Capability of ICP-MS (pneumatic nebulization and ETV) for Pt-analysis in different matrices at ecologically relevant concentrations

ICP-MS both with conventional nebulization and with ETV (Electro Thermal Vaporization) have been applied for the determination of Pt in different matrices, e.g. occupational samples like urine and dust samples. It can be used also for other matrices like soil, plants, tissues etc. dependent on the concentration ranges and on a suitable decomposition method. The evaluation, based on the different Pt-isotopes and the quality criteria (detection limit, precision, accuracy) is discussed. Very low determination limits in the range of 1 ng/l can be achieved by ICP-MS-ETV using the standard addition method. This method allows to determine Pt in urine without any sample pretreatment.     

ICP-MS determination of Pt in biological fluids of patients treated with antitumor agents: evaluation of analytical uncertainty

The estimation of the uncertainty associated to the analytical methods is necessary in order to establish the comparability of results. Methods of Pt determination in biological fluids lack very often of information about uncertainty of results, with likely implications when results are used to interpret the mechanism of action of platinum compound or when they are considered to optimise the clinical therapies.An inductively coupled plasma-mass spectrometer (ICP-MS) method for the determination of Pt in biological fluids (plasma, ultrafiltrate and urine) of patients treated with antitumor agents has been developed and validated. The limits of quantification (LOQ) in the three matrices were 1.0, 0.1, and 2.0 μg/l, respectively.Intraday and interday precisions and accuracies were in good agreement with the FDA criteria for the validation of analytical methods. The validation study was implemented by assessing the uncertainty evaluation for Pt determination in the different matrices according to EURACHEM/CITAC Guide.     

Determination of atenolol in human urine by emission-excitation fluorescence matrices and unfolded partial least-squares with residual bilinearization

A second-order multivariate calibration method based on a combination of unfolded partial least-squares (U-PLS) with residual bilinearization (RBL) has been applied to second-order data obtained from excitation-emission fluorescence matrices for determining atenolol in human urine, even in the presence of background interactions and fluorescence inner filter effects, which are both sample dependent. Atenolol is a cardioselective beta-blocker, which is considered a doping agent in shoot practice, so that its determination in urine can be required for monitoring the drug. Loss of trilinearity due to analyte-background interactions which may vary between samples, as well as inner filter effects, precludes the use of methods like parallel factor analysis (PARAFAC) that cannot handle trilinearity deviations, and justifies the employment of U-PLS. Successful analysis required to include the background in the calibration set. Unexpected components appear in new urine samples, different from those used in calibration set, requiring the second-order advantage which is obtained from a separate procedure known as residual bilinearization (RBL). Satisfactory results were obtained for artificially spiked urines, and also for real urine samples. They were statistically compared with those obtained applying a reference method based on high-performance liquid chromatography (HPLC).     

A cleanup method for perchlorate determination in urine

There is increasing concern about perchlorate exposure because of perchlorate's potential effects on organisms as a thyroid hormone disruptor, as well as its contamination of the environment being much more widespread than previously thought. Perchlorate is excreted primarily into urine, therefore, evaluating perchlorate residues in urine should be a reasonable approach for determining exposure and if successful could be used as an effective biomarker of perchlorate exposure. Since the presence of ions and other biomolecules in matrices like urine usually confounds accurate determination of perchlorate by ion chromatography, it is necessary to develop efficient methods for perchlorate determination in these matrices. We developed a method that reduces the background signal of urine, which is typically the problem with the analysis of biological fluids and tissues by ion chromatography. Relatively high recovery of perchlorate was shown. In cow urine samples spiked with perchlorate at 2.5, 10, and 100 μg/L, perchlorate recoveries were 67% ± 2.5, 77% ± 3.6, and 81% ± 1.7 (mean ± S.D.), respectively. In addition, the detection limit was as low as 12.6, 12.3, and 18.7 μg/L in cow, vole, and human urine samples, respectively.     

