Removal efficiency and toxicity reduction of 4-chlorophenol with physical, chemical and biochemical methods.

Chlorophenols are well-known priority pollutants and many different treatments have been assessed to facilitate their removal from industrial wastewater. However, an absolute and optimum solution still has to be practically implemented in an industrial setting. In this work, a series ofphysical, chemical and biochemical treatments have been systematically tested for the removal of 4-chlorophenol, and their results have been compared in order to determine the most effective treatment based on removal efficiency and residual by-product formation. Chemical treatments based on advanced oxidation processes (AOP) produced the best results on rate and extent of pollutant removal. The non-chemical technologies showed advantages in terms of complete (in the case of adsorption) or easy (enzymatic treatments) removal of toxic treatment by-products. The AOP methods led to the production of different photoproducts depending on the chosen treatment. Toxic products remained in most cases following treatment, though the toxicity level is significantly reduced with combination treatments. Among the treatments, a photochemical method combining UV, produced with a KrCl excilamp, and hydrogen peroxide achieved total removal of chlorophenol and all by-products and is considered the best treatment for chlorophenol removal.

Rhizoremediation of pentachlorophenol by Sphingobium chlorophenolicum ATCC 39723.

Sphingobium chlorophenolicum is well known as a pentachlorophenol (PCP) degrader. The objective of this study was to evaluate PCP degradation in a loamy sandy soil artificially contaminated with PCP using phytoremediation and bioaugmentation. Measurements of PCP concentrations were carried out using high performance liquid chromatography analyses (HPLC). The toxic effect of PCP on plants was studied through the monitoring of weight plant and root length. The biodegradation of PCP by S. chlorophenolicum in soil was assessed with a bioluminescence assay of Escherichia coli HB101 pUCD607. Bacterial analyses were carried out by plating on Mineral Salt Medium (MSM) for S. chlorophenolicum, MSM for PCP-degrading/tolerant organisms and Trypticase Soy Broth Agar (TSBA) for heterotrophic organisms. The introduction of S. chlorophenolicum into soil with plants showed a faster degradation when compared to the non-inoculated soil. The monitoring of the plant growth showed a protective role of S. chlorophenolicum against the toxicity of PCP. The bioassay confirmed that initial toxicity was lowered while degradation progressed. There was a significant increase of organisms tested in the roots in comparison to those in the soil. This study showed that the presence of S. chlorophenolicum enhanced the PCP degradation in a loamy soil and also it had a protective role to prevent phytotoxic effects of PCP on plant growth. The combined use of bioaugmentation and plants suggests that the rhizosphere of certain plant species may be important for facilitating microbial degradation of pesticides in soil with important implications for using vegetation to stabilize and remediate surface soils.

Feasibility study on the characterization of thin layers by charged-particle activation analysis

The purpose of this feasibility study was to investigate the possibilities and limitations of Charged-Particle Activation Analysis (CPAA) as a thin layer characterization method, i.e., the determination of the mass thickness or the composition of a thin layer. Therefore industrially important layers of sputtered Al, AlOx, TiQx (all three from the packaging industry), YBa2Cu3O6+delta, and Y2O3-stabilized ZrO2 (both superconducting industry) on different substrates were analyzed, and thereby the accuracy, the detection limits, and the precision of the method were studied. To test the accuracy, the same materials were also analyzed with neutron activation analysis (NAA) and inductively coupled plasma mass spectrometry (ICPMS). The results of CPAA compared with the results of NAA and ICPMS showed no significant difference at the 95% confidence level. The detection limits expressed as mass thickness were about 10-2 microg cm-2 or expressed as thickness 0.04 nm for a monatomic layer of Al. The experiments showed that the precision of the method depends only on the counting statistics. Generally we can conclude that CPAA is an absolute method for the characterization of "thin" layers, with respect to composition and mass thickness determinations.

Multielement analysis of polyethylene using solid sampling electrothermal vaporization ICP mass spectrometry

Next to laser ablation (LA) also electrothermal vaporization (ETV) from a graphite furnace as a means of sample introduction opens possibilities for direct analysis of solid samples using inductively coupled plasma mass spectrometry (ICPMS). In this paper, it is demonstrated that solid sampling ETV-ICPMS is very well suited for the determination of metal traces in polyethylene. A limited multielement capability is often cited as an important drawback of ETV-ICPMS. However, by studying the effect of monitoring an increasing number of mass-to-charge ratios on the signal profile (integrated signal intensity and repeatability) of selected analyte elements, the multielement capability of (solid sampling) ETV-ICPMS was systematically evaluated, and the results obtained suggest that, with a quadrupole-based ICPMS instrument, at least 11 elements can be determined "simultaneously" (from the same vaporization step), in essence without compromising the sensitivity or the precision of the results obtained. In this work, the "simultaneous" determination of Al, Ba, Cd, Cu, Mn, Pb, and Ti in a polyethylene candidate reference material has been accomplished, despite the large variation in analyte concentration (from 5 ng/g for Mn to 500 microg/g for Ti) and in furnace behavior (volatility) they exhibit. To avoid premature losses of Cd during thermal pretreatment of the samples, Pd was used as a chemical modifier. Two different calibration methods--external calibration using an aqueous standard solution and single standard addition--were studied and the results obtained were compared with those obtained using neutron activation analysis (NAA) and/or with the corresponding (candidate) certified values (if available). Single standard addition was shown to be preferable (average deviation between ICPMS result and reference value < 3%), although--except for Ba--acceptable results could also be obtained with external calibration.

