José Ignacio García Alonso

Reference values for trace and ultratrace elements in human serum determined by double-focusing ICP-MS

Reference values for trace and ultratrace elements concentrations in healthy human serum, measured by double-focusing inductively coupled plasma-mass spectrometry (ICP-MS), are presented. Blood donors from Asturias (Spain) were selected as the reference population (n=59). Blood samples were collected, after donation, taking the necessary precautions to avoid contamination. All subjects analyzed had normal renal function and nutritional status, as shown from their creatinine and albumin levels. A total number of 14 elements (Al, Ca, Cr, Mn, Fe, Co, Cu, Zn, Rb, Sr, Mo, Cd, Pb, and U) were monitored almost simultaneously. Serum samples were diluted 1+4 with ultrapure water and matrix interferences were corrected using Sc, Ga, Y, and Tl as internal standards. Fe, Cu, and Zn were also determined by isotope dilution analysis (IDA).Reference trace element concentrations intervals observed containing 95% of the reference distribution after excluding outliers are presented. Fourteen serum samples from hemodialysis patients were also analyzed for comparison. High levels of Al, Cr, Sr, Mo, Mn, Pb, U, Co, and Cu and low levels of Fe, Zn, and Rb were found in the serum samples from hemodialysis patients compared to the corresponding reference values observed in this work.

Metal chelate fluorescence enhancement in micellar media: mechanisms of surfactant action

The results obtained for fluorescence measurements of different metallic chelates in micellar media are discussed. AlIII, NbV and TaV complexes with flavonols, 8-hydroxyquinoline derivatives, azo dyes and anthracene derivatives are readily solubilised and they fluoresce in aqueous micellar solutions of different surfactants. The general trends of surfactant action are discussed in terms of the type of reagent and surfactant, the solubilisation of the chelates in the micelles, competition and quenching reactions and the formation of new species. As a result of the observations reported, these fluorimetric and phosphorimetric reactions could be utilised for the determination of a wide variety of metals.

Flow-injection and liquid chromatographic determination of aluminum based on its fluorimetric reaction with 8-hydroxyquinoline-5-sulphonic acid in a micellar medium

Abstract Aluminum reacts with 8-hydroxyquinoline-5-sulphonic acids (HQS) in cationic micelles of cetyltrimethylammonium bromide (CTAB) to form a strongly fluorescent compound. In the micellar media the formation of the Al—HQS complex is very fast, allowing a useful continuousdetermination of aluminum in flow systems. At pH 6.3, for 2 × 10 -4 M HQS and 2 × 10 -3 M CTAB the detection limit for a luminum by flow injection is 0.1 ng ml -1 . The calibration is linear up to 100 ng ml -1 and the peak-height precision is 2% at the 10 ng ml -1 level. Interfences are greatly decreased compared with the batch method. The reaction has also been applied to the post-column detection by ion chromatography of aluminium in fresh and high-salinity wates and for speciation of aluminium in blodd serum after separation of serum proteins by ion-exchange liquid chromatography.

Performance characteristics of a glove box inductively coupled plasma mass spectrometer for the analysis of nuclear materials

A commercial inductively coupled plasma mass spectrometer (Elan 250) was modified in order to analyse nuclear materials in a glove box. The nebulizer, plasma torch and sliding interface are situated inside the glove box while the mass spectrometer and associated electronics are outside. The sensitivity of the modified instrument is slightly reduced compared with the original owing to a flange that separates the mass spectrometer from the vacuum interface. This has modified the original distance between the skimmer cone and the ion lens system. The plasma torch is mounted in a fixed position and the load coil is now separated 25 mm from the tip of the sampling cone. Optimum plasma operating conditions, stability of the signal and isotopic ratios, levels of oxide and hydroxide polyatomic ions were evaluated in the modified instrument for selected fission products and actinides. The effect of the ion lens settings on sensitivity and mass discrimination were studied in detail. Interference effects due to heavy matrix elements (U and Pu) were also studied.

Analytical approaches to the problem of protein binding of aluminium in blood serum

Ultrafiltration and chromatographic techniques were used to study protein binding and aluminium speciation in blood serum. Ultrafiltration studies were carried out using both a stirred Amicon ultrafiltration cell and an Amicon Centrifree Micropartition Unit (MPS-1). The latter device proved to be less prone to contamination and results obtained showed that only about 8% of the aluminium in normal serum is ultrafilterable. Experiments with patients undergoing desferrioxamine (DFO) chelation therapy showed that the ultrafilterable aluminium in their serum increased by up to 74% because of the formation of a low relative molecular mass chelate with the DFO. High-performance liquid chromatography (HPLC) separation of serum proteins was carried out with an ion-exchange column of TSK DEAE-3SW (150 mm long × 7.5 mm i.d., 10-µm particle size) using a sodium acetate gradient (0–0.5 M) at pH 7.4 (Tris-HCl buffer). Proteins were detected spectrophotometrically at 280 nm and the aluminium was determined by electrothermal atomisation atomic absorption spectrometry of 0.5-ml fractions collected at the end of the HPLC column. Results obtained with this system suggest that transferrin is the only aluminium binding protein in normal serum. However, in the presence of DFO in serum, most of the aluminium proved to be bound to the drug. Only a very small fraction remains bound to the transferrin for a 2 mg l–1 concentration of DFO in serum.

