Practical and quality-control aspects of multi-element analysis with quadrupole ICP–MS with special attention to urine and whole blood

Two screening methods were developed for rapid analysis of a great number of urine and blood samples within the framework of an exposure check of the population after a firework explosion. A total of 56 elements was measured including major elements. Sample preparation consisted of simple dilution. Extensive quality controls were applied including element addition and the use of certified reference materials. Relevant results at levels similar to those found in the literature were obtained for Co, Ni, Cu, Zn, Sr, Cd, Sn, Sb, Ba, Tl, and Pb in urine and for the same elements except Ni, Sn, Sb, and Ba in blood. However, quadrupole ICP–MS has limitations, mainly related to spectral interferences, for the analysis of urine and blood, and these cause higher detection limits. The general aspects discussed in the paper give it wider applicability than just for analysis of blood and urine—it can for example be used in environmental analysis.     

Ethers as ligands. Part VI. Transition metal(II) complexes with 18-crown-6

Summary Seven new coordination compounds are reported with the cyclicpolyether 18-crown-6 as the ligand,viz. [Mg(18-crown-6) (H₂O)₂](SbCl₆)₂, [M(18-crown-6)(MeNO₆)₂](SbCl₆)₂ with M is Ca²⁺ and Sr²⁺, [M(18-crown-6)(MeNO₂)](SbCl₆)₂ with M is Mn²⁺ and Co²⁺, and [M(18-crown-6)](SbCl₆)₂ with M is Ni²⁺ and Zn²⁺.     

HPLC–MS determination of the oxidation products of the reaction between α- and β-pinene and OH radicals

Biogenic non-methane hydrocarbons such as isoprene, alpha-pinene, and beta-pinene, are emitted by forests in very large quantities. To evaluate the role of alpha- and beta-pinene and their contribution to the global production of trace gases and especially aerosol precursors, a study of the oxidation mechanism of alpha- and beta-pinene with hydroxyl radicals must be conducted.The degradation products of both monoterpenes with hydroxyl radicals were identified and quantified in a fast-flow reactor. The products were collected on a liquid-nitrogen trap coated with a 2,4-DNPH solution to which two internal standards (benzaldehyde-2,4-DNPH and tolualdehyde-2,4-DNPH) had been added. The collection method was based on the in situ conversion of aldehyde and/or ketone compounds to their 2,4-dinitrophenylhydrazone derivatives. The derivatives were analyzed by HPLC-MS using APCI(-). TIC chromatograms and mass spectral data for the various oxidation products are presented.For alpha-pinene, pinonaldehyde is the most important degradation product, with smaller amounts of acetone, formaldehyde, campholenealdehyde, and acetaldehyde. For beta-pinene, nopinone and formaldehyde are the most abundant products, of almost equal importance, whereas acetone and acetaldehyde are minor compounds.     

Spektrophotometrische Bestimmung von Chrom(III) mit Pyridin-2,6-dicarbons?ure

Zusammenfassung Die Störungen der spektrophotometrischen Bestimmung von Cr^III mit Pyridin-2,6-dicarbonsäure nach Hartkamp wurden in einer chemischen Weise beseitigt. Die Bestimmung von Cr^III in Anwesenheit der ungefähr 200fachen Menge Cu, Ni, Al, Mn, Zn oder Fe^III, und der 100fachen Menge Co konnte mit befriedigender Genauigkeit durchgeführt werden.

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Summary The interferences in the spectrophotometric determination of chromium(III) with pyridine-2,6-dicarbonic acid according to Hartkamp have been eliminated in a chemical way. Satisfactory results have been obtained in the determination of Cr^III in presence of a 200-fold excess of Cu, Ni, Al, Mn, Zn, or Fe^III and a 100-fold excess of Co.

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Die Autoren danken Frau A. Gijben-Daalder und Herrn G. Feenstra für die genaue Durchführung vieler Experimente.     

