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Chromatographic systems for the separation of amino acid mixtures on RP-18 as a stationary phase have been elaborated. The best results were obtained using methanol-water (1:1, v/v; 1:3, v/v; 1:5, v/v) as a mobile phase.The following amino acids have been examined: asparagine, arginine monohydrochloride, cystine, cysteine chloride, glycine, histidine monohydrochloride, hydroxyproline, isoleucine,...
The feasibility of chromium(VI) preconcentration on to activated alumina in a continuous flow system with spectrophotometric detection was investigated. Chemical and flow variables, and the influence of concomitant species were studied both with and without preconcentration systems. The best results were obtained by using a 2.5 cm long, 1.6 mm i.d. alumina minicolumn, and selecting 1 10 -...
Two simple, inexpensive and rapid iodometric and spectrophotometric procedures were developed for trace amount determination of ruthenium. The proposed methods were based on the oxidation of ruthenium(II or III) with sodium periodate at pH 2.4-3.6, masking the excess periodate with sodium molybdate. The released iodate was then allowed to react with KI at pH 3, with subsequent determination of the...
A spectrophotometric study of palladium complexation in concentrated nitrate and acid solutions is presented. The water activity of the solutions was fixed to control activity coefficients. The existence of the species PdNO +3 , Pd(NO 3 ) 2 and PdOHNO 3 has been evidenced and their stability was evaluated. An activity diagram for the predominance of soluble...
The reagent 3,8,13,18-tetramethyl-21H,23H-porphine-2,7,12,17-tetrapropionic acid or coproporphyrin-I (CPI) was used for the spectrophotometric determination of copper(II) and cobalt(II) in the presence of pyridine and imidazole catalysts. Optimum conditions were investigated and the methods were applied to the determination of parts per billion levels of copper(II) and cobalt(II). The Sandell sensitivities...
Scandium in the presence of cerium(III) forms, with p-acetylchlorophosphonazo (CPApA), a heteropolynuclei ternary β-complex of scandium-cerium-CPApA. The complex gives a very sensitive reaction for scandium with a molar absorptivity of Sc = 2.29 10 5 l mol -1 cm -1 due to the cocoloration effect. Most foreign ions can be tolerated in considerable...
A new polymeric chromogenic reagent PA.FPNS has been synthesized by condensing polyallylamine (PA) with 3-(4-formylphenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid (FPNS) and its properties studied. In alkaline media, PA.FPNS reacts with magnesium to form a water-soluble blue complex, whose absorption maximum is at 604 nm. The molar absorptivity ( ) of the complex is 5.2 x 10 4 1...
A flow-injection manifold is proposed for determination of nitrite based on the reaction with 3,6-diamino acridine (proflavin sulfate) in hydrochloride acid medium. The assembly is adapted for nitrate determination by including a reductive column filled with copperized cadmium. The influence of foreign substances is also studied. The method gives a linear calibration graph over the range 0 06-4mg...
A simple and rapid spectrophotometric method for the determination of Isoproturon and Metoxuron is described based on alkaline hydrolysis of the compounds to their corresponding primary amines, followed by diazotization and coupling with ethylacetoacetate in alkaline medium. The chromogenic species obeys Beer's law up to 15 and 9 μg ml -1 for Isoproturon and Metoxuron respectively. ...
A simple and sensitive spectrophotometric method is developed for the determination of titanium in aqueous medium. The metal ion forms a reddish brown coloured complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range 1-7. The complex shows two absorption maxima, one at 430 nm and the other at 500 nm. The reagent shows appreciable absorbance of 430 nm and negligible...
A new pyridylazo reagent, 5-(5-nitro-2-pyridylazo)-2,4-diaminotoluene (5-NO 2 -PADAT) has been synthesized, and found to be a good chromogenic reagent for palladium. In sulfuric acid, hydrochloric acid and perchloric acid palladium reacts with 5-NO 2 -PADAT to form a 1:1 chelate, exhibiting an absorption maximum at 592 nm. The apparent molar absorptivity is 1.25 10 5 1...
An automatic direct spectrophotometric method for the simultaneous determination of nitrite and nitrate by flow-injection analysis has been developed. Nitrite reacts with 3-nitroaniline in the presence of hydrochloric acid (0.96-1.8 M HCl or pH 0.5-0.7) to form a diazonium cation, which is subsequently coupled with N-(1-naphthyl)-ethylenediamine dihydrochloride to form a stable purple azo dye, the...
A rapid, sensitive and simple spectrophotometric method is developed for the determination of isoniazid (INH) with sodium 1,2-naphthoquinone-4-sulphonate and cetyltrimethyl ammonium bromide (CTA) in alkaline medium. Beer's law is obeyed in the range of INH concentrations of 2-5.6 μg ml -1 at the maximum absorption of 500 nm. Sensitivity is enhanced by the addition of CTA. The method...
A study of the absorption spectra of the food colourants Tartrazine (E-102), Amaranth (E-123) and Curcumin (E-100) in various organic solvents and pH media, have been carried out. In addition, the spectral behaviour in aqueous micellar systems of anionic, cationic and non-ionic surfactants, as well as β-cyclodextrin, was investigated. Analytical methods are proposed for the determination of the...
A rapid and sensitive spectrophotometric method has been developed for the quantitative determination of some phenothiazine derivatives as the pure substances and in different dosage forms. The method is based on the formation of red coloured products with 1% iodic acid in sulphuric or phosphoric acid medium. The reaction involves oxidation of the phenothiazine nucleus into a semiquinonoid radical...
A highly sensitive detection system using a semiconductor laser (SCL) and a thin long flow-through cell (TLFCT) to match flow-based analysis, such as flow injection analysis (FIA), has been developed. The SCL was a GaAlAs semiconductor laser emitting at 780 nm (5 mW), and the TLFTC, which has a 100 mm thin long light path, was made of a poly(tetrafluoroethylene) (PTFE) rod. The sensitivity was essentially...
A direct spectrophotometric procedure for the determination of theophylline in plasma is proposed. This procedure is based on the apparent content curves method and it is not necessary to know the nature and contents of interferent substances. Bias errors introduced by plasma and metabolites are avoided. The results obtained are in agreement with those provided by an immunofluoroassay used as a...
A new suite of 10 programs concerned with equilibrium constants and solution equilibria is described. The suite includes data preparation programs, pretreatment programs, equilibrium constant refinement and post-run analysis. Data preparation is facilitated by a customized data editor. The pretreatment programs include manual trial and error data fitting, speciation diagrams, end-point determination,...
A simple, sensitive and selective method for the spectrophotometric determination of drugs, viz., sulphamethoxazole, tetracycline HCl, amidopyrine, nifurtimox and isoniazid and biologically important amino acids, cysteine, aspartic acid and arginine based on their reactivity with chloramine-T (CAT) is proposed. The method involves the addition of excess CAT of a known concentration in the presence...
Reaction of selenium with 2,3-diaminonaphthalene was reinvestigated with bromide ion as a catalyst. In acid medium, selenium reacts with the above reagent to form a complex extractable with cyclohexane and with an absorption maximum at 378.5 nm. The molar absorptivity of the complex is 17.5 10 3 1 mol -1 cm -1 . Beer's law is obeyed in the range 0.5-12 mg 1...
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