Biomedical subjects

J M Riviello

Publications and source records attributed to J M Riviello.

6 recordsLinked to original sources

PubMed2001

Effect of ion-exchange site and eluent modifiers on the anion-exchange of carboxylic acids.

The chromatographic behavior of carboxylic acids has been investigated, on three different latex-based anion-exchange columns, in order to define the effect of the ion-exchange site structure on selectivity. The analytical columns produced are characterized by alkyl amines containing zero, one or two hydroxyl groups on the anion-exchange functional site. Divalent carboxylic acids, namely fumaric, maleic, trans-beta-hydromuconic, trans,trans-muconic, oxalic, malonic, succinic, glutaric, adipic, malic, tartaric and mucic acids, have been chosen as test solutes. The performance of the three stationary phases has been studied employing NaOH eluents and has been discussed with respect to the different hydrophilicity of the ion-exchange sites and analytes. Considering on previous results obtained using organic solvents (methanol and acetonitrile) with carbonate eluents on a highly hydrophilic column, the performance of the three exchangers has also been studied using acetonitrile, methanol and n-propanol. The chromatographic behavior was similar for the three columns studied, but the different organic solvents gave variations in selectivity. In order to characterize these differences, particle size measurements of the latices were performed both in pure water and in the presence of each organic solvent studied.

Anion Exchange Resins↗

PubMed2000

Determination of ammonium in seawater by column-switching ion chromatography.

A system which combines column switching and concentration was developed. A binary eluent mechanism was developed to study the effect of high sample concentration matrix on retention time shifts of the trace analyte. Separation conditions were chosen according to this mechanism to reduce the retention time shift of ammonium in the presence of high concentration sodium ion: high concentration sulfuric acid (25 mmol/l) was used as the eluent, and a hydronium-selective column of high capacity--a CS12 column, was employed. Since the retention time shift was reduced, the interval between onset and the complete elution of a high concentration ammonium standard (10 mg/l) was directly defined as the column-switching time window, which greatly simplified the procedure for determining the time window. Results showed that for ammonium below 1 mg/l, 90% ammonium was introduced and concentrated. Detection limits of 12.8 microg/l were obtained for ammonium with sodium at 1000 mg/l.

Ammonia↗

PubMed1999

Use of ion chromatography for the determination of heavy and transition metals in biochemical samples.

A novel, highly sensitive method for simultaneous separation and determination of Cu2+, Ni2+, Zn2+, Cd2+, Co2+, Mn2+ and Pb2+ in biochemical samples was developed and evaluated by ion chromatography. All of these metals were well separated on a bifunctional ion-exchange column by a concentration gradient of oxalic acid and sodium chloride eluents, coupled with spectrophotometric detection after post-column derivatization with 2-[(5-bromo-2-pyridyl)azo]-5-diethylaminophenol at 560 nm. The method detection limits (signal-to-noise 3:1) were at microg l(-1) levels. The calibration graphs were linear (r2>0.999) over two-orders of magnitude. This technique was optimized and validated by analyzing five standard biochemical references.

Animals↗

PubMed1998

Determination of eight synthetic food colorants in drinks by high-performance ion chromatography.

Eight synthetic food colorants (Amaranth, Brilliant Blue, Indigo Carmine, New Red, Ponceau 4R, Sunset Yellow, Tartrazine, Allura Red) were determined by high-performance ion chromatography on an anion-exchange analytical column with very low hydrophobicity and visible absorbance detection. Gradient elution with hydrochloric acid-acetonitrile effected both the chromatographic separation of these colorants and the on-line clean-up of the analytical column, which was very advantageous for routine analysis. High-performance ion chromatography may be a solution to the chromatographic analysis for some water-soluble, organic analytes with strong hydrophobicity. The method has been applied to the determination of colorants in drinks and in instant drink powder. No time-consuming pretreatment, as used in conventional liquid chromatography, was needed.

Artifacts↗

PubMed1998

On-line pretreatment and determination of Pb, Cu and Cd at the microgram l-1 level in drinking water by chelation ion chromatography.

A novel, highly sensitive method for the simultaneous separation and determination of lead, copper, cadmium and other transition metals in drinking water was achieved by on-line sample pretreatment of chelation ion chromatography. Manganese, which coeluted with cadmium, was oxidized to permanganate by ammonium persulfate before injection. Permanganate, with bulk quantity of alkali, alkaline earth metals, iron and aluminum, was eliminated by pyrophosphoric acid-ammonium acetate buffer solution (pH 5.5), while retaining heavy and transition metals on a selective chelating resin (MetPac CC-1 column). Then, they were disabsorbed and transferred to a sulfonated cation exchanger (TMC-1 column). Finally, the concentrated trace metals were separated on a bifunctional ion-exchange column (CS5A) by a concentration gradient of oxalic acid and sodium nitrate eluents, coupled with post-column spectrophotometric detection with 2-[(5-bromo-2-pyridyl)azo]-5-diethylaminophenol (5-Br-PADAP) at 560 nm. The separation and color-development conditions were optimized. The detection limits for the method (signal-to-noise ratio = 3:1) were at or below the microgram l-1 level. The results of drinking water analyses were satisfactory.

Cadmium↗

PubMed1990

Chelation ion chromatography as a method for trace elemental analysis in complex environmental and biological samples.

The development and evaluation of a new method for the determination of trace transition and rare-earth elements based on the combination of chelation and ion chromatography are described. The new method, chelation ion chromatography (Chelation IC), uses a chelating column to concentrate and separate transition and rare-earth elements from the common alkali and alkaline-earth metals, as well as other matrix components, prior to analysis by ion chromatography. The sample fraction from the chelating column contains only the concentrated analyte ions, thus eliminating interfering matrix components from complex matrices such as seawater and digested biological, botanical, and geological materials. This combination of chelation and ion chromatography provides a technique that makes possible the determination of trace elements in complex matrices that have proven to be difficult or impossible to analyze by ion chromatography or conventional atomic spectroscopy techniques.

Animals↗