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Spiros A Pergantis

Publications and source records attributed to Spiros A Pergantis.

10 recordsLinked to original sources
PubMed2007

Determination of selenosugars in crude human urine using high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry.

The narrow gap between essentiality and toxicity of selenium requires detailed investigations on selenium metabolism in order to find suitable indicators for the selenium status in the human body. Current methods for quantitative selenium speciation in human urine are based on separation by high-performance liquid chromatography (HPLC) coupled online with elemental mass spectrometry (MS), and the potential of molecular MS detection techniques for the reliable identification and quantification of selenosugars in crude human urine has not been utilized. Now we report the development of an HPLC tandem mass spectrometric (MS/MS) method for the reliable determination in crude human urine of three significant selenium urinary metabolites, collectively termed selenosugars, namely methyl 2-acetamido-2-deoxy-1-seleno-beta-D-galactopyranoside (SeGalNAc), methyl 2-acetamido-2-deoxy-1-seleno-beta-D-glucopyranoside (SeGluNAc) and methyl 2-amino-2-deoxy-1-seleno-beta-D-galactopyranoside (SeGalNH2). Reversed-phase HPLC, with and without cation-exchange guard columns, was applied for the separation of the selenosugars, and atmospheric pressure chemical ionization (APCI) and selected reaction monitoring (SRM) were used for selective and sensitive detection. The collision-induced dissociation behaviour of the selenosugars was studied in detail using APCI triple quadrupole MS/MS and electrospray ion trap MS. The developed method was applied to urine samples collected prior to and after selenium supplementation for the quantification of SeGalNAc using both external calibration and the method of standard additions. Additionally, SeGalNH2 was detected in urine samples after Se supplementation. Finally, neutral loss scanning was explored as a possible method for the detection of unknown methyl-selenosugars.

Atmospheric Pressure↗
PubMed2006

Improved arsenic speciation analysis for extracts of commercially available edible marine algae using HPLC-ES-MS/MS.

Their increasing commercial availability and their rather high total arsenic contents necessitate a more detailed arsenic speciation analysis of marine algal products. Compared to current HPLC-ICPMS methods, HPLC on-line with electrospray tandem mass spectrometry in the selected reaction monitoring mode (HPLC-ES-SRM) offers much higher detection selectivity with similarly high sensitivity for most known organoarsenic species. This study demonstrates the advantages of HPLC-ES-SRM for the detection of the main as well as trace arsenic species in extracts of 12 commercially available marine algal powders. The main focus was the unambiguous identification of the detected arsenic species. Four quality control tools were applied for this purpose, including matching chromatographic retention times, comparing SRM transition ratios, recording product ion spectra, and determining accurate masses. As a result, evidence was obtained for the presence of 19 organoarsenic species in the analyzed algal extracts. The method of standard addition was used for quantification. Estimated matrix effects on the analyte signal were similar for most of the investigated arsenic species in extracts of different types of brown algae. This allowed the comparison of the contents of the arsenic species present in the 12 algal extracts on the basis of normalized peak areas. A partial correlation of the arsenic speciation pattern with the algal family or algal order, respectively, was found.

Arsenicals↗
PubMed2006

Mass spectrometric identification and characterization of antimony complexes with ribose-containing biomolecules and an RNA oligomer.

