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Peak Area (peak + area)
Selected AbstractsDEVONIAN CARBONATES OF THE NIGEL PEAK AREA, ROCKY MOUNTAINS, CANADA: A FOSSIL PETROLEUM SYSTEM?JOURNAL OF PETROLEUM GEOLOGY, Issue 3 2008J. Köster In this study we report on Devonian (Frasnian , Famennian) limestones and dolostones exposed near Nigel Peak in the Main Ranges of the Canadian Rocky Mountains. These carbonates are a proximal facies of the Southesk-Cairn Carbonate Complex. The investigated strata are stratigraphically equivalent to the oil- and gas bearing Nisku Formation in the subsurface of the Western Canada Sedimentary Basin, about 300 km to the east. The rocks were investigated by polarisation and cathodoluminescence microscopy, total organic carbon analysis, Rock-Eval pyrolysis, solid bitumen reflectance measurements, gas chromatography and fluid inclusion analysis. Thin section analyses showed that silt-grade quartz and saddle dolomite increase upward from the base of the stratigraphic section, and that porosities are generally low. This is due to reduction of pore space due to early cementation and extensive dolomitization. Cathodoluminescence identified up to four generations of calcite cements. TOC values ranged from 0.2 to 2.4 %. Rock-Eval pyrolysis of carbonate samples resulted in measurable S1 peaks but not S2 peaks, indicating that there was no residual petroleum generation potential. Organic petrographic analyses identified dispersed kerogen and migrabitumen, and calculated vitrinite reflectance values were around 4 % on average which implies peak temperatures of 234,262 °C (due to deep burial) or 309,352 °C (due to short term hydrothermal heating). Fluid inclusion data indicates at least one pulse of hot fluids with elevated homogenization temperatures of > 300 °C, and this may explain the high thermal maturity of the studied rocks. [source] On-line preconcentration and enantioseparation of thalidomide racemates by CEC with the hyphenation of octyl and norvancomycin monolithsELECTROPHORESIS, Issue 4 2009An-Na Tang Abstract A method was developed for simultaneous preconcentration and chiral separation of thalidomide enantiomers in human urine by CEC in combination with self-concentration and solvent gradient effects. A 4,cm long octyl (C8) monolithic column was hyphenated with a 15,cm long norvancomycin (NVC)-bonded monolithic column via a fluorinated ethylene,propylene interface. Sample solution was injected into the C8 monolithic column, the two thalidomide enantiomers were first preconcentrated on the C8 monolithic column, and then separated with a further concentration on the NVC-bonded monolithic column by CEC. Injection of 34.8,mm plug of sample solution gave 278- and 298-fold enhancement in sensitivity, and detection limits of 90 and 94,,g/L for the two thalidomide enantiomers. Peak areas of the two isomers were linear in a range of 0.5,50,mg/L. The precision for five replicate injections of 10,mg/L were 0.8,0.9 and 1.1,2.3% for the migration time and peak height, respectively. The developed method was applied to the determination of racemic thalidomide in spiked human urine samples. [source] Role of Proton Magnetic Resonance Spectroscopy in Differentiating Oligodendrogliomas from AstrocytomasJOURNAL OF NEUROIMAGING, Issue 1 2010Sanjeev Chawla PhD ABSTRACT BACKGROUND AND PURPOSE Preoperative differentiation of astrocytomas from oligodendrogliomas is clinically important, as oligodendrogliomas are more sensitive to chemotherapy. The purpose of this study was to assess the role of proton magnetic resonance spectroscopy in distinguishing astrocytomas from oligodendrogliomas. METHODS Forty-six patients [astrocytomas (n= 17) and oligodendrogliomas (n= 29)] underwent magnetic resonance imaging and multi voxel proton magnetic resonance spectroscopic imaging before treatment. Peak areas for N-acetylaspartate (NAA), creatine (Cr), choline (Cho), myo-inositol (mI), glutamate/glutamine (Glx), and lipids + lactate (Lip+Lac) were analyzed from voxels that exhibited hyperintensity on fluid-attenuated inversion recovery images and were normalized to Cr from each voxel. The average metabolite/Cr ratios from these voxels were then compared between astrocytomas and oligodendrogliomas. Receiver-operating curve analyses were used as measures of differentiation accuracy of metabolite ratios. A threshold value for a metabolite ratio was estimated by maximizing the sum of sensitivity and specificity. RESULTS A significant difference in mI/Cr was observed between astrocytomas and oligodendrogliomas (.50 ± .18 vs. 0.66 ± 0.20, P < .05). Using a threshold value of .56 for mI/Cr ratio, it was possible to differentiate oligodendrogliomas from astrocytomas with a sensitivity of 72.4% and specificity of 76.4%. CONCLUSION These results suggest that mI/Cr might aid in distinguishing oligodendrogliomas from astrocytomas. J Neuroimaging 2010;20:3-8. [source] Investigation of metabolite changes in the transition from pre-invasive to invasive cervical cancer measured using 1H and 31P magic angle spinning MRS of intact tissueNMR IN BIOMEDICINE, Issue 2 2009Sonali S. De Silva Abstract The aim of this study was to determine the metabolic changes in the transition from pre-invasive to invasive cervical cancer using high-resolution magic angle spinning (HR-MAS) MRS. Biopsy specimens were obtained from women with histologically normal cervix (n,=,5), cervical intraepithelial neoplasia (CIN; mild, n,=,5; moderate/severe, n,=,40), and invasive cancer (n,=,23). 1H HR-MAS MRS data were acquired using a Bruker Avance 11.74,T spectrometer (Carr,Purcell,Meiboom,Gill sequence; TR,=,4.8,s; TE,=,135,ms; 512 scans; 41,min acquisition). 