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Chromatography/fourier Transform Infrared Spectroscopy and its Applications (Practical Spectroscopy)
Chromatography/fourier Transform Infrared Spectroscopy and its Applications (Practical Spectroscopy) -
Annual Book of Astm Standards, 1987: Analytical Methods-Spectroscopy, Chromatography, Temperature Measurement, Computerized Systems, Vol 14.01: gene
Annual Book of Astm Standards, 1987: Analytical Methods-Spectroscopy, Chromatography, Temperature Measurement, Computerized Systems, Vol 14.01: gene -
Gas Chromatography-Mass Spectroscopy:Applications in Microbiology
Gas Chromatography-Mass Spectroscopy:Applications in Microbiology -
Analysis of caffeine, theobromine and theophylline in coffee by near infrared spectroscopy (NIRS) compared to high-performance liquid chromatography (HPLC) ... [An article from: Analytica Chimica Acta]
Analysis of caffeine, theobromine and theophylline in coffee by near infrared spectroscopy (NIRS) compared to high-performance liquid chromatography (HPLC) ... [An article from: Analytica Chimica Acta]
This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Coffee is one of the most important raw materials within the international trade, for which highest quality is demanded. Due to the high number of samples to be analysed, new analytical techniques providing fast and reliable data about the quality are essential. Therefore, we established a new analytical method based on near infrared spectroscopy (NIRS) for the quantitation of the three main alkaloids caffeine (Caf), theobromine (Tbr) and theophylline (Tph) in roasted coffee after discrimination of the rough green beans into Arabic and Robusta. This validated method was compared to the most commonly used liquid chromatography (LC) connected to UV and mass spectrometric (MS) detection. In this course non-porous silica-C18 showed to enable the analysis of the three alkaloids with high robustness within ~2.5min, compared to 20min employing porous silica-C18 as a stationary phase. As analysis time plays an important role in choosing a reference method for the calibration of the NIR-spectrometer, the non-porous silica-C18 phase offers a very fast method. Coupling of the optimised LC method to a mass spectrometer (MS) via an electrospray ionisation (ESI) interface not only allowed to identify Caf, Tbr and Tph by their characteristic fragmentation pattern using collisionally induced dissociation (CID), but also to quantitate the content of the three analytes, which was found to be 6% higher compared to UV-detection. The validated LC-UV method was chosen as a reference method for the calibration of the NIRS system. Analysis of 83 liquid coffee extracts in random order resulted for Caf and Tbr in values for S.E.E. (standard error of estimation) of 0.34, 0.40g/100g, S.E.P. (standard error of prediction) of 0.07 and 0.10g/100g with correlation coefficients of 0.86 and 0.85 in a concentration range between 0.10 and 4.13g/100g. Compared to LC the lower limit of detection (LOD) of the NIRS-method is found at 0.05g/100g compared to 0.244-0.60ng/100g in LC, which makes it impossible to analyse Tph by NIRS. Therefore, main focus is put on the NIRS analysis of caffeine and theobromine. Nevertheless, NIRS offers a serious alternative to LC for the coffee producing industry because of the short analysis time of a few seconds and a guaranteed high sample throughput. -
Hyphenation of column liquid chromatography and Raman spectroscopy via a liquid-core waveguide: chemometrical elimination of spectral eluent background [An article from: Analytica Chimica Acta]
Hyphenation of column liquid chromatography and Raman spectroscopy via a liquid-core waveguide: chemometrical elimination of spectral eluent background [An article from: Analytica Chimica Acta]
This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
In column liquid chromatography (LC) coupled to conventional Raman spectroscopy (RS) removal of the spectral background of the eluent is often demanding, because of the strong signals of the organic modifier. A new chemometrical method is proposed, called the eluent background subtraction (EBS) method, which can correct for small shape and intensity differences of the eluent spectra. The variations in the eluent spectra are modelled using principal component analysis (PCA). The PCA loading vectors are subsequently used for eluent background correction of the elution spectra of the analyte. The loading vectors are fitted under these spectra by an asymmetric least-squares method. This method was successfully applied under various experimental conditions and performed much better than conventional background correction methods. Analyte detectability was improved by (weighted) averaging of all elution spectra and smoothing via a p-spline function. -