Mass spectrometric techniques have been used to study the interaction of inorganic Sb(V) with biomolecules containing a ribose or deoxyribose moiety. Electrospray (ES) mass spectra of reaction mixtures containing inorganic Sb(V) and one of several biomolecules (adenosine, cytidine, guanosine, uridine, adenosine-5'-monophosphate, adenosine-3',5'-cyclic monophosphate, ribose, or 2'-deoxyadenosine) afforded high-mass antimony-containing ions corresponding to Sb(V)-biomolecule complexes of stoichiometry 1:1, 1:2, or 1:3. The complexes were characterized by collision-induced dissociation (CID) tandem mass spectrometry (MS) using ion-trap multistage MS. The CID results revealed that Sb(V) binds to the ribose or deoxyribose moiety. Structures are proposed for the Sb-biomolecule complexes. Analysis of the reaction mixtures by reversed-phase chromatography coupled on-line to either inductively coupled plasma (ICP) MS or ES-MS showed that in solution Sb(V) forms complexes with all the analyzed biomolecules with vicinal cis hydroxyl groups. Evidence (from size-exclusion chromatography ICP-MS and direct infusion ES-MS) of complexation of Sb(V) with an RNA oligomer, but not with a DNA oligomer, supports the suggestion that the presence of vicinal cis hydroxyl groups is critical for complexation to occur. This is the first direct evidence of complexation of Sb(V) with RNA. Results obtained by studying the effect of changing reaction conditions, i.e. pH, reaction time, and Sb/biomolecule molar ratio, on the extent of Sb-biomolecule formation suggest the reaction may be of physiological importance. Selected reaction monitoring (SRM) and precursor-ion-scanning tandem MS were investigated to determine their potential to detect trace levels of the Sb-biomolecule complexes in biological samples. Application of SRM MS-MS in combination with high-performance liquid chromatography enabled successful detection of an Sb-adenosine complex that had been spiked into a complex biological matrix (liver homogenate).

Antimony↗
PubMed2006

Precursor ion scanning for the non-targeted detection of individual arsenosugars in extracts of marine organisms.

Arsenosugars are a group of arsenic compounds reported to be present in a wide variety of marine organisms. Numerous such compounds have been identified and characterized in marine organisms; however, unknown arsenosugar species may also be present. This indicates the need for an analytical technique suitable for their non-targeted detection. One such technique is tandem mass spectrometry operated in the precursor ion scanning mode. This technique is based on scanning for precursor ions that give specific product ions, characteristic of the compounds under investigation. In the present study two subgroups of arsenosugar species were examined, the oxo- and the thioarsenosugars, the CID behavior of which is well known from previous studies. In the case of the oxoarsenosugars characteristic product ions were observed at m/z 237 and 97, and for the thioarsenosugars at m/z 253 and 97. Validation of this approach was carried out by analyzing extracts of two commercial kelp powders with known contents of arsenosugar species. All arsenosugars reported to exist in these materials were detected successfully using the precursor ion scanning approach. The limits of detection for the oxo- and the thioarsenosugar species, and the selectivity and sensitivity of the method, strongly indicate the suitability of this approach for the non-targeted detection of arsenosugars in extracts of marine origin.

Animals↗
PubMed2006

Identification of the novel thio-arsenosugars DMThioAsSugarCarboxyl, DMThioAsSugarCarbamate and DMThioAsSugarAdenine in extracts of giant clam tissues by high-performance liquid chromatography online with electrospray tandem mass spectrometry.

Recently, the identification of four thio-arsenosugars in extracts of marine samples was reported. The biosynthesis of these arsenic species is most likely closely related to the well known oxo-arsenosugars. Due to their symbiotic algae giant clams contain oxo-arsenosugars with Carboxyl-, Carbamate- and Adenine-aglycone in significant amounts. Now we provide evidence for the presence of the thio analogues of these three arsenosugars in tissue extracts of the giant clams Tridacna maxima and Tridacna derasa. Anion-exchange high-performance liquid chromatography (HPLC) online with electrospray tandem mass spectrometry was applied for the identification of the thio-arsenosugars and the indirect quantification via their oxo analogues.

Animals↗
PubMed2005

First report on the detection and quantification of arsenobetaine in extracts of marine algae using HPLC-ES-MS/MS.

The detection of arsenobetaine in extracts of marine algae is reported here for the first time. The application of liquid chromatography coupled online with electrospray tandem mass spectrometry in the selected reaction monitoring mode provided improved performance for the detection of low amounts of arsenobetaine in the presence of high amounts of arsenosugars.

Arsenicals↗
PubMed2005

Liquid chromatography online with selected reaction monitoring electrospray mass spectrometry for the determination of organoarsenic species in crude extracts of marine reference materials.

