Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 7 de 7
Filter
Add more filters










Database
Publication year range
1.
Anal Biochem ; 549: 113-118, 2018 05 15.
Article in English | MEDLINE | ID: mdl-29567404

ABSTRACT

Flow injection analysis-tandem mass spectrometry has become widely used for analysis of many biomarkers in various biological matrices. To improve the sensitivity, the compounds are often determined as their butylesters. Since the concentration of urinary excreted compounds are generally reported after normalization to creatinine, the aim of this study was to investigate the possibility of creatinine determination in urine samples which underwent butylation. The impact of derivatization on urinary creatinine determination was investigated by measuring of underivatized and derivatized samples. The 10% creatine to creatinine conversion was observed during butylation, what above 700 µmol creatine/mmol creatinine caused significant creatinine overestimation. In that case, correction for creatine conversion rate was done. QC samples at six concentration levels were examined and precision and accuracy values fulfill the European Medicine Agency validation requirements. The elaborated method was applied for determination of creatinine in 41 real human urine samples. Determined creatinine concentrations were in the range of 0.27-22.3 mmol/L, linearity was confirmed within the concentration range of 0.27-31.7 mmol/L. Obtained results highly correlated with routinely used enzymatic assay for all tested samples and proposed method provide reliable determination of creatinine in butylated urine in a single run with butylesters of other analytes of interest.


Subject(s)
Creatinine/urine , Tandem Mass Spectrometry/methods , Acetylation , Child , Child, Preschool , Female , Humans , Male , Sensitivity and Specificity
2.
Article in English | MEDLINE | ID: mdl-25531871

ABSTRACT

A new arrangement of the INCAT (inside needle capillary adsorption trap) device with Carbopack X and Carboxen 1000 as sorbent materials was applied for sampling, preconcentration and injection of C6C19n-alkanes and their monomethyl analogs in exhaled breath samples. For the analysis both GC-MS/MS and GC×GC-FID techniques were used. Identification of the analytes was based on standards, measured retention indices and selective SRM transitions of the individual isomers. The GC-MS/MS detection limits were in the range from 2.1 pg for n-tetradecane to 86 pg for 5-methyloctadecane. The GC×GC-FID detection limits ranged from 19 pg for n-dodecane to 110 pg for 3-methyloctane.


Subject(s)
Alkanes/analysis , Breath Tests/methods , Gas Chromatography-Mass Spectrometry/methods , Alkanes/chemistry , Humans , Limit of Detection , Reproducibility of Results , Tandem Mass Spectrometry/methods
3.
Ceska Slov Farm ; 61(1-2): 21-5, 2012 Feb.
Article in Slovak | MEDLINE | ID: mdl-22536649

ABSTRACT

Pharmaceutical and food industries are increasingly focused on the great potential of plant secondary metabolites or natural substances which can be used as therapeutics or model compounds for development of new drugs. The paper is devoted to the use of metabolomics, metabolic profiling and metabolic "fingerprint" for the identification of individual active phyto-substances in plant extracts, in profiling of unique groups of plant secondary metabolites that can be used to improve the classification of several species of medicinal plants as well as for a better characterization and quality control of medicinal extracts, tinctures and phytotherapeutic products prepared from these plants. Combined analytical methods and multivariate statistical analysis are used for metabolite identification. Using this approach, medicinal plants are evaluated not only on the basis of a limited number of pharmacologically important metabolites but also based on the fingerprints of minor metabolites and bioactive molecules.


Subject(s)
Metabolomics , Phytotherapy , Plants, Medicinal/chemistry , Chemistry, Analytic
4.
J Chromatogr A ; 1219: 173-6, 2012 Jan 06.
Article in English | MEDLINE | ID: mdl-22137778

ABSTRACT

The developed method for trace analysis of volatile components in plasma allows direct injection of up to 150 samples to the GC-MS/MS system without injector cleaning. This method requires no modification of plasma and the working environment does not interfere with the determination of these analytes. The method allows simultaneous quantification of non-polar sevoflurane and its polar metabolite hexafluoroisopropanol (free, unconjugated form). It is characterized by high repeatability and sensitivity with the detection limit of 0.009 mg L(-1) for sevoflurane and 0.018 mg L(-1) for hexafluoroisopropanol and the linear range 0.050-150 mg L(-1). The method was used to determine the concentration of sevoflurane and hexafluoroisopropanol in plasma samples of 7 patients undergoing general anesthesia with sevoflurane. The average concentration of sevoflurane and free hexafluoroisopropanol was 57.2 mg L(-1) and 0.39 mg L(-1), respectively. The method can be applied for clinical monitoring, as well as for analytical toxicology.