31P HR-MAS spectra were obtained from the normal subjects and cancer patients only (as acetic acid applied before tissue sampling in patients with CIN impaired spectral quality) using a 1H-decoupled pulse-acquire sequence (TR,=,2.82,s; 2048 scans; 96,min acquisition). Peak assignments were based on values reported in the literature. Peak areas were measured using the AMARES algorithm. Estimated metabolite concentrations were compared between patient diagnostic categories and tissue histology using independent samples t tests. Comparisons based on patient category at diagnosis showed significantly higher estimated concentrations of choline (P,=,0.0001) and phosphocholine (P,=,0.002) in tissue from patients with cancer than from patients with high-grade dyskaryosis, but no differences between non-cancer groups. Division by histology of the sample also showed increases in choline (P,=,0.002) and phosphocholine (P,=,0.002) in cancer compared with high-grade CIN tissue. Phosphoethanolamine was increased in cancer compared with normal tissue (P,=,0.0001). Estimated concentrations of alanine (P,=,0.01) and creatine (P,=,0.008) were significantly reduced in normal tissue from cancer patients compared with normal tissue from non-cancer patients. The estimated concentration of choline was significantly increased in CIN tissue from cancer patients compared with CIN tissue from non-cancer patients (P,=,0.0001). Estimated concentrations of choline-containing metabolites increased from pre-invasive to invasive cervical cancer. Concurrent metabolite depletion occurs in normal tissue adjacent to cancer tissue. Copyright © 2008 John Wiley & Sons, Ltd. [source] Microfluidic chip-capillary electrophoresis for two orders extension of adjustable upper working range for profiling of inorganic and organic anions in urineELECTROPHORESIS, Issue 18 2010Wen Peng Guo Abstract To meet the need for onsite monitoring of urine anions, a microfluidic chip-capillary electrophoresis device was designed, fabricated and tested to extend the upper CE working range for an enhancement up to 500 fold (100 fold for sample dilution and 5 folds for CE injection) in order to analyze highly variable anionic metabolites in urine samples. Capillaries were embedded between two PMMA plates with laser-fabricated microchannel patterns to produce the microfluidic chip-capillary electrophoresis to perform standard/sample dilution and CE injection with adjustable dilution ratios. A circular ferrofluid valve was incorporated on-chip to perform cleanup and conditioning, mixing and dilution, injection and CE separation. Under optimized conditions, a complete assay for four samples can be achieved within an hour for 15 anions commonly found in urines. Satisfactory working ranges (0.005,500,mM) and low detection limits (0.5,6.5,,M based on S/N =2) are obtained with satisfactory repeatability (RSD, n=5) 0.52,0.87% and 4.1,6.5% for migration time and peak area, respectively. The working ranges with two orders adjustable upper extension are adequate to cover all analytes concentrations commonly found in human urine samples. The device fabricated shows sufficiently large experimentally verifiable enhancement factor to meet the application requirements. Its reliability was established by more than 94% recoveries of spiked standards and agreeable results from parallel method comparison with conventional ion chromatography method. The extension of the upper CE working range enables flexible onsite dilution on demand, a quick turn-around of results, and a low-cost device suitable for bedside monitoring of patients under critical conditions for metabolic disorders. [source] Electromigration diffusivity spectrometry: A way for simultaneous determination of diffusion coefficients from mixed samplesELECTROPHORESIS, Issue 17 2010Suhua Yang Abstract A novel method was proposed for simultaneous measurement of diffusion coefficients, (D), from mixed samples by electrophoresis and termed electromigration-based diffusivity spectrometry. After theoretical treatment, D- equation for practical use has been deduced. With a modified CE system built in laboratory, electromigration-based diffusivity spectrometry has been realized and validated to suit for fast and accurate determination of diffusivities of mixed aromatic amino acids, phenols and aromatic organic acid, giving diffusivity spectra by peak area versus D, much similar to mass spectra. The precision of the measurement was found to critically depend on pH value of running buffer, which should be so selected that the analytes and internal standards could be charged at above 0.5e. The standards have to be selected at an electric flux far from each other and from analytes. In these cases, sample and running buffer concentrations, voltage and system temperature were found to have only negligible impact on the determination. In our test, the obtained measuring precision was generally kept within 1% for five runs, and the measured values of D agreed well with those from literature, with a deviation of less than 2.2% after the right use of calibration standards. [source] SPE and large-volume sample stacking in MEKC for determination of doxycycline in biological fluids: Comparison of direct injection to SPE-MEKCELECTROPHORESIS, Issue 21 2008Rade Injac Abstract A novel and simple method has been developed for the determination of doxycycline (DOX) in biological fluids. The method is based on SPE, large-volume sample stacking (LVSS) and MEKC with UV-DAD detection. Six SPE cartridges have been used in investigation for sample clean up and pre-concentration (Supelco® LC-8, LC-18, LC-SCX, and LC-WCX, as well as StrataÔ-X and X-C). DOX was determined on a 56,cm (effective length 50,cm)×50,,m id fused-silica capillary. The BGE was 20,mM borate buffer, pH 9.3, containing 80,mM SDS and 7.5%,v/v of methanol (30,s×50,mbar), and the temperature and voltage were 25°C and 30,kV, respectively. The analytical wavelength was set at 210,nm. Under optimized conditions it is possible to determine DOX in human serum, urine, semen, tears and saliva with recovery of 97.5% (RSD 2.5%). The method was shown to be sensitive (LOD is 1,,g/L) and precise (intra-day RSD 0.2 and 2.4%; inter-days 0.4 and 3.5% for migration time and peak area, respectively). Results for developed SPE-LVSS-MEKC were compared with LVSS-MEKC method with direct sample injection. The new LVSS-MEKC method is presented as a useful technique for rapid determination without extraction procedure of DOX in human urine and serum, using 80,mM of SDS, 10%,v/v of methanol and 40,mM borate buffer (pH 9.3; 30,s×50,mbar; 25°C; 30,kV; 350,nm), but not for the other biological fluids, according to lower sensitivity of the method and because of the sample