1,721,136 research outputs found
N-(pyrrole-2-carboxyl) glycine a diagnostic marker of hyperprolinaemia type II: Mass spectra of trimethylsilyl derivatives
No full textHeadspace solid-phase microextraction profiling of volatile compounds in urine: application to metabolic investigations
No full textVolatile compounds contribute substantially to the metabolic pool in man. Their analysis in body fluids is problematic. We investigated headspace solid-phase microextraction (HS-SPME) with Carboxen–polydimethylsiloxane fibres and gas chromatography–mass spectrometry for profiling urinary volatile components. These fibres were more sensitive for very volatile and sulfur compounds than three other phases tested. We detected a wide range of compounds in normal urine at acid and alkaline pH. Profiles presented for five individuals with metabolic disturbances demonstrate abnormal accumulation of sulfur compounds, fatty acids and plasticisers. HS-SPME can complement profiling of non-volatile compounds in metabolic investigations and could be a useful extension of the diagnostic repertoire
Solid-phase extraction in clinical biochemistry
No full textIn order to measure low concentrations of analytes in plasma and urine, it is often necessary to extract and concentrate them. With solid-phase extraction (SPE), this is achieved by partitioning the analytes between a solid and a liquid or headspace vapour. A wide range of high-quality materials is now available to do this, offering a variety of separation modes for different applications. These include partitioning using reversed-phase, normal-phase, ion-exchange, restricted-access and immunoaffinity sorbents or molecularly imprinted polymers and, increasingly, combinations of these processes. Solid-phase microextraction was introduced to analyse volatile and semi-volatile compounds. The range of sampling formats has expanded from simple packed syringes to cartridges, disks, SPE pipette tips and 96-well plates. These developments have facilitated automated off- and on-line sample processing. The basic principles of SPE and the recent innovations are reviewed here. This is a technological growth area. Some of the developments are finding application in clinical toxicology. However, they could also be of wider value in clinical chemistry - for example, for analyses of volatile and non-volatile metabolites, peptides, radioactive elements and trace metal speciation
Polynuclear aromatic hydrocarbon emissions from diesel engines
No full textSIGLELD:D48190/84 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
3-Penten-2-one, a novel aldehyde adduct, is a biomarker for increased acetaldehyde in urine
No full textDiagnostic profiling of urine for volatile compounds of around 400 patients using headspace solid-phase microextraction (HS-SPME) in alkaline conditions identified 3-penten-2-one (approximately 1 to >6.3 ?mol/L) in 26 patients. Five were in barbiturate coma. 3-Penten-2-one, previously of unknown origin, was shown to be formed by aldol condensation of acetaldehyde with acetone or acetoacetate during analysis. Semi-quantification of acetaldehyde using in-fibre derivatisation HS-SPME, showed high concentrations in five urine (33–348 ?mol/L) and two plasma (17 and 43 ?mol/L) samples. Hence, urinary 3-penten-2-one is a useful biomarker for increased accumulation of acetaldehyde during abnormal metabolic stres
- …
