Estimation of Uncertainty for Measuring Codeine Phosphate Tablets Formulation Using UV-Vis Spectrophotometry

Analytical results represent a very important part in a quality control program. Uncertainty estimation is an important step in method validation. The objective of this paper is to study the uncertainty of measurement estimation in the quantitative determination of codeine phosphate from pharmaceutical formulations using UV-VIS spectrophotometry. The uncertainty estimation was performed using the Ishikawa diagram. The estimation of uncertainty components proved to be a good way for the experimental model to obtain low contribution of uncertainty to the analytical result.     

水合肼还原重量法测定银

样品经过硝酸分解后,用过量的氨水分离铅、铁、铝等金属离子,用EDTA掩蔽铜、锌和其他残留的金属离子,用水合肼作还原剂,将银还原成单质沉淀,过滤,洗涤,灼烧,恒重。该方法用于实际样品测定,结果与其他方法测定值一致,误差均在允许范围内;分别对银含量为2.54%和10.00%的样品重复测定12次,相对标准偏差（RSD）分别为1.50%和0.64%,此方法适用于1%以上银含量的测定。     

高碘酸盐氧化罗丹明B催化光度法测定钌

在０．７２ｍｏｌ／Ｌ磷酸和９０℃水浴条件下,钌催化高碘酸盐氧化罗丹明Ｂ（ＲＢ）,据此建立了高灵敏催化光度测定钌的方法。方法的检出限为８．０×１０＾－１２ｇ／ｍＬ,测定范围为０．２～１５ｎｇ／２５ｍＬ,对５、１０、１５ｎｇ／２５ｍＬＲｕ（Ⅲ）测定的相对标准偏差分别为８．６７％,５．９４％和１．８５％。本反应对Ｒｕ（Ⅲ）、ＲＢ、ＫＩＯ４和Ｈ３ＰＯ４均为一级反应,表观活化能为３６．０５ｋＪ／ｍｏｌ。１３     

Rapid Method for the Micro-Determination of Hydrazine by Amperometric Titration With Potassium Iodate

Abstract

An amperometric method, with potassium iodate as the titrant, for the rapid and precise determination of micro amounts of hydrazine salts is described. Hydrazine dihydrochloride, hydrazine sulfate and hydrazine hydrate could be quantitatively analyzed at the concentration range of 4 × 10^?7 -4×10^?3 M in the presence of 5 M hydrochloric acid. Hydrazine salts, 2×10^?4 -4×10^?3 M, were titrated in 5 minutes with a relative error and a relative standard deviation of 0.1%. It was also found that hydrazine dihydrochloride can be precisely determined, without any interference, even in the presence of hydroxylamine which is ten times as much as the former.

The suitable applied potential between the rotating platinum indicator microelectrode and the silver plate-silver chloride reference electrode was + 0.7V.     

Implementation of an Analytical Method for Spectrophotometric Evaluation of Total Phenolic Content in Essential Oils

Over the past decade, there has been growing interest in polyphenols’ research since these compounds, as antioxidants, have several health benefits, such as preventing neurodegenerative diseases, inflammation, cancer, cardiovascular diseases, and type 2 diabetes. This study implements an analytical method to assess the total phenolic content (TPC) in essential oils using Folin–Ciocalteu’s phenol reagent and quantifies the individual phenolic compounds by liquid chromatography. Thus, the research design and methodology included: (1) extraction of essential oil from dried thyme leaves by hydrodistillation; (2) spectrophotometric measurement of TPC by Folin–Ciocalteu method; and (3) identification and quantification of individual phenolic compounds by high-performance liquid chromatography-diode array detection/electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS). Results revealed a TPC of 22.62 ± 0.482 mg GAE/100 µL and a polyphenolic profile characterized by phenolic acids (52.1%), flavonoids (16.1%), and other polyphenols (31.8%). Thymol, salvianolic acid A, and rosmarinic acid were the major compounds of thyme essential oil. The proposed analytical procedure has an acceptable level of repeatability, reproducibility, linearity, LOD (limit of detection), and LOQ (limit of quantification).     