Development of an analytical method for monitoring worker populations exposed to platinum-group elements

The increasing industrial use of platinum-group elements (PGEs), namely Ir, Pd, Pt and Rh, and related allergies such as rhinitis, conjunctivitis, asthma, urticaria and contact dermatitis, have led to a growing need to monitor selected populations of exposed workers. In this study, the levels of PGEs were measured in indoor airborne particulate matter and in biological samples taken from employees of a plant where car catalytic converters are produced and precious metals are recovered from spent carbon catalysts. The development of an analytical procedure based on quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) for the analysis of PGEs in airborne particulate matter and on sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) for the analysis of PGEs in blood, serum, urine and hair is described. For airborne particulate matter deposited on filters, the limits of detection (LoDs) were found to be 0.006 ng m⁻³, 0.020 ng m⁻³, 0.018 ng m⁻³ and 0.006 ng m⁻³ for Ir, Pd, Pt and Rh, respectively. Repeatability of measurements ranged from 1.8 to 8.5%, while recovery was in the range from 92 to 102%. For biological samples LoDs in blood, serum, urine and hair ranged from (in ng l⁻¹) 0.2–0.6 for Ir, 5–10 for Pd, 1–3 for Pt and 2–3 for Rh. For all biological materials, the repeatability varied from 1.1 to 12% for the four elements. Recovery data for the determination of PGEs in biological matrices were found to range from 84.0 to 107.8%. The method was applied to the determination of either total or respirable airborne PGEs collected from five different work areas in the plant. The difference between areas with high and low exposure correlates closely with metal levels in hair, blood and urine. The correlation coefficients between Pt in airborne particulate matter and Pt in biological materials was 0.994, 0.991 and 0.970 for blood, hair and urine, respectively.     

Determination of some additional trace elements in certified standard reference materials (soils, sludges, sediment) by ICP-emission spectrometry

Summary The concentration of some additional elements like Ag, Au, B, Ba, Be, Co, Li, Mo, Na, P, Pt, and S in some standard reference materials (SRM's) were determined by using high resolution ICP (Inductively Coupled Plasma)-emission spectrometry. The materials used were three soils and three sludges from the BCR (Community Bureau of Reference, European Communities) and one sediment from NBS (National Bureau of Standards, USA). The aqua regia soluble and the total content using HF-treatment were shown. The given results are the mean values of 6 independent measurements for each material and for each decomposition method (certification conditions). The quantitative determination of Au and Pt was not possible due to severe spectroscopic interferences, which could not be eliminated. Beside the concentration values also the measured detection limits and the limits of determination for each element in the matrices under investigation are given. For comparison and for testing the validity of the decomposition procedures, also certified elements like Cd, Cu, Ni and Zn have been analysed in all the samples.

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Bestimmung einiger zusätzlicher Spurenelemente in zertifizierten Referenzmaterialien (Boden, Schlamm, Sediment) durch ICP-Emissions-Spektrometrie

     

Platinum determination by inductively coupled plasma–sector field mass spectrometry (ICP–SFMS) in different matrices relevant to human biomonitoring

The analytical challenges of Pt determination by ICP-SFMS posed by different human tissues and fluids have been critically assessed. Investigated samples were (1) urine, (2) serum of cancer patients sampled during chemotherapy with carboplatin, (3) microdialysates (20 micro L sample volume) collected from tumor and non-tumor tissue, and, finally-for the first time-(4) human lung tissue to study background concentrations of inhaled platinum. Sample preparation involved microwave digestion and open vessel treatment or simple dilution (microdialysates). Depending on the sample preparation and introduction systems used (microconcentric nebulization, ultrasonic nebulization with and without membrane desolvation) excellent procedural detection limits (3s criterion) of 0.35 pg g(-1) for urine, 420 pg g(-1) for serum, 400 pg g(-1) for lung tissue and 13 pg g(-1) for microdialysates could be obtained. Ultratrace concentrations of 1-40 pg g(-1), and 1000-3000 pg g(-1) were measured in urine and human lung tissue, respectively, as typical for samples in environmental studies. Quantification was carried out by IDMS and standard addition in the case of urine samples. Internal standardization could not correct for non-spectral interferences in external calibration. In the serum and microdialysates of patients during chemotherapy with carboplatin, elevated Pt levels ranging between 0.01 and 10 micro g g(-1) were determined by external calibration ((195)Pt isotope). For all investigated samples spectral interferences could be excluded by following different strategies. High-resolution control measurements ((194)Pt, (195)Pt) were performed in the case of elevated Pt levels, i.e. for microdialysates and serum samples. An Hf/Pt ratio of 0.4 was determined in human lung samples. An HfO formation ratio of 0.2% was assessed for standard solutions at the present experimental conditions, revealing that the contribution of (179)Hf(16)O, (178)Hf(17)O, (177)Hf(18)O to the (195)Pt isotope signal used for quantification was not significant.     

