Sulfur speciation by capillary zone electrophoresis. Determination of dithionite and its decomposition products sulfite, sulfate and thiosulfate in commercial bleaching agents.

In this paper, a capillary zone electrophoretic (CZE) method was developed for the separation of the sulfur species dithionite (S2O4(2-)), sulfite (SO3(2-)), sulfate (SO4(2-)) and thiosulfate (S2O3(2-)). A carrier electrolyte (pH 7.0) containing 1.

Comparative study of the determination of peroxomonosulfate, in the presence of other oxidants, by capillary zone electrophoresis, ion chromatography, and photometry.

Several methods for quantitative determination of peroxomonosulfate in detergents, in the presence of other oxidants, have been investigated. The photometric technique applied was based on the well-known starch-iodine reaction. The oxidizing agent was quantified by determining the amount of iodine produced.

Voltammetric trace analysis of DNA and RNA.

A voltammetric determination of DNA/RNA is described. The new aspect is the use of the extracellular endonuclease Serratia marcescens in the sample preparation. Using this enzyme it is possible to determine DNA/ RNA with a detection limit of 2-5 pg/mL.

Sulfur speciation by capillary zone electrophoresis: conditions for sulfite stabilization and determination in the presence of sulfate, thiosulfate and peroxodisulfate.

Capillary zone electrophoresis (CZE) was used for the separation of the sulfur species SO3(2-), SO4(2-), S2O(3-) and S2O8(2-). Using an electrolyte system with 9.5 mmol L(-1) potassium chromate as UV-absorbing probe and 1 mmol L(-1) diethylenetriamine (DETA) as electroosmotic flow modifier, various possibilities for the stabilization of sulfite and electrophoretic separation of the sulfur anions were investigated.

[Chemometric evaluation of in vitro studies of bioavailability of zinc in selected foodstuffs and menus].

Using simulated digestion-juices for extraction of 31 foodstuffs and 4 menues, 7 variables were subjected to measuring various polarographic parameters as well as determining antagonists of zinc absorbtion, and were evaluated by chemometric methods. Correlations between the different variables were determined by factor analysis, and 4 factors were extracted. By means of cluster analysis it was established whether similarities between the 31 foodstuffs and 4 menues are existing.

Solid-phase extraction of the chromium(III)-diphenylcarbazone complex prior to ion-pair chromatography and application to geological samples.

A method for the pre-treatment of acid samples prior to ion chromatography is described. In a strong acid medium, Cr(VI) oxidizes diphenylcarbazide, the resulting products forming a stable complex which can be transferred in a methanolic medium by solid-phase extraction using polyethylene as sorbent. This methanolic sample solution can be injected directly into a chromatographic system with a silica-based column.

Speciation of Cr(III) and Cr(VI) and separation of common anions by ion pair chromatography with trans-1,2-diaminecyclohexane-N,N,N',N'-tetraacetic acid.

A reversed phase ion pair chromatographic method for the simultaneous determination of Cr species and common anions on a C(18)-bonded stationary phase was developed by using acetonitrile-water (2:98 v/v) containing 1.0 mM tetrabutylammonium hydroxide and 0.5 mM trans-1,2-diaminecyclohexane-N,N,N',N'-tetraacetic acid (DCTA) at pH 6.

Immobilized enzymes as tools in food analysis.

A lot of publications described the possibilities of using selective enzymatic reactions in analysis, but not much authors described applications for the analysis of real samples. In this paper important publications, which described different applications in food analysis, are reviewed. In the first section the use of biosensors for food analysis, in the second section the combination of immobilized enzymes and flow injection analysis and in the last section the use of immobilized enzymes in combination with HPLC are described.

[Analysis of element species and the question of the bioavailability of calcium from different types of bread].

In NaCl and NaCl/HCl extracts from 11 kinds of bread and flour the calcium ion concentrations in comparison to the total calcium contents were determined by a calcium-selective electrode. Crisp-breads showed the slowest values of extractable calcium and calcium ion concentrations in the extracts. Differentiated investigations on calcium binding in the neutralized extracts were carried out with a view to studying calcium resorption in the duodenum.

[Determination of aluminum traces in dialysis concentrates].

To determine traces of aluminium in dialyse concentrates trouble free and accurate by atomic absorption spectrometry a special procedure of enrichment was developed. The aluminium chromazurol S complex is adsorbed selectively at polyethylene powder whereby the disturbanced matrix (KCl) is separated. After elution by a 0.

