Bio-sniffers for ethanol and acetaldehyde using carbon and Ag/AgCl coated electrodes

Monitoring of ethanol and acetaldehyde in expired gas after drinking is an effective method for assessment of alcohol metabolic function. We have developed bioelectronic gas sensors (bio-sniffers) for convenient measurement of ethanol and acetaldehyde. The bio-sniffers were fabricated using a simple process and inexpensive method. The process consisted of coating carbon and Ag/AgCl on a filter paper using screen-printing, and immobilizing alcohol oxidase and aldehyde dehydrogenase on the carbon electrode. These bio-sniffers showed good response to ethanol and acetaldehyde vapor and were used to sense these vapors in the concentration range 1.0 to 100 ppm and 0.2 to 4.0 ppm, respectively. The calibration ranges cover the alcohol and acetaldehyde concentration in breath air after drinking. The bio-sniffer for acetaldehyde is applicable also to evaluate other aldehydes (i.e. formaldehyde as volatile organic compounds).

     

Spectrophotometric flow injection determination of chloride in ethanol

A flow injection procedure is described for the spectrophotometric determination of chloride in ethanol, based on the mercury(II) thiocyanate—iron(III) reaction. Effects of reagent composition and ethanol content of the sample are investigated in detail. The proposed system can analyse 120 samples of ethanol (94–100% v/v) per hour, with a relative standard deviation lower than 1%, when the chloride content ranges from 0.1–6.0 ppm. Recoveries of ca. 96% are found.     

Spectrophotometric determination of periodate and glycerol with 5,5-dimethyl-1,3-cyclohexanedione bisthiosemicarbazone monohydrochloride

A direct spectrophotometric method for the determination of periodate (1—10 ppm) is based on the formation of a yellow oxidation product of 5,5-dimethyl-1,3-cyclohexanedione bisthiosemicarbazone monohydrochloride in aqueous solution at pH 0.5—1.2. The molar absorptivity at 415 nm is 1.72 × 10⁴ l mol^-1 cm^-1. The relative standard deviation is 0.8% for 8.0 ppm periodate. A modification to this procedure is used for the indirect spectrophotometric determination of glycerol (2–10 ppm), via the Malaprade reaction.     

Individual and simultaneous enzymatic determination of ethanol and acetaldehyde in wines by flow injection analysis

The individual and simultaneous enzymatic determination of ethanol and acetaldehyde in wine by flow injection analysis is described. Individual determinations of 0.002–0.016% (v/v) ethanol or 1.0–8.0 μg ml^?1 acetaldehyde with r.s.d. 0.7% and 0.5%, respectively, are done with a single-beam spectrophotometer, based on the use of alcohol dehydrogenase and aldehyde dehydrogenase. A diode-array detector and dual reagent injections are used for the simultaneous determination of the two compounds. The errors are 〈 3.5% and 〈 2.0% for ethanol and acetaldehyde, respectively, when the method is applied to wine samples.     

Kinetic Spectrophotometric Determination of Acetaldehyde

ABSTRACT

A method for determination of trace quantities of acetaldehyde based on its inhibition effect on the malachite green-sulfite reaction is described. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance at 613 nm by a fixed time method of 60 seconds. The method allows the determination of acetaldehyde in the range of 0.2-10 μg/ml. The limit of detection was 0.1 μg/ml and the relative standard deviation for ten determinations of 2 μg/ml acetaldehyde was 1.8%. The method is applied to the determination of acetaldehyde in chemical industrial waste water with satisfactory results.     

Isophthaldihydroxamic acid as analytical reagent: Spectrophotometric determination of manganese

The reactivity of isophthaldihydroxamic acid against inorganic ions is established. The spectrophotometric study of its reaction with Mn(II) shows that a complex of stoichiometry 1:2 (Mn:L) is formed (? = 3760 liters · mol^?1 · cm^?1 at 490 nm). A spectrophotometric method is developed for the determination of manganese in the range 3–9 ppm.     