The large number of arsenic species known to be present in marine samples and their broad range of chemical properties pose a significant challenge for arsenic speciation analysis. The predominantly used ICPMS detection online with HPLC only provides element-selective information, which is not sufficient for the identification of arsenic species without standards. However, electrospray tandem mass spectrometry in the selected reaction monitoring (SRM) mode enables molecule-selective detection with high sensitivity for quantification. A new HPLC-ES-SRM method was developed for the determination of more than 20 organoarsenic species. Two chromatographic systems were compared, an anion exchange method and a combined cation anion exchange method. Collision-induced dissociation breakdown curves were constructed for all arsenic species investigated and used to optimize the SRM conditions. External calibration was performed with mixed standard solutions containing 21 arsenic species. Two SRM transitions were monitored for most of the analytes, and their intensity ratio was used for quality control. The developed methods were applied for the quantification of arsenic species in extracts of four marine reference materials. Spiking experiments revealed, especially for the early-eluting analytes on the anion exchange system, significant signal suppression by coeluting matrix constituents. Therefore, the standard addition approach was used for quantification. AsB, the major arsenic species in tuna CRM 627 and DORM-2, was accurately quantified with the combined cation anion exchange ES-SRM method.

Animals↗
PubMed2005

Arsenic compounds in the haemolymph of the Dungeness crab, Cancer magister, as determined by using HPLC on-line with inductively coupled plasma mass spectrometry.

Arsenobetaine, two arsenosugars, dimethylarsinate and several unidentified arsenic species were detected in extracts of the haemolymph of the Dungeness crab, Cancer magister, by using HPLC-ICP-MS. This is the first report of the presence of arsenosugars in the haemolymph/blood of marine animals. Total, extractable and residual arsenic concentrations were determined by ICP-MS. The concentration of total arsenic was in the range of 1.4-3.8 [micro sign]g ml(-1). Nearly all (98%) the arsenic was found to be extractable, and accounted for primarily by arsenobetaine, two arsenosugars and dimethylarsinate. The results demonstrate that arsenic compounds present in the diet of crabs are not fully metabolized in the gut. They are, at least partly, taken up into the haemolymph. The concurrence of arsenobetaine and arsenosugars suggests that the use of repeated haemolymph sampling in crustaceans could facilitate investigations into the kinetics of the biotransformation pathways of arsenic compounds. Finally, the present study clearly demonstrates the unique capabilities of HPLC-ICP-MS for the detection and identification of minor arsenic components amongst the predominant arsenobetaine.

Animals↗
PubMed2002

Arsenosugar identification in seaweed extracts using high-performance liquid chromatography/electrospray ion trap mass spectrometry.

The development of analytical techniques suitable for providing structural information on a wide range of elemental species is a growing necessity. For arsenic speciation a variety of mass spectrometric techniques, mainly inductively coupled plasma mass spectrometry (ICP-MS) and electrospray tandem mass spectrometry (ES-MS/MS) coupled on-line with high-performance liquid chromatography (HPLC), are in use. In this paper we report the identification of arsenic species present in samples of marine origin (seaweed extracts) using ES ion trap mass spectrometry (IT) multistage mass spectrometry (MS(n)). Both reversed-phase and anion-exchange HPLC have been coupled on-line to ES-ITMS. Product ion scans with multiple stages of tandem MS (MS(n); n=2-4) were used to acquire diagnostic data for each arsenosugar. The spectra contain structurally characteristic fragment ions for each of the arsenosugars examined. In addition it was observed that upon successive stages of collision-induced dissociation (CID) a common product ion (m/z 237) was formed from all four arsenosugars examined. This product ion has the potential to be used as an indicator for the presence of dimethylated arsenosugars (dimethylarsinoylribosides). The HPLC/ES-ITMS(n) method developed allows the sensitive identification of arsenosugars present in crude seaweed extracts without the need for extended sample preparation. In fact, sample preparation requirements are identical to those typically employed for HPLC/ICP-MS analysis. Additionally, the resulting product ions are structurally diagnostic of the arsenosugars examined, and tandem mass spectra are reproducible and correspond well to those obtained using other low-energy CID techniques. As a result, the HPLC/ES-ITMS(n) approach minimises the potential for arsenic species misidentification and has great potential as a means of overcoming the need for characterised standards.

Arsenates↗