催化极谱法连续测定岩石中钨和钼

本文提出了在二苯基乙醇酸-二苯胍-氯酸钠催化极谱体系测钨后,加入少许钛铁试剂,使钼产生一个极灵敏的导数波。谊波形尖锐、对称,便于测量钼。建立的连测体系简便灵敏,用于岩石样品中钨和钼的测定,取得了满意的效果。     

Trace determination of platinum-I. A catalytic method using pulse polarography

Experimental conditions are given for the development of a well-defined catalytic polarographic wave for PT(II) after chelation with ethylenediamine. Direct-current polarographic studies of the wave characteristics indicate that it is of the catalytic hydrogen type, sensitive to pH changes, temperature, and electrode characteristics. By differential pulse polarography a single, sharp peak at -1.62 V is obtained, allowing trace determination of Pt(II) in the range 0.01-1.0 ppm with a linear calibration and a detection limit of 0.003 ppm. The catalytic wave is shown to suffer little interference from other platinum-group metals at 1:1 concentration ratio to Pt, except for Rh(III).     

Inorganic polarography in organic solvents-II: polarographic examination of the molybdenum(V) thiocyanate complex in diethyl ether

A procedure involving the solvent extraction of molybdenum(V) thiocyanate into diethyl ether followed by a direct polarographic examination of the organic phase offers a selective method for the determination of molybdenum down to 0.5 ppm. Only molybdenum, amongst 21 elements examined, is observed to give a reduction wave under the recommended conditions. The method is evaluated with respect to various experimental factors and is applied to the determination of molybdenum in mild and alloy steels.     

Spectrophotometric and polarographic studies of pyridin-2-aldehyde guanylhydrazone-Fe(II) system

The analytical properties of iron(II)-PAG system are described. The optimal conditions for a spectrophotometric determination of iron are

shown. A determination of Fe(II) with PAG can be performed in a concentration range varying from 0.5 to 4.7 ppm of iron, the molar absorptivity is 1.3 × 10⁴ liters · mol^?1, at 380 nm and the relative error (95% confidence level) is ±0.3% for 1.9 ppm of iron.A polarographic behavior of iron(II)-PAG system has been attempted. Iron gives well-defined diffusion-controlled reduction wave with half-wave potential ?0.42 V at 8.5 pH value. The electrode process is discussed.     

Determination of tungsten by calcium atomization inhibition titration

A method for the determination of tungsten utilizing inhibition effect on calcium emission in hydrogen-air flame is described. The technique is based on atomization inhibition titration (AIT) and subsequent release by means of lanthanum. The signal enhancement following the lanthanum addition is proportional to the tungsten concentration up to 0.8 ppm W. A detection limit of 0.013 ppm and a determination limit of 0.12 ppm were found. The effect of 13 foreign ions on the tungsten determination was investigated.     

Determination of oxygen in certain gases : Improved winkler method

An improved method is described for the determination of micro-amounts of oxygen gas in argon, carbon dioxide, helium, hydrogen and nitrogen by the Winkler. procedure. The technique is such that a mean standard deviation of ± 0.33 ppm oxygen with a reproducibility of ± 0.67 is obtained for gases varying in oxygen content from 1 to 30 ppm. The results are reproducible on a day-to-day basis. The reagent blank is equivalent to about 2.5 ppm with a deviation of 0.2 ppm. The method can be used for oxygen gas determination from 1 to 1.50 ppm. The accuracy of the method is ± 0.1 ppm for the lower range of oxygen concentrations.The method may also be extended to higher oxygen-containing gases, except that the oxygen determination is made by titration and smaller gas samples are used.     

Heavily Boron Doped Diamond Electrodes for Ultra Sensitive Determination of Ciprofloxacin in Human Urine

Ciprofloxacin is one of the most potent fluoroquinolone antibiotics in medical treatment with a widely effective antibacterial activity. Aim of the presented paper was to use boron doped diamond electrodes for a sensitive, simple and reliable voltammetric determination of ciprofloxacin in human urine samples. Prior to the electrochemical analyses, an optimal boron doping level was determined in order to achieve the highest sensitivity. A set of boron doped diamond electrodes with the doping level in the range from 0 to 20 000 ppm B/C was used for this purpose. Electrochemical behavior of ciprofloxacin was investigated using cyclic voltammetry in an ammonium acetate buffer (pH 5), where ciprofloxacin provided a well‐defined irreversible oxidation peak at a potential of + 1.15 V. Under optimal experimental conditions, the calibration curve obtained by square‐wave voltammetry was linear in a concentration range from 0.15 to 2.11 μmol/L (R²=0.9974). A very low limit of detection (0.05 μmol/L) was obtained for the BDD electrode with the highest doping level. The developed square wave method was successfully applied to the determination of ciprofloxacin in human urine samples with a very good recovery (from 97 to 102%).     