Monitoring of Organotin Pollution in Bizerta Channel (Northern Tunisia): Temporal Trend from 2002 to 2010

Imposex and tributyltin (TBT) body burden were quantified in the gastropod Hexaplextrunculus collected from the Bizerta channel between 2002 and 2010. Except for the imposex frequency that remained maximal (100%), all the other imposex indices decreased throughout the study period. Similarly, TBT levels also decreased over time, being the less frequent compound among butyltins, with a proportion of 22.2%, against 42.9% for dibutyltin (DBT) and 34.9% for monobutyltin (MBT). These findings reflect the effectiveness of new generation of TBT-free antifouling paint introduced in the Tunisian market and global ban of TBT on reducing the environmental impact of this biocide.

Different Quantification Approaches for the Analysis of Biological and Environmental Samples Using Inductively Coupled Plasma Mass Spectrometry

For the analysis of biological and environmental materials by inductively coupled plasma mass spectrometry (ICP-MS), several quantification procedures can be used depending on the precision and accuracy required. Semi-quantitative methods based on the molar response curve were compared with conventional external calibration and standard additions for the analysis of waters and sewage sludges. For the analysis of biological materials, where higher quality data were required, isotope dilution analysis using enriched isotopes was applied. It was observed that the molar sensitivity for different elements in ICP-MS was a simple function of the mass of the isotopes measured after normalization for ionization efficiency which could be fitted to a third-order polynomial equation. Element ionization adjustments for the third-order polynomial, using the Saha equation, allowed the calculation of the plasma ionization temperature and electron density. For the determination of trace metals in waters and sewage sludges, the samples were spiked with different internal standards, ionization corrections were performed and the results obtained agreed with those obtained by external calibration and standard addition within a factor of 2 but, on average, the agreement was within 20%. The determination of molybdenum in biological reference materials was performed by isotope dilution analysis taking into account possible sources of error in the measurements by ICP-MS such as mass discrimination, detector dead time, isobaric interferences and random error propagation.

Characterization of spent nuclear fuel dissolver solutions and dissolution residues by inductively coupled plasma mass spectrometry

The direct analysis of dissolved spent nuclear fuel by inductively coupled plasma mass spectrometry (ICP-MS) allows the elemental and isotopic composition of the irradiated fuel to be determined without any chemical separation. A qualitative evaluation was carried out on the effects of fission, β-decay and neutron-capture reactions during fuel irradiation. Semiquantitative analysis of fission products and actinides in the spent-fuel dissolver solution and in the dissolved residues was performed by referring to a response curve. Comparison of the semiquantitative data with computer predictions of fission products inventory showed satisfactory agreement. The analysis of small spent fuel samples by ICP-MS was used to assess the type and irradiation of the fuel in pattern recognition studies. Quantitative analysis of the fuel solutions and residues was performed only for selected elements because of the presence of isobaric interferences. Isotope dilution analysis was applied for polyisotopic elements; standard additions with an internal standard was used for monoisotopic elements. Elements determined in the residues included Zr, Mo, Tc, Ru, Rh Pd, U and Pu. Neodymium was also determined in dissolver solutions of fast neutron-irradiated fuels and the results were compared with those given by thermal ionization mass spectrometry.

Imposex and butyltin burden in Bolinus brandaris (Mollusca, Gastropoda) and sediment from the Tunisian coast

The present study aimed at analyzing the imposex incidence and the presence of butyltins namely tributyltin (TBT) with its di- and mono-substituted metabolites in Bolinus brandaris whole tissues and in surface sediments at seven sites from the Tunisian coast during one campaign in May 2010. Butyltin levels were evaluated using isotope dilution GC–MS. Except the population collected from Zarat site, imposex was found in snails from the remained six sites with a maximal incidence and sterility (closure of the vaginal opening) registered in Carrier bay. Both imposex indices VDSI and RPLI showed a positive correlation with tissue concentrations of TBT. Total butyltin concentrations in sediments were higher in sites located in the vicinity of shipping areas with levels of TBT high enough to cause environmental concern if there is no legislative restriction and enforcement for the sale and use of these chemicals in Tunisia. These results further confirmed that B. brandaris is a good bioindicator of butyltin pollution in the studied areas. In addition, this study provided recent and new data on sediment butyltin concentrations that could serve for long-term monitoring of TBT pollution in Tunisia and the Mediterranean Sea.

Potential of Nassarius nitidus for monitoring organotin pollution in the lagoon of Bizerta (northern Tunisia)

Imposex and butyltin burden were assessed in Nassarius nitidus, Bolinus brandaris and Hexaplex trunculus collected at five stations in the Bizerta lagoon. Biological analysis showed that imposex followed type (a) in N. nitidus (distal evolution), against type (d) in the two muricids (proximal evolution). Imposex indices were higher in sites located nearby sources of tributyltin and N. nitidus was the least affected species of the five sites, followed by B. brandaris and H. trunculus. Butyltin analysis showed lower accumulation in N. nitidus followed by H. trunculus and B. brandaris. This study has allowed the gathering of data on imposex in a snail studied for the first time in Tunisia (N. nitidus). It suggests the possibility of using such snail as a complementary species for organotin monitoring programs in the Mediterranean and further confirmed that H. trunculus is the most suitable species for such investigations.