荷移反应光度分析法测定异烟肼

我国药典用滴定法测定异烟肼的含量。文献上亦有用氯胺-T法,2,4-二硝基氯苯比色法,普鲁士蓝比色法等测定异烟肼。基于有机含氮化合物作为电子给予体可以与π-电子接受体产生荷移反应。本文通过对苯醌在醇-水介质中与异烟肼的电荷转移配合物,提出了异烟肼的光度测定法。     

Improving continuous chemiluminescence determination method of formaldehyde in the atmosphere: reducing interference of acetaldehyde and others by using iodoform reaction

ABSTRACT

The continuous and selective determination method of formaldehyde (HCHO) in ambient air using chemiluminescence method has been developed. The counter current flow tube was used to collect gaseous formaldehyde. The major interferences of HCHO determination from acetaldehyde, ethanol, and ferrous ion were removed by applying iodoform reaction. Effect of acetaldehyde on chemiluminescence signal of formaldehyde at the same concentration was reduced from 19 to 0.3% by applying iodoform reaction. Subsequently, HCHO was online detected by measuring chemiluminescence produced from the reaction of HCHO, gallic acid, H₂O_2, and KOH. The limit of detection (S/N = 3) was 4.5 ppbv in air. The calibration graph was linear up to 6.25 ppmv. HCHO concentration measured by the present method showed good agreement with that obtained by the 2–4 DNPH-HPLC method.     

Spectrophotometric determination of phosphate using lanthanum chloranilate

The spectrophotometric determination of phosphate using lanthanum chloranilate has been investigated. It is possible to determine 3–300 ppm of phosphate with an accuracy of ±2%, if suitable conditions are chosen. Chloride or nitrate ions do not interfere up to 400 ppm. Interference from sulphate ion can be compensated for by adding a large amount of sulphate both to the sample and to the standard solutions. This method is simpler, has less critical reaction conditions, and develops a much more stable coloration than the conventional heteropolyacid methods.     

Spectrophotometric determination of niobium and its application to niobium-stabilized stainless steel

A spectrophotometric method is described for the determination of niobium by means of its reaction with tannin and thioglycollic acid. The yellow-orange colour developed with the reagent mixture at pH 4 is measured at 410-420 nm and obeys Beer's law between 0.5 and 10 ppm niobium. The method is suitable for the determination of niobium in niobium-stabilized stainless steel and other types of steels containing niobium, but a prior separation of niobium is necessary. Titanium interferes even in traces.     

水杨基荧光酮胶束增敏流动注射分光光度法测定微量锗

本文将锗一水杨基荧光酮一溴化十六烷基三甲基铵胶束五色体系应用于流动注射分析，建立了测定微量锗的快速方法。方法采用单通道流路及合并带流路进行试验。对有关的管路参数及试剂浓度等影响因素进行了探讨。优化的流动注射分析体系对锗的检测灵敏度高、重现性好。方法用于混合成试样及有机锗生物制品中锗的测定，结果满意。     

3,5,7,4'-Tetrahydroxyflavone (kaempferol) as a chromogenic reagent for gallium and indium

3,5,7,4'-Tetrahydroxyflavone (kaempferol) forms yellow chelates with indium and gallium. Based on this reaction, a sensitive spectrophotometric method for the determination of gallium and indium alone and in presence of other metals and alloys has been developed. Beer's law is obeyed up to 2.8 and 1.44 ppm for indium and gallium respectively.     

Electroanalysis and determination of acetaldehyde in fuel ethanol using the reaction with 2,4-dinitrophenylhydrazine

The voltammetric reduction of acetaldehyde was studied in 0.1 M LiOH: LiCl (60: 40 v/v). Well-defined waves can be seen at −1.77 and −1.60 V with the use of hanging mercury and glassy carbon electrodes. Acetaldehyde was shown to react at room temperature with the 2,4-dinitrophenylhydrazine and the product exhibited a differential pulse voltammetric peak at −0.90 V, which was well separated from the peaks of the derivative. This allowed the indirect determination of acetaldehyde in the presence of 0.1 M ethanol/tetrabutylammonium perchlorate after 10 min of reaction. Calibration graphs were obtained for 1.00 × 10⁻⁶−1.00 × 10⁻⁴ M of acetaldehyde. The detection limit is 8.14 × 10⁻⁷ M. The method has been applied satisfactorily to the determination of total aldehyde in fuel ethanol samples without any pretreatment. The text was submitted by the authors in English.     

Spectrophotometric determination of copper in alloys using naphthazarin

Naphthazarin (5,8-dihydroxy-1,4-naphthoquinone; Naph) is proposed as a chromogenic reagent for the spectrophotometric determination of copper(II). The polynuclear complex has a mole ratio of Cu:Naph=4:6 in a 50% v/v ethanol/water medium containing 0.1 M ammonium acetate and 1.5% (w/v) sodium dodecyl sulfate. The copper-naphthazarin complex shows an absorption maximum at 330 nm with a molar absorptivity of 1.84x10(4) l mol(-1) cm(-1). Beer's law is obeyed up to 4.5 ppm of copper(II). The method was applied for copper determination in alloy samples with satisfactory results.     

