Quantitation of camphechlor/toxaphene in cod-liver oil by integration of the HRGC/ECD-pattern

Summary Quantitation of camphechlor/toxaphene in biological matrices like cod-liver oil or fish is difficult because it is a very complex mixture of alicyclic polychlorinated compounds. Furthermore, many toxaphene components are biotransformed and photodegraded and the complex mass spectral fragmentation pattern of HRGC/MSD (electron impact (EI)) cannot be used for quantitation at the g/g-level or below. The use of several indicator-peaks after ECD-detection using the technical standard mixture for calibration does not characterize the entire pattern in a biological sample. Two averaging integration methods that are based on the entire HRGC/ECD-pattern of toxaphene compounds after separation from the PCB congeneres by adsorption chromatography on silicagel, allow a fast and accurate quantitation of the mixture in biological samples, e.g. cod-liver oil. Biological degradation does not disturb the determination because the whole pattern of the complex mixture is considered instead of only a few compounds of the parent mixture which could be degraded or not.     

Comparison of high resolution gas chromatography with electron impact and negative ion mass spectrometry detection for the determination of coplanar polychlorobiphenyl congeners in sewage sludges

The three most toxic coplanar PCB 77, 126 and 169 have been identified and quantified at ultra trace levels (0.02-4.8 ng/gdw) in swiss sewage sludge samples applying high resolution capillary gas chromatography (HRGC) and electron impact (EI) as well as negative ion chemical ionization (NCI) mass spectrometry (MS). NCI mass spectra have been dominated by the molecular ion as base peak and virtually no fragmentation has been observed. Detection limits of the planar PCB under single ion monitoring (SIM) conditions have been typically 100 fg for NCI-MS and 1 pg for EI-MS. NCI-MS was the preferred detection method for the determination of very low concentrations of these important contaminants in sewage sludge samples.     

Comparison of high resolution gas chromatography with electron impact and negative ion mass spectrometry detection for the determination of coplanar polychlorobiphenyl congeners in sewage sludges

The three most toxic coplanar PCB 77, 126 and 169 have been identified and quantified at ultra trace levels (0.02–4.8 ng/gdw) in swiss sewage sludge samples applying high resolution capillary gas chromatography (HRGC) and electron impact (EI) as well as negative ion chemical ionization (NCI) mass spectrometry (MS). NCI mass spectra have been dominated by the molecular ion as base peak and virtually no fragmentation has been observed. Detection limits of the planar PCB under single ion monitoring (SIM) conditions have been typically 100 fg for NCI-MS and 1 pg for EI-MS. NCI-MS was the preferred detection method for the determination of very low concentrations of these important contaminants in sewage sludge samples.     

Determination of coplanar and non-coplanar polychlorinated biphenyls in human serum by gas chromatography with mass spectrometric detection: electron impact or electron-capture negative ionization?

A time- and cost-saving method for the congener-specific analysis of polychlorinated biphenyls (PCBs) in human serum has been developed and validated. After two fast extraction and clean-up steps, analyses were performed using gas chromatography coupled with mass spectrometry with single ion monitoring (GC/SIM-MS), either in electron impact (EI) or electron-capture negative ionization (ECNI) mode. For the determination of dioxin-like congeners, an improvement in EI-MS sensitivity is desirable and use of NI is thus preferred. The procedure was validated for 12 dioxin-like congeners by analyzing spiked samples on three different days and using (13)C(12)-labelled analogues as internal standards. When using an NCI source, the limit of quantification was assessed at 0.01 microg/L, except for PCBs #77 and #81, which cannot be reliably detected below 0.05 microg/L. For the lower chlorinated non-dioxin-like congeners, NI offers less selectivity because of limited fragmentation. Electron impact ionization and electron-capture negative ionization mode can therefore be considered to be complementary for the determination of PCB congeners in the general population.     

Determination of pesticides and PCBs in honey by solid-phase extraction cleanup followed by gas chromatography with electron-capture and nitrogen–phosphorus detection

A multiresidue method for determination of 15 organochlorine pesticides (OCPs), six polychlorinated biphenyls (PCBs), and seven organophosphorus pesticides (OPPs) is implemented for routine determinations of residues in honey. The method involves solid-phase extraction cleanup and determination by GC–ECD/NPD. Quantitation limits ranged from 0.1 to 0.6 g kg^–1 honey for OCPs and PCBs, and from 5.0 to 25.0 g kg^–1 honey for OPPs. Recoveries of OCPs ranged between 77.4 and 94.0%; for PCBs they were from 63.8 to 73.5%. Recovery assays for OPPs varied from 66.7 to 98.1%. The method was applied to the analysis of 111 honey samples from Aragón, Spain. The results obtained indicated a low level of contamination by pesticide residues and PCBs, which can contribute to ensuring the consumer has a safe wholesome supply of honey.     