composition. [source] Determination of gaseous and particulate carbonyls in air by gradient-elution micellar electrokinetic capillary chromatographyELECTROPHORESIS, Issue 19 2008Hui Sun Abstract A new continuous-flow gradient-elution micellar electrokinetic capillary chromatography method is developed for the determination of airborne carbonyls after derivatization with 2,4-dinitrophenylhydrazine. A total of 16 carbonyls can be determined with detection limits ranging from 0.94 to 8.50,mg/L, working range from 4.72 to 346,mg/L, and repeatabilities (relative standard deviation, n=5) from 1.23 to 4.6% or 3.93 to 7.6% for migration time and peak area, respectively. Coupling with denuder-filter sampling, a preliminary survey has been conducted to determine gaseous and particulate carbonyls from air sampled at a roadside station. The method is shown to have sufficient sensitivity for 1-h sampling of ambient carbonyls with detection limits ranging from 0.045 to 1.2,,g/m3 and working range from 0.11 to 43.3,,g/m3 at a flow rate of 10,Lpm. The method requires minimal modification of commercially available capillary electrophoresis equipment and can differentiate gaseous and particulate carbonyls to provide essential information and objective data for adopting effective measures to combat the discharge of carbonyl compounds to the atmosphere. [source] Fast quantitative determination of diuretic drugs in tablets and human urine by microchip electrophoresis with native fluorescence detectionELECTROPHORESIS, Issue 16 2007Kamal Tolba Abstract Microchip electrophoresis (MCE) with native fluorescence detection has been applied for the fast quantitative analysis of pharmaceutical formulations. For this purpose, methods for fast separation and sensitive detection of the unlabeled diuretic drugs, amiloride, triamterene, bendroflumethiazide (BFMTZ), and bumetanide were developed. An epifluorescence setup was used enabling the coupling of different lasers into a commercial fluorescence microscope. The detection sensitivity of different excitation light sources was compared utilizing either a HeCd laser (,exc,=,325,nm), a frequency quadrupled Nd:YAG laser (,exc,=,266,nm), or a mercury lamp (,exc,=,330,380,nm). At optimal conditions using the HeCd laser, the drugs were separated within 15,s with LODs less than 1,,g/mL for the four compounds. A linear relationship between concentration and peak area was obtained in the concentration range of 0.05,20,,g/mL with a mean correlation coefficient of around 0.996 for all analytes. The method was successfully applied to the analysis of the respective drugs in commercial formulations and in human urine without interference from other constituents. These data show that MCE has a great potential for reliable drug analysis. [source] Determination of xanthohumol in hops (Humulus lupulus L.) by nonaqueous CEELECTROPHORESIS, Issue 6 2007Javor Kac Dr. Abstract Xanthohumol (XN) is a prenylated chalcone with antimutagenic and anticancer activity from hops. A nonaqueous reverse polarity capillary electrophoretic method for the determination of XN in hop extract was developed and validated. The optimal parameters were a 64.5,cm long fused-silica capillary with 50,,m id at 25°C; 30,kV negative voltage (anode at detector side of the capillary); nonaqueous buffer with 75,mM NaOH and 50,mM boric acid in methanol; hydrodynamical injection with 10,mbar for 40,s; and detection at 440,nm. XN, isoxanthohumol (IX), colupulone, adlupulone, and n -lupulone were well resolved on the electropherogram. The LOD for XN was 0.05,mg/L and RSD for peak area was below 3%. The amount of XN in different samples of hop pellets varied from 0.14 to 0.42%. [source] In-capillary solid-phase extraction,capillary electrophoresis for the determination of chlorophenols in waterELECTROPHORESIS, Issue 16 2006Luo-Hong Zhang Abstract A novel CE method combined with SPE in a single capillary was developed for analysis of chlorophenols in water. A frit of 0.5,mm was first made by a sol-gel method, followed by packing a SPE sorbent in the inlet end of the capillary. Two phenol derivatives, 2,4-dichlorophenol and 2,4,5-trichlorophenol, were used as the model compounds. By loading sample solutions into the capillary, the two chlorophenols were extracted into the sorbent. They were desorbed by injecting only about 4,nL of methanol. Finally, the analytes were separated by conventional CE. The technique provided a concentration enhancement factor of over 4000-fold for both chlorophenols. The detection limits (S/N,=,3) of 2,4-dichlorophenol and 2,4,5-trichlorophenol were determined to be 0.1,ng/mL and 0.07,ng/mL, respectively. For replicate analyses of 5,ng/mL of 2,4-dichlorophenol, within-day and between-day RSDs of migration time, peak height and peak area were in the range of 1.8,2.0%, 4.0,4.4% and 4.1,4.6%, respectively. The method shows wide linear range, acceptable reproducibility and excellent sensitivity, and it was applied to the analyses of spiked river water samples. The capillary packed with the SPE sorbents can be used for more than 400 runs without performance deterioration. [source] Automatic analysis of multiplex ligation-dependent probe amplification products (exemplified by a commercial kit for prenatal aneuploidy detection)ELECTROPHORESIS, Issue 22 2005Tommy Gerdes Dr. Abstract For use in routine prenatal diagnostics, we developed software and methods for automatic aneuploidy detection based on a commercial multiplex ligation-dependent probe amplification (MLPA) kit. Software and methods ensure a reliable, objective, and fast workflow, and may be applied to other types of MLPA kits. Following CE of MLPA amplification products, the software automatically identified the peak area for each probe, normalized it in relation to the neighboring peak areas of the test sample, computed the ratio relative to a reference created from normal samples, and compensated the ratio for a side effect of the normalization procedure that scaled all chromosomally normal DNA peak areas slightly up or down depending on the kind of aneuploidy present. For the chromosomes 13, 18, 21, X, and Y, probe reliability weighted mean ratio values and corresponding SDs were calculated, and the significance