Freek Ariese

Guidelines for terms related to chemical speciation and fractionation of elements. Definitions, structural aspects, and methodological approaches (IUPAC Recommendations 2000)

This paper presents definitions of concepts related to speciation of elements, more particularly speciation analysis and chemical species. Fractionation is distinguished from speciation analysis, and a general outline of fractionation procedures is given. We propose a categorization of species according to isotopic composition of the element, its oxidation and electronic states, and its complex and molecular structure. Examples are given of methodological approaches used for speciation analysis. A synopsis of the methodology of dynamic speciation analysis is also presented.

SYNCHRONOUS FLUORESCENCE SPECTROMETRY OF FISH BILE - A RAPID SCREENING METHOD FOR THE BIOMONITORING OF PAH EXPOSURE

Abstract The uptake of polycyclic aromatic hydrocarbons (PAHs) by fish can be determined by screening the gall bladder bile for PAH metabolites. Conjugated 1-hydroxy pyrene is a major metabolite in bile of fish exposed to PAH polluted sediment. Synchronous fluorescence spectrometry is presented as a rapid screening technique for the determination of this compound; the complete analysis takes only 2–3 min. HPLC with fluorescence detection was used to validate the assay. Calibration methods, using either free 1-hydroxy pyrene or the pyrene-1-glucuronide conjugate as a reference standard, were investigated. The technique was applied to a mesocosm study in which the uptake of PAHs by flounder ( Platichthys flesus ) from polluted sediment was studied. Direct contact with the sediment proved the most important factor; the uptake through water phase or diet was less significant. The usefulness of 1-hydroxy pyrene analysis in bile as a monitoring tool for PAH exposure is discussed.

Analytical methods for determining metabolites of polycyclic aromatic hydrocarbon (PAH) pollutants in fish bile. A Review.

The determination of polycyclic aromatic hydrocarbon (PAH) metabolites in bile can serve as a tool for assessing environmental PAH exposure in fish. Biliary PAH metabolite levels can be measured using several analytical methods, including simple fluorescence assays (fixed fluorescence detection or synchronous fluorescence spectrometry); high-performance liquid chromatography with fluorescence detection (HPLC-F); gas chromatography-mass spectrometry (GC-MS) after deconjugation, extraction and derivatization of the bile sample, and finally by advanced liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) methods. The method alternatives are highly different both with regard to their analytical performance towards different PAH metabolite structures as well as in general technical demands and their suitability for different monitoring strategies. In the present review, the state-of-the-art for these different analytical methods is presented and the advantages and limitations of each approach as well as aspects related to analytical quality control and inter-laboratory comparability of data and availability of certified reference materials are discussed.

Room temperature phosphorescence in the liquid state as a tool in analytical chemistry

A wide-ranging overview of room temperature phosphorescence in the liquid state (RTPL1) is presented, with a focus on recent developments. RTPL techniques like micelle-stabilized (MS)-RTP, cyclodextrin-induced (CD)-RTP, and heavy atom-induced (HAI)-RTP are discussed. These techniques are mainly applied in the stand-alone format, but coupling with some separation techniques appears to be feasible. Applications of direct, sensitized and quenched phosphorescence are also discussed. As regards sensitized and quenched RTP, emphasis is on the coupling with liquid chromatography (LC) and capillary electrophoresis (CE), but stand-alone applications are also reported. Further, the application of RTPL in immunoassays and in RTP optosensing—the optical sensing of analytes based on RTP—is reviewed. Next to the application of RTPL in quantitative analysis, its use for the structural probing of protein conformations and for time-resolved microscopy of labelled biomolecules is discussed. Finally, an overview is presented of the various analytical techniques which are based on the closely related phenomenon of long-lived lanthanide luminescence. The paper closes with a short evaluation of the state-of-the-art in RTP and a discussion on future perspectives.

Organotin Levels in Seafood

Tolerable average residue levels (TARL) for tributylin (TBT) in seafood products were calculated based on the tolerable daily intake (TDI) of TBT and the seafood consumption of the average consumer in various countries. Data from the literature show that these TARLs in seafood are exceeded in one or more samples in nine of the 22 countries for which data were available, i.e. Canada, France, Italy, Japan, Korea, Poland, Taiwan, Thailand and USA. In Italy also the average TBT residue level in seafood exceeded the TARL with a factor of 2.5, while in Japan the average TBT residue level in seafood almost equaled the TARL for this country. For the majority of countries, however, no data on organotin levels in seafood were available. This study shows that there is a need for country-specific maximum residue limits (MRL) for TBT in seafood products and that TBT levels in seafood should be monitored more regularly.

UV-B Absorbance and UV-B absorbing compounds (para-coumaric acid) in pollen and sporopollenin: the perspective to track historic UV-B levels.