Subject(s)
Gas Chromatography-Mass Spectrometry/methods , Methyl Ethers/blood , Propanols/blood , Tandem Mass Spectrometry/methods , Anesthetics, Inhalation/blood , Humans , Limit of Detection , Linear Models , Reproducibility of Results , Sevoflurane
5.
J Chromatogr A ; 1218(13): 1767-74, 2011 Apr 01.
Article in English | MEDLINE | ID: mdl-21349524

ABSTRACT

Isomer mixtures of monomethyl branched saturated C7-C23 fatty acid methyl esters (FAME) were prepared by performing a methylene insertion reaction to the straight chain FAME and this study model was completed by using commercially available standards of C4-C7 FAME. The equivalent chain lengths (ECL) of all 220 C4-C23 monomethyl branched FAME on OV-1 stationary phase were measured, achieving an average repeatability of ±0.0004 ECL units. The monomethyl branched FAME was identified by GC on the basis of regularity of the fractional chain lengths (FCL) dependence on the number of carbon atoms (C(z)) of individual homologous series of methyl 2-, 3-, …, 21-FAME. The prediction of retention of the first homologues, having the new position of methyl group beginning at higher carbon atoms number, and analogously for the second, third, fourth, and other members of the homologous series, allowed the dependence FCL=f(C(z)) for the first and subsequent members of beginning homologous of monomethyl derivatives of FAME. The identification was confirmed by mass spectrometry. All of the methyl isomers of FAME, which could not be completely separated by gas chromatography due to having a methyl group in surroundings of the middle of the carbon chain, were resolved by mass spectrometry using deconvolution in a SIM-mode. Measured gas chromatographic and mass spectrometric data were applied for identification of the monomethyl branched saturated FAME in tongue coating.


Subject(s)
Fatty Acids/chemistry , Gas Chromatography-Mass Spectrometry/methods , Biomarkers/analysis , Biomarkers/chemistry , Fatty Acids/analysis , Humans , Molecular Structure , Silicones/chemistry , Tongue/chemistry
6.
J Chromatogr A ; 1216(14): 2757-61, 2009 Apr 03.
Article in English | MEDLINE | ID: mdl-19056089

ABSTRACT

A generally known problem of GC separation of trans-7;cis-9; cis-9,trans-11; and trans-8,cis-10 CLA (conjugated linoleic acid) isomers was studied by GC-MS on 100m capillary column coated with cyanopropyl silicone phase at isothermal column temperatures in a range of 140-170 degrees C. The resolution of these CLA isomers obtained at given conditions was not high enough for direct quantitative analysis, but it was, however, sufficient for the determination of their peak areas by commercial deconvolution software. Resolution factors of overlapped CLA isomers determined by the separation of a model CLA mixture prepared by mixing of a commercial CLA mixture and CLA isomer fraction obtained by the HPLC semi-preparative separation of milk fatty acids methyl esters were used to validate the deconvolution procedure. Developed deconvolution procedure allowed the determination of the content of studied CLA isomers in ewes' and cows' milk samples, where dominant isomer cis-9,trans-11 is eluted between two small isomers trans-7,cis-9 and trans-8,cis-10 (in the ratio up to 1:100).


Subject(s)
Gas Chromatography-Mass Spectrometry/methods , Linoleic Acids, Conjugated/isolation & purification , Milk/chemistry , Animals , Chromatography, High Pressure Liquid , Isomerism
7.
J Chromatogr A ; 1194(2): 161-4, 2008 Jun 20.
Article in English | MEDLINE | ID: mdl-18495138

ABSTRACT

A newly designed needle trap device with Carbopack X as a sorbent material is used for sampling, preconcentration and injection of volatile analytes benzene, toluene, ethylbenzene and xylenes (BTEX) into gas chromatograph. The closed system of stripping the analytes from water samples was used. An injection port with a modified metal liner was used to desorb analytes trapped in needle trap device. The main advantage of needle trap device consists in the simple methodology and easiness and rapidity of the analysis. Needle trap device is suitable for sampling in field. The experimental parameters as breakthrough volume of stripping gas, linearity, repeatability and limit of detection (LOD) and quantification (LOQ) were investigated. LOD ranges from 0.05 to 0.07 microgL(-1) and relative standard deviation ranges from 0.5% to 11.6% at concentrations 5 and 0.1 microgL(-1), respectively.


Subject(s)
Benzene Derivatives/analysis , Benzene/analysis , Chromatography, Gas/methods , Toluene/analysis , Xylenes/analysis , Chromatography, Gas/instrumentation , Solid Phase Extraction , Volatilization
SELECTION OF CITATIONS
SEARCH DETAIL
...