Alexandra Lásztity

Identification of potential environmental sources of childhood lead poisoning by inductively coupled plasma mass spectrometry. Verification and case studies

The isotopic determination of lead in blood and environmental materials by inductively coupled plasma mass spectrometry was used for the identification of potential sources of childhood lead poisoning. Sample preparation methods for blood, dust, paint, sediment and soil were evaluated and the recovery of total lead and the lead isotope composition of samples were determined. Verification of the measurement accuracy and precision was obtained for standard reference materials and a number of practical cases of childhood lead poisoning from an unknown source were studied.

Use of a new type of 8-hydroxyquinoline-5-sulphonic acid cellulose (sulphoxine cellulose) for the preconcentration of trace metals from highly mineralised water prior their GFAAS determination

Sulphoxine cellulose microcolumn was used in an FI-GFAAS system for the preconcentration of trace metals, Cd, Co, Ni, Pb and V from water and from highly mineralised water and also in the presence of complexing agent, e.g. citrate. The recovery was quantitative at pH 5 for all of the elements from NIST 1643c trace elements in water SRM and from highly mineralised water samples. No significant difference was found in the sorption of V(IV) and V(V) during preconcentration. The preparation of the 8-hydroxyquinoline-5-sulphonic acid cellulose (sulphoxine-cellulose) by Mannich reaction from aminoethyl cellulose or via chlorodeoxy and ethylenediamine cellulose is also described.

Lead hydride generation for isotope analysis by inductively coupled plasma mass spectrometry

The sensitivity and precision of the determination of trace amounts of lead can be improved significantly with a combination of continuous hydride generation, isotope dilution and inductively coupled plasma mass spectrometry (ICP-MS). Both the conventional Thompson U-shaped and a microporous polytetrafluoroethylene (PTFE) tube gas-liquid separator were evaluated. The limit of detection for lead was restricted to the range 0.01–0.05 µg l–1 by the reagent blanks. Iron and copper ions exhibit a serious interference on the lead hydride generation. Sulphosalicylic acid and sodium cyanide, dissolved in sodium tetrahydroborate (III) solution, were used to eliminate the iron and copper interferences, respectively. Lead in National Bureau of Standards (NBS) Standard Reference Material (SRM) Trace Elements in Water (1643a) was determined by the isotope dilution-hydride generation technique. Good agreement was obtained between the certified and the experimental results. Lead isotope abundances were also determined for NBS SRM 981 Common Lead and various galena samples.

On-line isotope dilution and sample dilution by flow injection and inductively coupled plasma mass spectrometry

A systematic investigation was made to demonstrate the applicability of a flow injection system for on-line isotope dilution and on-line sample dilution, as obtained by merging the sample solution with the spike solution or with the diluent, respectively. The effect of the sample to spike ratio on the precision and accuracy was examined, and the advantages and limitations of the proposed technique are demonstrated.

Sample analysis by on-line isotope dilution inductively coupled plasma mass spectrometry

An on-line isotope dilution technique is developed by coupling commercial flow injection instruments with an inductively coupled plasma mass spectrometer. Application of the technique is demonstrated by the determination of lead concentrations in diverse standard reference materials. The precision of the method, using optimum sample to spike ratios and a steady-state merging stream, is better than 1%. The approach simplifies sample preparation and analysis, and matrix effects have no influence on the determinations.

Determination of trace elements in pharmaceutical substances by graphite furnace atomic absorption spectrometry and total reflection X-ray fluorescence after flow injection ion-exchange preconcentration

Abstract Flow injection iminodiacetic acid ethyl cellulose (IDAEC) microcolumn preconcentration and graphite furnace atomic absorption spectrometry determination of trace metals (Cd, Co, Ni, Pb) were carried out without decomposition of the drug matrix. The two forms of chromium Cr(III) and Cr(VI) were separated using IDAEC and anion exchanger diethylaminoethyl (DE)-cellulose, respectively. The detection limits of trace elements in pharmaceutical substances (sugars, sorbitol, mannitol, paracetamol, amidopyrine, chloral hydrate) after a 10-fold preconcentration in 1–5% m/v solution of pharmaceuticals were in the 0.3–29 ng g −1 range. The measured concentration of trace elements in substances investigated was below 100 ng g −1 . The spike recovery was close to 100%. The capability of total reflection X-ray fluorescence technique for the determination of trace elements in pharmaceuticals with and without preconcentation was explored.