Measurement of [methyl-carbon-11]thymidine and its metabolites in head and neck tumors.

UNLABELLED: We made routine measurements of [methyl-11C]thymidine and its metabolites in human venous blood in 13 patients with head and neck tumors. METHODS: Patients underwent PET imaging 10-30 min after bolus injection. Venous samples were collected at various intervals and water-soluble 11C-metabolites were analyzed with semipreparative HPLC on a C18 column with isotonic phosphate solution as an eluant. RESULTS: After rapid clearance, total radioactivity remained constant at a level of about 1.2% of the initial injected activity. CONCLUSION: In this group of patients with head and neck cancers, our results show that kinetic differences in various 11C-metabolites are small.

[Methyl-carbon-11] thymidine for in vivo measurement of cell proliferation.

UNLABELLED: [Methyl-11C]thymidine and PET provide an in vivo, noninvasive, quantitative approach for studying nucleoside uptake in cells on condition that the fraction of metabolites in the total accumulated activity is known. METHODS: Using an animal model (Wistar rats), two independent approaches were followed. In the first approach, total accumulated activity in rapidly dividing tissue after intravenous injection of [methyl-11C]thymidine, respectively, [methyl-11C]thymine (first metabolite), was compared. In the second approach, the liver was surgically isolated to avoid thymidine catabolism. RESULTS: After injection of [methyl-11C]thymidine, tissue activity consists of both labeled thymidine and metabolites, while after injection of [methyl-11C]thymine, it consists only of metabolites. The fraction of metabolites ranged from 9% to 44%. Comparing the specific activity with and without liver function yielded similar results. The calculated amount of metabolites was about 10%. CONCLUSION: In spite of the intense in vivo catabolism, major activity in rapidly dividing tissue consists of [methyl-11C]thymidine.

Bismuth in human serum: reference interval and concentrations after intake of a therapeutic dose of colloidal bismuth subcitrate.

A sensitive method for the determination of the bismuth concentration in human serum is described. Analyses were carried out by inductively coupled plasma-mass spectrometry (ICP-MS), after a simple dilution of the samples with nitric acid. The detection limit of the applied method is 0.007 microgram/l whereas relative standard deviations varied from 5.7 to 13.6%. Determination of reference values in human serum of healthy adults gave a range from < 0.007 to 0.067 microgram/l (19 persons). Bismuth concentrations in serum were also measured before, during and after the intake of therapeutic doses of colloidal bismuth subcitrate (CBS). About 1.5-2 h after the intake of one tablet of CBS, the bismuth concentration in serum was found to have increased 51-1483 times (two apparently healthy volunteers and six hospitalized patients), showing that the serum bismuth concentrations can increase by several orders of magnitude during the intake of CBS. During the intake of four tablets of CBS per day by two apparently healthy volunteers, bismuth concentrations in serum after an overnight fast were found to be, respectively, 5.56 and 8.1 micrograms/l on day 15 and 4.28 and 13.6 micrograms/l on day 29. After stopping the therapy, the concentration of bismuth in serum slowly returned towards normal over a period of months.

Synthesis of 6-methyl[11C]-2'-deoxyuridine and evaluation of its in vivo distribution in Wistar rats.

In this study, 6-methyl-2'-deoxyuridine, an artificial nucleoside, was labeled with 11C in the methyl position. Tissue distribution of 6-methyl[11C]-2'-deoxyuridine was investigated in normal Wistar rats and compared to the behavior of the natural nucleoside [methyl-11C]thymidine. High renal clearance, up to at least 20% of the injected activity, was noticed during the 20 min period following injection. Tissue distribution as determined by dynamic PET studies of both 11C-labeled nucleosides was significantly different for most of the organs.

Evaluation of [11C]thymidine for measurement of cell proliferation in fast dividing tissues.