Fluorometric determination of indomethacin in serum by high performance liquid chromatography with in-line alkaline hydrolysis

Summary A fluorometric method for determining indomethacin in serum by reversed-phase high performance liquid chromatography has been developed. Deproteinized serum containing indomethacin was injected directly onto a C18-bonded vinyl alcohol copolymer column with an alkaline mobile phase (pH 10.0, 35% acetonitrile in phosphate buffer), and was detected fluorometrically (Ex. 298 nm and Em. 375 nm) via postcolumn in-line alkaline hydrolysis at high temperature (140°C). The calibration curve was linear over the range of 0.1–10.0 g/ml when injecting a volume of 10 l of deproteinized serum. The detection limit (signal-to-noise ratio=3) for indomethacin in serum was 10 ng/ml using a 20-l aliquot of deproteinized serum.     

Determination of ochratoxin A in Portuguese rice samples by high performance liquid chromatography with fluorescence detection

A sensitive and accurate analytical method for the determination of ochratoxin A (OTA) in rice, based on extraction with phosphate-buffered saline/methanol, an immunoaffinity column (IAC) for clean-up, and high performance liquid chromatography with fluorescence detection (HPLC-FD), is described. The limit of quantification of the proposed method was 0.05 g kg^–1. Recovery of OTA from rice samples spiked at 0.05 g kg^–1 was 92%, with a within-day RSD of 5.4%. The proposed method was applied to 42 rice samples from Portugal and the presence of OTA was found in six samples at concentrations ranging from 0.09 to 3.52 g kg^–1. The identification of OTA was confirmed by methyl ester derivatization and then HPLC analysis. The daily intake of OTA by the Portuguese population was also estimated.     

Capillar-Gas-Chromatographie mit ECD- und MS-Detektion zur quantitativen Bestimmung von Pentachlorphenol im menschlichen Plasma und Harn

Zusammenfassung Pentachlorphenol (PCP) wurde im Plasma und Harn mittels Capillar-Gas-Chromatographie und ECD-Detektion erfaßt. Die parallele Analyse mit einem massenselektiven Detektor erbrachte nahezu identische Werte (r=0,9978). Die Nachweisgrenzen lagen bei ca. 5 g PCP/l Harn bzw. ca. 10 g PCP/l Plasma. Die Untersuchung von 27 Personen ohne beruflichen bzw. besonderen usuellen Kontakt mit Pentachlorphenol ergab mediane PCP-Konzentrationen im Plasma von 28 g/l (95.0 Perzentil 149 g/l) bzw. im Harn von 10 g/l (95.0 Perzentil 55 g/l).

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Determination of pentachlorophenol in human plasma and urine samples by capillary gas chromatography with ECD- and MS-detection

Summary Pentachlorophenol (PCP) levels in plasma and urine samples were determined by capillary gaschromatography and EC-detection. The results of the parallel analysis of samples with a selective mass detector correlated well (r=0.9978). The detection limits were around 5 g PCP/l urine and around 10 g PCP/l plasma respectively. A study on 27 persons occupationally not exposed to PCP or without a known special ecological intake of PCP showed median PCP levels of 28 g/l plasma (95.0 percentile: 149 g/l plasma) and 10 g/l urine (95.0 percentile: 55 g/l).

     

Determination of cadmium in orthophosphoric acid by graphite furnace atomic absorption spectrometry

Summary Cadmium has been determined in analytical-reagent grade orthophosphoric acids by direct graphite furnace atomic absorption spectrometry with Zeeman background correction. The detection limit was 3.0 pg cadmium, corresponding to 1.0 g/l of cadmium in the concentrated acid. Most of the acids analyzed contained 2–5 g/l of cadmium. The method was checked using electrochemical preconcentration of cadmium, followed by flame atomic absorption spectrometry.     

Polypyrrole modified stainless steel frits for on-line micro solid phase extraction of ochratoxin A

Polypyrrole (PPy) was electrochemically synthesized on stainless steel frits as a sorbent for the micro solid phase extraction (SPE) of ochratoxin A (OTA). Using 20 l of standard solution under a fast flow rate of 0.5 ml/min, 80% recovery of OTA was achieved in the concentration range from 0.1–10 pg/l. This good recovery was achieved within a short residence time of 1.2 s. A binding capacity of 1 ng OTA was estimated for each PPy-modified frit, or 2 ng OTA for two frits in series. The bound OTA could be pulsed eluted (PE) with 20 l of 1% triethylamine in acetonitrile. On-line coupling of this PPy-on-a-frit and PE technique to high performance liquid chromatography (HPLC) was straightforward. On-line SPE-PE-HPLC results clearly demonstrated the capability of PPy-on-a-frit to bind OTA in the presence of red wine, beer, and orange juice components.     