Development of atomic spectrometric methods for trace metal analysis of pharmaceuticals

Palladium, platinum and rhodium impurities were determined in pharmaceuticals by ICP-MS. The detection limits were 15, 2.8, 2.5 ng/g for palladium in enalapril maleate, platinum in calcium folinate and rhodium in levodopa, respectively. The rhodium impurity was also determined by the GFAAS method as well. ICP-MS and TXRF methods were applied for screening of other metal impurities of pharmaceuticals.

Addition of tertiary amines in the semiquantitative, multi-element inductively coupled plasma mass spectrometric analysis of biological materials

A semiquantitative inductively coupled plasma mass spectrometric (ICP-MS) analysis protocol for biological materials was developed to include water-soluble tertiary amines with microwave heated sample preparation. Certified reference materials digested with HNO3, H2O2 and HF required addition of H3BO3 and a solution of tertiary amines (CFA-C reagent) to dissolve insoluble fluorides and neutralize free fluorides. Commercial semiquantitative analysis software that evaluates the entire m/z range and includes pre-programmed corrections for spectroscopic interferences was applied to investigate matrix interferences resulting from 10% tertiary amines and chlorides (added as 1% HCl). Measurement parameters including m/z range, spectrometer sensitivity and number of elements in the external calibration were evaluated. The accuracy of the semiquantitative analysis improved when the standard solution was matrix matched; interference-free isotopes were selected for some elements instead of scanning the whole m/z range, and additional elements with m/z values of under 80 were included for updating the instrument pre-calibration response factor. This semiquantitative analysis approach can be applied successfully for the multi-element analysis of biological materials when optimum instrumental conditions are employed. Thirty-eight elements were determined in six certified reference materials and food samples with a precision of 1–20% and accuracy of 1–50%. The determinations of Al, K, Na and Si were unreliable.

Arsenic determination in environmental, biological and food samples by inductively coupled plasma mass spectrometry

Methodology developed with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of total arsenic in soil, house dust, and childrens daily diet and faecal samples is described. Microwave oven dissolution, high temperature, pressure vapour phase acid digestion, and dry ashing with conventional thermal and microwave furnace heating and Mg(NO3)2 ashing aid are compared for sample preparation. Arsenic recovery from reference materials and spiked samples is between 94.8 and 109%. The ICP-MS Elan 5000a As detection limits (3sb) were 2.0 ng g–1 in freeze-dried human faeces prepared by closed-vessel, microwave-heated digestion and 1.1 ng g–1 in freeze-dried childrens diets prepared by furnace ashing with an ashing aid.

On-line dilution, steady-state concentrations for inductively coupled plasma atomic emission and mass spectrometry achieved by tandem injection and merging-stream flow injection

Steady-state concentrations have been achieved by on-line dilution, flow injection techniques with conventional instrumentation. An approach employing tandem injection for on-line dilution was applied to obtain a steady-state concentration. The deviation from signal stability resulting from concentration variations or ripples hampered exploitation of this approach for on-line dilution except over a limited range. However, when tandem injection was coupled with a single- or, especially, a double-confluence for the diluent, dilution was achieved over a wide range (up to 900-fold). Further, steady-state concentrations were obtained without concentration ripples. With the combined tandem injection and merging stream the emission signal variation with inductively coupled plasma (ICP) spectrometry compares well with that obtained for direct sample nebulisation. Simple relationships for calculation of the anticipated dilution have been derived and validated experimentally. Flow configurations were designed to implement on-line dilution approaches under optimum conditions. Although these developments for on-line dilution are initially intended for sequential multi-element ICP spectrometric analysis, they should prove to be of general use.