JOURNAL OF FOOD QUALITY, Issue 3 2007
EKERO, LU GÜLTEN
ABSTRACT Analysis of 40 oil samples showed that 38 of them were contaminated with benzo(a)pyrene (BaP). Thirty of the 38 BaP-contaminated edible oil samples did not have any label of a brand name. BaP content for the 38 contaminated edible oil samples were in the range of 1.22,74.89 ppb. Sixteen of the contaminated oil samples had BaP content of more than 10 ppb, which is the maximum tolerable limit for the Turkish Food Codex Regulation. BaP contents of samples for each type of oil were significantly different (P < 0.05) from each other. [source]

DETERMINATION OF AFLATOXIN CONTAMINATION IN OLIVES BY IMMUNOAFFINITY COLUMN USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

JOURNAL OF FOOD QUALITY, Issue 2 2006
CAVIT BIRCAN
ABSTRACT Eighty-two whole black olive samples gathered from six different olive oil processing facilities were surveyed to determine levels of aflatoxins using immunoaffinity column extraction and reversed-phase high-performance liquid chromatography. Two different analytical procedures adopted for the analysis of aflatoxins were investigated for their suitability by spiking the blank olive samples with five different known levels of aflatoxins to determine which one had higher recovery rates. Although some of the olive samples had been exposed to adverse conditions, such as rain and high temperatures, none were found to contain aflatoxins at the determined detection limit. Although the samples were kept in high relative humidity (75%) and high temperature (30C) for 3 months and were tested at 1-month intervals, no aflatoxins were detected. In addition, the olives were inoculated on a potato dextrose agar medium and incubated for 7 days at 25C to characterize the microflora. Because there is no evidence of aflatoxins in fresh whole olives, the next step of processing the contaminated olives into olive oils and testing them for the aflatoxins was not pursued. [source]

DETERMINATION OF PIGMENTS AND BINDERS IN POMPEIAN WALL PAINTINGS USING SYNCHROTRON RADIATION , HIGH-RESOLUTION X-RAY POWDER DIFFRACTION AND CONVENTIONAL SPECTROSCOPY , CHROMATOGRAPHY

ARCHAEOMETRY, Issue 2 2010
A. DURAN
The employment of synchrotron techniques complemented by conventional laboratory systems has allowed us to deepen and improve our knowledge of Roman wall painting procedures. The palette identified in wall paintings from Pompeii and Herculaneum from the second century bc includes goethite, hematite, cinnabar, glauconite, Egyptian blue, and other components such as calcite and aragonite. Proof of the use of organic binders is provided by FTIR and PY,GC/MS. Therefore, the possibility of the use of ,a secco' techniques cannot be ruled out. Pigments in wall paintings are usually found in small percentages and conventional X-ray diffractometers do not detect them. Synchrotron radiation , high-resolution X-ray powder diffraction has allowed identification with only a few micrograms of sample. [source]

THE STUDY OF NABATAEAN ORGANIC RESIDUES FROM MADÂ'IN SÂLIH, ANCIENT HEGRA, BY GAS CHROMATOGRAPHY , MASS SPECTROMETRY,

ARCHAEOMETRY, Issue 4 2009
C. MATHE
Four Nabataean samples collected in some of the monumental tombs of Madâ'in Sâlih, ancient Hegra, in Saudi Arabia, have been studied by gas chromatography coupled with mass spectrometry. These samples are textile fragments that are either covered with a black layer or bound together with some black amorphous substance. Fatty acids and triterpenoic compounds were detected. Eight triterpenic compounds were identified: ursa-9(11),12-dien-3-ol, ursa-9(11),12-dien-3-one, olean-9(11),12-dien-3,-ol, ,-amyrone, ,-amyrin, ,-amyrone, ,-amyrin and lupeol. The resinous chemical composition and these pentacyclic alcohols, in considerable proportion, indicate a resin of the Burseraceae family, possibly of the genus Canarium. [source]

Separation and Detection of Narcotic Drugs on a Microchip Using Micellar Electrokinetic Chromatography and Electrochemiluminescence