Dosage de micro quantités de cuivre bivalent par précipitation en picrate de cupritétrammine

Résumé On propose une méthode de dosage de microquantités de cuivre-II par précipitation sous forme de picrate de cupritétrammine. Cette méthode est fondée sur la précipitation du cuivre-II en présence d'un excès de picrate de sodium en milieu ammoniacal et sur le dosage colorimétrique de l'acide picrique résiduel après extraction sous forme de picrate de bleu de méthylène.Cette méthode permet le dosage de 1 à 10 g de cuivre-II, avec une erreur maximale de ± 5%.La présence des cations zinc (jusqu'à 200g), argent (jusqu'à 500g), cobalt (jusqu'à 50g), cadmium (jusqu'à 100g), nickel (jusqu'à 20,g) et chrome (jusqu'à 50 g) ne gêne pas le dosage.Cette méthode peut servir à doser le cuivre dans les cendres végétales.

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Summary A method is suggested for the determination of micro amounts of copper(II) by precipitation as the picrate of cupritetrammine. This method is based on the precipitation of the copper(II) in the presence of an excess of sodium pierate in an ammoniacal milieu and on the colorimetric determination of the residual picric acid, after extraction in the form of the picrate of methylene blue. This procedure permits the determination of from 1 to 10g of Cu(II) with a maximum error of ± 5%.The determination is not impaired by the presence of the cations: zinc up to 200 g), silver (up to 500g), cobalt (up to 50g), cadmium (up to 100g), nickel (up to 20g), and chromium (up to 50g).This method may be employed for determining copper in vegetable ashes.

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Zusammenfassung Bin Verfahren zur Bestimmung von Mikromengen Kupfer(II) durch Fällung als Kupfertetrammin-Pikrat wird vorgeschlagen. Es beruht auf der Fällung von Kupfer in Gegenwart überschüssigen Natriumpikrats in ammoniakhaltiger Lösung und der kolorimetrischen Bestimmung der restlichen Pikrinsäure nach Extraktion als Methylenblaupikrat. 1 bis 10g Cu(II) lassen sich mit einem maximalen Fehler von ± 5% bestimmen. Die Anwesenheit von < 200g Zn, < 500 g Ag, < 50g Co, < 100g Cd, < 2°g Ni und < 50g Cr stört die Bestimmung nicht. Das Verfahren eignet sich zur Bestimmung von Kupfer in Pflanzenasehen.

     

Flow injection analysis at μl/min flow rates

The characteristics of knitted open tube (KOT) figure eight reactors and coil reactors at l/min flow rates were compared using plate height (H) calculations and peak height measurements. Peak broadening independent of flow rate was seen for the figure eight KOT but not the coil at flow rates of 150–300 l/min. Below 150 /min, the plate height values of both reactors were inversely proportional to flow rate. It was concluded that a 0.5-m KOT figure eight reactor is the most effective way to introduce delay time for a 1 1 injection size and tubing of 0.3 mm I.D. Enhancement of peak height response was particularly pronounced at flow rates less than 100 l/min.     

Zur Bestimmung der 6 polycyclischen aromatischen Kohlenwasserstoffe nach der Trinkwasser-Verordnung an einer speziellen C18-Umkehrphasen-Trenns?ule

Zusammenfassung Zur Kontrolle des in der Trinkwasser-Verordnung von 1975 festgelegten Wertes von 0,25 g C pro Liter Trinkwasser für 6 polycyclische aromatische Kohlenwasserstoffe (paK) kann ein relativ einfaches flüssigkeitschromatographisches System verwendet werden. Neben einer käuflichen C₁₈-Umkehrphasen-Spezialsäule wird im isokratischen Betrieb Methanol oder Acetonitril als mobile Phase eingesetzt und die UV-Absorption bei 254 nm zur Detektion und quantitativen Messung herangezogen. Zur Gewährleistung der Selektivität sollte die Temperatur der Trennsäule beachtet werden. Die Erfassungsgrenze für die Summe der 6 paK liegt bei 0,007 g pro Liter Wasserprobe — etwa 1/30 des zu prüfenden Grenzwertes.