1992 Annual Book of Astm Standards: Section 14 General Methods and Instrumentation : Vol 14.01 Analytical Methods-Spectroscopy; Chromatography; Comp (Annual Book of a S T M Standards Volume 1401)
1992 Annual Book of Astm Standards: Section 14 General Methods and Instrumentation : Vol 14.01 Analytical Methods-Spectroscopy; Chromatography; Comp (Annual Book of a S T M Standards Volume 1401) -
Annual Book of Astm Standards, 1986: Molecular & Mass Spectroscopy; Chromatography; Resinography; Temp Measurement... /Vol 14.01 Pcn 01-140186-39
Annual Book of Astm Standards, 1986: Molecular & Mass Spectroscopy; Chromatography; Resinography; Temp Measurement... /Vol 14.01 Pcn 01-140186-39 -
The discrimination of automotive clear coat paints indistinguishable by Fourier transform infrared spectroscopy via pyrolysis-gas chromatography-mass spectrometry ... [An article from: Analytica Chimica Acta]
The discrimination of automotive clear coat paints indistinguishable by Fourier transform infrared spectroscopy via pyrolysis-gas chromatography-mass spectrometry ... [An article from: Analytica Chimica Acta]
This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
It has been shown that by using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), it is possible to discriminate between a variety of automotive clear coat paints, indistinguishable by Fourier transform infrared spectroscopy (FT-IR). -
Essential Oils: Analysis by Capillary Gas Chromatography and Carbon 13-NMR Spectroscopy
Essential Oils: Analysis by Capillary Gas Chromatography and Carbon 13-NMR Spectroscopy
In addition to capillary gas chromatography and GC-MS, carbon-13 NMR spectroscopy provides an alternative method for essential oils analysis. The excellent visual spacing of the signals enables oil samples to be analyzed without preliminary separation of their components. Also, information relating to the molecular structure of the oil constituents can be ascertained from the measured chemical shifts. This second edition clearly demonstrates the power of the technique in the characterization of essential oils, based on 60 sample oils chosen for their industrial importance together with the 188 carbon-13 NMR spectra of significant components. Supporting data are presented using capillary gas chromatography.
Key features of the Second Edition:
* 18 new essential oils are included, five oils are replaced and five oils with less or little importance are deleted
* Revision of numerous analyses taken over from the 1st edition
* Capillary gas chromatograms of 60 commercially important essential oils
* Qualitative and quantitative analytical results of those essential oils
* Carbon-13 NMR analyses of those essential oils without separation of their components
* Carbon-13 NMR spectra of 188 most important oil constituents are given (67 are new in the 2nd edition)
This collection of 13C NMR and GC data is aimed at essential oils and natural products chemists, NMR research groups, university departments of chemistry, pharmacy, botany, and food science, as well as those working in the essential oils, perfumes, flavours and food technology industries. -
Arsenic speciation in Chinese brake fern by ion-pair high-performance liquid chromatography-inductively coupled plasma mass spectroscopy [An article from: Analytica Chimica Acta]
Arsenic speciation in Chinese brake fern by ion-pair high-performance liquid chromatography-inductively coupled plasma mass spectroscopy [An article from: Analytica Chimica Acta]
This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Ion-pair reverse-phase HPLC-inductively coupled plasma (ICP) MS was employed to determine arsenite [As(III)], dimethyl arsenic acid (DMA), monomethyl arsenic (MMA) and arsenate [As(V)] in Chinese brake fern (Pteris vittata L.). The separation was performed on a reverse-phase C18 column (Haisil 100) by using a mobile phase containing 10mM hexadecyltrimethyl ammonium bromide (CTAB) as ion-pairing reagent, 20mM ammonium phosphate buffer and 2% methanol at pH 6.0. The detection limits of arsenic species with HPLC-ICP-MS were 0.5, 0.4, 0.3 and 1.8ppb of arsenic for As(III), DMA, MMA, and As(V), respectively. MMA has been shown for the first time to experimentally convert to DMA in the Chinese brake fern, indicating that Chinese brake fern can convert MMA to DMA by methylation.
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