ELECTROANALYSIS, Issue 6 2008
Yan Du
Abstract A new approach for fast and sensitive electrochemiluminescence (ECL) detection of narcotic drugs on a microchip after separation by micellar electrokinetic chromatography (MEKC) is presented, taking the cocaine and its hydrolysate ecgonine as the test analytes. The mixture of hydrophilic BMIMBF4 ionic liquid (IL) and sodium dodecyl sulfate (SDS) was used directly as the buffer of MEKC with less noisy baselines, lower electrophoretic current and satisfactory separation performance. This developed microchip MEKC,ECL system was successfully applied to the determination of two very similar narcotics, heroin and codeine, within 100s in urine sample and was demonstrated as a promising method in clinical and forensic analysis. [source]

Selective Analysis of Secondary Amines Using Liquid Chromatography with Electrochemical Detection (LC-EC)

ELECTROANALYSIS, Issue 21 2006
Celia
Abstract In a mixture of primary and secondary aliphatic amines, the primary amines were derivatized (masked) with o -phthalaldehyde (OPA) followed by derivatization of the remaining secondary amines with ferrocenecarboxylic acid chloride (FAC). The "tagged" amines were analyzed by LC-EC (liquid chromatography with electrochemical detection) using in-series dual electrode detection. Chemically-reversible oxidation of the FAC tagged secondary amines and their subsequent complementary oxidation and reduction signals coupled with chemically-irreversible oxidation of OPA tagged primary amines provided the selectivity for quantitative secondary amine analysis. The procedure was also applied for the selective identification of fragment 4,11 (N -terminus-proline) of Substance P in the presence of other Substance P fragments with primary amino acids as their N -termini. [source]

Solid-Phase Reactive Chromatography (SPRC): A New Methodology for Wittig and Horner,Emmons Reactions on a Column under Microwave Irradiation

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2010
Saada C. Dakdouki
Abstract A new methodology named solid-phase reactive chromatography (SPRC), which combines reaction, separation, and purification into a single unit for the preparation of small samples, is described. This method was illustrated in the synthesis of some natural bioactive compounds, namely, methoxylated analogues of resveratrol, alkylresorcinols, and 5-aryl-2,4-pentadienoates, over a column of alumina-KF under microwave irradiation by using the Wittig and Horner,Emmons reactions. This approach permitted the preparation of the target olefins with high purity and good to excellent yields in short reaction times. [source]

Simultaneous Determination of Fluorine, Chlorine, Bromine and Iodine in Six Geochemical Reference Materials Using Pyrohydrolysis, Ion Chromatography and Inductively Coupled Plasma-Mass Spectrometry

GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 4 2009
Hélène Balcone-Boissard
halogènes; pyrohydrolyse; chromatographie ionique; spectrométrie de masse couplée à une source de plasma induit; matériaux géologiques de référence Concentrations of halogens (fluorine, chlorine, bromine and iodine) were determined in six geochemical reference materials (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2). Halogens were first extracted from powdered samples using a pyrohydrolysis technique, then hydrolysis solutions were analysed by ion chromatography for F and Cl and inductively coupled plasma-mass spectrometry for Br and I. The detection limits in solutions were 100 ,g l,1 for both F and Cl and 10 ng l,1 for Br and I. Considering the extraction procedure, performed on a maximum of 500 mg of sample and producing 100 ml of pyrohydrolysis solution, detection limits in rock samples were 20 mg kg,1 for F and Cl and 2 ,g kg,1 for Br and I. The mean analytical errors on the studied composition ranges were estimated at 10 mg kg,1 for F and Cl, 100 ,g kg,1 for Br and 25 ,g kg,1 for I. The concentration values, based on repeated (generally > 10) sample analysis, were in good agreement generally with published values and narrowed the mean dispersion around mean values. Large dispersions are discussed in terms of samples heterogeneity and contaminations during sample preparation. Basaltic RMs were found to be more suitable for studies of halogen compositions than differentiated rock material, especially granites , the powders of which were heterogeneous in halogens at the 500 mg level. Les concentrations en halogènes (fluor, chlore, brome et iode) on été déterminées dans 6 matériaux géologiques de référence (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2), distribués par le GSJ, l'USGS et le CRPG. Les halogènes étaient d'abord extraits des échantillons, disponibles sous forme de poudre, par pyrohydrolyse. F et Cl sont ensuite analysés par chromatographie ionique, Br et I par spectrométrie de masse couplée à une source de plasma induit. Les limites de détection sont de 100 ,g l,1 pour F et Cl, et de 10 ng l,1 pour Br et I, respectivement. L'extraction des halogènes était réalisée sur 500 mg de poudre de roche, produisant 100 ml de solution d'extraction. Ainsi, pour les échantillons de roche, les limites de détection étaient de 20 mg kg,1 pour F et Cl, et 2 ,g kg,1 pour Br et I. L'erreur analytique moyenne sur la gamme de concentration étudiée est estimée à 10 mg kg,1 pour F et Cl, 100 ,g kg,1 pour Br et 25 ,g kg,1 pour I. Les valeurs de concentrations données, obtenues par l'analyse répétée (> 10) du même échantillon étaient en accord avec les valeurs reportées dans la littérature. Elles présentent en général une plus faible dispersion autour de la valeur moyenne. Dans le cas d'une importante dispersion des résultats, celle-ci est discutée en terme d'hétérogénéité de l'échantillon analysé et de contamination durant la préparation du matériel de référence. Les échantillons de référence de composition basaltique se révèlent être plus appropriés pour étudier les compositions en halogènes que les matériaux correspondant à des roches différenciées, en particulier des granites dont la distribution en halogènes apparaît hétérogène dans les poudres à l'échelle d'un aliquot de 500 mg. [source]