Determination of Sulfide in Spring and Wastewater by a New Kinetic Spectrophotometric Method

A simple, rapid, and sensitive method has been developed for the determination of trace amounts of sulfide based on its reaction with thionine. The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of the dyestuff at 600 nm by the fixed time method. After optimization of the measuring conditions the calibration curves were found linear up to 38.0 ppm (four regions), and the theoretical limit of detection was 0.076 ppm and the relative standard deviation for determination of 1.0 ppm sulfide (n = 10) was found to be 2.7%. The proposed method was applied successfully to the determination of sulfide in spring water and wastewater samples.     

Microwave digestion of bottom sediments from Lake Baikal for the inductively coupled plasma mass-spectrometric determination of their elemental composition

A microwave digestion procedure with the use of specially designed autoclaves and a domestic microwave oven is proposed for the mass-spectrometric determination of the elemental composition of bottom sediments. The throughput of sample preparation in routine analysis was considerably increased because of the elimination of a purification step. Reaction mixture compositions and microwave digestion conditions were chosen to reach complete decomposition (within the limits of error of semiquantitative ICP MS analysis) of Baikal bottom sediments with respect to the majority of elements. It was found that the procedure is unsuitable for the determination of Sn, Zr, Nb, Hf, As, and Sb. The approximate concentrations of elements in a BIL-1 certified reference material of Baikal bottom sediments were found: Tl, 0.52 ± 0.16 ppm; Bi, 0.33 ± 0.10 ppm; I, 14.3 ± 4.3 ppm; Cd, 0.31 ± 0.09 ppm; and Pb, 0.24 ± 0.07 ppm.     

Determination of ATP using chelation-enhanced fluorescence

A method for the direct determination of ATP that exhibits reasonable sensitivity, and responds to very few interferants, has been developed. The chelation-enhanced fluorescence between N-(anthracen-9'-yl methyl)tris(3-aminopropyl) amine and adenosine 5'-triphosphate is utilized in this determination. The method was tested in batch and flow-injection analysis (FIA) modes. The typical detection limit for FIA determination of ATP is 1 muM, with a linear range of 0.5-100 ppm. A typical relative standard deviation at 20 ppm is 2.3%.     

Determination of ammonia based on the electro-oxidation of hydroquinone in dimethylformamide or in the room temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

The results detail a novel methodology for the electrochemical determination of ammonia based on its interaction with hydroquinone in DMF. It has been shown that ammonia reversibly removes protons from the hydroquinone molecules, thus facilitating the oxidative process with the emergence of a new wave at less positive potentials. The analytical utility of the proposed methodology has been examined with a linear range from 10 to 95 ppm and corresponding limit-of-detection of 4.2 ppm achievable. Finally, the response of hydroquinone in the presence of ammonia has been examined in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluormethylsulfonyl)imide, [EMIM][N(Tf)₂]. Analogous voltammetric waveshapes to that observed in DMF were obtained, thereby confirming the viability of the method in either DMF or [EMIM][N(Tf)₂] as solvent.     

Ion chromatographic determination of ammonia in air using a sampling tube of porous carbon.

The ion chromatographic determination of ammonia in air using a sampling tube of porous carbon carbonized at 500 degrees C was examined. When the mean recovery and the reproducibility for a series of five determinations were examined for 1 and 10 ppm ammonia gases, the mean recovery (n = 5) and the relative standard deviation were 97.0% and 3.5% for 1 ppm and 86.9% and 2.8% for 10 ppm, respectively. Furthermore, the recovery from 10 ppm ammonia gas increased with an increase in the extraction time, and a recovery of 99.7% was obtained for 180 min of extraction time. The mean collection efficiency for 1 and 10 ppm ammonia gas was 102.5% and 96.5%, respectively. The relation between the sampling volume and the peak area was linear, and the linearity was 0.999 of the correlation coefficient. The ammonia gas concentration in an actual goat shed could be determined by this sampling device for a sampling volume of 5 L at a flow rate of 1 L/min; 0.79 ppm of the determination value practically agreed as compare with 0.78 ppm from collection by a boric acid solution.     

Spectrophotometric determination of fluoride a comparative study and a suggestion for evaluating photometric data

Summary Attempts were made to develop a method for fluoride determination using the demasking principle; the result was negative. Using the method of bleaching, ferric-sulfosalicylate, ferric-tiferronate, titanium-chromotropic acid and zirconium-alizarin coloured systems have been thoroughly investigated and compared for use as reagents for fluoride determination. Ferric-sulfosalicylate system has been proved to be the best. A new method of comparing photometric data has been suggested. Error in fluoride determination by ferric-sulfosalicylate method according to the method calculation suggested is between 1.80 percent and 4.60 percent, when the fluoride concentration is from 16 to 40 ppm. The method gives reproducible results when the fluoride concentration is in the range of 0.8 ppm to 4.0 ppm.     