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Determination of the 6 polycyclic aromatic hydrocarbons according to the drinking water regulation by a special column: dependence of retention upon temperature, detection limit of UV-absorbance, selection of mobile phases

Summary The value of 0.25 g C of six polycyclic aromatic hydrocarbons (PAH) per litre of drinking water according to the drinking water regulation can be controlled with the aid of a relatively simple HPLC-system. A special commercially available C₁₈-reversed phase column is used in an isocratic run with methanol or acetonitrile as the mobile phase and the detection is achieved by a UV-spectrophotometer at 254 nm. The temperature of the column should be observed to ensure the selectivity for the separation of the PAH. The detection limit of the sum of the six PAH is 0.007 g per litre of drinking water — 1/30 of the value to be controlled.

     

Thermoanalytical investigation of the guest-release process in aromatic-guest clathrates of three-dimensional metal complex hosts

The guest-release process was investigated in terms of the activation energy evaluated by thermogravimetry for the en-Td-type clathratescatena--[catena--(ethylenediamine)cadmium(II) tetra--cyanocadmate(II) or -mercurate(II)]-benzene(1/2), -benzene-d ₆(1/2), and -pyrrole(1/2), the Hofmannen-type clathratescatena-[catena--(ethylenediamine)cadmium(II) tetra--cyanonickelate(Il)]-benzene (1/2) and -pyrrole(1/2), the Hofmann-pn-type clathratecatena-[catena--(dl- orl-propylenediamine (cadmium(II) tetra--cyanonickelate(II)]-pyrrole(2/3), and the pn-Td-type clathratescatena-[catena--(dl-propylenediamine) or -(l-propylenediamine)cadmium(II) tetra--cyanocadmate(II)]-benzene(2/3). Values of the activation energy are correlated with the structural change in the metal complex host accompanied by the release of the guest molecules. The crystal structure ofcatena-[ethylenediaminecadmium tetra--cyanonickelate(II)], the residual host of the Hofmann-en-type, has been analyzed to elucidate the correlation.     

Gas-chromatographic determination of total polychlorinated aromates and chloro-paraffins following catalytic reduction in the injection port

Summary The extract of an unknown sample may contain a mixture of different patterns of chloro-aromates or chloroparaffins, from which every pattern itself consists of various isomers with a different number of chlorines at different substitution sites.As proposed by Cooke et al. [6], these substances were reduced upon injection into the gas Chromatograph, so that every compound from one pattern formed the identical dechlorinated compound. These carbon skeletons were then characterized by gas-chromatographic separation. Using an FID, total polychlorinated aromates and paraffins were determined.A gas Chromatograph Carlo Erba 4200 was used. The insert was filled with a 2 cm layer of the catalyst mixture, 1.0% palladium chloride and approx. 12 mg/g sodium hydroxide on Chromosorb P.Following clean-up, 1 l of the sample dissolved in hexane was used for GC. A capillary column DB 5, 15 m, 0.45 m, was used. Hydrogen served as reactor and as carrier gas. In the case of chloro-aromates, the initial temperature was 100 °C, after 1 min it was raised to 260 °C at a + 10 °C/ min rate. For chloro-paraffins, the initial temperature of 60 °C was raised after 1 min to 220 °C at a + 5 °C/min rate.An FID was used for quantitative determination.The following substances were examined: polychlorinated biphenyls (PCBs) and terphenyls (PCTs), polychlorinated benzyltoluenes, chloro-paraffins (C₁₀–C₁₇), DDT and, further, some polybrominated compounds.For the chlorinated compounds, limits of determination were in the range of 5 g/ml hexane solution.The brominated compounds were not quantitatively reduced. It may be expected that further modification of the method should also lead to complete debromination.

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Gas-chromatographische Gruppen-Bestimmung polychlorierter Aromaten und Chlorparaffine nach katalytischer Reduktion im Injektorblock

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Dedicated to Prof. H. Harnisch on the occasion of his 60th birthday     

Determination of propanil in rice, potatoes and water by HPLC

Summary A simple and specific quantitative HPLC method for the analysis of propanil residues in rice, potatoes and water is described. The method is based on simple extraction steps, column clean-up, HPLC separation using a reversed phase column (RP-C18) and UV-detection. With this analytical system, propanil residues can be detected at the 5 ng/g level in rice and potatoes and at the 1 ng/ml level in water. Recovery rate in the range of 0.005–1 g/g is 87.3±6.9% in rice and 85.4±8.2% in potatoes and in the range of 0.001–10 g/ml 95.2±13% in water.

