P. P. Coetzee

Vanadium speciation by ion chromatography

An ion-chromatographic method, using a carbonate-buffered (1,2-cyclohexylenedinitrilo)tetraacetic acid (CDTA) eluant, is described for the simultaneous determination of vanadium(IV) and vanadium(V). Vanadium(IV) was, after pre-column complexation with CDTA, separated from vanadium(V) (as vanadate) by anion-exchange chromatography. The analytical range is 0.5 to 20 μg/ml and 0.25 to 10 μg/ml for vanadium(IV) and vanadium(V), respectively. Detection limits are estimated to be 145 and 70 ng/ml for vanadium(IV) and vanadium(V), respectively.

On-line preconcentration of silver on activated alumina and determination in borehole water by flow injection atomic absorption spectrophotometry

SummaryA micro column of activated alumina in the basic form was used in conjunction with flame atomic absorption for the preconcentration and determination of silver in borehole water. The silver was accumulated on the alumina column by pumping sample solution at pH 4 through the column at a rate of 5 cm3 min-1 for 5 min. By incorporating an injection valve and a simple interfacing device into the system, silver was determined by elution into the nebulizer of an atomic absorption spectrophotometer with 500 μl of 2 mol l-1 nitric acid. Regeneration of the alumina to its basic form was achieved by 0.15 mol l-1 ammonia solution pumped through the column at 5 ml min-1 for 2 min. A detection limit of 4 μg l-1 was measured, based on a sample volume of 25 ml. The relative standard deviation was less than ±5% at concentration levels above 10 μg l-1.

Deprotection Techniques for Phosphine-Borane Complexes: Methods and Extraction Coefficients

Triarylphosphine-, diarylalkylphosphine-, and trialkylphosphine-borane complexes were deprotected using various amines and acids. After deprotection, the resulting borane species were extracted from the free phosphines using various solvent systems. The aqueous layers were analyzed for borane making use of inductively coupled plasma optical emission spectroscopy; and extraction coefficients were then calculated from the analytical data.

Separation of 203Pb by ion-exchange chromatography on chelex 100 after production of 203Pb by the Pb(p, xn)203Bi→EC.β+ 203Pb nuclear reaction☆

Abstract Bismuth radioisotopes, produced by 50-MeV proton bombardment of a lead target in a cyclotron, are separated from the lead target material by ion-exchange chromatography on a column containing 5.0 ml of Chelex 100. After a decay period of 24 hr, the 203Pb formed in situ is eluted from the column and then separated from 200Tl and 201Tl on a second ion-exchange column containing 0.5 ml of Chelex 100. Separations are sharp and carrier-free 203Pb is obtained.

Multi-element X-ray fluorescence analysis of thin films using a mono-standard calibration procedure

SummaryA semi-fundamental approach to calibration for multi-element X-ray fluorescence analysis of thin films is described. The curve, calibration line slope vs. atomic number, is calculated using known values for mass absorption coefficients, fluorescent yields and detector efficiency. This curve is then standardised for a particular matrix by determining the slope of at least one matched standard or via a standard addition procedure for one element. The technique is applied to the analysis of industrial waste water.

Simultaneous determination of toxic heavy metals in Metformin hydrochloride using reversed-phase high-performance liquid chromatography

SummaryA rapid and sensitive reversed phase HPLC technique was developed for the determination of seven toxic heavy metals in biological matrices. Cd, Pb, Ni, Co, Bi, Cu and Hg could be detected and quantified at ppb level in Metformin hydrochloride, a pharmaceutical product used in the treatment of certain cases of diabetes. This was achieved by the evaluation of the stability of NaDEDTC in the presence of water and different buffers at different pH-values. A direct injection/on-column derivatization HPLC procedure was developed employing NaDEDTC as chelating agent, a C-18 reversed phase analytical column and a photodiode array detector. Dilute metal ion solutions could be analyzed by direct injection of the test sample. The analysis of trace levels of metals in a pure pharmaceutical product however required the inclusion of a sample preparation step prior to analysis.

Mono-standard calibration approach to multi-element XRF analysis of thin films using polychromatic excitation

SummaryA reliable method is described for the calculation of slopes of calibration lines for thin-film samples using polychromatic excitation. Theoretically calculated slopes for elements within one series, e.g. the K-series, are normalized using one or two known slopes for elements in the series. The mathematical equations used to interpolate slopes as a function of atomic number are based on the fundamental relationship between fluorescent intensity and atomic number, fluorescent yield, detector efficiency, concentration and mass absorption coefficients. Kramers formula is used to approximate the shape of the primary radiation spectrum. The method was applied to the analysis of thin films.

Indirect spectrophotometric determination of BIDA, DISIDA, DTPA and MDP in labelled compounds.

N-(4-(n-butyl)-acetanilide)iminodiacetic acid (BIDA), N-(2,6-diisopropylacetanilide)iminodiacetic acid (DISIDA), diethylenetriaminepentaacetic acid (DTPA) and methylene diphosphonic acid (MDP) are used in labelling kits. The contents of BIDA, DISIDA or MDP of the 99mTc-labelled compounds can be determined (indirectly) spectrophotometrically with copper, eriochrome cyaanine R (ECC) and dodecylethyldimethylammonium bromide (DEDA) in a sodium barbital buffered system at pH 8.5. The calibration curves obey Beers Law from 0 to 40 micrograms/25 mL for BIDA and DISIDA, 0 to 60 micrograms/25 mL for DTPA and 0 to 100 micrograms/10 mL for MDP.

Reverse-phase chromatographic separation of Co(II) and Co(III) as the Co(DEDTC)3 and Co(acac)3 complexes

Abstract A reverse-phase chromatographic method is described for the simultaneous determination of Co(II) and Co(III) using gradient elution of the Co(DEDTC)3 and Co(acac)3 complexes, respectively, with phosphate buffered acetonitrile water mixtures. The separated Co species are detected spectrophotometrically at 322 nm. The analytical range of the method is 0.1 to 1.25 μg/ml for Co(II) and 0.1 to 1.5 μg/ml for Co(III).

Separation of Ruthenium and Molybdenum by Cation Exchange Chromatography on Ag 50W-X4 in a Nitric Acid-Ethylenediamine Mixture

The 99Mo-99Tc-generator is widely used in nuclear medicine. 99Mo can be obtained from the fission of 235U in a nuclear reactor. 103Ru is one of the numerous fission products to be separated from 99Mo. 103Ru can easily be separated from 99Mo by cation exchange chromatography on AG 50W-X4 in a nitric acid- ethylenediamine mixture. Ruthenium is sorted as a positively charged ruthenium-ethylenediamine complex from a mixture containing 0,10M nitric acid and 0,01M ethylenediamine or 1,0M nitric acid and 0,10M ethylenediamine. Molybdenum passes through the resin column and can be separated from the ethylenediamine by ion exchange chromatography on aluminium oxide or manganese dioxide.