Routine Analyses of Trace Elements in Geological Samples using Flow Injection and Low Pressure On-Line Liquid Chromatography Coupled to ICP-MS: A Study of Geochemical Reference Materials BR, DR-N, UB-N, AN-G and GH

GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2-3 2001
Jean Carignan
géostandards; éléments traces; flow injection; chromatographie liquide; ICP-MS We describe analytical procedures for trace element determinations developed at the CNRS Service d'Analyse des Roches et des Minéraux (SARM) and report results obtained for five geochemical reference materials: basalt BR, diorite DR-N, serpentinite UB-N, anorthosite AN-G and granite GH. Results for rare earth elements, U and Th are also reported for other reference materials including dunite DTS-1, peridotite PCC-1 and basalt BIR-1. All rocks were decomposed using alkali fusion. Analyses were done by flow injection ICP-MS and by on-line low pressure liquid chromatography (LC)-ICP-MS for samples containing very low REE, U and Th concentrations. This latter method yielded limits of determination much lower than data by direct introduction and eliminated possible isobaric interference on these elements. Although results agree with most of the working values, when available, results for some elements differed slightly from the recommended concentrations. In these cases, we propose new values for Co, Y and Zn in basalt BR, Zr in diorite DR-N, Sr and U in granite GH, and Ga and Y in anorthosite AN-G. Furthermore, although the Sb concentration measured in AN-G was very close to our limit of determination, our value (0.3 ± 0.1 ,g g,1) is much lower than the reported working value of 1.4 ± 0.2 ,g g,1. These new values would need to be confirmed by a new inter-laboratory programme to further characterise these reference materials. Results obtained for REE, Th and U concentrations using the on-line low pressure LC-ICP-MS yielded good limits of determination (ng g,1to sub-ng g,1for rocks and ng l,1to sub-ng l,1for natural waters) and accurate results. The efficiency of the matrix separation allowed accurate measurements of Eu without the need to correct the BaO isobaric interference for samples having Ba/Eu ratios as high as 27700. For REE concentrations in PCC-1 and DTS-1, differences with values reported in the literature are interpreted as resulting from possible heterogeneity of the reference materials. Thorium and U values are proposed for these two samples, as well as for AN-G and UB-N. Nous rapportons les procédures d'analyse pour les éléments traces développées au Service d'Analyse des Roches et des Minéraux (SARM) du CNRS et les résultats obtenus pour 5 géostandards: le basalte BR, la diorite DR-N, la serpentinite UB-N, l'anorthosite AN-G et le granite GH. Des résultats obtenus pour les Terres Rares (REE), l'uranium et le thorium sont aussi rapportés pour d'autres matériaux de référence tels que la dunite DTS-1, la péridotite PCC-1 et le basalte BIR-1. Les roches ont été décomposées par fusion alcaline. Les analyses ont été faites par Flow Injection ICP-MS et par chromatographie liquide basse pression en ligne sur un ICP-MS pour les très faibles teneurs en REE, U et Th. Cette dernière méthode permet d'avoir une meilleure limite de détermination que celle par introduction directe et d'éliminer certaines interférences isobariques sur ces éléments. Bien que, dans la majorité des cas, nous ayons mesuré les valeurs de référence telles que rapportées dans la littérature, certaines concentrations mesurées diffèrent légèrement des valeurs recommandées. Ainsi, nous proposons de nouvelles valeurs de Co, Y et Zn pour le basalte BR, de Zr pour la diorite DR-N, de Sr et U pour le granite GH et de Ga et Y pour l'anorthosite AN-G. De plus, bien que la concentration en Sb mesurée pour AN-G soit très proche de notre limite de détermination, notre valeur (0.3 ± 0.1 ,g g,1) est bien inférieure à celle rapportée dans la littérature (1.4 ± 0.2 ,g g,1). Ces nouvelles valeurs devraient être confirmées par une nouvelle campagne de caractérisation inter laboratoire pour ces géostandards. Les résultats obtenus pour les REE, U et Th par chromatographie liquide basse pression en ligne sur un ICP-MS sont justes et livrent des limites de détermination faibles au niveau du ng g,1à sub-ng g,1pour les roches et ng l,1à sub-ng l,1pour les eaux naturelles. La séparation de la matrice est efficace et permet une mesure juste de Eu sans correction d'interférence générée par l'oxyde de Ba, et ce même pour des échantillons possédant des rapports Ba/Eu très élevés, de l'ordre de 27700. Les concentrations en REE mesurées pour les échantillons PCC-1 et DTS-1 peuvent être significativement différentes de celle rapportées dans la littérature, probablement à cause d'une hétérogénéité de ces échantillons. Des valeurs de concentrations en U et Th sont proposées pour ces deux échantillons ainsi que pour AN-G et UB-N. [source]