Comparison between external and internal standard calibration in the validation of an analytical method for 1-hydroxypyrene in human urine by high-performance liquid chromatography/tandem mass spectrometry

1-Hydroxypyrene is a metabolite of pyrene, a member of the class of polycyclic aromatic hydrocarbons (PAHs) whose toxic properties in some cases include carcinogenicity. The determination of 1-hydroxypyrene in human urine is used as a biological indicator for exposure to PAHs, which is related to the combustion of organic materials, like smoking, living in urban environments, and eating grilled or smoked food. The determination of 1-hydroxypyrene by high-performance liquid chromatography (HPLC) with fluorescence detection has very good sensitivity but it is not highly specific: this can reduce accuracy in the quantitative determination of low levels of analyte in a complex matrix like urine. An HPLC method that uses triple quadrupole mass detection has been validated with the objective both to improve the signal-to-noise (S/N) ratio and to achieve the maximum specificity for the analyte in those urine samples that are richer in possible inteferents. The calibration range for 1-hydroxypyrene is from 0.005-0.1 microg/L in the urine of non-smoking healthy volunteers. After solid-phase extraction, samples were analyzed by HPLC/tandem mass spectrometry (MS/MS) in the multiple reaction monitoring (MRM) mode. In order to obtain reliable results quantitative analysis must be performed by means of the internal standard method (we used deuterium-labelled 1-hydroxypyrene): the method accuracy is not less than 85%. The S/N ratio at a concentration of 0.1 microg/L is about 10, and therefore this can be considered the lowest limit of quantitation. The method performance does not change if urine samples are measured using a calibration curve prepared in methanol, thus reducing the time of analysis and costs.     

Assessment of immobilized yeast for the separation and determination of platinum in environmental samples by flow-injection chemiluminescence and electrothermal atomic absorption spectrometry

The yeast Saccharomyces cerevisiae immobilized in calcium alginate beads was used for separation and subsequent determination of Pt in environmental samples by flow-injection chemiluminescence (FI-CL) and electrothermal atomic absorption spectrometry (ETAAS). The application of a yeast column resulted in an increase in the tolerable matrix ions concentration compared to direct measurements by both detection techniques. The developed FI-CL method of Pt determination based on the catalytic effect of Pt(IV) ions on luminol oxidation in alkaline medium is characterized by a low limit of detection (0.15 ng mL^?1), and good sensitivity and precision, and can be used for analysis of Pt in water samples. Determination of Pt in more complex environmental samples can be carried out by ETAAS (LOD?=?6 ng mL^?1) after introduction of a column clean-up step with 10 mM nitric acid. The accuracy of the method was confirmed by analyzing the certified reference material of platinum ore (SARM-7), spiked grass, and road dust samples.     

On-line Chloride Interference Removal for Arsenic Determination in Waste Water and Urine by ICP-MS Using a Modified Capillary

The determination of arsenic in environmental samples like waste waters from industrial effluents and in biological samples like urine is very important due to the toxic nature of some of its species at moderate levels of exposure. The objective of this study was to evaluate the capability of modified anionic capillaries to remove chloride for ICP-MS determination of arsenic, which causes spectral interference due to formation of 40 Ar 35 Cl + . Also high chloride content gives non-spectral interferences. The results indicate that arsenic at a concentration higher than 1 µg L m 1 in a matrix with a chloride content up to 600 mg L m 1 can be accurately determined using a 3-aminopropyltrimethoxysilane (APTMS) modified capillary connected to a microconcentric nebuliser (MCN). The interference level of chloride is considerably reduced due to its retention in the capillary. The method has been successfully applied and validated for waste water and by recovery tests for urine (diluted 1 : 15) samples.     