Spectrophotometric Method for the Estimation of Vitamin C in Drug Formulations

Abstract

The use of 1-chloro-2, 4-dinitrobenzene is described for spectrophotometric estimation of ascorbic acid. The procedure is based on the interaction of ascorbic acid with 1-chloro-2, 4-dinitrobenzene in alkaline medium. The product absorbs maximally at 380 nm and has the molar absorptivity 0.14 × 10⁴1 mole^?1cm^?1. Beer's law is obeyed in the concentration range 0.12–0.6 mg/10ml of ascorbic acid.     

A Novel Estimation Method of the Distribution of Carboxyl Groups Within Copolymer Particles Using Isothermal Titration Calorimeter

Summary: A novel quantitative method using isothermal titration calorimeter (ITC) for the estimation of the distribution of carboxyl groups within polymer particles has been proposed. The method has been employed to clarify the difference in the distribution between the particles prepared by batch emulsion copolymerization of styrene and methacrylic acid under inefficient and efficient stirring conditions. At inefficient stirring, monomer was floating as a layer on the aqueous medium, whereas at efficient stirring, the monomer phase was dispersed as droplets. Under inefficient stirring, methacrylic acid (MAA) polymerized faster than styrene (S) due to a slower diffusion rate of S than MAA into the aqueous medium, while under efficient stirring, S and MAA copolymerized at similar rates. ITC measurement showed that under inefficient stirring, the carboxyl groups were distributed mainly in the center of the particles, and their number decreased toward the surface. On the other hand, under efficient stirring, carboxyl groups were distributed homogeneously inside the particle.     

A Potential Method Using Ge{iPrNC[N(SiMe3)2]NiPr}2, (Et3Si)2Te and Anhydrous Hydrazine for Germanium Tellurides

A germanium(II)‐guanidine derivative of formula Ge{iPrNC[N(SiMe₃)₂]NiPr}₂ ( 1 ) was synthesized and characterized by ¹H NMR, ¹³C NMR, elemental analysis, and X‐ray diffraction method. Thermal property was also studied to identify its thermal stability and volatility. More importantly, compound 1 was synthesized to develop a new method for germanium tellurides, where anhydrous hydrazine was introduced to prompt the activity of germanium(II) guanidines (or derivatives) towards (Et₃Si)₂Te. Solution reaction of compound 1 , (Et₃Si)₂Te, and anhydrous hydrazine was investigated to pre‐identify the feasibility of this combination for ALD process. The EDS data of the black precipitate from this reaction verified the potential of this method to manufacture germanium tellurides.     

新的铬天青B直接光度法测定血清总铁结合力

为建立新的铬天青B直接光度法测定血清总铁结合力（TIBC）,在表面活性剂存在下,用铬天青B（CAB）为显色剂测定了血TIBC。结果表明,该法线性范围0～160μmol／L,平均回收率为99．4％,批内变异系数（CV）和批间变异系数分别为0．020、0．035,与临床检验操作规程推荐的方法比较具有良好的相关性,线性回归方程和相关系数分别为y=1．0033x＋0．4510,r=0．9982;60例健康男性血清TIBC含量为46．2～75．8μmol／L（x±2s）,60例健康女性血清TIBC含量为51．8～76．9μmol／L（x±2s）。用新的铬天青B直接光度法测定血清总铁结合力方法简便、灵敏可靠,适合临床应用。     

A New Spectrophotometric Method for the Determination of Cerium Using Leuco Disulphine Blue

A new, simple, highly sensitive spectrophotometric method for the determination of trace amounts of cerium(IV) is described. The method is based on the oxidation of leuco disulphine blue (LDSB) to its blue form of disulphine blue by Ce(IV) in a sulfuric acid medium (pH 1.3–3.0); the absorbance of the formed dye is measured in an acetate buffer medium (pH 3.0–4.8) at 635 nm. The color system obeys Beer's law in the concentration range from 0.5 to 5.5 g mL^–1 cerium with a molar absorptivity of 1.75 × 10⁴ L mol^–1 cm^–1 and a Sandell's sensitivity of 0.008 g cm^–2. All variables were studied in order to optimize the reaction conditions. The developed method has been successfully applied to the determination of cerium in high purity rare-earth oxides, soil, natural water, plant tissue, human hair, and rock samples.     