Drug,Membrane Interaction on Immobilized Liposome Chromatography Compared to Immobilized Artificial Membrane (IAM), Liposome/Water, and Octan-1-ol/Water Systems

HELVETICA CHIMICA ACTA, Issue 2 2010
Xiangli Liu
Abstract The objective of this study was to investigate drug,membrane interaction by immobilized liposome chromatography (ILC; expressed as lipophilicity index log,Ks) and the comparison with lipophilicity indices obtained by liposome/H2O, octan-1-ol/H2O, and immobilized artificial membrane (IAM) systems. A set of structurally diverse monofunctional compounds and drugs (nonsteroidal anti-inflammatory drugs and , -blockers) were selected in this study. This set of solutes consists of basic or acidic functionalities which are positively or negatively charged at physiological pH,7.4. No correlation was found between log,Ks from ILC and lipophilicity indices from any of the other membrane model systems for the whole set of compounds. For structurally related compounds, significant correlations could be established between log,Ks from ILC and lipophilicity indices from IAM chromatography and octan-1-ol/H2O. However, ILC and liposome/H2O systems only yield parallel partitioning information for structurally related large molecules. For hydrophilic compounds, the balance between electrostatic and hydrophobic interactions dominating drug partitioning is different in these two systems. [source]

Thin Layer Chromatography for the Detection of Unexpected Reactions in Organometallic Combinatorial Catalysis

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2003
Olivier Lavastre
Abstract Thin layer chromatography (TLC) represents a fast and inexpensive alternative to NMR spectroscopy or analytical methods based on chromatography for the detection of unexpected products in organometallic combinatorial catalysis. This screening test led to the detection of the catalytic system [Ir(COD)Cl]2/PPh3 for isomerisation of diolefinic substrates instead the expected ring closing metathesis (RCM) reaction. [source]

PURIFICATION AND CHARACTERIZATION OF BACTERIOCIN FROM WEISSELLA PARAMESENTEROIDES DFR-8, AN ISOLATE FROM CUCUMBER (CUCUMIS SATIVUS)

JOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2010
AJAY PAL
ABSTRACT Bacteriocin from Weissella paramesenteroides DFR-8 isolated from cucumber (Cucumis sativus) was purified by using only two steps, viz., pH-mediated cell adsorption,desorption method and gel permeation chromatography. A single peak observed in the purity check by analytical Reverse Phase-High Performance Liquid Chromatography (Waters 600 analytical HPLC system, Milford, MA) and a single band (molecular weight,3.74 kDa) shown on SDS-PAGE analysis strongly indicated the homogeneity of the bacteriocin preparation. Treatment with proteolytic enzymes abolished the antimicrobial activity indicating the proteinaceous nature of bacteriocin. The purified bacteriocin exhibited a broad inhibitory spectrum against foodborne pathogens and spoilage microorganisms, including gram-negative bacteria such as Salmonella typhimurium, Vibrio parahaemolyticus, Aeromonas hydrophila and Listeria monocytogenes. Response surface methodology was employed to study the interactive effect of temperature and pH on bacteriocin activity, and a regression equation was developed. The bacteriocin retained full activity after storage at,20C for 90 days, while partial and complete activity loss was observed when stored at 4 and 37C, respectively. PRACTICAL APPLICATION In recent years, bacteriocins of lactic acid bacteria have gained much attention as food biopreservatives because of their origin from generally regarded as safe organisms. In spite of various bacteriocins studied worldwide, studies on bacteriocins of Weissella paramesenteroides remain rare. The present work involves the purification of bacteriocin up to absolute homogeneity from W. paramesenteroides, an isolate first time reported from cucumber (Cucumis sativus). The purified bacteriocin (molecular weight ,3.74 kDa) was found to inhibit a large number of foodborne pathogens, including Listeria monocytogenes, which is resistant to commercially available bacteriocin, i.e., nisin. The application of central composite rotatable design enabled us to design a regression equation from which the residual activity of bacteriocin can be predicted at any given conditions of temperature and pH within the experimental domain. The broad inhibitory spectrum and thermostability of bacteriocin suggest its potential application in food preservation. [source]

Analysis of Volatile Compounds in Beef Fat by Dynamic-Headspace Solid-Phase Microextraction Combined with Gas Chromatography,Mass Spectrometry

JOURNAL OF FOOD SCIENCE, Issue 5 2008
A. Watanabe
ABSTRACT:, A solid-phase microextraction (SPME) technique has been applied to the determination of the volatile compounds, including diterpenoids and lactones, in cooked beef fat. The ability of static-headspace SPME to extract lactones was disappointing, regardless of the type of SPME fiber or the temperature used. Dynamic-headspace SPME extraction with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C, by contrast, enabled the analysis of volatiles, including delta-lactones, gamma-lactones, and diterpenoids, with 50-/30-,m divinylbenzene-Carboxen on a polydimethylsiloxane fiber at 100 °C. Fifty-three compounds were identified from only 0.20 g of rendered beef fat, and 76% of these showed reliable peak size repeatability: the coefficient of variation was less than 10% on the total ion chromatograms obtained from gas chromatography,mass spectrometry (GC,MS) analysis. Some lactones showed higher CV values (>10%), but single-ion mode GC,MS analysis reduced them to 10% or less. In a study of beef samples available to the Japanese market, our analytical procedure revealed significantly higher levels of 1-hexanol, octadecane, ethyl tetradecanoate, gamma-nonalactone, but lower levels of delta-decalactone, delta-dodecalactone, and neophytadiene, in Japanese Black cattle than in beef imported from Australia. [source]

Effect of Conductivity, pH, and Elution Buffer Salinity on Glycomacropeptide Recovery from Whey Using Anion Exchange Chromatography

JOURNAL OF FOOD SCIENCE, Issue 4 2005
Hatice N. Tek
ABSTRACT: The objective of this study was to investigate the effect of whey conductivity, pH, and the salt concentration of the elution buffer on glycomacropeptide recovery and its extent of contamination using anion exchange chromatography. Glycomacropeptide was isolated from Mozzarella whey. Samples were analyzed for glycomacropeptide and contaminating whey proteins. Mass balances and percent recoveries were calculated from these data. Glycomacropeptide recovery increased substantially with decreasing conductivity and increasing pH of the whey feed stream. Increasing the pH, but not increasing the conductivity, increased contamination of the glycomacropeptide by primarily beta-lactoglobulin. Salt concentration of at least 0.1 M was required for complete elution of bound glycomacropeptide. These data define conditions needed for glycomacropeptide recovery by a process chromatography system that uses food-grade buffers, operates at industrially relevant flow rates, and achieves up to 98% recovery. [source]

Whey Protein Isolate and ,-Lactalbumin Recovery from Lactic Acid Whey Using Cation-Exchange Chromatography

JOURNAL OF FOOD SCIENCE, Issue 2 2004
K. N. Turhan
ABSTRACT: The objective of this work was to develop a process to fractionate proteins from lactic acid whey, which is underused compared with sweet whey, using food-grade buffers and cation-exchange chromatography. Bound proteins were desorbed either all at once to make whey protein isolate (WPI), or in 2 steps to 1st make ,-lactalbumin (ALA) and then WPI depleted in ALA. Recovery and purity using lactic acid whey were comparable to previously reported processes using sweet whey. Capacity and throughput were slightly lower using lactic acid whey. This research provides a basis for adding value to the 6 million metric tons of lactic acid whey produced annually in the United States. [source]

