Flow-injection extraction-spectrophotometric determination of permanganate with the ethylene-bis(triphenylphosphonium) cation

Permanganate is determined spectrophotometrically at 545 nm after extraction into chloroform of the ion-associate, ethylene -bis (triphenylphosphonium) permanganate. The carrier stream is pH 6 buffer containing 10% (w/v) ammonium fluoride and the reagent stream is 0.25% (w/v) ethylene-bis (triphenylphosphonium) bromide. The injection rate is 24 h^?1. Th calibration graph is linear up to 25 μg ml^?1 and the detection limit is 0.58 μg m^?1 Mn (VII), based on 250- μl injections. The system is applied to the determination of manganese in a range of steels.     

Flow-injection extraction-spectrophotometric determination of perchlorate with brilliant green

Perchlorate (0-2.5 μg ml^?1) is determined spectrophotometrically at 640 nm after extraction into benzene of its ion-associate with Brilliant Green in a flow-injection manifold with a membrane separator. The injection rate is 20 h^?1. The detection limit is 36 ng ml^?1, based on 250-μl injections. The system is applied to the determination of perchlorate in potassium chlorate after prior selective destruction of chlorate.     

Flow-injection extraction-spectrophotometric determination of imipramine in pharmaceuticals with methyl orange

Imipramine in aqueous solution is extracted into 1,2-dichloroethane as its ion-pair with Methyl Orange in an unsegmented flow system and quantified spectrophotometrically. A linear calibration graph was obtained between 0.79 and 25.3 mug/ml of imipramine. Up to 45 samples/hr can be processed with a RSD of 0.88-1.6%. The method was satisfactorily applied to the determination of imipramine in pharmaceutical preparations.     

Spectrophotometric determination of manganese in low-alloy steels after its extraction as triphenylsulphonium permanganate

Summary Manganese(VII) (0–100 g) can be determined spectrophotometrically at 548 nm after its extraction as triphenylsulphonium permanganate into chloroform. The effects of pH, reagent conditions and diverse ions are reported. The system has been applied to the determination of manganese in a range of steels. For the determination of 60 g of manganese the relative standard deviation was 0.5% (n=7).     

Flow-injection extraction spectrophotometric determination of dichromate with the tetramethylenebis(triphenylphosphonium)cation

Chromium(VI) (0–5 μg) can be determined spectrophotometrically at 365 nm after flow-injection extraction into chloroform of the ion-associate, tetramethylenebis(triphenylphosphonium) dichromate. The carrier stream is distilled water and the reagent stream contains 1 M sulphuric acid and 0.5% (w/v) tetramethylenebis(triphenylphosphonium) bromide. The sampling rate is 24 h^?1. The calibration graph is linear up to 20 μg ml^?1 and the detection limit is 0.44 μg ml?1 chromium, based on injection volumes of 250 μl. The system has been applied to the determination of chromium in a range of steels.     

Solvent extraction-spectrophotometric determination of rare earths with chlorophosphonazo-III

The rare-earth chlorophosphonazo III chelates are easily extracted from an aqueous solution (pH 1.1-1.5) into n-butanol. The absorbance at the absorption maximum (at 668 nm) is about 3 times that in aqueous solution. The spectrophotometric determination of rare earths has been investigated.     

Flow-injection extraction spectrophotometric determination of bismuth as tetraiodobismuthate(III) with the tetramethylenebis(triphenylphosphonium) cation

Bismuth can be determined spectrophotometrically at 495 nm after its extraction as tetramethylenebis(triphenylphosphonium) tetraiodobismuthate(III) into dichloromethane. The carrier stream is 2 M sulphuric acid and the reagent stream contains 2% (w/v) potassium iodine and 0.4% (w/v) tetramethylenebis(triphenylphosphonium) bromide. The injection rate is 20 h^-1. The calibration graph is linear up to 20 μ ml^-1 bismuth and the detection limit is 0.24 μ ml^-1 bismuth, based on injection volumes of 250μl. The system has been applied to determination of bismuth in pharmaceutical samples.     

