Showing papers by "Spiros A. Pergantis published in 2009"

Atomic spectrometry update. Elemental speciation

Abstract: This is the fourth Atomic Spectrometry Update (ASU) to focus specifically on developments in elemental speciation and covers a period of approximately 12 months from January 2011. The International Union for Pure and Applied Chemistry (IUPAC) has evaluated speciation and provided a definition as follows: “speciation analysis is the analytical activity of identifying and/or measuring the quantities of one or more individual chemical species in a sample; the chemical species are specific forms of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure; the speciation of an element is the distribution of an element amongst defined chemical species in a system.” This review therefore deals with all aspects of the analytical speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. The review does not cover operationally defined ‘speciation’, which is correctly termed fractionation. As with all ASU reviews1–6 the coverage of the topic is confined to those methods that incorporate atomic spectrometry as the measurement technique. However, in the spirit of meeting the needs of the subject, material is incorporated that is not strictly “atomic spectrometry” but the separation or sample introduction technique used could also be coupled with an atomic spectrometry detector. For the most part, such procedures are those in which some form of molecular MS is used for speciation measurements. As the content of this Update shows, the field is now maturing as evidenced by the extent to which the speciation of particular elements or technique combinations have been the subject of review articles. However, it is becoming increasingly difficult to ascertain the analytical details of the methodologies applied in speciation analysis, particularly where the paper is published in an ‘application’ based journal.

Serum Total Selenium Status in Greek Adults and Its Relation to Age. The ATTICA Study Cohort

Abstract: The trace element selenium is an essential micronutrient for human health and its low levels in serum are implicated in the pathogenesis of several chronic diseases. Therefore, the determination of total selenium in serum may contribute to the assessment of the health and nutritional status of certain populations. The objective of the present work was to determine total selenium in the serum of 506 healthy volunteers that participated in the ATTICA study. Selenium was determined in serum by using the technique of inductively coupled plasma mass spectrometry. The mean serum selenium concentration was determined to be 91.8 ± 33.7 μg/L (N = 506); 87.6% of women and 88.5% of men had serum selenium concentration below 125 μg/L, the cutoff considered to be required for optimal glutathione peroxidase activity. No association was found between serum selenium levels and the gender of the participants while a significant decline of selenium with age (p < 0.0001) was observed. According to our results, no anthropometric, lifestyle, nutritional, or biochemical indices were able to affect the association between serum selenium and age. This result may indicate that other factors such as selenium distribution as well as retention may be affecting the relationship between serum selenium and age.

Selenosugar determination in porcine liver using multidimensional HPLC with atomic and molecular mass spectrometry

Abstract: A methodology based on liquid chromatography coupled online with atomic and molecular mass spectrometry was developed for identifying trace amounts of the selenosugar methyl 2-acetamido-2-deoxy-1-seleno-β-D-galactopyranoside (SeGalNAc) in porcine liver, obtained from an animal that had not received selenium supplementation. Sample preparation was especially critical for the identification of SeGalNAc by molecular mass spectrometry. This involved liver extraction using a Tris buffer, followed by sequential centrifugations. The resulting cytosolic fraction was pre-concentrated and the low molecular weight selenium (LMWSe) fraction obtained from a size exclusion column was collected, concentrated, and subsequently analyzed using a tandem dual-column HPLC–ICP-MS system which consisted of strong cation exchange (SCX) and reversed phase (RP) columns coupled in tandem. Hepatocytosolic SeGalNAc was tentatively identified by retention time matching and spiking. Its identity was further confirmed by using the same type of chromatography on-line with atmospheric pressure chemical ionization tandem mass spectrometry operated in the selected reaction monitoring (SRM) mode. Four SRM transitions, characteristic of SeGalNAc, were monitored and their intensity ratios determined in order to confirm SeGalNAc identification. Instrument limits of detection for SeGalNAc by SCX-RP HPLC–ICP-MS and SCX-RP HPLC–APCI-MS/MS were 3.4 and 2.9 μg Se L−1, respectively. Selenium mass balance analysis revealed that trace amounts of SeGalNAc, 2.16 ± 0.94 μg Se kg−1 liver (wet weight) were present in the liver cytosol, corresponding to 0.4% of the total Se content in the porcine liver.