The purpose of this study was to investigate the possibility of using [11C]thymidine as a tumor marker for positron emission tomography studies. Biodistribution studies were set up to investigate the in vivo behavior of [11C]thymidine. Simultaneously, the DNA incorporation in fast dividing tissues and catabolism was studied. Our results confirm that [11C]thymidine can be used for detection of cell proliferation by positron emission tomography. As such, it can produce supplementary information in cancer research.

Comparison of phenyl-type columns in the development of a fast liquid chromatographic system for eighteen opiates commonly found in forensic toxicology.

We report a precise and reliable method for the detection of 18 of the most commonly found opiates on the Belgian legal and illicit market, by ion-exchange, reversed-phase high-performance liquid chromatography, using a conventional phenyl-type analytical column (150x4.6 mm I.D., particle size 5 microm) and diode-array detection. We also describe a performance (efficiency and sensitivity) comparison of this column to a recently developed "high-speed" column (53x7.0 mm I.D., particle size 3 microm) packed with the same stationary phase, and used under slightly adjusted flow and gradient conditions. The final method, using the "high-speed" column, showed a significant reduction (55%) in analysis time without loss of resolution and sensitivity.

Simultaneous determination of in total 17 opium alkaloids and opioids in blood and urine by fast liquid chromatography-diode-array detection-fluorescence detection, after solid-phase extraction.

A fast liquid chromatographic method with tandem diode array-fluorescence detection for the simultaneous determination of in total 17 opium alkaloids and opioids is presented. Blank blood and urine samples (1 ml) were spiked with different concentrations of a standard mixture, as well as with the internal standard, butorphanol (2000 ng/ml). After solid-phase extraction, based on weak cation exchange (Bond Elut CBA SPE columns), the extracts were examined by HPLC-DAD-FL. By using a "high-speed" phenyl column (53 x 7.0 mm I.D., particle size 3 microm) eluted with a gradient system (A: water-methanol (90:10, v/v), B: methanol, both containing 25 mM triethylammoniumformate (pH(A) = 4.5)) all compounds could be baseline separated within 12 min. The method was validated and its applicability was demonstrated by the analysis of real-time forensic cases.

Non-spectral interferences encountered with a commercially available high resolution ICP-mass spectrometer.

Results of a systematic study concerning non-spectral interferences observed with a commercially available high resolution ICP-mass spectrometer are reported and compared to observations made with a quadrupole-based instrument. In general, matrix effects were observed to be to a large extent comparable for both instruments used. In all cases, the matrix-induced signal suppression or enhancement was seen to depend in a regular way on the mass number of the nuclides monitored. In most cases, the ionization potential of the nuclides has little or no influence on the extent of suppression or enhancement. For As, Se and Te, the introduction of 2.5% ethanol, 0.5 mol/l H(2)SO(4), or to a lesser extent 0.5 mol/l H(3)PO(4), leads to an exceptional increase in the signal intensity for both instruments. Registration of signal behaviour plots (signal intensity as a function of the nebulizer gas flow rate) in different matrices revealed that both the height of the plot and the optimum nebulizer gas flow rate are a function of the matrix composition. Finally, no indication was found that the acceleration of the extracted ions over 8000 V with the high resolution instrument would lead to an alleviation of space charge effects when compared to a quadrupole-based ICP-mass spectrometer.

Determination of low amounts of platinum in environmental and biological materials using thermospray nebulization inductively coupled plasma-mass spectrometry.

A description is given of the experimental arrangement for thermospray nebulization of discrete liquid samples (100 microl) into an inductively coupled plasma-mass spectrometer (ICP-MS). The determination of ultratrace levels of platinum in environmental and biological materials is described. This method comprises an off-line sample enrichment by adsorptive chromatography, elution with ethanol and subsequent analysis of the evaporated eluate. The quantification of the concentration was performed with isotope dilution. The recovery, precision, accuracy and detection limit of the method are discussed.

A mathematical correction method for spectral interferences on selenium in inductively coupled plasma mass spectrometry.

Despite the fact that Se has six isotopes, its determination in biological samples by inductively coupled plasma mass spectrometry is seriously hampered by spectral interferences. The resolution of quadrupole mass analyzers is insufficient to resolve Se(+) from molecular species having the same nominal mass. A mathematical correction method based on signal ratio measurement of (78)Se(+)/(76)Se(+) and (78)Ar(+)(2)/(76)Ar(+)(2) is described. It allows us to correct for the argon dimer interference at m/z 78 and thus to determine Se down to the 1 mug/l level. The method was applied to the determination of Se in human serum. Good agreement with the certified value was obtained.

The determination of molybdenum in a sea water candidate reference material by inductively coupled plasma-mass spectrometry.