for being outside a reference interval around ratio 1.0 was tested. p,,,1% suggested aneuploidy and 1,<,p,,,5% suggested potential aneuploidy. Individual peaks, where the normalized area was situated more than 4 SD from the corresponding reference, suggested possible partial deletion or gain. Sample quality was automatically assessed. Control probes were not required. Having used the software and methods for two years, we conclude that a reliable, objective, and fast workflow is obtained. [source] Determination of tryptamine derivatives in illicit synthetic drugs by capillary electrophoresis and ultraviolet laser-induced fluorescence detectionELECTROPHORESIS, Issue 12 2005Carolin Huhn Abstract A method based on separation by capillary electrophoresis combined with UV-laser-induced fluorescence detection (,ex,=,266,nm) was developed for the determination of nine tryptamine derivatives of forensic interest and potential matrix constituents. The composition of the separation electrolyte was optimized with respect to the resolution of solutes of interest and to the sensitivity of fluorescence detection. Native ,-cyclodextrin was employed as a complex forming modifier of the electrophoretic separation and fluorescence-enhancing agent. With the help of a stacking procedure, limits of detection of 0.1,6,µg/L for all analytes were obtained. The repeatability for the peak area (at a concentration of the analyte about 100 times the LOD) was less than 2.3%,RSD. A second HPLC method was developed, and its analytical parameters were evaluated for an estimation of the accuracy of the CE-LIF method and for method comparison. The results of the determination of tryptamine derivatives in the samples of forensic interest obtained with the two independent methods are in good agreement. [source] Development of a new hybrid technique for rapid speciation analysis by directly interfacing a microfluidic chip-based capillary electrophoresis system to atomic fluorescence spectrometryELECTROPHORESIS, Issue 11 2005Feng Li Abstract This paper represents the first study on direct interfacing of microfluidic chip-based capillary electrophoresis (chip-CE) to a sensitive and selective detector, atomic fluorescence spectrometry (AFS) for rapid speciation analysis. A volatile species generation technique was employed to convert the analytes from the chip-CE effluent into their respective volatile species. To facilitate the chip-CE effluent delivery and to provide the necessary medium for subsequent volatile species generation, diluted HCl solution was introduced on the chip as the makeup solution. The chip-CE-AFS interface was constructed on the basis of a concentric "tube-in-tube" design for introducing a KBH4 solution around the chip effluent as sheath flow and reductant for volatile species generation as well. The generated volatile species resulting from the reaction of the chip-CE effluent and the sheath flow were separated from the reaction mixture in a gas-liquid separator and swept into the AFS atomizer by an argon flow for AFS determination. Inorganic mercury (Hg(II)) and methylmercury (MeHg(I)) were chosen as the targets to demonstrate the performance of the present technique. Both mercury species were separated as their cysteine complexes within 64 s. The precision (relative standard deviation, RSD, n = 5) of migration time, peak area, and peak height for 2 mg·L,1 Hg(II) and 4 mg·L,1 MeHg(I) (as Hg) ranged from 0.7 to 0.9%, 2.1 to 2.9%, and 1.5 to 1.8%, respectively. The detection limit was 53 and 161 µg·L,1 (as Hg) for Hg(II) and MeHg(I), respectively. The recoveries of the spikes of mercury species in four locally collected water samples ranged from 92 to 108%. [source] On-line concentration of proteins in pressurized capillary electrochromatography coupled with electrospray ionization-mass spectrometryELECTROPHORESIS, Issue 7-8 2005Zhen Liang Abstract Pressurized capillary electrochromatography (pCEC) and electrospray ionization-mass spectrometry (ESI-MS) have been hyphenated for protein analysis. Taken cytochrome,c, lysozyme, and insulin as samples, the limits of detection (LODs) for absolute concentrations are 10,11,mol (signal-to-noise ratio S/N = 3) with relative standard deviations (RSDs) of retention time and peak area, respectively, of less than 1.7% and 4.8%. In order to improve the detection sensitivity, on-line concentration by field-enhanced sample-stacking effect and chromatographic zone-sharpening effect has been developed, and parameters affecting separation and detection, such as pH and electrolyte concentration in the mobile phase, separation voltage, as well as enrichment voltage and time, have been studied systematically. Under the optimized conditions, the LODs of the three proteins could be decreased up to 100-fold. In addition, the feasibility of such techniques has been further demonstrated by the analysis of modified insulins at a concentration of 20,,g/mL. [source] On-line preconcentration for capillary electrophoresis-atomic fluorescence spectrometric determination of arsenic compoundsELECTROPHORESIS, Issue 12 2004Xue-Bo Yin Abstract An on-line preconcentration method was developed for capillary electrophoresis (CE) with hydride generation-atomic fluorescence spectrometric (HG-AFS) detection of arsenite, arsenate, dimethylarsenic acid, and monomethylarsenic acid. These arsenic species were negatively charged in the sample solution with high pH. When the potential was applied to the electrophoretic capillary, the negatively charged analyte ions moved faster and stacked at the boundary of sample and CE buffer with low pH. So, high sample pH in combination with low buffer pH allowed the injection of large sample volumes (, 1100 nL). Comparison of the preconcentration of analyte solution, prepared with doubly deionized water and that prepared with lake or river water, indicated that preconcentration was independent on the original matrix. With injection of ,1100 nL sample, an enrichment factor of 37,50-fold was achieved for the four species. Detection limits for the four arsenic species ranged from 5.0 to 9.3 ,g·L,1. Precisions (RSDs, n = 5) were in the range of 4.9,6.7% for migration time, 4.7,11% for peak area, and 4.3,7.1% for peak