UV-B absorbance and UV-B absorbing compounds (UACs) of the pollen of Vicia faba, Betula pendula, Helleborus foetidus and Pinus sylvestris were studied. Sequential extraction demonstrated considerable UV-B absorbance both in the soluble (acid methanol) and insoluble sporopollenin (acetolysis resistant residue) fractions of UACs, while the wall-bound fraction of UACs was small. The UV-B absorbance of the soluble and sporopollenin fraction of pollen of Vicia faba plants exposed to enhanced UV-B (10 kJ m(-2) day(-1) UV-B(BE)) was higher than that of plants that received 0 kJ m(-2) day(-1) UV-B(BB). Pyrolysis gas chromatography-mass spectrometry (py-GC-MS) analysis of pollen demonstrated that p-coumaric acid and ferulic acid formed part of the sporopollenin fraction of the pollen. The amount of these aromatic monomers in the sporopollenin of Vicia faba appeared to increase in response to enhanced UV-B (10 kJ m(-2) day(-1) UV-B(BE)). The detection limit of pyGC-MS was sufficiently low to quantify these phenolic acids in ten pollen grains of Betula and Pinus. The experimental data presented provide evidence for the possibility that polyphenolic compounds in pollen of plants are indicators of solar UV-B and may be applied as a new proxy for the reconstruction of historic variation in solar UV-B levels.

Liquid chromatography with atmospheric pressure chemical ionization and electrospray ionization mass spectrometry of flavonoids with triple-quadrupole and ion-trap instruments

With 15 flavonoids as test compounds, the analytical performance of four modes of LC-MS, multiple MS (MSn) and tandem MS operation (atmospheric pressure chemical ionization (APCI), electrospray ionization, positive and negative ionization) was compared for two mass spectrometers, a triple-quadrupole and an ion-trap instrument. Two organic modifiers, methanol and acetonitrile, and two buffers, ammonium acetate and ammonium formate, were used. In general, the use of APCI in the negative ion mode gave the best response, with the signal intensities and the mass-spectral characteristics not differing significantly between the two instruments. The best results were obtained when methanol-ammonium formate (pH 4.0) was used as LC eluent. Under optimum conditions full-scan limits of detection of 0.1-30 mg/l were achieved in the negative APCI mode. Here it needs to be emphasized that up to 2-order response differences were found both between analytes and between modes of ionization. This implies that one should be very cautious when interpreting data on the screening of real-life samples. The main fragmentations observed in the MSn spectra on the ion-trap, or the tandem MS spectra on the triple-quadrupole were generally the same. The advantage of the former approach is the added possibility to ascertain precursor-->product ion relationships.

Determination of isoflavone glucoside malonates in Trifolium pratense L. (red clover) extracts: quantification and stability studies.

Isoflavones, their glucosides and their glucoside malonates were determined in red clover leaf extracts using reversed-phase LC coupled to atmospheric pressure chemical ionisation mass spectrometry (APCI-MS), UV and fluorescence detectors and the stability of the malonates was investigated. Extracts can be stored at least 1-2 weeks at -20 degrees C without loss of malonates. In LC-separated fractions the malonates are most stable when stored at low temperature after evaporation to dryness. The concentrations of eight major isoflavones ranged from 0.04 to 5 mg/g leaves.

Organic contaminants and trace metals in flounder liver and sediment from the Amsterdam and Rotterdam harbours and off the Dutch coast

Organic contaminants [polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenylethers (PBDEs), nonylphenols], organotin compounds and trace metals (cadmium, chromium, mercury and zinc) were determined in flounder (Platichthys flesus) liver and sediment from the Amsterdam harbour (North Sea Canal) and Rotterdam harbour (Euromonding) and off the Dutch coast between the Amsterdam and Rotterdam harbour mouths in order to assess the level of contamination in these harbours and to study contamination gradients.

Pyrene metabolites in the hepatopancreas and gut of the isopod Porcellio scaber, a new biomarker for polycyclic aromatic hydrocarbon exposure in terrestrial ecosystems

The object of this study was to investigate the formation of pyrene metabolites by the isopod Porcellio scaber as a possible tool in the environmental risk assessment of polycyclic aromatic hydrocarbon (PAH) exposure in terrestrial ecosystems. The formation of pyrene metabolites was studied after either pulse exposure to a single high dose, or prolonged exposure (14 d) to a lower dosage. Exposure studies were carried out with unlabeled or radiolabeled pyrene, ion pair chromatography was used for analysis, and reference conjugates were synthesized. We also measured pyrene metabolites in field—exposed animals, to explore their use as biomarkers of PAH exposure. Analysis of the hepatopancreas and gut of single isopods revealed the formation of five products, one of which was 1-hydroxypyrene. Four of the remaining products were identified as phase II metabolites of 1- hydroxypyrene, with UV absorption and fluorescence characteristics similar to that of pyrene. One metabolite was identified as pyrene−1-glucoside, which is in accordance with high rates of glucosidation, reported for these isopods. Another conjugate was identified as pyrene−1-sulfate. None of the metabolites coeluted with a pyrene−1-glucuronide reference obtained from fish bile. A fifth metabolite detected by on—line scintillation detection did not exhibit any absorption at 340 nm, possibly because one of the aromatic rings of pyrene had lost its aromatic character. Although pyrene is not known for its toxicity, it usually co—occurs with other PAHs that are transformed into toxic products. Investigating the metabolism of pyrene can provide information with regard to the biotransformation capacity of invertebrate species and uptake and elimination kinetics. Because pyrene is one of the most predominant PAHs in the environment, analysis of its metabolites provides an extra tool for the environmental risk assessment of ecosystems with regard to PAH exposure, bioavailability, and biotransformation.