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Minor Extent (minor + extent)
Selected AbstractsIn Quest of the Double Rotaxane Formation of the Bis(coronand) (1,5),(2,4)-Durenetetrayl-bis(18-crown-5) with Organomagnesium CompoundsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2004Gerard P. M. van Klink Abstract The interaction between the title compound, bis(coronand) 8,and the diarylmagnesium compounds Ph2Mg and (p - tBuC6H4)2Mg in diethyl ether leads to the formation of 1:2 complexes (9 and 10, respectively), irrespective of the initial ratio of the components. In [D8]toluene, the three complex types can be discerned by 1H NMR spectroscopy: double side-on (9a, 10a), side-on/rotaxane (9b, 10b), and, to a very minor extent, double rotaxane (9c, 10c). In the case of 10a and 10b, the temperature dependence showed that rotaxane formation is enthalpically favored at the expense of a more negative entropy. As crystals suitable for structure determination could not be obtained from 9 and 10, the interaction of 8 with the sterically less demanding Hg(SCN)2 was studied. In this case, analogous pseudorotaxanes are formed exclusively, and both the 1:2 complex [8·{Hg(SCN)2}2] (11) and its 1:1 analogue 12 were observed. The double rotaxane structure of 11 was confirmed by X-ray crystal structure determination. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Mass spectrometry study of ecto-5,-nucleotidase from bull seminal plasmaFEBS JOURNAL, Issue 16 2000Carlo Fini The structure of ecto-5,-nucleotidase from bull seminal plasma, containing a glycosyl-phosphatidylinositol anchor, was studied using mass spectrometry. MALDI-MS analysis of intact protein indicated a mass of 65 568.2 Da for the monomeric form, and it also showed a heterogeneous population of glycoforms with the glycosidic moiety accounting for ,,6000 Da. MALDI-MS analysis showed that Asn53, Asn311, Asn333 and Asn403 were four sites of N -glycosylation. GC-MS analysis provided information on the glycosidic structures linked to the four asparagines. Asn53, Asn311 and Asn333 were linked to high-mannose saccharide chains, whereas the glycan chains linked to Asn403 contained a heterogeneous mixture of oligosaccharides, the high-mannose type structure being the most abundant and hybrid or complex type glycans being minor components. By combining enzymatic and/or chemical hydrolysis with GC-MS analysis, detailed characterization of the glycosyl-phpsphatidylinositol anchor was obtained. MALDI spectral analysis indicated that the glycosyl-phosphatidylinositol core contained EtN(P)Man3GlcNH2 -myo-inositol(P)-glycerol, principally modified by stearoyl and palmitoyl residues or by stearoyl and myristoyl residues to a minor extent. Moreover, 1-palmitoylglycerol and 1-stearoylglycerol outweighed 2-palmitoylglycerol and 2-stearoylglycerol. The combination of chemical and enzymatic digestions of the protein with the mass spectral analysis yielded a complete pattern of S,S bridges. The protein does not contain free thiols and its eight cysteines are linked by intramolecular disulfide bonds, the pairs being: Cys51,Cys57, Cys353,Cys358, Cys365,Cys387 and Cys476,Cys479. This work resolves details of the structure of ecto-5,-nucleotidase, with particular regard to the localization and composition of the glycidic moiety, number and localization of the disulfide bridges and characterization of the glycosyl-phosphatidylinositol anchor. [source] Annual cycle and inter-annual variability of gross primary production and ecosystem respiration in a floodprone river during a 15-year periodFRESHWATER BIOLOGY, Issue 5 2006URS UEHLINGER Summary 1. Temporal variation in ecosystem metabolism over a 15-year period (1986,2000) was evaluated in a seventh order channelised gravel bed river (mean annual discharge 48.7 m3 s,1) of the Swiss Plateau. The river is subject to frequent disturbance by bed-moving spates. Daily integrals of gross primary production (GPP) and ecosystem respiration (ER) were calculated based on single-station diel oxygen curves. 2. Seasonal decomposition of the time series of monthly metabolism rates showed that approximately 50% of the variation of GPP and ER can be attributed to season. Annual GPP averaged 5.0 ± 0.6 g O2 m,2 day,1 and showed no long-term trend. 3. Ecosystem respiration, averaging 6.2 ± 1.4 g O2 m,2 day,1, declined from 8.8 to 4.1 g O2 m,2 day,1 during the 15-year period. This significant trend paralleled a decline in nitrate and soluble reactive phosphorus concentrations, and the biochemical oxygen demand discharged by sewage treatment facilities upstream of the study reach. The ratio of GPP to ER (P/R) increased from 0.53 to about 1 as consequence of ER reduction. 