height, respectively. The recoveries of the four species in locally collected water solution spiked with 0.1 ,g·mL,1 (as As) ranged from 83 to 109%. [source] Investigation of a capillary electrophoretic approach for direct quantification of apolipoprotein A-I in serumELECTROPHORESIS, Issue 9 2003Rainer Lehmann Abstract In the present study a rapid, reproducible and robust capillary electrophoresis (CE) procedure for the quantification of apolipoprotein A-I (Apo A-I) in serum without pretreatment has been developed (total run time, 11 min). The coefficients of variation (CV; n = 10) for the relative peak area are 1.8% at a concentration of 145 mg/dL and 1.6% at 196 mg/dL; and for the inter-assay 8.9% at 161 mg/dL (10 consecutive days), i.e., similar to the CVs of a high-throughput immunonephelometric routine assay. The CV for the migration time is 0.4% (n = 20). The robustness of the CE approach was tested in patient samples with hemolysis, hyperbilirubinemia and hyperlipidemia. A comparison of 99 Apo A-I serum values with results of a fixed-time immunonephelometric routine assay showed a positive constant bias of 60% (mean) for the immunonephelometric values, no deviation from linearity, but significant deviations in several samples. Investigations on interferences in the CE analyses gave no evidence that CE failed. Our study shows that CE is amenable to a fast analysis and a reproducible and reliable quantification of Apo A-I level in sera of various clinical samples. [source] Accumulation of heterocyclic nitrogen in humified organic matter: a 15N-NMR study of lowland rice soilsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2000N. Mahieu Summary Recent intensification of cropping and the attendant longer submergence of the soil for lowland rice in tropical Asia appear to have altered the nature of the soil organic matter, and perhaps also nutrient cycling. To identify the dominant forms of organic nitrogen in the soils we extracted the labile mobile humic acid (MHA) and the more recalcitrant calcium humate (CaHA) fractions from soils under several long-term field experiments in the Philippines and analysed them by 15N-nuclear magnetic resonance spectroscopy. Amide N dominated the spectra of all humic acid (HA) samples (60,80% of total peak area). Its proportion of total spectral area increased with increasing intensity of cropping and length of time during which the soil was flooded and was greater in the MHA fraction than in the CaHA fraction. Simultaneously the spectral proportion of free amino N and other chemical shift regions decreased slightly with increasing length of submergence. Heterocyclic N was detected at modest proportions (7,22%) and was more prevalent in more humified samples, especially in the CaHA of aerated soils. Correlations of spectral proportions of heterocyclic N with other properties of the HA, reported elsewhere, were highly significant. Correlations were positive with visible light absorption (r=,0.86) and concentration of free radicals (r=,0.85), both of which are indices of humification, and negative with concentration of H (r=,,0.86), a negative index of humification. Correlations of spectral proportions of amide N with these properties were also highly significant but in each case of opposite sign to that of heterocyclic N. Proportions of heterocyclic N declined with increasing duration of submergence. The results suggest that (i) 15N-NMR can reproducibly measure some portion of heterocyclic N, (ii) formation of heterocyclic N is associated solely with gradual humification occurring over many years, and (iii) the abundant phenols in the submerged rice soils did not promote formation of heterocyclic N, and hence some other process is responsible for a substantial decrease in the availability of native N associated with intensive rice cropping. [source] MarqX: a new program for whole-powder-pattern fittingJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2000Y. H. Dong MarqX is a computer program for the modelling of powder diffraction data. It can be used for an unconstrained profile fitting (pattern decomposition, PD) or constrained modelling of the whole powder pattern (Pawley method, PM), for single- as well as multiple-phase samples. The program output includes: lattice parameters or peak positions (for PM and PD, respectively), width and shape of the diffraction peak (in terms of half width at half-maximum and mixing parameter of a pseudo-Voigt function), corrected for the instrumental broadening component, intensity, peak area and profile asymmetry. In addition, errors on the goniometer zero and shift in sample position with respect to the goniometric axis can also be modelled, together with distance and relative intensity of the spectral components of the X-ray beam (e.g.K,1 and K,2). Specific output files are provided for line-profile analysis, including the Williamson,Hall plot and Warren,Averbach method. [source] Quantitative analysis of MRP-8 in gingival crevicular fluid in periodontal health and disease using microbore HPLCJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 12 2001Fionnuala T. Lundy Abstract Background: The protein components of GCF can be separated by reverse-phase microbore HPLC on a C18 column with detection on the basis of 214 nm absorbance. A single major symmetrical protein peak eluting with a retention time of 26 min (50% acetonitrile) was evident in gingival crevicular fluid (GCF) from periodontitis patients but not in healthy GCF. This protein was identified as human MRP-8 by N-terminal amino acid sequencing and liquid chromotography quadropole mass spectrometry. Aims: To quantify the amount of MRP-8 detectable in GCF from individual healthy, gingivitis and periodontitis affected sites and to study the relationship, if any, between the levels of this responsive protein and periodontal health and disease. Methods: GCF was sampled (30 s) from healthy, gingivitis, and periodontitis sites in peridontitis subjects (n=15) and from controls (n=5) with clinically healthy gingiva and no periodontitis. Purified MRP-8 was sequenced by Edmann degradation and the phenylthiohydantoin (PTH) amino acid yield determined (by comparison of peak area with external PTH amino acid