Simultaneous determination of Pt and Rh by catalytic adsorptive stripping voltammetry, using hexamethylene tetramine (HMTA) as complexing agent

Characteristics of the adsorption/electro-reduction of Pt/Rh hexamethylene tetramine (HMTA) complex on static mercury drop electrode surface were studied. Cyclic voltammetry was carried out to get the insight about the mechanistic behaviour of the catalytic current obtained in the voltammetric scan of Pt/Rh HMTA complex in acidic solution. Adsorptive stripping voltammetry using HMTA as the complexing agent was found to be highly sensitive method for the determination of Pt/Rh. Voltammetric measurements were carried out using hanging mercury drop electrode (HMDE) as the working electrode, a glassy carbon rod as the counter and an Ag/AgCl/KCl_saturated as the reference electrode. Various electrochemical parameters like deposition potential, deposition time, concentration of the ligand, supporting electrolyte etc. were optimized. The detection limit of Pt and Rh was found to be 4.38 pML⁻¹ and 2.80 pML⁻¹, respectively for the deposition time of 30 s. Simultaneous determination of Pt(II) and Rh(III) in water samples was possible. The method was found to be free from the commonly occurring interfering ions such as Cu(II), Cd(II), Zn(II), Pb(II), Cr(III), Cr(VI), Fe(III), Fe(II), Ni(II) and Co(II). Spike recovery tests for both Pt and Rh in tap water and sea water samples were also carried out. The method has been verified by analyzing certified reference material (WMG-1).     

On-line determination of trace levels of palladium by flame atomic absorption spectrometry

A preconcentration method is developed for the on-line determination of palladium in complex matrices with flame atomic absorption spectrometry (FAAS). The flow system comprised of a minicolumn filled with polyamine Metalfix-Chelamine resin which is highly selective for Pt(IV), Au(III) and Pd(II). Best preconcentration conditions are established by testing different resin quantities, sample and eluent solution volumes, and adsorption and elution steps flow rates. Sample volumes of 4.7 ml of palladium solutions resulted in an enrichment factor of twenty at the optimum hydrodynamic conditions. This value can be increased by injecting larger volumes of sample solution. The method is sensitive, easy to operate and permitted the determination of sub-mg l⁻¹ levels of palladium with a detection limit of 0.009 mg l⁻¹. The resin was used up to 60 times in consecutive retention-elution cycles without any appreciable deterioration in its performance. The applicability of this method was tested by determining the palladium content in synthetic geological samples as well as in the pellet-type used car catalyst reference material.     

Development of a selective graphene quantum dots based electrochemical sensor for the determination of estrone in different water matrices and synthetic urine

Estrone (E1) is associated with various health and environmental issues, necessitating the development of analytical methods for monitoring E1 in different matrices. In this context, the present study reports the development of a graphene quantum dot-based electrode (GQD/E) to detect estrone in water and urine samples. Voltammetric measurements under optimized conditions demonstrated the feasibility of using GQD/E to detect estrone at trace levels in aqueous samples. Two linear dynamic ranges were obtained at concentrations from 0.05 to 10.00 μmol L⁻¹, with limit of detection (LOD) and quantification (LOQ) of 28.0 and 96.0 nmol L⁻¹, respectively. Furthermore, the LOD value obtained in this study is one of the lowest ever reported in the literature for the electrochemical determination of E1. The method response showed no significant variation in the current intensity of E1 in the presence of the 16 interferents. The recovery values obtained by using GQD/E to quantify estrone in fortified samples of seawater, tap water, wastewater and synthetic urine ranged from 95.9 to 108.1 %, indicating that the method presents highly sensitive for detecting estrone in aqueous matrices.     