A new tandem route to angular tetraquinanes. Synthesis of the Waihoensene ring system

[formula: see text] This paper describes a new tandem reaction sequence leading to angularly fused polyquinanes from squaric acid-derived bicyclo[6.3.0]-undecadienediones. Such compounds undergo a dual Michael addition. The enolate form in the first intermolecular addition undergoes the second intramolecular transannular addition to give the angular polyquinanes. A particularly interesting example is a catalytic transformation of cis-13-methylyricyclo[10.3.0.0]pentadeca-4(5),12(13)-diene-3 ,14-dione to (3R*,3aS*,5aR*,9aR*,11aR*)-3-methyl-1,2,3,5,5a,6 ,7,10,11,11a-decahydro-4H- pentaleno[6a,1-c]indene-2,10-dione, a compound having the tetracyclic ring system found in the natural product waihoensene. The mechanism and synthetic scope of these reactions are discussed.     

Validation studies and proficiency testing

Genetically modified organisms (GMOs) entered the European food market in 1996. Current legislation demands the labeling of food products if they contain <1% GMO, as assessed for each ingredient of the product. To create confidence in the testing methods and to complement enforcement requirements, there is an urgent need for internationally validated methods, which could serve as reference methods. To date, several methods have been submitted to validation trials at an international level; approaches now exist that can be used in different circumstances and for different food matrixes. Moreover, the requirement for the formal validation of methods is clearly accepted; several national and international bodies are active in organizing studies. Further validation studies, especially on the quantitative polymerase chain reaction methods, need to be performed to cover the rising demand for new extraction methods and other background matrixes, as well as for novel GMO constructs.     

Improved determination of flavour compounds in butter by solid-phase (micro)extraction and comprehensive two-dimensional gas chromatography

The practicability and potential of comprehensive two-dimensional gas chromatography (GC x GC) coupled to both conventional flame ionisation (FID) and time-of-flight mass spectrometric (TOF-MS) detection, were compared with those of conventional one-dimensional (1D) GC, with the determination of flavour compounds in butter as an application. For polar flavour compounds, which were collected from the aqueous fraction of butter by means of solid-phase extraction (SPE), it was found that GC x GC dramatically improves the overall separation. Consequently, quantification and preliminary identification based on the use of ordered structures, can be performed more reliably. The improvement effected by replacing 1D-GC by GC x GC is considerable also in the case of TOF-MS detection, as illustrated by the high match factors generally obtained during identification. GC x GC was also used successfully for the characterisation of volatile flavour compounds in the headspace of butter collected by solid-phase microextraction (SPME) and to study the effect of heat treatment on the composition of butter samples in more detail.     

Study of the carbonyl products of terpene/OH radical reactions: detection of the 2,4-DNPH derivatives by HPLC-MS

The oxidation of the terpenes - and -pinene, limonene and ³-carene by hydroxyl radicals has been investigated in a fast-flow reactor coupled to a liquid nitrogen trap for collecting the carbonyl compounds. Identification of the products was performed via 2,4-dinitrophenylhydrazone (DNPH) derivatization of the carbonyls to form the mono- and di-DNPH derivatives, which were analysed by high-performance liquid chromatographic (HPLC)-DAD (diode array detector) and HPLC-mass spectrometry (HPLC-MS). Both electrospray ionization [ESI(–)] and atmospheric pressure chemical ionization [APCI(–)] were suitable for the detection of the DNPH derivatives of formaldehyde, acetaldehyde, myrtanal, campholene aldehyde, perillaldehyde, acetone, nopinone, trans-4-hydroxynopinone and 4-acetyl-1-methylcyclohexene. Also the mono-DNPH derivatives of the dicarbonyl compounds pinonaldehyde, endolim and caronaldehyde could be identified. The MS² spectra generated in the ion trap of the mass spectrometer allowed us to distinguish between aldehydes and ketones on the basis of the characteristic fragment ion m/z 163 for the aldehydes. For the quantitative analysis of the mono-DNPH derivatives, ESI(–) in combination with single ion monitoring (SIM) detection showed the lowest detection limits. For the quantification of the dicarbonyl compounds, the acid-sensitive di-DNPH derivatives had to be formed by keeping the acidity in the acid-catalysed derivatization reaction at about 1.7 mM H₂SO₄. Detection of these dicarbonyl compounds can only be performed by APCI(–) with somewhat lesser sensitivity than by HPLC-DAD.