Isolation and Identification of Bitter Peptides of Tryptic Hydrolysate of Soybean 11S Glycinin by Reverse-phase High-performance Liquid Chromatography

JOURNAL OF FOOD SCIENCE, Issue 8 2003
I M.-R.
ABSTRACT: The 21 peptides purified from the bitter fraction of tryptic hydrolysates of soybean 11S glycinin by using gel-permeation high-performance liquid chromatography (HPLC) and a series of 3 C18 reverse phase (RP)-HPLC were in the molecular weight range of 200-1400 Da and showed mostly the hydrophobicity of less than 1400 cal/mol. Although the primary structures of the bitter peptides from 11S glycinin were not exactly the same as those of the proglycinin, many bitter peptides were basic mimics of the common structure, indicating the significance of the primary structure of a peptide playing a role in the bitter taste perception. [source]

Capillary Zone Electrophoresis and Micellar Electrokinetic Capillary Chromatography for Determining Water-Soluble Vitamins in Commercial Capsules and Tablets

JOURNAL OF FOOD SCIENCE, Issue 1 2001
S-C. Su
ABSTRACT: A rapid method was developed for simultaneously determining thiamine, riboflavin, pyridoxine, nicotinamide, nicotinic acid, and ascorbic acid. It was tested on 15 samples. The peaks of all components were cleanly separated with good resolution by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MECC). CZE was performed with 0.02 M borate buffer, and MECC was performed with 4% acetonitrile in 0.02 M borate/phosphate buffer containing 0.1 M sodium dodecyl sulfate. Average recoveries for all components were 80.3% to 103.7% with coefficients of variation being less than 5%. Thiamine, nicotinic acid, and pyridoxine contents were consistent with those labeled on the packages, but nicotinamide, riboflavin, and ascorbic acid contents of some samples were less. [source]

Analyses of Glycolipids in Clove, Red Pepper, and Nutmeg by High-Performance Liquid Chromatography

JOURNAL OF FOOD SCIENCE, Issue 6 2000
H. Suzuki
ABSTRACT: To determine the existence of glycolipids (neutral glycosphingolipid and glycoglycerolipid) in clove, red pepper, and nutmeg, we performed silica gel chromatography and high-performance liquid chromatography (HPLC) using an Aquasil-SS column and a C8 -reversed-phase silica gel column. HPLC (Aquasil-SS column) with a UV absorption detector was used to analyze neutral glycosphingolipid. These chromatograms showed two typical peaks in clove lipids. UV-HPLC (C8 -reversed phase silica gel column) was also used to analyze glycoglycerolipid. The chromatograms indicated a small peak in clove lipids. Moreover, we observed the same two peaks in the glycolipid fraction of clove lipid when we used HPLC (Aquasil-SS column) with a differential refractometer detector. These results suggest that clove may contain new and plural neutral glycosphingolipids. [source]

Age Determination of Ballpoint Pen Ink by Thermal Desorption and Gas Chromatography,Mass Spectrometry,

JOURNAL OF FORENSIC SCIENCES, Issue 4 2008
Jürgen H. Bügler Ph.D.
Abstract:, Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography,mass spectrometry (GC,MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. [source]

Blood Cyanide Determination in Two Cases of Fatal Intoxication: Comparison Between Headspace Gas Chromatography and a Spectrophotometric Method*

JOURNAL OF FORENSIC SCIENCES, Issue 6 2007
Veniero Gambaro M.Sc.
Abstract:, Blood samples of two cases were analyzed preliminarily by a classical spectrophotometric method (VIS) and by an automated headspace gas chromatographic method with nitrogen-phosphorus detector (HS-GC/NPD). In the former, hydrogen cyanide (HCN) was quantitatively determined by measuring the absorbance of chromophores forming as a result of interaction with chloramine T. In the automated HS-GC/NPD method, blood was placed in a headspace vial, internal standard (acetonitrile) and acetic acid were then added. This resulted in cyanide being liberated as HCN. The spectrophotometric (VIS) and HS-GC/NPD methods were validated on postmortem blood samples fortified with potassium cyanide in the ranges 0.5,10 and 0.05,5 ,g/mL, respectively. Detection limits were 0.2 ,g/mL for VIS and 0.05 ,g/mL for HS-GC/NPD. This work shows that results obtained by means of the two procedures were insignificantly different and that they compared favorably. They are suitable for rapid diagnosis of cyanide in postmortem cases. [source]

