Fadi R. Abou-Shakra

The role of trace elements in male infertility

The elemental status of seminal plasma collected from four populations subdivided on the basis of sperm counts is presented. Elemental analysis was performed by inductively coupled plasma-source mass spectrometry (ICP-MS) for calcium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, lead, rubidium, selenium, vanadium, and zinc. The majority of elements reflected no statistically significant differences among the four groups. The role of trace elements in infertility may be more directly related to sperm and whole semen than seminal plasma levels.

The determination of protein phosphorylation on electrophoresis gel blots by laser ablation inductively coupled plasma-mass spectrometry

Laser ablation interfaced with inductively coupled plasma-mass spectrometry is described as a new method to determine the presence of phosphorylated proteins on electrophoresis gel blots. The method was applied to the phosphoprotein beta-casein with good detection levels being observed at 16 pmole. Attempts at using the technique to detect beta-casein on electrophoresis gels are also described.

Enzymatic digestion for the determination of trace elements in blood serum by inductively coupled plasma mass spectrometry

A non-specific protease enzyme (pronase) was used to demonstrate the potential of enzymatic digestion as an alternative sample preparation method for the determination of trace elements in blood serum by ICP-MS. By measuring the number of peptide bonds in solution, it was found that this digestion led to a 40% reduction in the level of plasma protein in the samples. Based on the data obtained, it appears that the majority of these proteins were broken down into smaller polypeptides. Using this digestion technique, a high degree of instrument stability was achieved during the continuous analysis of blood serum over a 3 h period. Selective enhancement of the selenium signal was observed during these analyses. A charge-exchange mechanism between C + ions and selenium atoms in the plasma, which leads to the formation of excited Se + ions, is proposed and is supported by data related to the ionization/excitation energies of the various species involved in this reaction. It was also demonstrated that in order to achieve good accuracy, calibration must be conducted using matrix-matched standards. Finally, the accuracy of the technique is demonstrated by showing excellent agreement between the experimental results and the certified values for Seronorm certified serum reference material.

Determination of five arsenic species in aqueous samples by HPLC coupled with a hexapole collision cell ICP-MS

A new method has been developed for the simultaneous determination of AsV, monomethylarsenic (MMA), dimethylarsenic (DMA), AsIII, and arsenobetaine (AsB) in aqueous samples. The method utilizes a multi-mode ion exchange column coupled with a hexapole collision cell inductively coupled plasma mass spectrometer (ICP-MS). A mixture of 10 mM NH4NO3 and 0.05% HNO3 was used as the mobile phase, pumped by a high-performance liquid chromatography (HPLC) pump running in an isocratic mode at a flow rate of 0.4 mL min−1. Under these conditions, the five As species were separated within 14 min. The column outlet was connected directly to the ICP-MS via a low flow Meinhard concentric nebulizer. A river water certified reference material (SLRS-4), spiked with five As species at 20 µg L−1 (As cation) each, was used to validate the chromatographic separation and quantification in a real sample matrix. Based on replicate analyses of SLRS-4, the precision varied from 2% for AsV to 10% for MMA. The detection limits (3s) ranged from 0.02 µg L−1 for AsB to 0.4 µg L−1 for MMA. The new method was applied to water samples collected during As toxicity test experiments. The results indicated that transformation of inorganic As species (AsV and AsIII) occurred during the toxicity test experiments, but no methylation of inorganic As species was detected.

High-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for the analysis of xenobiotic metabolites in rat urine: application to the metabolites of 4-bromoaniline

The use of HPLC-ICP-MS for the profiling and quantification of the metabolites of 4-bromoaniline following reversed-phase gradient chromatography is demonstrated. In the 0-8 h post dose sample, which contained the highest concentrations of compound-related material, it was possible to detect at least 16 metabolites of the compound. The methodology described offers the possibility of obtaining metabolite profiles and quantification for drugs and other xenobiotics in biological fluids and excreta without the requirement for radiolabelled tracers.