Kinetic spectrophotometric determination of acetaldehyde in medical ethanol

A novel method has been introduced for the determination of trace amounts of acetaldehyde in medical ethanol based on its inhibition effect on the reaction between piperidine and sodium nitroprussiate. The reaction is monitored by a spectrophotometric technique, measuring a decreasing rate of absorbance at 560 nm during a fixed time of 60 s. The method allows for the determination of acetaldehyde in the range of 2.5–55 ppm. The limit of detection is 0.5 ppm and the relative standard deviation for 16 determinations of 30.0 ppm acetaldehyde is 0.038, while it is 0.173 in the common simple spectrophotometric method. The reliable results make the proposed method applicable to the determination of acetaldehyde in medical ethanol. The text was submitted by the authors in English.     

Determination of phenylephrine hydrochloride by flow injection analysis with chemiluminescence detection

A new method is proposed for the determination of phenylephrine hydrochloride by flow injection analysis with direct chemiluminescence detection. The method is based on the oxidation of the drug by potassium permanganate in sulfuric acid medium at 80 degrees C. The calibration graph is linear over the range 0.03-8 ppm phenylephrine hydrochloride, with a relative standard deviation (n = 51, 0.5 ppm) of 1.1% and sample throughput of 134/h. The influence of 38 different foreign compounds was tested, and the method was applied to the determination of phenylephrine hydrochloride in 8 different pharmaceutical formulations.     

Extraction - Spectrophotometric Determination of Phosphate Using N-Phenylbenzohydroxamic Acid

Abstract

A simple solvent extraction and spectrophotometric method for the determination of micro amount of phosphate (PO₄) is described. Phosphate is selectively separated from associated elements by reacting it with calcium and extracting excess calcium with N-phenylbenzohydroxamic acid (PBHA) at pH 11.3. The excess calcium was determined in ultra-violet and visible region and hence the phosphate content was calculated. The Beer's law is obeyed in the range 0.5 ? 10.0 ppm at 340 nm and 0.25 - 8.0 ppm at 560 nm of phosphate for a fixed amount of calcium (20.0 ppm). These results are also compared with those obtained by atomic absorption spectrophotometry. The method has been applied for the determination of phosphate in pharmaceutical and other samples.     

稀土—4—（2—吡啶偶氮）间苯二酚螯合物的高效液相色谱分离和测定

本文讨论了反相离子对液相色谱法分离和检测稀土-4-(2-吡啶偶氮)间苯二酚螯合物的各种条件,在12 min内完成了9种稀土螫合物的分离,校正曲线的线性范围是(ppm):La(0.01～3.20),Ce(0.03～2.8),Pr(0.06～3.5),Nd(0.05～3.8),Sm(0.01～3.0),Eu(0.05～3.4),Tb(0.02～3.0),Ho(0.01～3.4),Er(0.06～4.0).变异系数小于1.2％.     

Spectrophotometric determination of carbon monoxide with ruthenium(II) octaethylporphyrin

A novel spectrophotometric method for the estimation of carbon monoxide at levels from 2 to 250 ppm is presented. The method is empirical and based on formation of a carbonyl complex of ruthenium(II) octaethylporphyrin and measurement of the difference in absorbance at 393.5 nm between this complex and the porphyrin reagent. Oxygen and nitrogen do not interfere and up to 300 ppm of sulphur dioxide and about 1500 ppm of carbon dioxide can be tolerated in determination of carbon monoxide at the 4 and 10 ppm levels. Hydrogen sulphide interferes and must be removed before the determination. The method has been tested over the range 2-45 ppm of carbon monoxide with 16 synthetic and 2 commercial standard air samples. The average error was +/- 3%. Application to urban-air samples and car-exhaust gases yielded acceptable results. The main disadvantages are the tedious preparation of the initial ruthenium(III)-porphyrin compound and the decomposition of the reagent in the presence of hydrazine.     

吸收光谱电化学测定铜的研究

West等人^[1-2]首先研究了镉、钴、铬、铜、铁、锰、镍、铅等金属离子和某些有机化合物在铂电极上的吸收光谱电化学特性,并导出定量分析公式,但迄今为止,此法还未用于实际样品分析。本文在以前工作基础上,用原子吸收分光光度计,着重试验了钠、钙、镁、铝等对铜的影响,直接测定了腐蚀剂和氯化钠中的铜,获得了良好的结果。     

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.