4. Bed moving spates reduced GPP by 49% and ER by 19%. Postspate recovery of GPP was rapid between spring and autumn and slow during winter. Recovery of ER lacked any seasonal pattern. Annual patterns of daily GPP and to a minor extent of daily ER can be described as a sequence of recovery periods frequently truncated by spates. 5. The study showed that disturbance by frequent bed-moving spates resulted in major stochastic variation in GPP and ER but annual patterns were still characterised by a distinct seasonal cycle. It also became evident that stream metabolism is a suitable method to assess effects of gradual changes in water quality. [source] Highly Convenient, Clean, Fast, and Reliable Sonogashira Coupling Reactions Promoted by Aminophosphine-Based Pincer Complexes of Palladium Performed under Additive- and Amine-Free Reaction ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2009Jeanne Abstract Sequential addition of 1,1,,1,,-phosphinetriyltripiperidine and 1,3-diaminobenzene or resorcinol to toluene solutions of (cyclooctadiene)palladium dichloride [Pd(cod)(Cl)2] under nitrogen in "one pot" almost quantitatively yielded the aminophosphine-based pincer complexes {[C6H3 -2,6-(XP{piperidinyl}2)2]Pd(Cl)} (X=NH 1; X=O 2). Complex 1 (and to a minor extent 2) proved to be efficient Sonogashira catalysts, which allow the quantitative coupling of various electronically deactivated and/or sterically hindered and functionalized aryl iodides and aryl bromides with several alkynes as coupling partners within very short reaction times and low catalyst loadings. Importantly, in contrast to most of the Sonogashira catalysts, which either are both air- and moisture-sensitive and/or require the addition of co-catalysts, such as copper(I) iodide [CuI], for example, or a large excess of an amine, the coupling reactions were carried out without the use of amines, co-catalysts or other aditives and without exclusion of air and moisture. Moreover, the desired products were exclusively formed (no side-products were detected) without employing an excess of one of the substrates. Ethylene glycol and potassium phosphate (K3PO4) were found to be the ideal solvent and base for this transformation. Experimental observations strongly indicate that palladium nanoparticles are not the catalytically active form of 1 and 2. On the other hand, their transformation into another homogeneous catalytically active species cannot be excluded. [source] Predictive Validity of Measures of Comorbidity in Older Community Dwellers: The Insufficienza Cardiaca negli Anziani Residenti a Dicomano StudyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2 2006Mauro Di Bari MD OBJECTIVES: To compare the ability of five measures of comorbidity to predict mortality and incident disability in basic activities of daily living (BADLs) in unselected older persons. DESIGN: An assessment of the data obtained from the Insufficienza Cardiaca negli Anziani Residenti a Dicomano (ICARe Dicomano) Study, a longitudinal epidemiological survey on heart failure in older people. SETTING: Dicomano, a small, rural town near Florence, Italy. PARTICIPANTS: The entire population aged 65 and older living in Dicomano, Italy, was enrolled in the ICARe Dicomano Study. MEASUREMENTS: At baseline (1995), comorbidity was quantified in 688 participants, based on clinical diagnoses, using disease count (DC), Charlson Comorbidity Index (CCI), Index of Co-Existent Diseases (ICED), and Geriatric Index of Comorbidity (GIC), or on drug use, using Chronic Disease Score (CDS). Incident ADL disability was assessed in 1999 and vital status in 2004. RESULTS: Mortality increased with the severity of comorbidity, with hazard ratios around 2 when comparing the highest and the lowest quartiles of DC, CCI, and ICED in Cox regressions adjusted for age, sex, and physical and cognitive performance. Prediction of mortality with GIC and CDS was only borderline significant. All measures predicted incident ADL disability; the strongest risk gradient (hazard ratio=8.2 between the highest and lowest quartiles) was observed with ICED. Physical and, to a minor extent, cognitive performance added significantly to predicting mortality and incident BADL disability. CONCLUSION: All the measures of comorbidity predicted death and BADL disability in older community dwellers. DC, CCI, and ICED performed better than GIC and CDS. Physical performance measures are strong, independent contributors to the prediction of these outcomes. [source] Properties of solid solutions of poly(ethylene oxide)/epoxidized natural rubber blends and LiClO4JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008C. H. Chan