Flow-injection determination of meptazinol with electrochemical detection

A flow-injection analysis system incorporating a glassy carbon voltammetric detector cell is described. Meptazinol (0.01–10 μg ml^-1) can be determined by electro-chemical oxidation in a carrier stream of 0.05 M sodium acetate—0.1 M acetic acid in 98% ethanol at sampling rates up to 80 samples per hour.     

Flow-injection spectrophotometric determination of cobalt by extraction as tetrathiocyanatocobaltate(II) with the ethylenebis(triphenylphosphoniu) cation

Cobalt (0–10 μg) may be determined spectrophotometrically at 625 nm after flow-injection extraction into chloroform of the ion associate ethylenebis(triphenylphosphonium) tetrathiocyanatocobaltate(II). The carrier stream contained 10% (w/v) ammonium fluoride and the reagent stream contained 0.5% (w/v) ethylenebis (triphenylphosphonium) bromide and 5% (w/v) ammonium thiocyanate. The injection rate was 20 h^?1. The calibration graph is linear up to 20 μg ml^?1 and detection limit is 0.23 μg ml^?1 cobalt, based on injection volumes of 500 μl. The system has been applied to the determination of cobalt in a range of tool steels.     

Flow-injection spectrophotometric determination of salbutamol with 4-aminoantipyrine

A flow-injection method is proposed for the determination of salbutamol. The method involves the condensation of salbutamol with 4-aminoantipyrine in the presence of hexacyanoferrate (III) in alkaline medium, producing a coloured quinoneimide that was detected absorptiometrically at 500 nm.

The values of four variables (two reactor lengths and two reagent concentrations) were optimised by means of the sequential simplex method and their influence studied in univariant way.

The method was validated and compared with the HPLC method established in the United States Pharmacopeia (USP). Linearity was demonstrated in the range 0–74.1 mg/L of salbutamol sulfate (r² = 0.9999). Commercial samples of pharmaceuticals containing salbutamol sulfate (tablets and oral solutions) were analysed and the results obtained with the proposed method agreed with the USP method in less than 1.6%, with precision similar to the HPLC method (1%–2% R.S.D.). The sampling frequency was 75 samples/hour.     

Flow-injection determination of iodide with a silver electrode

A procedure is developed for the flow-injection determination of iodide using a modified silver electrode; it extends the analytical range of iodide by an order of magnitude as compared to potentiometric determination using an iodide-selective electrode with a polycrystalline membrane. The detection limit is 7 μg/L. The procedure was used to determine iodide in natural mineral waters and model solutions. The throughput was 20–25 samples/h.     

Flow-injection determination of malate with immobilized malate dehydrogenase

Malate dehydrogenase (MDH) is immobilized chemically on controlled-pore glass and used on-line in a glass minicolumn (25×2.5 mm i.d.). Malate solution passes through the minicolumn of immobilized MDH and the NADH formed is monitored spectrophotometrically from 9 × 10-^?4 down to 7 × 10^?6 M (36 ng in 40 μl) at 50 samples h^?1.     

Flow-injection spectrofluorimetric determination of ethylenethiourea

A flow-injection configuration is proposed for the fluorimetric determination of ethylenethiourea. The procedure is based on the inhibitory effect of ethylenethiourea on the oxidation of thiamine to thiochrome by mercury(II). A linear calibration graph was obtained between 0.1 and 2.0 μg mL^–1, with a sampling rate of 40 samples per hour and a relative standard deviation of about 1.11%. The usefulness of the method was tested for the determination of ethylenethiourea residues in water, milk, potatoes, pear, grape and apple. Received: 26 January 1998 / Revised: 6 April 1998 / Accepted: 9 April 1998     