standards). This value was subsequently used to calculate the relative amount of protein in the peak eluting with a retention time of 26.0 min (MRP-8) in individual GCF chromatograms. Results: Higher levels of MRP-8 were detected in inflammatory sites: periodontitis 457.0 (281.0) ng; gingivitis 413.5 (394.5) ng compared with periodontally healthy sites in diseased subjects 14.6 (14.3) ng and in controls 18.6 (18.5) ng, p=0.003. There was at least 20-fold more MRP-8 in the inflammatory compared with the healthy sites studied. Conclusions: The preliminary data indicate that MRP-8 is present in GCF, with significantly greater amounts present at diseased than healthy sites. A systematic study of the relationship of this protein to periodontal disease could prove useful in further clarifying whether MRP-8 could be a reliable GCF biomarker of gingivitis and periodontitis. Zusammenfassung Grundlagen: Der Proteingehalt des GCF, abgetrennt werden mit einer reversphasigen Microbore-HPLC auf einer C18-Säule mit Detektion auf der Basis der Absorption von 214 nm. Ein einziges symmetrisches Protein-Hauptpeak-Eluat, der mit einer Retentionszeit von 26 Minuten eluiert wurde (50% Acetonnitril) war in gingivalen Sulkusfluid (GCF) von Parodontitispatienten deutlich sichtbar, jedoch nicht im GCF von Gesunden. Dieses Protein wurde mitels N-terminaler Aminosären-Sequenzierung und Flüssigkeits-Chromatographie mit Quadropol-Massenspektrometrie als humanes MRP-8 identifiziert. Ziele: Quantifizierung der Menge an MRP-8, die im GCF von gesunden Personen, Patienten mit Gingivitis und mit Parodontitis nachweisbar ist und Studieren der eventuell möglichen Beziehungen zwischen den Titern dieses Reaktionsproteins und parodontaler Gesundheit bzw. Erkrankung. Methoden: Bei Parodontitispatienten (n=15) wurde das GCF von gesunden Bereichen, sowie von Stellen mit Gingivitis und Parodontitis gewonnen (30 Sek.) sowie bei Kontrollpersonen (n=5) mit klinisch gesunder Gingiva und ohne Parodontitis. Das gereinigte MRP-8 wurde mittels Edman-Degradierung Sequenziert und der Phenyl-Thiohydantoin (PTH) Aminosäure-Yield bestimmt (durch Vergleich der Peakbereiche mit externen PTH Aminosäurestandards). Darauffolgend wurde dieser Wert verwendet, um die relative Menge des Proteins im Peak-Eluat mit einer Retentionszeit von 26.0 Min. (MRP-8) in den individuellen Chromatogrammen zu berechnen. Ergebnisse: An entzündeten Stellen wurden höhere Titer von MRP-8 nachgewiesen: Parodontitis 457.0 (281.0) ng; Gingivitis 413.5 (394.5) ng verglichen mit parodontal gesunden Stellen bei erkrankten Patienten 14.6 (14.3) ng und den Kontrollen 18.6 (18.5) ng, p=0.003. An den entzündeten Stellen gab es im Vergleich mit den gesunden Stellen wenigstens 20 mal mehr MRP-8. Schlußfolgerungen: Die vorläufigen Daten zeigen, daß MRP-8 im GCF vorhanden ist und an erkrankten Stellen signifikant höhere Mengen vorhanden sind, als an gesunden Stellen. Eine systematische Studie der Beziehung dieses Proteins zur Parodondalerkrankung könnte sich als nützlich erweisen, um des weiteren zu klären, ob MRP-8 eine verläßlicher Biomarker für Gingivitis und Parodontitis ist. Résumé Origine: Les composants proéiques du fluide gingival peuvent être séparés par HPLC microbore en phase inverse sur une colonne C18 avec une détection sur une base d'absorption de 214 nm. Un unique pic majeur symétrique ayant un temps de rétention de 26 min (50% acetonitrile) était manifeste dans le fluide gingival (GCF) des patients atteints de parodontite, mais pas chez les patients sans. Cette protéine fut identifiée comme étant l'MRP-8 humaine après séquençage de l'acide aminé N terminal et spectrométrie de masse quadropole par chromatographie liquide. But: L'objectif est de quantifier la quantité de MRP-8 détectable dans le GCF de site sains, atteints de gingivite ou de parodontite et d'étudier, s'il y en a, la relation entre les niveaux de cette réponse protéique et la santé et la maladie parodontale. Méthodes: Le GCF frut prélevé (30 s) dans des sites sains, atteints de gingivite ou de parodontite, chez des sujets atteints de parodontite (n=15) ou chez des contrôles (n=5), ayant une gencive cliniquement saine sans parodontite. Le MRP-8 purifié fut séquencé par dégradation d'Edmann et le débit d'acide aminé phenylthiohydantoine (PTH) déterminé (par comparaison avec la surface de pic avec des standards d'acide aminé PTH externe). Cette valeur fut ensuite utilisée pour calculer la quantité relative de protéine dans le pic avec un temps de rétention de 26.0 mn (MRP-8) sur des chromatogrammes individuels de GCF. Résultats: De plus hauts niveaux de MRP-8 étaints détectés dans les sites inflammatoires: Parodontite 457.0 (281.0) ng; gingivite 413.5 (394.5) ng par rapport aux sites sains des sujets malades 14.6 (14.3) ng et des sujets contrôles 18.6 (18.5) ng, p=0.003. Il y avait au moins 20× plus de MRP-8 dans les sites inflammatoires par rapport au sites sains. Conclusions: Les données préliminaires indiquent que la MRP-8 est présente dans le GCF, en quantité significativement plus importante dans les sites malades. Une étude systèmatique de la relation entre cette protéine et la maladie parodontale pourrait se révéler utile pour encore plus expliciter si MRP-8 pourrait être un biomarqueur fiable du GCF des gingivites et des parodontites. [source] Phenolic Composition of Authentic Pineapple JuiceJOURNAL OF FOOD SCIENCE, Issue 1 2002L. Wen ABSTRACT: The phenolic composition of authentic pineapple juice concentrate was analyzed by HPLC. Nine major peaks accounting for 70% of total peak area were characterized and their concentrations measured in 54 commercial samples. Means and standard deviations were as follows (mg/100 mL single-strength juice, normalized to 12.8 °Brix): tyrosine, 3.6(1.4); serotonin, 1.8(0.8); dimethylhydroxylfuranone, 1.4(0.7); dimethylhydroxylfuranone ,-glucoside, 6.2(3.0); tryptophan, 2.2(0.9); S-sinapyl-L-cysteine, 1.1(0.6); N-,-L-glutamyl-S-sinapyl-L-cysteine, 2.3(1.1); S-sinapyl glutathione, 5.4(1.4); and a p -coumaric acid-like phenolic compound (calculated as p -coumaric acid), 0.5(0.4). This information will be useful for evaluation of authenticity and quality. [source] Passport Examination by Polarized Infrared SpectraJOURNAL