以上不变。最佳实验条件下,磷含量在0.00～0.80μg/mL范围内符合比尔定律,最大摩尔吸光系数εmax,730 nm=3.32×104L.mol-1.cm-1。对钢标样进行多次测定相对误差小于5%,回收率在99.3%～104.3%之间,适用于比色钢中磷含量的快速、准确测定。     

磷钼钨三元杂多酸光度法测定药物中的抗坏血酸

研究了抗坏血酸与磷钼钨三元杂多酸的显色反应，提出了借磷钼钨杂多蓝测定抗坏血酸的分光光度法。最大吸收波长为７３０ｎｍ，抗坏血酸在０．０８～１０ｍｇ／Ｌ范围内线性良好。回归方程为Ａ＝１．０５×１０４Ｃ＋０．０１７，线性相关系数γ＝０．９９９５，表观摩尔吸光系数ξ７３０＝１．０５×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，方法检出限为０．０４ｍｇ／Ｌ，回收率为９４～１０２％，相对标准偏差≤１．５％（ｎ＝８）。本方法由于钨钼的混合配位增强了氧化能力，较之二元杂多酸的方法，省去了水浴加热等操作，只需在室温下反应３０ｍｉｎ，吸光值至少可稳定６ｈ。过量的黄色杂多酸可加入适量的氢氧化钠溶液分解，从而获得色泽纯正的高灵敏度显色体系。     

耐尔蓝-钍钼杂多酸光度法测定钍

本文研究超高灵敏光度法测定钍。在聚乙烯醇（PVA）存在下，耐尔蓝（NB）与钍钼杂多酸络阴离子形成离子缔合物。在1．2mol／L高氯酸介质中缔合物的最大吸收位于590nm，摩尔吸光系数ε值4．45×106L·mol－1·cm－1，钍量在0～28μg／L范围服从比耳定律；测定极限C（Th）3．4μg／L（n＝9）；对20μg／LTh分析9次的相对标准偏差1．5％；缔合物的摩尔组成Th：Mo：NB＝1：12：3。考察了50多种共存离子影响，允许100倍量Ce（Ⅲ）、50倍量U（Ⅵ）和等量Ti（Ⅳ）存在。本法用于地质样品中钍的测定，结果满意。     

Spectrophotometric determination of vitamin C in citrus fruits using peri-naphthindan-2,3,4-trione

Analytical and Bioanalytical Chemistry - A spectrophotometric method for the determination of vitamin C in lemon, orange, and grapefruit juices is described. It is based on the reaction with...     

Spectrophotometric molybdenum determination with thiolactic acid

A quick, selective method for molybdenum(VI) is based on the formation of a yellow thiolactic acid complex. The complex is formed at pH 1.0-1.6, and the absorbance is measured at 365 nm.     

Spectrophotometric determination of cerium with sulphanilic acid

In the presence of other rare earths, cerium(IV) can be determined spectrophotometrically by its reaction with sulphanilic acid with which it produces a red colour. Solutions containing 28-210 ppm of cerium absorb at 495 mmicro according to Beer's law. Other rare earths, except neodymium, and many common ions do not interfere. Strong oxidising agents and neodymium in greater than fifty times the concentration of cerium interfere with this method. The precision depends on the control of pH and time. Cerium alloys have been analysed by this method and the results are compared with those obtained by another spectrophotometric method.     

Spectrophotometric determination of bismuth with diethylenetriaminepenta-acetic acid

Diethylenetriaminepenta-acetic acid is used for spectrophotometric determination of bismuth (at 270 nm) in 1.6 M perchloric acid. The system obeys Beer's law in the range 1–40 μg/ml. The method has been tested for the determination of bismuth in pure lead and polymetallic ores.     

Spectrophotometric determination of cobalt with gluconic acid

Summary A new spectrophotometric method is proposed for determining cobalt using gluconic acid as a chromogenic reagent. The parameters fundamentally affecting the absorbance of the complex are studied and obeyance of Beer's law between 5.33 and 53.3 g of Co²⁺/ml has been found. Measurements have to be carried out at 330 nm. The complex is formed in the molar ratio 11.

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Spektralphotometrische Bestimmung von Kobalt mit Hilfe von Gluconsäure

Zusammenfassung Die vorgeschlagene Methode verwendet Gluconsäure als farbbildendes Reagens. Untersucht wird der Einfluß verschiedener Parameter auf die Absorption des Kobalt(II)-Gluconsäure-Komplexes. Das Beersche Gesetz gilt im Bereich von 5,33–53,3 g Co²⁺/ml. Die Messung der Absorption erfolgt bei 330 nm. Das Molverhältnis des Komplexes beträgt 11.

     

Spectrophotometric determination of iron with quinolinic acid

Quinolinic acid forms two complexes with ferrous ion. One is formed at pH 5.9 and has maximum absorption at 420 mμ; the metal to reagent ratio is 1:2 and the instability constant is about 7.10^-9. The other complex is formed with an excess of potassium cyanide and shows maximum absorption at 440 mμ; the metal to reagent ratio is 1:1 the instability constant is only 2.73?10^-5. The latter complex adheres to Beer's law from 1 to 16 p.p.m. of iron, and its optimum concentration range is 4^-16 p.p.m. of iron, where the percent relative error per 1% absolute photometric error is only 2.94.The reagent is highly specific and can be used spectrophotometrically for the determination of very small quantities of iron in presence of many cations.     

Spectrophotometric determination of copper with uramyldiacetic acid

A new method for the spectrophotometric determination of copper using uramyldiacetic acid as chromogenic reagent is proposed. The complex is formed in a wide pH range (2.5–9); but in order to avoid the potential conversion of UDA in murexide it is convenient to work at pH < 3: and has a maximum of absorption at 775 nm. Beer's law is obeyed in the interval 20–420 μg of copper(II)/ml. The Ringbom optimal range falls between 70 and 400 μg of copper(II)/ml, with a minimum photometric error of 2.8. The reaction between the metal and the ligand takes place in the ratio 1:1. The method has been applied to the determination of copper in ores with low content of the metal.     

Spectrophotometric determination of tranexamic acid with chloranil

Tranexamic acid is reacted with aqueous alcoholic chloranil, buffered at pH 9, to give a complex with maximum absorption at 346 nm and with an apparent molar absorptivity of 15.7 x 10(3) l.mole(-1).cm(-1). A(max) is linearly related to concentration over the range 2-10 mug ml . When applied to tablets labelled as containing 500 mg each, the mean found was 496 +/- 4 mg. The results were comparable with those of the traditional formol titration method for amino-acids.