Comparison of selenium levels in pre-eclamptic and normal pregnancies

Abnormal placentation is the likely cause of the slow fetal growth and the high levels of circulating lipid peroxides found in severe preeclampsia. These peroxides are probably responsible for the high thromboxane:prostacyclin ratio found in this disease and may participate in the endothelial cell damage which is its most notable feature. Selenium (Se), because of its role in glutathione peroxidase, is suggested to be an important component of the removal system for these damaging peroxides. Serum-Se concentrations have therefore been measured in 19 pairs of pre-eclamptic women and matched controls. Infant birth-weights were recorded. No significant difference was found in the concentrations of Se in pre-eclamptic and control groups. Serum Se was found to be low in both groups. Birthweights were significantly lower in the pre-eclamptic group. The interpretation of serum-Se measurements from the third trimester of a pre-eclamptic pregnancy is complicated by the reduced fetal growth and probable lower Se take-up by the fetus in such a pregnancy. The merits of alternative measurements, such as total intravascular Se, placental Se, or samples from an earlier stage of gestation, are discussed. The importance of factors other than Se to the activity of glutathione peroxidase, and of other antioxidants to pre-eclampsia, is stressed.

Determination of selenium in blood serum by hydride generation inductively coupled plasma mass spectrometry

Continuous flow hydride generation inductively coupled plasma mass spectrometry (ICP-MS) was used for the determination of selenium in blood serum. The connector between the spray chamber and the ICP torch was replaced by a [graphic omitted]-piece, which allowed the hydride gases to be mixed with argon (fed through the nebulizer and spray chamber) before arriving at the plasma. The performance of the system was optimized with and without introduction of water to the nebulizer (wet and dry plasma). The dry plasma offered high short-term signal stability with the relative standard deviation approaching statistical limits. This was not the case for the wet plasma, but the latter demonstrated higher sensitivity, and when combined with internal standard correction, good long- and short-term stability. The influence of iron and copper on the selenium signal was evaluated and showed no significant effect at the levels expected in serum. In order to achieve acceptable accuracy, special attention was paid to the choice of digestion procedure. Good precision (2.27% relative standard deviation) was obtained on nine separate analyses of a quality control blood serum. Analysis of second generation human blood serum reference material and of three different quality control blood serum samples gave results within two standard deviations of the means, a negative bias being observed in all cases. Possible explanations of this bias are discussed.

Trace elemental content of biological materials. A comparison of NAA and ICP-MS analysis.

The advantages and disadvantages of neutron activation analysis (NAA) and inductively coupled plasma-source mass spectrometry (ICP-MS) for the analysis of biological materials is reviewed.Comparison is made between NAA (instrumental) and ICP-MS (conventional pneumatic solution nebulization and laser ablation) analysis of the biological reference material National Bureau of Standards (NBS) SRM 1577 Bovine Liver. Relatively good agreement is achieved between the results for the 18 elements analyzed by both techniques and those either certified or reported in the literature. Elemental concentrations for Li, Mg, Al, Ca, Cr, Mn, Fe, Cu, Zn, Br, Rb, and Cs are also reported for IAEA Mixed Human Diet (H9), NBS SRM 909 Human Serum, and NBS SRM 1577a Bovine Liver, analyzed by solution nebulization ICP-MS.

Investigations into the use of inductively coupled plasma mass spectrometry for the determination of gold in plant materials

The measurement of gold in plant materials using inductively coupled plasma mass spectrometry is assessed in terms of instrument conditions and methodology problems encountered with the type of digestion method used. Factors including the nebulizer flow rate, forward power and selection of internal standard were optimized for maximum sensitivity and signal stability. Furthermore, different digestion procedures were compared for their recovery and reproducibility. Indigenous plants collected from the vicinity of a mine were analysed for their gold content. Levels of gold in the plant materials ranging from 5 to 7450 ng g–1(dry mass) were noted with an instrumental detection limit of 0.04 ng ml–1. The data obtained provide an indication of the concentration and dispersal of gold within the surficial environment of the mine and surrounding area.

Determination of trace amounts of cobalt in blood

Abstract The analysis of cobalt in whole blood and blood fractions has been carried out using three different analytical techniques namely, electrothermal atomic absorption spectrometry, inductively coupled plasma mass spectrometry and cathodic stripping voltammetry. This study showed that inductively coupled plasma mass spectrometry was the better equipped technique for conducting such analyses due to its low detection limits and wide linear dynamic range. The results ranged between 0.7 - 2.62 μg/l for plasma, 1.02 - 2.31 μg/l for serum, and 0.66 - 1.28 μg/l for whole blood. The introduction of different forms of cobalt to Wistar rats resulted in a differing distribution of the element between serum and whole blood. This observation suggests that there are at least two modes of Co uptake and transport depending on the administered or taken chemical form.