Research Article: Fingerprinting Analysis of Saposhnikovia divaricata using 1H Nuclear Magnetic Resonance Spectroscopy and High Performance Liquid Chromatography

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2010
Yue-Yang Xin
The 1H nuclear magnetic resonance (1H NMR) fingerprints of fractionated non-polar and polar extracts (control substance for plant drug [CSPD] A and B) from the roots of 12 specimens of Saposhnikovia divaricata (Turcz.) Schischk were achieved with Fourier Transform (FT)-NMR spectrometer and assigned by comparison to each other and to the 1H NMR spectra of the isolated individual compounds. These fingerprints were found to be uniform in terms of the specificity for the implication of all 12 specimens being systematically of the same origin. The uniformity was further affirmed by high performance liquid chromatography (HPLC), which also revealed exactly identical specificity for the identified S. divaricata species with the 1H NMR appearances of corresponding CSPD on the part of the composition of characteristic constituents when comparing to corresponding individual compounds. This investigation unambiguously shows that the specific signals from the chemotaxonomically significant compounds of chromones and coumarins in S. divaricata are exhibited distinctively in the composite features of both 1H NMR fingerprints and HPLC profiles. The 1H NMR and HPLC profiles established can successfully be used as reference for the authentication of the origin of S. divaricata species as well as for chemotaxonomic studies. [source]

The application of carbon isotope ratio mass spectrometry to doping control

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2008
Adam T. Cawley
Abstract The administration of synthetic steroid copies is one of the most important issues facing sports. Doping control laboratories accredited by the World Anti-Doping Agency (WADA) require methods of analysis that allow endogenous steroids to be distinguished from their synthetic analogs in urine. The ability to measure isotope distribution at natural abundance with high accuracy and precision has increased the application of Gas Chromatography,Combustion,Isotope Ratio Mass Spectrometry (GC,C,IRMS) to doping control in recent years. GC,C,IRMS is capable of measuring the carbon isotope ratio (,13C) of urinary steroids and confirm their synthetic origin based on the abnormal 13C content. This tutorial describes some of the complexities encountered by obtaining valid ,13C measurements from GC,C,IRMS and the need for careful interpretation of all relevant information concerning an individual's metabolism in order to make an informed decision with respect to a doping violation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Determination of clavulanic acid in calf plasma by liquid chromatography tandem mass spectrometry

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 11 2006
Tim Reyns
Abstract A method for the quantification of clavulanic acid in calf plasma using high-performance liquid chromatography combined with electrospray ionization (ESI) mass spectrometry, operating in the negative ionization mode (LC-MS/MS), is presented. Sample preparation includes a simple and fast deproteinization with acetonitrile and a back-extraction of the acetonitrile with dichloromethane. Chromatography is performed on a reversed-phase PLRP-S polymeric column using 0.05% formic acid in water and acetonitrile. The limit of quantification is 25 ng/ml, which is lower than other published methods using ultraviolet (UV), fluorimetric or mass spectrometric detection. The limit of detection is calculated to be 3.5 ng/ml. The stability of clavulanic acid was demonstrated according to The Guidelines of Bioanalytical Method Validation of The Food and Drug Administration (FDA): freeze and thaw stability, short-term stability, long-term stability, stock solution stability and postpreparative stability. The method is used in a pharmacokinetic and bioequivalence study of amoxycillin/clavulanic acid formulations in calves. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Ticlopidine quantification in human plasma by high-performance liquid chromatography coupled to electrospray tandem mass spectrometry.