Abstract Solid solutions of blends of poly(ethylene oxide) (PEO) and epoxidized natural rubber (ENR) comprising 12 wt % of LiClO4 were studied. Two glass transition temperatures, corresponding to the Tgs of the constituents, confirm immiscibility of the polymers over the entire composition range. It turns out that the Tgs of both polymers slightly increase after addition of salt to the blends. This shift is approximately constant over the whole range of blend composition. Accordingly, Tg measurements reveal that the salt dissolves to approximately equal relative amounts in the two phases. The degree of crystallinity of PEO in blends with ENR descends only to a minor extent with ENR content. However, addition of salt leads first to decreasing crystallinity and second this decrease becomes more pronounced with the addition of ENR. It shows that under these experimental conditions the salt content in PEO increases as compared to ENR. As one expects, the rate of isothermal crystallization does not change in blends as long as PEO is in excess. The situation changes again when salt is added. The rate decreases in a certain range of crystallization temperatures when ENR is added, demonstrating that salt is favorably dissolved in PEO. Conductivity was measured in polymers comprising different salt concentrations. A power-law dependence of conductivity on salt concentration was found. It results that the mobility of charge carriers in PEO exceeds that of ENR by five orders of magnitude. Therefore, the conductivity in blends is primarily governed by PEO as long as PEO is in excess. Conductivity measurements reveal again that salt is preferably dissolved in PEO. The distribution coefficient is estimated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Functions and regulation of human artemis in double strand break repair,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2007Kirsten Dahm Abstract Cells, which lacked the activity of the nuclease Artemis, retained approximately 10% of unrepaired double strand breaks (DSBs) at later timepoints after ionizing radiation. Ionizing radiation induced hyperphosphorylation of Artemis mainly by ATM and in ATM deficient cells to a minor extent by DNA PK. After induction of DSBs with modified ends by a high dose of calicheamicin ,1, Artemis was phosphorylated by DNA PK. The type of calicheamicin ,1-induced DSBs is likely to represent a subclass of DSBs induced by ionizing radiation. DNA PK-dependent phosphorylation of Artemis after treatment with DSB inducing agents increased the cellular retention of Artemis, maintained its interaction with DNA ends and activated its endonucleolytic activity. The following model is suggested: ATM-dependent phosphorylation of Artemis after ionizing radiation could prevent DNA PK-dependent phosphorylation and activation of undesired endonucleolytic activity at DSBs, which do not require endonucleolytic processing by Artemis. The Artemis:DNA PK complex could be involved in the repair of DSBs, which carry modified ends and are refractory to repair by otherwise lesion specific enzymes because of the presence of an inhibitory lesion in the opposite strand. J. Cell. Biochem. 100: 1346,1351, 2007. © 2007 Wiley-Liss, Inc. [source] New designer drug, 2,5-dimethoxy-4-propylthio-,-phenethylamine (2C-T-7): studies on its metabolism and toxicological detection in rat urine using gas chromatography/mass spectrometry,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 1 2005Denis S. Theobald Abstract Studies are described on the metabolism and toxicological analysis of the phenethylamine-derived designer drug 2,5-dimethoxy-4-propylthio-,-phenethylamine (2C-T-7) in rat urine using gas chromatography/mass spectrometry (GC/MS). The identified metabolites indicated that 2C-T-7 was metabolized by hydroxylation of the propyl side chain followed by N -acetylation and sulfoxidation and also by deamination followed by oxidation to the corresponding acid or by reduction to the corresponding alcohol. To a minor extent, 2C-T-7 was also metabolized by S -dealkylation followed by N -acetylation, S -methylation and sulfoxidation. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid,liquid extraction microwave-assisted acetylation allowed the detection of an intake of a dose of 2C-T-7 in rat urine that corresponds to a common drug users' dose. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of 2C-T-7 in human urine. Copyright © 2005 John Wiley & Sons, Ltd. [source] Influence of response factors on determining equilibrium association constants of non-covalent complexes by electrospray ionization mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2003Valérie Gabelica Abstract A method for determining the equilibrium association constant of a complexation reaction A + B , AB by electrospray ionization mass spectrometry is described. The method consists in measuring the relative intensities of the peaks corresponding to A and to AB in equimolar A,B solutions at different concentrations C0. The results are fitted by a non-linear least-squares procedure, with the two variable parameters being the equilibrium association constant Ka and a factor R, defined by I(AB)/I(A) = R × [AB]/[A]. The factor R is the ratio between the response factors of AB and A, and corrects for the relative electrospray responses of the complex and the free substrate A, mass discrimination of instrumental origin and/or moderate in-source dissociation. The method is illustrated with the following two systems: complexes between a double-stranded 12-base pair oligonucleotide and minor groove binders, and cyclodextrin complexes with ,,,-dicarboxylic acids. For the oligonucleotide complexes, it is found that the response of the complex is not dramatically different to the response of the free oligonucleotide duplex, as the double helix conformation is disturbed by the drug only to a minor extent. In the case of cyclodextrin complexes, these complexes were found to have a much higher response than free cyclodextrin. This may be due to the fact that cyclodextrin is neutral in solution, whereas the complex is charged, but it can also stem from the fact that a significant proportion of the complex is in a non-inclusion geometry. The present method requires the exact determination of the concentrations of the reactants and is applicable to 1 : 1 complexes. Copyright © 2003 John Wiley & Sons, Ltd. [source] Effect of Lewis acids on the Diels,Alder reaction in ionic liquids with different activation modesJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 4 2008Ana Vidi Abstract The Diels,Alder reaction has been examined in room temperature ionic liquids with high molar concentrations of Lewis acids under various conditions. A molar ratio of 10% catalyst gave a large increase in the selectivity and the yield of the reaction. The effect of catalysts on reaction rates was also examined under 100,MPa of pressure which leads to modest improvements in reaction rates. Ultrasound and microwave dielectric heating were also shown to improve the rate and, to a minor extent, selectivity of the examined reactions. Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis and characterization of alkylated N -vinylformamide monomers and their polymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2004Lianjun Shi Abstract N -alkyl- N -vinylformamide monomers (alkyl: n -butyl, hexyl, decyl, and dodecyl) are synthesized in two steps: first, preparation of N -vinylformamide potassium salt by the reaction of N -vinylformamide (NVF) with potassium t -butoxide, then reaction with alkyl bromide. All four monomers are liquid and are characterized by IR, 1H NMR, 13C NMR, and mass spectra. They exist as rotomers in solution and a 2D NOE experiment on the N -hexyl containing polymer shows the E isomer to be favored. The polymerizability of the four monomers is from good to fair, depending upon the length of alkyl chain on the N -atom--the longer the chain length, the lower lower the polymerizability of monomer. The hydrolysis of poly(N -hexyl- N -vinylformamide) and poly(N -dodecyl- N -vinylformamide) under acidic and basic conditions was examined. Studies show that hydrolytic cleavage of formyl groups of poly (N -alkylated- N -vinylformamide) depends on the hydrophobicity of the alkyl substituent on the N -atom under acidic conditions; both polymers were hydrolyzed to only a minor extent under alkaline conditions. The N -alkylated monomers can copolymerize with NVF and demonstrate amphiphilic properties. The copolymers demonstrate a critical aggregation concentration above which they can solubilize a water insoluble dye; the N -hexyl containing copolymer stabilizes a castor oil-in-water emulsion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4994,5004, 2004 [source] Specific IgE to allergens in cord blood is associated with maternal immunity to Toxoplasma gondii and rubella virusALLERGY, Issue 11 2008M. J. Ege Background:, Various studies have found reduced prevalences of atopic sensitization and atopic diseases in children previously exposed to infections or living conditions with a high microbial burden, such as the farming environment. Objective:, We sought to determine the relationships of cord blood immunoglobulin E (IgE) with maternal health conditions before and during pregnancy. Methods:, Pregnant women