OF FORENSIC SCIENCES, Issue 4 2007Shigeru Sugawara M.S. Abstract:, In this study, a new nondestructive technique for passport examination is proposed. In this technique, linearly polarized light is used to measure Fourier transform infrared (FT-IR) reflectance spectra of films on the biographical data page. Thirty genuine and thirty-five counterfeit Japanese passports and five marketed films pasted on name cards were examined. The measured spectra were analyzed as follows. The absorption spectra were obtained by the Kramers,Kronig transformations of reflectance spectra. The peak ratios were then calculated from the absorption spectra by adding the peak areas at 1126 and 1263 cm,1 and dividing the result by the peak area at 1727 cm,1. When nonpolarized light was used, the samples could not be distinguished by comparing the peak ratios. However, when polarized light was used, they were successfully distinguished by the comparison. Therefore, polarized light is useful for the forensic discrimination of passport films by the measurement of FT-IR spectra. [source] Quantitative multivoxel proton spectroscopy of the brain in developmental delayJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2009Krijn T. Verbruggen MD Abstract Purpose To assess whether proton MR spectroscopy of the brain in children with developmental delay reveals a consistent pattern of abnormalities. Materials and Methods Eighty-eight patients (median age, 4.6 years; interquartile range, 3.1,8.1 years) with unexplained developmental delay, were compared with 48 normally developing age-matched controls. Patients and controls were assigned to five age-groups. Multivoxel MR spectroscopy was performed on a volume of interest superior to the lateral ventricles. The relative levels of choline, creatine, N-acetyl aspartate, and glutamate/glutamine in 24 voxels containing white matter and 12 voxels containing gray matter were quantified in an operator-independent manner and expressed in proportion to the total metabolite peak area in the volume of interest. Results White matter choline in DD showed less decrease with age. Mean choline levels, compared with mean control levels, increased from 99 to 111% with increasing age. This was statistically significant in the highest age groups (P = 0.015 [7 < yr , 12.8] and P = 0.039 [12.8 < yr]). Other metabolites did not show clear alterations. Conclusion Proton MR spectroscopy in a group of patients with unexplained DD shows small differences in the metabolite pattern, compared with normally developing controls, that is, higher choline in the white matter. The pathophysiological origin and significance may relate to myelination and maturation of the white matter. J. Magn. Reson. Imaging 2009;30:716,721. © 2009 Wiley-Liss, Inc. [source] Triisobutylaluminum as cocatalyst for zirconocenes.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2001Abstract An investigation of the catalytic behavior of the dimethylated zirconocenes Me2SiCp*NtBuZrMe2 [Cp* = C5(CH3)4; 1Me], Me2SiCp2ZrMe2 (2Me), Cp2ZrMe2 (3Me), Ind2ZrMe2 (4Me), Me2SiInd2ZrMe2 (5Me), Et(2-MeInd)2ZrMe2 (6Me), and Me2Si(2-MeInd)2ZrMe2 (7Me) with the combined activator triisobutylaluminum (TIBA)/CPh3B(C6F5)4 (Al/Zr = 250; B/Zr = 1) in ethylene polymerizations at increased monomer pressures (5,11 bar, 30 °C) was carried out. Sterically opened zirconocenes in ternary catalysts gave rise to active species effective in the formation of low molecular weight polyethylenes (PEs). These active species tended to increase the PE molecular weight [1Me (2100) < 2Me (20,000) < 5Me (89,000) < 3Me (94,500)] under similar conditions. PE obtained with 4Me showed a bimodal gel permeation chromatography curve with a 64% peak area [weight-average molecular weight (Mw) = 43,000] and a 36% peak area (Mw = 255,000). The increase in sterical demands from the zirconocenes was also demonstrated by the reduction of the chain transfer to monomer, the reinsertion of vinyl-ended PE chains, and their ability for isomerization. These reactions were most pronounced for the zirconocenes 1Me and 2Me. The active species responsible for the formation of low molecular weight PEs deactivated quickly. The zirconocenes 6Me, 7Me, and (2-PhInd)2ZrMe2 (8Me) bearing substituent at the 2-position of the indenyl ring was activated with TIBA alone, yielding active species effective in ethylene and propylene polymerizations. PEs formed with 6Me,8Me complexes activated with TIBA had high molecular weights. An increase in the Al/Zr ratio in the catalytic system 8Me/TIBA from 50 to 300 led to an enhancement of the molecular weight of polypropylene (PP) samples from oligomeric products to an viscosity-average molecular weight of 220,000. The increase in the molecular weights of PPs with an increase in the propylene concentration was also observed. An analysis of the catalytic performance of the 8Me/TIBA system showed first-order dependency of the initial polymerization rates on the TIBA concentration and close to second-order dependency on propylene. The second-order dependency on the monomer concentration is explained in terms of the monomer participation in the initiation step of the polymerization reaction. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1915,1930, 2001 [source] Methacrylate ester-based monolithic columns for nano-LC separation of tocopherols in vegetable oilsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17-18 2010María Jesús Lerma-García Abstract The separation and determination of tocopherols (Ts) in vegetable oils by nano-LC chromatography with UV,vis detection using lauryl methacrylate ester-based monolithic columns has been developed. The separation of Ts was optimized in terms of mobile phase composition on the basis of the best compromise among efficiency, resolution and analysis time. Using a mobile phase composed of ACN/methanol/water, an excellent resolution between Ts was achieved within 18,min. The LODs were lower than 0.26,,g/mL, being repeatability values of retention time and peak area below 0.15 and 3.1%, respectively. The method was applied to the quantification of Ts and tocotrienols present in several vegetable oils from different botanical origins. [source] Use of different buffers for