Determination of Sulphide in Sewage Effluents Using a New Spectrophotometric Method

Abstract

A suitable indirect spectrophotometric method for the determination of sulphide in water, based on the reduction of 1,2-naphthoquinone-4-sulphonate (NS) has been developed. The excess of NS is spectrophotometrically determined based on the red colour produced in its reaction with sulphanilic acid at pH 4.0–6.5. Maximum colour intensity is obtained after 40 min and the apparent molar absorptivity at 470mm is 3.5×10³I.mol^?1.cm^?1. The sulphide concentrations can be calculated by the difference in absorption of blanks and samples.     

溶液中肼还原钴离子制备纳米金属钴的反应动力学

通过加入NaBH₄作为诱导剂, 可在室温下引发肼与Co^2＋在水-乙醇体系中的还原反应, 制得高纯度纳米金属钴粉. 机理研究表明, 该反应分二段进行: 第一段主要发生Co^2＋被N₂H₄还原的反应(2Co^2＋＋N₂H₄＋4OH^－＝2Co¯＋N₂­＋4H₂O), 第二段主要为金属Co催化的肼分解反应(N₂H₄＝N₂­＋2H₂­)和歧化反应(3N₂H₄＝N₂­＋4NH₃­). Co^2＋被N₂H₄还原是典型的自催化过程, 因此, 加入少量NaBH₄即可在288 K下启动反应. 通过测量气体产物的生成速率, 获得了Co^2＋还原的反应动力学方程, 发现Co^2＋, N₂H₄和产物Co的反应级数分别为1, 0和1, 反应活化能约为89 kJ/mol. 调节Co^2＋的浓度, 纳米金属钴的表面积可从11增加到25 m²/g.     

5-Br-PADCAP 直接光度法测定血清未饱和铁结合力

为建立简便、灵敏的双试剂自动化分析法测定血清未饱和铁结合力(UIBC),在表面活性剂存在下,用2-(5-溴-2-吡啶偶氮)-5-[(N,N-二羧基甲基)氨基]苯酚(5-Br-PADCAP)为显色剂测定血清UIBC。结果表明,线性范围0~90μmol/L,平均回收率101.57%,批内变异系数(CV)和批间变异系数分别为0.028、0.046,与日本和光UIBC测定试剂盒比较具有良好的相关性,线性回归方程和相关系数分别为y=1.0133x-0.3356,r=0.9961。108例健康人血清UIBC含量为31.65~50.81μmol/L(±2s)。用5-Br-PADCAP双试剂自动化分析法测定血清UIBC方法简便、灵敏可靠,适合临床应用。     

A New Spectrophotometric Method for the Determination of Ascorbic Acid Using Leuco Malachite Green

A new simple and sensitive and selective spectrophotometric method has been developed for the determination of ascorbic acid (AA) at trace level using a new reagent, leuco malachite green (LMG). AAreacts with potassium iodide‐iodate solution under acidic conditions to liberate iodine and the liberated iodine selectively oxidizes LMG to MG dye. The colour of the dye was measured at 620 nm. Beer's law is obeyed over the concentration range of 0.8–8 iμg μAA per 25 mL of final solution (0.032–0.32 ppm). The apparent molar absorptivity and Sandell's sensitivity of the method were found to be 2.98 × 10⁵ l mol⁻¹ cm⁻¹, 0.0042 μg cm⁻², and respectively. Statistical treatment of the experimental results indicates that the method is precise and accurate. The method is free from interference of common ions and many of the ingredients commonly found in pharmaceuticals. The reliability of the method was established by parallel determination against Leucocrystal violet (LCV) method. The method described was satisfactorily applied for the determination of AA in fruit juices, pharmaceuticals and biological samples.     