living in rural areas in five European countries were recruited in the third trimester of pregnancy. Information on maternal health during pregnancy was collected from maternity records and by questionnaires (n = 497). Specific IgE for inhalant and food allergens was assessed in cord blood and peripheral blood samples of the mothers. Results:, Inverse associations of cord blood IgE to seasonal allergens with positive maternal records for Toxoplasma gondii (adjusted odds ratio = 0.37 [0.17,0.81]) and rubella virus (adjusted odds ratio = 0.35 [0.13,0.96]) were found. The previously described effect of prenatal farm exposure on IgE to seasonal allergens was partly confounded by a positive maternal record for T. gondii. The number of maternal siblings, maternal contact to cats during pregnancy or during her first year of life, predicted a positive maternal record for T. gondii. Conclusions:, Maternal immunity to T. gondii and rubella may impact on atopic sensitization in the fetus. A positive T. gondii record explained the previously identified effect of prenatal farm exposure on IgE to seasonal allergens only to a minor extent. [source] Etomidate and thiopental inhibit platelet function in patients undergoing infrainguinal vascular surgeryACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2001A. Gries Background: Postoperative platelet hyperaggregability following general anesthesia has been reported in patients undergoing major vascular surgery. In contrast, since anesthetic agents inhibited platelet function both in vitro and in vivo, an increased risk for postoperative bleedings due to prolonged platelet dysfunction has been discussed. Nevertheless, data describing platelet-affecting properties of induction agents such as etomidate and thiopental in patients undergoing major vascular surgery are lacking. Methods: Platelet function was determined at 0, 2, 20, and 200 ,g/ml thiopental and at 0, 0.2, 2, 20 ,g/ml etomidate in vitro in blood samples drawn from 16 patients suffering from severe occlusive arterial disease. In addition, 30 patients undergoing vascular surgery were investigated before (PRE) and after anesthesia induction (T0) either with etomidate (ETO group, n=16) or thiopental (THIO group, n=14), and 2 h after the beginning of surgery (T2). Platelet function was determined according to platelet aggregation, in vitro bleeding time, and flow cytometric measurements. Results:In vitro, P-selectin expression was inhibited by etomidate at 2 and 20 ,g/ml (,28% and ,38%, respectively) and also by thiopental at 200 ,g/ml (,27%). In patients undergoing vascular surgery, anesthesia induction in the ETO group resulted in a 31% prolongation of the in vitro bleeding time and an inhibition of ADP- and collagen-induced platelet aggregation (,30% and ,17%, respectively) and of P-selectin expression (,25%) at T0. In the THIO group, only ADP-induced platelet aggregation was affected (,16%). At T2, all parameters had reached PRE level again in both groups. Furthermore, in comparison with the THIO group, operation time was significantly prolonged and transfusion volume was significantly increased in the ETO group. In addition, platelet count and hematocrit significantly decreased at T2, whereas levels of tPA, PAI-1, fibrinogen and antithrombin III and partial thromboplastin time remained unchanged in both groups during the study period. Conclusions: In the present study, etomidate and, to a minor extent, thiopental offered significant platelet inhibitory properties. Anesthetic-induced platelet inhibition may lead to higher transfusion rates and prolonged operation times. Therefore, anesthetic-related platelet inhibitory properties should be considered when searching for the anesthetic agent of choice, especially in patients with compromised hemostasis and co-existing bleeding disorders. [source] A lithium ionomer of poly(ethylene-co-methacrylic acid) copolymer as compatibilizer for blends of poly(ethylene terephthalate) and high density polyethylenePOLYMER ENGINEERING & SCIENCE, Issue 11 2002A. Retolaza Blends of 75/25 poly(ethylene terephthalate) (PET)/high density polyethylene (HDPE) containing poly(ethylene-co-methacrylic acid) partially neutralized with lithium (PEMA-Li) were obtained by direct injection molding in an attempt (i) to ameliorate the poor performance of the binary blend and (ii) to find the best compatibilizer content. The presence of PEMA-Li caused a nucleation effect on PET, and a decrease in the crystalline content of HDPE. The compatibilizing effect of PEMA-Li was due to the combined effects of interaction at the interface and chemical reactions. The ternary blends showed a complex morphology, with