detection and separation in determination of physio-active components in oolong tea infusion by CZE with amperometric detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2010Zhiyong Yang Abstract With a view of simultaneous determination of physio-active ingredients in oolong tea infusion: sugars, amino acids, epigallocatechin gallate and ascorbic acid, a novel CZE with amperometric detection method was studied. Operated in a wall-jet configuration, 100,mmol/L NaOH was used in detecting cell to lead the electrocatalysis oxidation behaviors of the analytes on a 300,,m diameter copper-disc electrode (working electrode), while in separating capillary, a mild alkaline running buffer consisting in a mixture of 30,mmol/L borate and 40,mmol/L phosphates charged and carried analytes to detecting end. The methodology research was performed for system stability and suitability. Under the optimal CE conditions, analytes could be separated within moderate time period. Good linearity between peak area and concentration existed over three orders of magnitude; lower RSD and LOD were achieved. The oolong tea infusion was assayed and result was satisfactory. [source] Sensitive determination of phenols in environmental water samples with SPE packed with bamboo carbon prior to HPLCJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2009Ru-Song Zhao Abstract Bamboo carbon, an inexpensive, readily available material, has attracted great attention in recent years because of adsorptive properties. In this paper, the potential of bamboo carbon as a SPE adsorbent for the determination of phenols, was investigated. Phenols are important environmental contaminants that may adversely affect human health. Parameters influencing extraction efficiency, including type of eluent, eluent volume, amount of adsorbent, as well as sample pH, volume, and flow rate were investigated and optimized. The optimized results exhibited excellent linear relationships between peak area and phenol concentrations over the range of 2.0,100 ng/mL, with precision between 2.2,7.2%. The LODs were 0.06,0.4 ng/mL for the eight phenols tested. The proposed method has been successfully applied to the analysis of several real-world environmental water samples. These results indicate that bamboo carbon may be used as a novel SPE adsorbent for the concentration and determination of phenols in real environmental water samples. [source] Quantitative capillary electrophoresis and its application in analysis of alkaloids in tea, coffee, coca cola, and theophylline tabletsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 2 2009Mengjia Li Abstract A quantitative CE (qCE) system with high precision has been developed, in which a 4-port nano-valve was isolated from the electric field and served as sample injector. The accurate amount of sample was introduced into the CE system with high reproducibility. Based on this system, consecutive injections and separations were performed without voltage interruption. Reproducibilities in terms of RSD lower than 0.8% for retention time and 1.7% for peak area were achieved. The effectiveness of the system was demonstrated by the quantitative analysis of caffeine, theobromine, and theophylline in real samples, such as tea leaf, roasted coffee, coca cola, and theophylline tablets. [source] Quantification of polyphenols with potential antioxidant properties in wines using reverse phase HPLCJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2008Neuza Paixão Abstract A RP-HPLC method with photodiode array detection (DAD) was developed to separate, identify and quantify simultaneously the most representative phenolic compounds present in Madeira and Canary Islands wines. The optimized chromatographic method was carefully validated in terms of linearity, precision, accuracy and sensitivity. A high repeatability and a good stability of phenolics retention times (< 3%) were obtained, as well as relative peak area. Also high recoveries were achieved, over 80.3%. Polyphenols calibration curves showed a good linearity (r2 >0.994) within test ranges. Detection limits ranged between 0.03 and 11.5 ,g/mL for the different polyphenols. A good repeatability was obtained, with intra-day variations less than 7.9%. The described method was successfully applied to quantify several polyphenols in 26 samples of different kinds of wine (red, rosé and white wines) from Madeira and Canary Islands. Gallic acid was by far the most predominant acid. It represents more than 65% of all phenolics, followed by p -coumaric and caffeic acids. The major flavonoid found in Madeira wines was trans -resveratrol. In some wines, (,)-epicatechin was also found in highest amount. Canary wines were shown to be rich in gallic, caffeic and p -coumaric acids and quercetin. [source] Capillary high performance liquid chromatography coupled with electrospray ionization mass spectrometry for rapid analysis of pinane monoterpene glycosides in Cortex MoutanJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2008Yue Song Abstract In this study, a rapid and reliable assay has been developed for quantification of pinane monoterpene glycosides in Cortex Moutan; it is based on capillary high performance liquid chromatography coupled with electrospray ionization mass spectrometry (capillary HPLC,ESI MS). This method utilizes capillary HPLC for the separation of seven pinane monoterpene glycosides in a methanol extract of the botanical sample followed by negative ion electrospray ionization and single ion monitoring (SIM). The compounds of interest in the sample were unambiguously identified on the basis of information about retention time and quasi-molecular ions ([M,H],) or adduct ions ([M+HCOO],). Validation parameters of the method were established. The linearity range was 1.01,105.5 ,g/mL with the square of correlation coefficients lying in the range of 0.9965,0.9997, limits of detection were on the fmol level, the average recoveries varied between 91.8 and 101.0%, and good precision values (RSD, 1.2,4.91%) for peak area were obtained. After validation, the applicability of the method for determination of these pinane monoterpene glycosides in Cortex Moutan has been demonstrated. [source] | |||||||||||||||||||