Isotope dilution gas chromatography/mass spectrometry for platinum determination in urine

The therapeutic importance of platinum (Pt) compounds, the growing accessibility of gas chromatography/mass spectrometry (GC/MS) systems in clinical laboratories, and the lack of a mass spectrometric method for the determination of Pt in biological samples motivated us to develop an isotope dilution GC/MS assay for Pt. The method is based on the use of lithium bis(trifluoroethyl) dithiocarbamate, Li(FDEDTC), as a chelating agent and enriched ¹⁹²Pt for isotope dilution. Conditions were optimized for the precise and accurate determination of isotope ratios of Pt by using a 10-m DB-l fused silica capillary column and a reverse-geometry double-focusing mass spectrometer with selected ion monitoring. An overall precision of 1% was obtained by combining within-run precision and between-run precision at the 10-ng level. No appreciable memory effect was observed when samples with different isotope ratios were analyzed sequentially. The method was validated by the quantitation of Pt in National Institute of Standards and Technology freeze-dried urine sample SRM 2670. A concentration value of 125 ± 6 /Lg/L (n = 6) was obtained by using four different sets of isotope ratios in the molecular ion and supports the National Institute of Standards and Technology recommended value of 120 ± ? μg/L. Limits-of-quantitation, estimated at 3 μg/L, are made possible by the high sensitivity of the method and the low blank value for Pt.     

Beseitigung des Matrixeffekts bei der Analyse von Edelmetallspuren mit induktiv gekoppeltem Plasma

Summary Spectral interferences associated with the determination of trace contents of Au, Ag, Pt and Pd in samples with complex matrices (hydrometallurgical solutions, metallurgical products and ore processing products) were investigated. It was found that it is necessary to separate Au, Pt and Pd from the matrix elements. The results obtained with various methods for separation and pre-concentration of these elements showed that in the case of hydrometallurgical solutions adsorption on activated carbon satisfies the requirements of analytical control. For the determination of these elements in ore processing products it is necessary to use additional extraction for their preconcentration. The most suitable organic solution found for the extraction of Au, Pt and Pd and their determination with ICP is isoamyl alcohol.     

Direct determination of nalidixic acid in urine by matrix isopotential synchronous fluorescence spectrometry

A new method for the determination of nalidixic acid in urine is proposed for concentrations between 25 and 1000 ng ml(-1) by means of matrix isopotential synchronous fluorescence spectrometry. This new technique is useful for the determination of compounds in samples with unknown background fluorescence, such as nalidixic acid in urine, without the need for tedious preseparation. The method was performed in ethanol/water medium (80% v/v), at an apparent pH of 2.9 provided by adding sodium monochloracetate/monochloroacetic acid buffer solution. The method was successfully applied to the determination of nalidixic acid in urine. Better sensitivity and reproducibility are achieved in these matrices than with the fluorimetric methods described in the literature.     

On the re-assessment of the optimum conditions for the determination of platinum, palladium and rhodium in environmental samples by electrothermal atomic absorption spectrometry and microwave digestion

The experimental conditions for the determination of platinum, palladium and rhodium by graphite furnace atomic absorption spectrometry (GFAAS) are re-assessed. A certified material (BCR-723) was used as a working sample and analyzed using various extraction and atomization procedures in order to find the optimal experimental conditions that enable the quantitative and reproducible detection of platinum, palladium and rhodium in environmental matrices. Evidently, literature observations regarding the atomization conditions were proven fairly adequate. However, the provision of the optimum extraction conditions revealed several parameters that lie behind the reported uncertainties. The appropriate combination between extraction conditions and atomization programs afforded a considerable improvement in the recoveries and analytical features of platinum, palladium and rhodium determination with GFAAS. Cross-examination of the analytical data with various CRMs (certified reference materials) was used to validate the robustness of the method in heterogeneous matrices bearing different element levels. Under the optimum experimental conditions the method permits the determination at concentrations as low as (LOD(3S/N)) 1.9 ng g(-1), 0.45 ng g(-1) and 0.6 ng g(-1) for Pt, Pd and Rh, respectively affording recoveries in the range of 93-101%. The method was successfully applied to the assessment of Pt, Pd and Rh accumulation in real road dust and soil samples in Greece.     

