James G. Tarter

Simultaneous determination of selected transition metal cations and inorganic anions by ion chromatography

The retention times and detection limits of a selected group of six transition metal cations and four inorganic anions determined using a simultaneous separation and detection system are presented. The over-all analysis time is usually less than 20 min and detection limits are at or near the 1 p.p.m. level. Two different systems are described, the first for the repetitive analysis of similar solutions and the second for samples of widely varying composition.

The Determination of Non-Oxidizable Species Using Electrochemical Detection in Ion Chromatography

Abstract The use of an electrochemical detector for the ion chromatographic detection of non-oxidizable anions such as F−, PO4 −3, NO3 −, and SO4 −2 is described. The electrochemical detector is placed in line after a fiber suppressor and responds to eluent pH changes as the dissociated acids pass through the detector. The intensity of the signal is dependent on the applied potential at the cell with 0.3V being an optimum. Minimum detection limits with a 0.10 mL sample injection volume are below 0.5 ppm for F−, Cl−, PO4 −3, NO3 −, and SO4 −2. No adverse effects on the silver working electrode have been observed.

Separation of Selected Transition Metal Ions and Divalent Metal Ions by HPLC Using UV-VIS Detection

Abstract The use of ethylenediaminetetraacetic acid, disodium salt, (pH 3-5) has been investigated as an eluant for the separation and detection of nanogram levels of selected divalent and trivalent metal ions. The effect of pH and eluant concentration upon the retention times and resolution of the system are given and the ability to alter the eluant characteristics to optimize the chromatographic results in different situations will be discussed. The method is less complicated than the method frequently used for transition metal ion determinations which uses a post-column derivitization reagent. This method is applicable to a wider range of metal ions and provides detection limits which are generally within two orders of magnitude of the post-column derivitization method.

The ION Chromatograhic Determination of Cr(III)-Cr(VI) Using an EDTA ELUANT

Abstract Recent work in our laboratory has involved the use of ethylene diaminete traacetic acid as an eluant for the ion chromatographic determination of transition metals. We have continued this investigation into the use of EDTA by developing a potential method for the determination of Cr(III) and Cr(VT) in the same solution at the ppm level. The method involves the separation of the species as anions—the monovalent Cr(III)-EDTA anion and the divalent dichromate ion—followed by the detection of the species using a variable wavelength UV detector. The detection limits are approximately 2 ppm and the precision and stability of the system are within 6% RSD over the course of a working day. The linear operating range is in excess of two orders of magnitude.

Non-suppressed determination of cations and anions using a differential conductivity detector

Systemes utilisant du materiel par HPLC. On utilise deux colonnes en serie (cations, anions), en parallele sur la colonne passive, et le detecteur

Rapid Analysis of Fluorine in Geological Samples with Ion Chromatographic Detection

Abstract A method is described for the analysis of fluorine in geological samples involving the decomposition of the sample with phosphoric acid and the measurement of the fluoride ion concentration using an ion chromatograph. The detection limit is below 5 g F in the original sample. Multiple analyses of NBS-91 Opal Glass yielded a relative standard deviation of less than 2.5%. In excess of 30 samples can be analyzed in an 8 hour day. Potential interference from high carbon containing samples, such as oil shales, is discussed.

Ion Chromatographic Determination of Phosphorus in Eight U.S.G.S. Standard Rocks

Abstract A method is described for the analysis of phosphorus in geological samples involving the decomposition of the sample with hydrofluoric acid in a quartz tube and the measurement of phosphate ion concentration using an ion chromatograph (Dionex 10) with an anion separator column (Wescan anion 269-001). The detection limit is between 0.05-0.5% P2O5 in the original sample. Multiple analyses of eight U.S.G.S. standard rocks yielded a relative standard deviation range between 2.37-16.67%. In excess of 15 samples can be analyzed in an 8 hour day.

The Detection of Organic Acids in A Non-Oxidation Mode Using an Amperometric Detector

Abstract A group of organic acids including benzoic acid and oxalic acid along with sodium nitrate were determined using anion exchange columns and amperometric detection. The eluants used in the work were orthochlorobenzoic acid and phthalic acid. The response time was less than ten minutes and the detection limits were between 20 and 50 ppm. Both silver and platinum working electrodes were investigated and the response of the analytes to the amperometetric detector was a function of electrode material, applied voltage, eluant composition, and analyte. The nature of the detection mechanism is one involving the disruption of the electrode equilibrium and does not involve a true oxidation-reduction process.

Narrow Bore Ion Chromatography with Commercially Available Ion Chromatographic Equipment

Abstract The use of narrow bore separator columns (inner diameter less than 1 μM) in high performance liquid chromatography has become a well established technique which has obvious advantages in specific situations over the use of traditional size separator columns. The work reported here investigates the use of traditional ion chromatographic equipment (essentially unmodified) for use in narrow bore ion chromatography. The only adjustments made to the equipment were some arrangements in the placement of valves and tubing in order to minimize extra-column dead volume. The columns used in this work were glass capillary columns of 1.0 mm inner diameter. A selected group of ion exchange resins were slurry packed into the column and the retention and separation characteristics of the narrow bore column were determined. The results of this investigation indicate that in certain cases the commercially available equipment is adequate for performing narrow bore ion chromatography. The distinct advantage of the u...