[Ion chromatographic analysis of cations and anions in mineral water].

For the simultaneous analysis of the cations Li, Na, K, Ca, and Mg as well as Mn and the anions hydrogen carbonate, chloride, sulfate and nitrate, silica gel- and polymer-based ion exchange materials with conductivity and spectrophotometric detection combined with a post-column derivatization system (PAR-Zn-EDTA for Ca, Mg, Mn) and also an ion-pair system with RP-18 phase were compared with a view to their application to mineral water samples. It is possible to determine Li, Na, and K in such samples with or without the suppressor technique using polymer columns. A polybutadiene maleic acid silica gel cation exchanger material makes feasible simultaneous analysis of alkaline and earth alkaline metals.

[A new HPLC procedure for cyclamate in food with pre-chromatographic derivatization].

A high-pressure liquid chromatography (HPLC) procedure for the detection of cyclamate in liquid and solid samples is presented, which depends on oxidation and the reaction of cyclohexylamine with o-phthaldialdehyde to form a condensation product. The results of the HPLC analysis, using an RP-C 18 separation system with UV detection at 242 nm are reported. Contents, from 2 to 400 mg/l, can be detected in less than 2 h (HPLC analysis within 20 min) with relative standard deviations of 4%.

[Food chemistry and technology aspects of nickel-deficient nutrition in endogenously-induced allergic contact eczemas].

With reference to endogenous nickel contact dermatitis, the quantity of nickel resorbed is dependent on the individual capacity for absorption, the element species of nickel in the food matrix and the total nickel content in the food. As the content of nickel varies widely in individual foods, it is difficult to make any definite dietary recommendations. The wide fluctuation in the nickel content of vegetable food stuffs is due to variations in the composition of soil.

Kinetic studies on nitrite and nitrate in rats by ion-pair chromatography.

A highly sensitive and specific ion-pair chromatographic method is presented for the simultaneous determination of nitrite (NO2-) and nitrate (NO3-) in plasma. The detection limits are 2 mumol NO2-/l and 8 mumol NO3-/l with recovery rates of 98-99%. The applicability of this method to clinical medicine is demonstrated using NO2- -loaded rats as a biological model: following intravenous infusion or intragastric application of NO2-, blood levels of NO2-, NO3- and methemoglobin are measured during 2-64 min.

[Differential analysis of the binding forms of iron in various plant foodstuffs].

In fourteen plant foodstuffs of various composition a differentiation of iron contents according to water soluble, in ethylacetate extractable, in labile contents and iron(II) or Fe(III) species in the water extract are carried out by the spectrophotometric Ferrozine method. High water-soluble labile iron parts and high iron(II) contents were found in fruit, high complexed parts in the water extract and ethylacetate extractable iron contents in protein rich foodstuffs. The iron total contents are situated between 1 and 90 ppm, the water soluble parts amount to 6 up to 60% of the total content according to the foodstuffs.

[Types of binding of iron, copper and zinc in various varieties of tea].

Extracts of several varieties of tea were separated by HPLC and the resulting substances detected by various techniques with a view to characterizing the fractions of organic metal complexes of copper, zinc, and iron. In addition to uv methods and conductivity measurements particular stress was laid on the application of HPLC coupled with chemical reaction detectors for metals (photometric determination of total content) and for functional groups, such as phenolic OH-, SH-, and NH-groups. The distribution of the different metals was found by coupling HPLC with AAS.

[Separation and fluorimetric determination of adrenaline and noradrenaline. Combination of a high-pressure liquid chromatograph with an automatic analysis system].

The possibilities for a high-pressure liquid chromatographic analysis combined with automatic fluorimetric detection of the catecholamines adrenaline and noradrenaline are described. The optimal conditions are given for a fast separation by ion exchange and reversed-phase chromatography, and for the sensitive fluorimetric determination of adrenaline by the trihydroxyindole technique when a high excess of noradrenaline is present.

[A rapid semiautomatic separation of urinary catecholamines (author's transl)].

The semiautomatic separation of the catecholamines, adrenaline and noradrenaline, is based on their adsorption onto aluminium oxide at pH 8.4, followed by batch elution with 0.05 mol/1 perchloric acid.