Analysis of cationic nutrients from foods by ion chromatography

Ionic content in plant extracts determined by ion chromatography with conductivity detection

A simple method is described for the determination of the ionic content of vegetable samples by ion chromatography with suppressed conductivity detection. Extracts of leaves of cucumber (Cucumis sativus), leaves and cotyledons of watermelon (Citrullus lanantus), cotyledons of zucchini (Cucurbitapepo), and leaves and roots of olive (Olea europaea) obtained at room temperature yielded chromatographic profiles with substantial differences in the relative contents of Cl-, NO3-, HPO4(2-) and SO4(2-) as well as of Na+, NH4+, K+, Mg2+ and Ca2+. Although NO3-, Cl- and K+ were common to each extracted sample and accounted for most of the ions present, two additional anion peaks (i.e. malate and oxalate) were detected. Among the vegetable tissues investigated, olive roots contained a considerable amount of oxalate (37 mg/g dry weight), while Na+, which is present in very low amount in extracted samples of leaves and cotyledons, represented ca. 30% of the cationic content of olive roots. In all the examined tissue extracts, K+ was the main cation (16-55 mg/g dry weight) and NO3-, Cl- and HPO4(2-) were the main inorganic anions.

Application of capillary isotachophoresis and capillary zone electrophoresis to the determination of inorganic ions in food and feed samples

The purpose of this review is to summarise critically the possibilities of capillary isotachophoresis and capillary zone electrophoresis for the determination of inorganic ions in food and feed samples. This article covers papers published since 1977.

Determination of inorganic ions in food and beverages by capillary electrophoresis

A review of the applications of electrophoresis to the determination of inorganic anions (sulphate, sulphite, phosphate, nitrate, nitrite and halides) and inorganic cations (ammonium, alkali and alkaline metals and trace elements) in food and beverages is presented.

State-of-the-art ion chromatographic determination of inorganic ions in food

A review of the applications of ion chromatography (IC) to the determination of inorganic ions in food is presented. The most promising sample preparation techniques, such as accelerated solvent extraction, supercritical fluid extraction, solid-phase extraction, UV photolysis, microwave-oven digestion and pyrohydrolysis are discussed. Among the various inorganic anions, nitrogen, sulphur and phosphorus species and halides are widely determined in foods and to a lesser extent only, cyanide, carbonate, arsenic and selenium species are considered. IC determination of inorganic cations deals with ammonium ion, alkali, alkaline-earth, heavy and transition metals particularly and only a small amount of literature is found on the other ones, like aluminium and plantinum. A particular advantage of IC over traditional techniques is the simultaneous determination of several species.

Practical capillary electrophoresis method for the quantitation of the acetate counter-ion in a novel antifungal lipopeptide

This is the first report of the validation of a capillary ion electrophoresis method for the quantitative determination of acetate (CH3COO-) levels in the acetate salt of a basic lipopeptide. The acetate counter-ion was detected using indirect photometric detection, 4.0 mM 4-hydroxybenzoic acid (HOC6H4COOH) as the carrier electrolyte and the chromophore mobile phase, and OFM Anion-BT as the electroosmotic flow (EOF) modifier. The EOF modifier is primarily a 20 mM myristyltrimethylammonium bromide (TTAB) solution. The apparent pH (pHapp) of the electrophoretic buffer was 6.0. The response was linear from 0.9 microgram/ml to 46 micrograms/ml (r2 = 0.9997). The capillary electrophoresis (CE) system is very efficient and stable, giving R.S.D. values of about 1.0% for the injection-to-infection precision without using internal standards. The method is accurate as judged by comparison to an ion-exchange HPLC method and by the 99.7% recovery of spiked acetate ion in the aqueous solution of the lipopeptide. The method is rugged with regard to critical method parameters, such as different operational voltages and effective capillary lengths. The overall precision is acceptable with a R.S.D. of 1.5% between 0.2-12% (w/w) acetate ion present in the drug substance without using an internal standard. Comparison to the ion-exchange chromatography and advantages of the CE method are discussed. This CE method has been submitted to and accepted by the regulatory agencies and is now in routine use within our laboratories.

Validation of a capillary electrophoresis method for the determination of potassium counter-ion levels in an acidic drug salt

This paper describes the first report of the validation of a capillary electrophoresis method for the quantitative determination of potassium levels in the potassium salt of an acidic drug. Validation criteria include precision, linearity, robustness and repeatability. The use of an internal standard enabled precision values of < 1% RSD to be obtained for peak area ratios. Careful control of capillary conditioning and temperature enabled migration time precisions of < 0.5% RSD. Results obtained by this method were in agreement with those generated by ion exchange chromatography and the theoretical potassium content of samples tested. Features of the method, compared to alternative analytical techniques, include simplicity, speed and accuracy. The method is now in routine use within our laboratories.