吗啡的流动注射分光光度法分析研究

本文建立了吗啡的流动注射分光光度分析法。在优化条件下,线性检测范围为30～700μg/ml,回归方程为h=0.0250+1.74×10~(-3)C,相关系数为0.9999,并用于吗啡样品的分析。回收率为99.9％,相对标准偏差为0.43％,样品分析速度为240次/小时。     

A Spectrophotometric Method for the Determination of Propoxur

A simple spectrophotometric technique is reported for the determination of propoxur using the coupling complexing agents namely 2-amino, 4-nitrophenol and 2,4-dimethoxy aniline. The u max observed for these coloured complexes were at 402 and 460 nm respectively. The recoveries of propoxur pesticides obtained using the above procedure were reported in their formulations, water and food grains.     

一种改进的合成Behera胺方法研究

以水合肼作为氢源,以T-1型雷尼镍作为催化剂,常压的条件下,在沸腾的甲醇中顺利地还原脂肪族硝基为氨基制备了Behera胺,反应时间短,易于操作,可以替代现有的合成方法.并制备了第二代树枝形硝基化合物4,用同样的方法还原4得到第二代树枝形Behera胺.     

UV-Vis Spectrophotometric Determination of the Dissociation Constants for Monochlorophenols in Aqueous Solution at Elevated Temperatures

The dissociation constants of monochlorophenols (2-, 3-, 4-chlorophenols) were examined using direct UV-vis spectroscopy at temperatures from 25 to 175^°C and at saturated vapor pressures in a high-temperature, high-pressure cell. The dissociation constant, K _a increased under experimental temperatures in the order: 2-chlorophenol, 3-chlorophenol, and 4-chlorophenol. The dissociation constant of 4-chlorophenol increased with increasing temperature under experimental conditions, while those of 2- and 3-chlorophenol reached maximum values at around 125^°C, and then decreased with further increases in temperature. The slope of (log K)/ (1/T) was nonconstant and positive, that is, endothermic, below 150^°C. The data on dissociation constants were analyzed by simultaneous regression to yield a five-term equation that described the Van't Hoff isobar. The magnitude of enthalpy H increased at 25^°C in the order: 3-chlorophenol, 4-chlorophenol, and 2-chlorophenol. The decrease in enthalpy at the absolute temperature was larger for 3-chlorophenol than for either 2- or 4-chlorophenol. Considering the equilibrium constant K _b for the isocoulombic reaction of monochlorophenol with OH^–, the nearly linear relationship of log K _b vs. 1/T for temperatures between 25 and 175^°C indicates that the C_p values for this isocoulombic reaction are low.     

A Novel Visible Spectrophotometric Method for the Determination of Methanol Using Sodium Nitroprusside as Spectroscopic Probe

A novel, rapid and reliable method has been established for the determination of methanol using sodium nitroprusside as a spectroscopic probe. This method indicates that the sodium nitroprusside can react with the methanol to form a colored product in the basic solution. The absorbance of the product is measured at the maximal absorption wavelength of 481 nm, and the amount of methanol can be calculated based on this absorbance. A good linear relationship of the concentration of methanol versus absorbance is observed with a linear range of 0.02‐6.0 mg mL^?1. The linear regression equation is A = 0.02484 + 0.29457C (mg mL^?1), with a correlation coefficient of 0.9991. The detection limit (3σ/k) is 0.012 mg mL^?1, while its R.S.D. is 1.5% and the recovery rate is 97.5‐102.5%. The parameters with regard to determination are optimized, and the reaction mechanism is discussed. This method has been successfully applied to determine methanol in variety of samples. Analytical results obtained by this new method were very gratifying.