Flow-injection spectrofluorimetric determination of ethylenethiourea

A flow-injection configuration is proposed for the fluorimetric determination of ethylenethiourea. The procedure is based on the inhibitory effect of ethylenethiourea on the oxidation of thiamine to thiochrome by mercury(II). A linear calibration graph was obtained between 0.1 and 2.0 μg mL^–1, with a sampling rate of 40 samples per hour and a relative standard deviation of about 1.11%. The usefulness of the method was tested for the determination of ethylenethiourea residues in water, milk, potatoes, pear, grape and apple. Received: 26 January 1998 / Revised: 6 April 1998 / Accepted: 9 April 1998     

Flow-injection spectrophotometric determination of chloramben

Abstract

A method for the dechlorination of PCB mixtures (Aroclor formulations) to biphenyl was extended to soils. The contaminated sample was mixed with magnesium flakes, potassium hexachloropalladiate (K₂PdCl₆), propan-2-ol and water then permitted to react for up to six hours. Biphenyl, recovered by extraction into hexane, was quantified by gas chromatography with flame ionization detection. The reaction was very efficient in propan-2-ol / water (～95%), surfactant emulsion or sand mixture and virtually complete in soil provided that excess magnesium (2 g) and the K₂PdCl₆ were added to the sample prior to the addition of water. Higher PCB loadings were readily determined in field contaminated soils either by direct determination within the matrix or by standard additions. However, analyte concentrations were appreciably over-estimated in Soxhlet or sonication extracts of a certified reference material that contained sub-ppm levels of analyte. The over-estimation is considered to result from the conversion in part of natural organic matter to biphenyl.     

去乙酰毛花苷的流动注射化学发光分析研究

在碱性介质中,去乙酰毛花苷对鲁米诺-KIO4发光体系有明显的抑制作用,且抑制效果与其质量浓度呈良好的线性关系,据此建立了去乙酰毛花苷的流动注射化学发光分析方法。该方法的线性范围为1.0×10-8~1.0×10-5g/mL,检出限为3.1×10-9g/mL,对1.0×10-7g/mL的去乙酰毛花苷进行连续11次平行测定,相对标准偏差为2.3%。可用于相应注射剂分析,并与药典方法进行对照。     

Flow-injection spectrofluorimetric determination of paracetamol

A flow-injection spectrofluorimetric determination of paracetamol is reported, based on the oxidation of the analyte with potassium hexacyanoferrate(III) immobilized on an anion-exchange resin, the fluorescence being enhanced with N,N′-dimethylformamide. Concentrations of paracetamol in the range 0.04–17.60 mg l^?1 are determined with a relative standard deviation of 1.5%. The injection rate is 25 samples h^?1. The influence of foreign species and the determination of paracetamol in several pharamaceutical formulations are also reported.     

Flow-injection determination of l-ascorbate with cucumber juice as carrier

Cucumber (Cucumis sativus L.) juice has a high l-ascorbate oxidase activity and can be used as the carrier solution in an amperometric flow-injection system for the determination of l-ascorbate. The determination time is 1 min. The calibration graph is linear over the range 5×10^?4–7×10^?3 M (RSD 4%). No enzyme purification is needed. The juice solution retains its activity for 8 days with recycling.     

Flow-injection determination of l-tyrosine in serum with immobilized tyrosinase

A flow-injection method for the determination of the serum l-tyrosine is described. The method involves the conversion of tyrosine into dopaquinone by reaction of tyrosinase, followed by derivation of the dopaquinone with fluorogenic agent 1,2-diphenylethylenediamine. Serum was deproteinized with tungstic acid. Sample solution was injected into a reactor (50 x 4 mm i.d.) packed with glass beads on which tyrosinase was immobilized. The fluorescence was detected at 480 nm (excitation at 350 nm). The calibration graph was linear for 5 x 10(-7)-2 x 10(-4)Ml-tyrosine; the detection limit was 2 x 10(-7)M.