two dispersed HDPE and PEMA-Li phases that contained a small internal dispersed phase, probably of PET. The compatibilizing effect of PEMA-Li was clearly shown by means of an impressive increase in the ductility and to a minor extent in the impact strength. The highest property improvement (ductility increase 1450%) appeared upon the addition of 45% PEMA-Li with respect to the HDPE phase, but taking into account the recycling interest, the ternary blend with the addition of roughly 22.5% PEMA-Li appears to be the most attractive. [source] Selective solid-phase isolation of methionine-containing peptides and subsequent matrix-assisted laser desorption/ionisation mass spectrometric detection of methionine- and of methionine-sulfoxide-containing peptidesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2003Tom Grunert Methionine residues and the oxidised forms in proteins are becoming more and more important in view of their biological function. In particular, methionine sulfoxide seems to have a regulatory function. This paper presents a fast strategy for simultaneous determination of methionine- and methionine-sulfoxide-containing peptides, involving application of methionine-specific solid-phase reagent chemistry combined with matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS). In the first step, methionine-containing peptides are covalently bound as sulfonium salts to glass beads, whereas methionine-sulfoxide-containing peptides and other methionine-free peptides are not bound and are washed out. The wash solution is used for MALDI-MS analysis to determine the molecular masses of these peptides and to perform, if necessary, seamless post-source decay (PSD) fragment ion analysis. Methionine-sulfoxide-containing peptides can be identified due to the characteristic metastable loss of methanesulfenic acid from the protonated molecules. In the second step, the bound peptides are cleaved from the matrix of the beads by addition of 2-mercaptoethanol at pH,8.5,8.8. The resulting peptides, mainly methionine-containing peptides, are analysed in a straightforward manner by MALDI-MS and seamless PSD. The strategy allows the fast identification of methionine- and methionine-sulfoxide-containing peptides even in complex tryptic digests, as demonstrated here for the glycoprotein antithrombin. These results show that sometimes methionine-containing tryptic peptides are not detected due to steric restrictions (e.g. glycosylation near the methionine residue) on the binding reaction, and that, on the other hand, some methionine-free peptides can be quite strongly bound non-covalently to the matrix of the beads. The latter observation indicates the necessity of seamless PSD fragment ion analysis for unambiguous identification. Furthermore, there are indications that oxidation of some methionine residues occurred to a minor extent during the solid-phase isolation steps. Copyright © 2003 John Wiley & Sons, Ltd. [source] Liquid chromatography/tandem mass spectrometry for the identification and determination of trichothecenes in maizeRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 10 2003Aldo Laganŕ A reliable, sensitive and selective liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed to determine four trichothecene mycotoxins (nivalenol, deoxynivalenol, fusarenon X and 3-acetyldeoxynivalenol) in maize. Sample preparation was performed by extracting the analytes with a mixture of acetonitrile and water, followed by a solid-phase extraction with Carbograph-4 cartridges as the purification step. For the LC/MS/MS analysis two interfacing systems, Turbo IonSpray (TISP) and atmospheric pressure chemical ionization (APCI), were compared in both negative and positive ion modes. LC and MS parameters were optimized to achieve better results and sensitivity. The effect of mobile phase modifiers such as ammonium acetate and formic acid on the ionization yield was also evaluated. The best results were obtained using the electrospray ionization (ESI) interface in negative ion mode and the multiple reaction monitoring mode (MRM) for the quantitation. The detection limits ranged between 10,ng/g for fusarenon X and 1.5,ng/g for deoxynivalenol. A linear working range was achieved with a standard deviation between 3 and 10% and recovery rates from the maize samples above 81%. The procedure was applied to the analysis of a set of maize samples collected from farms located in different areas of northern and central Italy. The investigated samples turned out to be contaminated primarily with deoxynivalenol and, to a minor extent, with its derivatives. Copyright © 2003 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||