Characterization of chemical interferences in the determination of unsaturated aldehydes using aromatic hydrazine reagents and liquid chromatography

Schulte-Ladbeck, Rasmus; Lindahl, Roger; Levin, Jan‐Olof; Kärst, Uwe

doi:10.1039/b101354h

Cited by 63 publications

(31 citation statements)

References 26 publications

(33 reference statements)

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“…This decomposition leads to the underestimation of the true value since the main peak no longer represents the complete acrolein hydrazone concentration. The original acrolein hydrazone on the sampler is partially re-arranged into a number of decomposition products identified as dimer or trimer acrolein-DNPH [13]. Due to these basic problems associated with the DNPH method, the overall uncertainty could only be improved by, for instance, taking the sum of all decomposition products.…”

Section: Resultsmentioning

confidence: 99%

Intermethod comparisons of active sampling procedures and analysis of aldehydes at environmental levels

Huynh

Vu-Duc

2002

Anal Bioanal Chem

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Within the framework of a European interlaboratory exercise, the Vito facility for the generation of controlled atmospheres was used to test the suitability of four sampling techniques for priority aldehydes namely formaldehyde, acrolein, acetaldehyde, and glutaraldehyde at the ranges of 0.5 to 150 microg x m(-3). The samplers are DNPH-containing impingers, DNPH-impregnated cartridges and filters, and 2-HMP coated XAD-2 tubes. The three first DNPH samplers are to be analyzed by HPLC and the latter by GC-MS for the oxazolidine derivatives. The intermethod comparison comprises two to five sets of experiments depending on the compounds of interest. The aim of the exercise was also to assess the chemical interferences caused by ozone, nitrogen dioxide, and ammonia when using different techniques for sampling and analysis. The active DNPH method (with minor modifications such as shorter sampling time, immediate elution after sampling, and/or eventually wetting of samplers) delivered results within the 30% overall relative uncertainty for formaldehyde, acetaldehyde, and acrolein at the upper microg x m(-3) levels. However, the results suggest that the current DNPH methods for aldehydes do not comply with the 30% minimum performance criteria at the sub microg x m(-3) level. Sampling of aldehydes in the presence of ozone and NO2 interferences by using a "scrubber" cartridge appears to be beneficial to the quality of results.

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Section: Resultsmentioning

confidence: 99%

Intermethod comparisons of active sampling procedures and analysis of aldehydes at environmental levels

Huynh

Vu-Duc

2002

Anal Bioanal Chem

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“…The cartridges were subsequently extracted with acetonitrile at the analytical laboratory. The collected hydrazones were separated by reversed-phase high-performance liquid chromatography and analysed by UV/VIS detection for formaldehyde and acetaldehyde [14] and by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) for acrolein following, in principle, the method described by Schulte-Ladbeck et al [15]. In order to validate the method for our application, formaldehyde and acetaldehyde have also been analysed using APCI-MS. A very good agreement has been obtained between the results obtained with the UV detector and the mass spectrometer; a plot of the UV results (abscissa) versus the MS results (ordinate) resulted in a straight line with a slope of 1.0045 and R 2 of 0.9937 for n = 35 samples.…”

Section: P Blomqvist Et Almentioning

confidence: 99%

Detailed determination of smoke gas contents using a small‐scale controlled equivalence ratio tube furnace method

Blomqvist¹,

Hertzberg²,

Tuovinen³

et al. 2007

Fire and Materials

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SUMMARYA series of tests including seven different materials and products have been conducted using a controlled equivalence ratio tube furnace test method. The main objective of the tests was to determine yields of fire-generated products at defined combustion conditions.The tube furnace test method was set up and run in close agreement with that described in BS 7990:2003. At the time of experimental work the new tube furnace method was in the process of becoming an international standard. It was thus of interest to make an assessment of the capability of the method for determining production yields of important toxic fire products from different types of materials and products.The test series included solid wood, flexible polyurethane (PUR), fire-retarded rigid PUR, a polyvinyl chloride (PVC) carpet, a high-performance data cable with fluorine-containing polymer matrix, a PVCbased cable sheathing material and fire-retarded polyethylene cable insulation material. Duplicate tests were generally conducted at both well-ventilated and vitiated combustion conditions with these materials.The smoke gases produced from the combustion were quantified for inorganic gases by FTIR technique in all tests. A more detailed analysis of the smoke gases was conducted for some of the materials. This extended analysis contained a detailed assessment of organic compounds including, e.g. volatile organic compounds, isocyanates, aldehydes and polycyclic aromatic hydrocarbons. The analysis further included measurement of the size distribution of fire-generated particles for some of the materials.The quantification of toxic inorganic gases produced by combustion at both well-ventilated and vitiated conditions was successful regarding repeatability and stability. Typical yields for the two fire stages investigated were determined for a wide range of materials and products. The detailed analysis of organic * Correspondence to: Per Blomqvist,

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“…All MD simulations were carried out using the GROMACS v 3.1.4 molecular dynamics simulation package (Schulte-Ladbeck et al, 2001). For the generation of topology files under GROMACS, the structure template coordinates file was split into two structure files, one for the protein and one for the ligand, to keep the two molecules in the same frame of reference.…”

Section: Methodsmentioning

confidence: 99%

Improvement of Cyclophosphamide Activation by CYP2B6 Mutants: From in Silico to ex Vivo

Nguyen¹,

Tychopoulos²,

Bichat³

et al. 2008

Mol Pharmacol

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Cyclophosphamide (CPA) is a chemotherapeutic agent that is primarily activated in the liver by cytochrome P4502B6 (CYP2B6) and then transported to the tumor via blood flow. To prevent deleterious secondary effects, P450-based gene-directed enzyme prodrug therapy (GDEPT) consists of expressing CYP2B6 in tumor cells before CPA treatment. Given the relatively low affinity of CYP2B6 for CPA, the aim of our work was to modify CYP2B6 to increase its catalytic efficiency (V max / K m ) to metabolize CPA into 4Ј-OH CPA. A molecular model of CYP2B6 was built, and four residues in close contact with the substrate were subjected to mutagenesis. Canine CYP2B11 exhibiting a particularly low K m to CPA, the amino acids exclusively present in the CYP2B11 substrate recognition sequences were substituted in human CYP2B6. All mutants (n ϭ 26) were expressed in Saccharomyces cerevisiae and their enzymatic constants (K m , V max ) evaluated using CPA as substrate. Five mutants exhibited a 2-to 3-fold higher catalytic efficiency than wild-type CYP2B6. A double mutant, comprising the two most effective mutations, showed a 4-fold increase in K m /V max . Molecular dynamic simulations of several mutants were found to be consistent with the observed modifications in catalytic efficiency. Finally, expression of the CYP2B6 114V/477W double mutant, contrary to wt CYP2B6, allowed switching of a resistant human head and neck cancer cell line (A-253) into a sensitive cell line toward CPA. Thus, we were able to obtain a new efficient CYP2B6 mutant able to metabolize CPA, an important step in the GDEPT strategy for human cancer treatment.

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Characterization of chemical interferences in the determination of unsaturated aldehydes using aromatic hydrazine reagents and liquid chromatography

Cited by 63 publications

References 26 publications

Intermethod comparisons of active sampling procedures and analysis of aldehydes at environmental levels

Intermethod comparisons of active sampling procedures and analysis of aldehydes at environmental levels

Detailed determination of smoke gas contents using a small‐scale controlled equivalence ratio tube furnace method

Improvement of Cyclophosphamide Activation by CYP2B6 Mutants: From in Silico to ex Vivo

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