In the framework of a certification campaign organized by BCR (Bureau Communautaire de Référence, Commission of the European Communities, Brussels) molybdenum was determined in a sea water candidate reference material (BCR CRM 403) using inductively coupled plasma-mass spectrometry. The determination was hampered by both non-spectral (signal suppression) and spectral interferences. Ten-fold dilution of the sea water and the use of a carefully selected internal standard allowed accurate correction for the signal suppression. Spectral interferences on Mo nuclides could mainly be attributed to BrO(+) and BrOH(+) ions. At the level of spectral overlap encountered, these interferences could be corrected for with sufficient accuracy by matrix matching of the blank for Br or by application of a mathematical correction method involving resolvation of a pair of simultaneous equations. Results obtained after application of anion exchange to separate Br from Mo confirmed the results obtained using the correction methods, proving the validity of the latter. A good agreement is established by comparison of the ICP-MS result with those obtained by other techniques in other laboratories.

The use of internal standards in ICP-MS.

Careful study of the matrix effect in ICP-MS showed that, in all cases studied, the magnitude of the signal suppression or enhancement depends in a regular way on the mass number. Hence, accurate correction for non-spectral interferences is only possible using an internal standard with mass number close to that of the analyte element(s). It is also shown that using an internal standard with mass number close to that of the analyte improves the precision. For both cases, the ionization energy of the internal standard seems to be of no or only secondary importance. To obtain optimal precision and accuracy, the internal standard should be selected as close in mass number as possible to that of the analyte element(s). When a number of elements over a considerable mass range are to be determined, several internal standards have to be used.

Investigation of HfO(+) interference in the determination of platinum in a catalytic converter (cordierite) by inductively coupled plasma mass spectrometry.

The determination of Pt in cordierite is subject to strong interference by spectral overlap from HfO(+) ions with all Pt isotopes. Two mathematical correction methods based on the HfO(+)Hf(+) ratio and a method for the chemical separation of Hf based on adsorption chromatography and isotope dilution were investigated to correct for this interference. Flow infection was used to prevent clogging of the cone orifice. To enhance the sensitivity and thus lower the detection limit, thermospray nebulization was used for sample introduction and the method was compared with pneumatic nebulization. In addition, the memory effects were evaulated for both systems. Analysis of artificial solutions (1 ng Pt ml(-1)) yielded results within 3% of the true value. Th Pt content (ca. 50 ng g(-1)) of a cordierite sample, previously exposed to exhaust gases, could be determined with precisions of about 10-25% and the results agreed with earlier determinations by other workers.

Determination of strontium in human serum by inductively coupled plasma mass spectrometry and neutron activation analysis: A comparison.

Strontium has been determined in a human serum reference material by ICP-MS and by NAA. By ICP-MS, results for (88)Sr and (86)Sr in both 10- and 5-fold diluted serum were in good agreement. For (88)Sr the precision was better than 3% and the detection limit was 0.05 mug/l. under the conditions used. The results were 25.5 mug/l. in the liquid serum or 0.281 mug/g in the lyophilized reference material. In the NAA the (87m)Sr produced was radiochemically separated by extraction with oxine in chloroform. The precision was about 10% and the detection limit 0.02-0.05 mug/g.

Heroin impurity profiling: trends throughout a decade of experimenting.

Heroin is still one of the most frequently abused drugs of today. All over the world, law enforcement agencies try to eradicate the illicit production and trafficking of this potent and highly addictive narcotic. To this aim, important information is provided by physical and chemical toxicological analysis of confiscated samples, with special attention for the identification and the quantification of minor components, such as the impurities related to the origin and manufacturing. By combining these data complex characterisations, i.e. impurity profiles, chemical signatures or fingerprints, can be obtained and used for comparative analysis. This review focuses on heroin impurity profiling during the 1990s, proclaimed by the United Nations as the 'Decade for Eradicating Drug Abuse'. Special attention will be given to the new trends in analytical techniques as well as in data handling strategies, so called chemometrics, to produce these profiles. The latter can be used in comparative analysis of seized heroin samples for tactical (batch-to-batch comparison) and strategic (origin determination) intelligence purposes.

Evaluation of trace elements in human lung tissue. II. Recovery and analysis of inhaled particulates.

Inhaled particulate material, deposited in the lungs of eight Belgian individuals, is differentiated from the tissue with a digestion procedure using the enzyme ficin. This method is simple and efficient and yields a small amount of insoluble dust. The total element concentration of the tissue samples was determined by neutron activation analysis. The radioactive residues obtained after the digestion of the tissue were counted and are considered to represent the insoluble dust fraction. A major part of the Co, Cr, Sb and Sc was recovered in the residues, but only small fractions of the Cs, Rb and Zn. These findings confirm the assumption that Co, Cr, Sb and Sc are enriched in the lungs as a result of the accumulation of atmospheric contaminants. Further proof can be derived from the analogy between the elemental composition of the residue and that of atmospheric particulate matter collected in Belgium.