A new and sensitive method for the spectrophotometric determination of ethion in environmental and biological samples

A new and sensitive spectrophotometric method is described for the determination of sub ppm levels of the organophosphorus pesticide ethion based on the oxidation of ethion by potassium permanganate in phosphoric acid to sulphones and its hydrolysis under acidic condition at 100°C to release formaldehyde, which is then determined by a reaction with 1,3,5-trihydroxybenzene (phloroglucinol) in alkaline medium. Beer's law is obeyed in the range of 0.1–0.8 ppm of ethion at 460 nm. The analytical parameters have been optimized.     

Analytical applications of 3-acetyl-4-hydroxycoumarin—II Spectrophotometric determination of iron

3-Acetyl-4-hydroxycoumarin has been used for the spectrophotometric determination of iron^II. With iron^II this reagent forms an orange-red complex soluble in 50% (v/v) ethanol. The characteristics of the complex have been studied spectrophotometrically, and its molar composition determined. The complex obeys the Lambert-Beer law at 400 mμ within the concentration range 1.5–5.3 ppm of iron in the reaction mixture. The molar composition of iron^II-3-acetyl-4-hydroxy-coumarin shows that it contains iron and the coumarin in the molar ratio of 1:3. The limits of interference due to various cations and anions in the determination have been defined.     

A Simple Spectrophotometric Method for the Determination of Adrenaline by Reaction with Copper(II)-Neocuproine

Abstract

A new facile and sensitive spectrophotometric procedure for the quantitative determination of adrenaline has been established. The method is based principally on the interaction of the compound with Cu(II)-neocuproine and subsequent measurement of the cuprous neocuproine chelate produced in the reaction at 458 nm. Optimization of the reaction conditions was conducted. Beer's law was obeyed in the concentration range 0.4-2.4 ppm of adrenaline. The method finally developed has been successfully applied for the assay of the drug in some of its pharmaceutical formulations.     

Flow injection spectrophotometric determination of calcium in rain and snow with chlorophosphonazo III

Summary A spectrophotometric flow injection technique for the determination of calcium based on its color reaction with chlorophosphonazo III(CPA-III) is described. The complex formation of CPA-III with calcium ions was carried out in the presence of 0.01 mol/l oxalate at pH 2.8. Most of the common foreign ions did not interfere. Only strontium, barium and rare earth metals interfered. Under the optimum conditions, the calibration curve was linear up to 1.2 ppm calcium and the detection limit was 0.01 ppm for a sample volume of 120 l. The relative standard variations for 0.4 and 1.0 ppm calcium were 0.354 and 0.352%, respectively. The method was successfully applied to the determination of calcium in rain and snow.     

Titanium as Pollutant and a New Method for its Spectrophotometric and Atomic Absorption Spectrometric Microdetermination Mith N-p-Methoxyphenyl-2-Furylacrylohydroxamic Acid

Abstract

The paper briefly reviews the status of titanium as an environmental pollutant and presents a new method suitable for the microdetermination of the metals in plants, animal tissues and waters. The method is based on extractive separation of titanium as its chelate with N-p-methoxyphenyl -2-furylacrylohydroxamic acid (MFHA) in chloroform or isoamyl alcohol and subsequent spectrophotometric or atomic absorption spectrometric determination. MFHA was chosen from nine new hydroxamic acids as detailed in the paper. The overall sensitivity of the spectrophotometric method with chloroform as extracting solvent i s better than 1 ppb (0.001 ppm). For atomic absorption spectrometric determination isoamyl alcohol is used as extracting solvent and a sensitivity of 0.2 ppm, which is ten times better than attained earlier, is achieved. There was excellent agreement between the results obtained by the two different instrumental methods.     

Spectrophotometric determination of vanadium and its application to gas-turbine fuel-oils

A very sensitive spectrophotometric method for the determination of vanadium in furnace oils is described. The intense indigo-blue colour developed by the reaction of vanadium with tannin and thioglycollic acid is measured at a wavelength of 600 nm at pH 4 and obeys Beer's law between 0.5 and 5 ppm vanadium. The method is applicable to gas-turbine fuel-oil and special navy fuel-oils. The common mineral constituents usually present in such oils do not interfere.