Displacement solid-phase extraction on mercapto-functionalized magnetite microspheres for inductively coupled plasma mass spectrometric determination of trace noble metals

A flow injection online displacement solid-phase extraction (DSPE) via magnetic immobilization of mercapto-functionalized magnetite microspheres onto the inner walls of a knotted reactor (KR) coupled with inductively coupled plasma mass spectrometry was developed for selective preconcentration and determination of trace noble metals (Ru, Rh, Pd, Pt, Ir and Au) in complex matrices. Online DSPE of 2.7 mL aqueous solution gave the enhancement factors of 32-46 for the six noble metals in comparison with direct nebulization of aqueous sample solution, and the detection limits (3 s) of 2.1 ng L(-1) for Ru, 1.9 ng L(-1) for Rh, 2.5 ng L(-1) for Pd, 1.8 ng L(-1) for Ir, 1.9 ng L(-1) for Pt and 1.7 ng L(-1) for Au. The sample throughput of the developed method was about 20 samples h(-1), and the relative standard deviation for eleven replicate determinations of the noble metals at the 30 ng L(-1) level ranged from 1.2% to 2.1%. The recoveries of Ru, Rh, Pd, Pt, Ir and Au still maintained 90% even after successive 140 cycles of DSPE. The developed method was successfully applied to selective determination of trace Ru, Rh, Pd, Pt, Ir and Au in complex matrices.     

Determination of Gentian Violet in human urine and poultry feed by high performance liquid chromatography with electrochemical detection using a carbon fibre microelectrode flow cell

A sensitive and relatively selective high performance liquid chromatographic method for the determination of Gentian Violet (GV) in human urine and chicken feed is described. The method is based on solid-phase extraction, with subsequent reversed-phase chromatographic separation on a cyano column and amperometric detection using a carbon fibre microelectrode flow cell operated at + 1.3 V. The peak currents were directly proportional to GV concentration over the concentration range 1-30 ppb (for urine samples analysis) and 1-20 ppm for poultry feed analysis. Using this method, the minimum detectable concentration was estimated to be 0.5 ppb. The method was applied successfully to the determination of GV in human urine and in chicken feed, and it was concluded that the method could be applied to the quantitative analysis of GV in the presence of its major metabolite, leuco GV. In the proposed procedure, the occurrence of matrix effects during urine analysis was significant. The electrochemical pretreatment regime described in this paper was used to overcome these effects. Recovery studies were performed on both the human urine and chicken feed samples. The recovery of GV ranged from 92 to 96% in both matrices, with a relative standard deviation of less than 5.5%.     

Sensitive quantification of clozapine and its main metabolites norclozapine and clozapine-<Emphasis Type="Italic">N</Emphasis>-oxide in serum and urine using LC-MS/MS after simple liquid–liquid extraction work-up

An LC-MS/MS method for the determination of the atypic neuroleptic clozapine and its two main metabolites norclozapine and clozapine-N-oxide has been developed and validated for serum and urine. After addition of d4-clozapine as deuterated internal standard a fast single-step liquid–liquid extraction under alkaline conditions and with ethyl acetate as organic solvent followed. The analytes were chromatographically separated on a Synergi Polar RP column using gradient elution with 1 mM ammonium formate and methanol. Data acquisition was performed on a QTrap 2000 tandem mass spectrometer in multiple reaction monitoring mode with positive electrospray ionization. Two transitions were monitored for each analyte in order to fulfill the established identification criteria. The validation included the determination of the limits of quantification (1.0 ng/mL for all analytes in serum and 2.0 ng/mL for all analytes in urine), assessment of matrix effects (77% to 92% in serum, 21 to 78% in urine) and the determination of extraction efficiencies (52% to 85% for serum, 59% to 88% for urine) and accuracy data. Imprecision was <10%, only the quantification of norclozapine in urine yielded higher relative standard deviations (11.2% and 15.7%). Bias values were below ±10%. Dilution of samples had no impact on the correctness for clozapine and norclozapine in both matrices and for clozapine-N-oxide in serum. For quantification of clozapine-N-oxide in urine a calibration with diluted calibrators has to be used. Calibration curves were measured from the LOQ up to 2,000 ng/mL and proved to be linear over the whole range with regression coefficients higher than 0.98. The method was finally applied to several clinical serum and urine samples and a cerebro-spinal fluid sample of an intoxicated 13-month-old girl.