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Bestimmung von Propanil in Reis, Kartoffeln und Wasser durch HPLC

Zusammenfassung Eine einfache HPLC-Methode zur quantitativen Trennung und zum Nachweis der Propanilrückstände in Reis, Kartoffeln und Wasser wird beschrieben, mit der noch Mengen im ppb-Bereich erfaßbar sind. Das Verfahren besteht aus einem Extraktionsschritt, Aufreinigung auf einer Kieselgelsäule, der Trennung der Rückstände auf einer Umkehrphase (RP-C18) und der UV-Detektion. Die Methode gestattet im Bereich von 0,005–1 g/g eine Wiederfindungsrate von 87,3±6,9% in Reis, von 85,4±8,2% in Kartoffeln und im Bereich von 0,001–10 g/ml eine Wiederfindungsrate von 95,2±13% in Wasser.

     

Synthesis of Osmium–Palladium Mixed-Metal Clusters with 2-(diphenylphosphino)Pyridine as a Bridging Ligand

Reaction of the pentanuclear cluster [Os₅C(CO)₁₄(PPh₂py)] in CH₂Cl₂ with 1.2 equivalents of Pd(MeCN)₂Cl₂ led to the high-yield synthesis of the new osmium–palladium carbonyl cluster [Os₅PdC(CO)₁₄(-Cl)Cl(-PPh₂py)] 1. Cluster 1 is thermally unstable and converts slowly in refluxing CHCl₃ to [{Os₄C(CO)₁₀(-Cl)(-PPh₂py)}(₄-Pd){Os₄C(CO)₁₂(-Cl)}] 2 and [{Os₄ (₅-C)(CO)₁₂(-Cl)}₂(-Pd₂Cl₂)] 3 in 4% and 67% yield, respectively. Reaction of 1 with iodine gave [Os₅PdC(CO)₁₄(-Cl)I(-PPh₂py)] 4 and [{Os₄(₅-C)(CO)₁₂(-I)}₂(-Pd₂I₂)] 5 in moderate yields. All complexes have been characterized by spectroscopic and single-crystal X-ray diffraction analysis.     

Redox Properties of Rhodium(III) Oxo-Bridged Carboxylate Complexes

Chemical and electrochemical oxidation of rhodium (III) oxo-bridged carboxylate complexes was studied. The chemical [with O₃ and Ce(IV) salts] or electrochemical (at potentials of 1.00-1.20 V) oxidations of the binuclear complexes [Rh₂(-O)(-O₂CCH₃)₂(H₂O)₆]^{2 +} and [Rh₂(-O)(-O₂CCF₃)₂(H₂O)₆]^{2 +} leads to the superoxo complexes [Rh₂(-O)(O₂-)(-O₂CCH₃)₂(H₂O)₅]⁺ and [Rh₂(-O)(O₂ ^-)(-O₂CCF₃)₂(H₂O)₅]⁺ with terminal coordination of O₂-. The trinuclear acetate [Rh₃(₃-O)(-O₂CCH₃)₆(H₂O)₃]⁺, unlike its trifluoroacetate analog [Rh3(₃-O)(-O₂CCF₃)₆(H₂O)₃]⁺, is oxidized only electrochemically at a potential of 1.38 V. The oxidation of [Rh₃(₃-O)(-O₂CCH₃)₆(H₂O)₃]⁺ is reversible and involves formation of an unstable superoxo group O₂ ^- between two Rh₃III(₃-O) cores.     

Improved high-performance liquid chromatographic method for the determination of domoic acid and analogues in shellfish: effect of pH

Domoic acid (DA) is a naturally-occurring amino acid that causes a form of human intoxication called amnesic shellfish poisoning (ASP) following the consumption of shellfish. A rapid and sensitive HPLC-UV method has been developed for analysis of DA and analogues in shellfish without the need for SPE clean-up. Isocratic chromatographic separation of DA and its isomers from shellfish matrix interferences and from the prevalent amino acid, tryptophan, was achieved by careful control of the mobile phase pH. The optimised pH was found to be 2.5 when using a Luna(2) C₁₈ column. Sample extraction was verified with control extracts from shellfish spiked at 5.0 and 10.0 g/g of DA and with certified reference material. The average extraction efficiency was 98.5%. The calibration, based on mussel tissue spiked with DA standard, was linear in the range 0.05–5.0 g/ml (r=0.9999) and the detection limit (signal:noise 3:1) was better than 25 ng/ml. The DA assay achieved good precision; %RSD=1.63 (intra-day, n=6) and %RSD=3.7 (inter-day, n=8). This method was successfully applied to a variety of shellfish species, allowing the rapid screening of a large number of samples per day (20–30), without the need for SPE clean-up. Quantitative data were obtained for shellfish samples containing domoic acid in the concentration range 0.25–330 g/g. Using the same chromatographic conditions, LC-MS³ was used to determine DA and its isomers, isodomoic acid D and epi-domoic acid, in scallop tissues.