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 12 2004
Application to bioequivalence study
Abstract A rapid, sensitive and specific method to quantify ticlopidine in human plasma using clopidogrel as the internal standard (IS) is described. The analyte and the IS were extracted from acidified plasma by liquid,liquid extraction using diethyl ether,hexane (80 : 20, v/v). The extracts were analyzed by high-performance liquid chromatography coupled to electrospray tandem mass spectrometry (HPLC/MS/MS). Chromatography was performed isocratically on a Jones Genesis C8 4 µm analytical column (150 × 4.1 mm i.d.). The method had a chromatographic run time of 3.0 min and a linear calibration curve over the range 1.0,1000 ng ml,1 (r2 > 0.999427). The limit of quantification was 1.0 ng ml,1. This HPLC/MS/MS procedure was used to assess the bioequivalence of two ticlopidine 250 mg tablet formulations (ticlopidine test formulation from Apotex do Brasil, Brazil, and Ticlid from Sanofi-Synthelabo, standard reference formulation). A single 250 mg dose of each formulation was administered to healthy volunteers. The study was conducted using an open, randomized, two-period crossover design with a 2 week washout interval. Since the 90% confidence interval for Cmax and area under the curve ratios were all inside the 80,125% interval proposed by the US Food and Drug Administration, it was concluded that ticlopidine formulation from Apotex do Brasil is bioequivalent to Ticlid formulation with respect to both the rate and the extent of absorption. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Increased synthesis but decreased processing of neuronal proCCK in prohormone convertase 2 and 7B2 knockout animals

JOURNAL OF NEUROCHEMISTRY, Issue 6 2002
Jens F. Rehfeld
Abstract In addition to its role as a gut hormone, cholecystokinin (CCK) is a widespread and potent neurotransmitter. Its biosynthesis requires endoproteolytic cleavage of proCCK at several mono- and dibasic sites by subtilisin-like prohormone convertases (PCs). Of these, PC1 and PC2 are specific for neuroendocrine cells. We have now examined the role of PC2 and its binding protein, 7B2, in the neuronal processing of proCCK by measurement of precursor, processing-intermediates and bioactive end-products in brain extracts from PC2- and 7B2-null mice and from corresponding controls. PC2-null mice displayed a nine-fold increase of cerebral proCCK concentrations, and a two-fold increase in the concentrations of the processing-intermediate, glycine-extended CCK, whereas the concentrations of transmitter-active (i.e. ,-amidated and O -sulfated) CCK peptides were reduced (61%). Chromatography showed that O -sulfated CCK-8 still is the predominant transmitter-active CCK in PC2-null brains, but that the fraction of intermediate-sized CCK-peptides (CCK-58, -33 and -22) was eight-fold increased. 7B2-null brains displayed a similar pattern but with less pronounced precursor accumulation. In contrast with the cerebral changes, PC2 deficiency was without effect on proCCK synthesis and processing in intestinal endocrine cells, whereas 7B2 deficiency halved the concentration of bioactive CCK in the intestine. The results show that PC2 plays a major neuron-specific role in the processing of proCCK. [source]

The detection and quantification of lorazepam and its 3- O -glucuronide in fingerprint deposits by LC-MS/MS

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2009
Edward Goucher
Abstract The use of fingerprints as an alternative biological matrix to test for the presence of drugs and/or their metabolites is a novel area of research in analytical toxicology. This investigation describes quantitative analysis for the benzodiazepine lorazepam and its 3- O -glucuronide conjugate in fingerprints following the oral administration of a single 2 mg dose of lorazepam to five volunteers. Creatinine was also measured to investigate whether the amount of drug relative to that of creatinine would help to account for the variable amount of secretory material deposited. Fingerprints were deposited on glass cover slips and extracted by dissolving them in a solution of dichloromethane/methanol, containing tetradeuterated lorazepam as an internal standard. The samples were evaporated, reconstituted with mobile phase and analysed by LC-MS/MS. Chromatography was achieved using an RP (C18) column for the analysis of lorazapem and its glucuronide, and a hydrophilic interaction column (HILIC) for the analysis of creatinine. Lorazepam and its glucuronide were only detected where ten prints had been combined, up to 12 h following drug administration. In every case, the amount of lorazepam glucuronide exceeded that of lorazepam, the peak amounts being 210 and 11 pg, respectively. Adjusting for creatinine smoothed the elimination profile. To our knowledge, this represents the first time a drug glucuronide has been detected in deposited fingerprints. [source]

Book News: Static Headspace-Gas Chromatography.

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2006
Bruno / Ettre, Edited by Kolb, Leslie S.
[source]

Editorial: Chromatography in the Third World and in the First World

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2005
Philip Marriott
[source]

Advances in Chromatography and Electrophoresis & Chiranal 2005

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2005
Salvatore Fanali
[source]

EuSSS Meeting, held at Paris, October 7, 2004, 18:00,19:00 h, during the 25th International Symposium on Chromatography

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2005
Francesco Dondi
[source]