Chromatography coupling

Analytical chemistry has in recent years been equipped with a number of powerful means of investigation. Their application, especially that of gas-phase chromatography coupled with a mass spectrometer, has demonstrated the presence of a certain number of thiazoles in natural products such as fruits or cereals (287. 288, 297). The many results are shown in Table III-59. 

Reference methods for criteria (19) and hazardous (20) poUutants estabHshed by the US EPA include sulfur dioxide [7446-09-5] by the West-Gaeke method carbon monoxide [630-08-0] by nondispersive infrared analysis ozone [10028-15-6] and nitrogen dioxide [10102-44-0] by chemiluminescence (qv) and hydrocarbons by gas chromatography coupled with flame-ionization detection. Gas chromatography coupled with a suitable detector can also be used to measure ambient concentrations of vinyl chloride monomer [75-01-4], halogenated hydrocarbons and aromatics, and polyacrylonitrile [25014-41-9] (21-22) (see Chromatography Trace and residue analysis). 

The use of separation techniques, such as gel permeation and high pressure Hquid chromatography interfaced with sensitive, silicon-specific aas or ICP detectors, has been particularly advantageous for the analysis of siUcones in environmental extracts (469,483—486). Supercritical fluid chromatography coupled with various detection devices is effective for the separation of siUcone oligomers that have molecular weights less than 3000 Da. Time-of-flight secondary ion mass spectrometry (TOF-sims) is appHcable up to 10,000 Da (487). 

Solid-phase microextraction (SPME) was used for headspace sampling. The FFA were extracted from the headspace with PA, Car/PDMS, and CW/DVB fibers. It was examined whether addition of salt (NaCl) and decreasing the pH by addition of sulphuric acid (H SO ) increased the sensitivity. FFA were analyzed using gas chromatography coupled to mass spectrometry in selected ion monitoring. 

In this work ion-exchange and gel-permeation chromatography coupled with membrane filtration, photochemical oxidation of organic metal complexes and CL detection were applied to the study of the speciation of cobalt, copper, iron and vanadium in water from the Dnieper reservoirs and some rivers of Ukraine. The role of various groups of organic matters in the complexation of metals is established. 

Reprinted from Journal of High Resolution Chromatography, 21, D. Juchelka et al., Multidimensional gas chromatography coupled on-line with isotype ratio mass specti ometry (MDGC-IRMS) progress in the analytical authentication of genuine flavor components , pp. 145-151, 1998, with peraiission from Wiley-VCH. 

One example of normal-phase liquid chromatography coupled to gas chromatography is the determination of alkylated, oxygenated and nitrated polycyclic aromatic compounds (PACs) in urban air particulate extracts (97). Since such extracts are very complex, LC-GC is the best possible separation technique. A quartz microfibre filter retains the particulate material and supercritical fluid extraction (SPE) with CO2 and a toluene modifier extracts the organic components from the dust particles. The final extract is then dissolved in -hexane and analysed by NPLC. The transfer at 100 p.1 min of different fractions to the GC system by an on-column interface enabled many PACs to be detected by an ion-trap detector. A flame ionization detector (PID) and a 350 p.1 loop interface was used to quantify the identified compounds. The experimental conditions employed are shown in Table 13.2. 

GC-MS gas chromatography coupled with mass spectrometry HDL heavy-duty liquid or laundry liquid... 

Size exclusion chromatography coupled to static light scattering (SEC-MALLs) Molecular weight, molecular weight distribution. Polydispersity. Radius of gyration and distribution solution conformation and flexibility. Method of choice for moleciflar weight work. [4]... 

Meyer M., Morgenstern B. 2003. Characterization of Gelatine and Acid Soluble Collagen by Size Exclusion Chromatography Coupled with Multi Angle Light Scattering (SEC-MALS). Biomacromolecules 4,1727-1732. 

Planas C, Caixach J, Santos FJ, et al. 1997. Occurrence of pesticides in Spanish surface waters. Analysis by high resolution gas chromatography coupled to mass spectrometry. Chemosphere 34(ll) 2393-2406. 

GUO c, CAO G, SOFIC E and PRIOR R L (1997) High-performance liquid Chromatography coupled with coulometric array detection of electroactive components in fruits and vegetables Relationship to oxygen radical absorbance capacity, J Agric Food Chem, 45, 1787-96. 

The data in Table I are also significant in terms of the type of analysis to determine the presence of NDMA. In all cases analysis was done using gas chromatography coupled with a Thermal Energy Analyzer, a sensitive, relatively specific nitrosamine detector (12). Further, in six of the studies, the presence of NDMA in several samples was confirmed by gas chromatography-mass spectrometry (GC-MS). The mass spectral data firmly established the presence of NDMA in the beer samples. 

For human studies, the choice of stable isotopes is limited because radioisotopes are associated with ionization radiation and thus with some potential harmful effects for humans. Studying the bioavailability of compounds labeled with stable isotopes requires complex techniques such as gas chromatography coupled with mass spectrometry (GC-MS), liquid chromatography coupled with MS (LC-MS), and atmo-... 

Mnllen, W., Lean, M.E.J., and Crozier, A., Rapid characterization of anthocyanins in red raspberry frnit hy high-performance liqnid chromatography coupled to single qnadrupole mass spectrometry, J. Chromatogr. A, 966, 63, 2002. 

Tian, Q. et al., Screening for anthocyanins using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry with precursor-ion analysis, product-ion analysis, common-neutral-loss analysis, and selected reaction monitoring, J. Chromatogr. A, 1091, 72, 2005. 

Hvattum, E., Determination of phenolic compounds in rose hip (Rosa canina) using liquid chromatography coupled to electrospray ionisation tandem mass spectrometry and diode-array detection, Rapid Commun. Mass Spectrom., 16, 655, 2002. 

LC-MS/MS Liquid chromatography coupled with tandem mass spectrometry LC-NMR Liquid chromatography coupled with nuclear magnetic resonance TLC Thin-layer chromatography... 

LC-MS/MS Liqmd chromatography coupled to tandem mass spectrometry... 

Microbes of differing physiologic types, acting in consortia, appear to be more destructive than monocultures. Methods for examining consortia are based on the detection of lipid biomarkers that are characteristic for different classes of microbes. These can be analyzed by gas chromatography coupled with mass spectrometry [512]. 

Gas chromatography coupled with mass spectrometric detection has also been applied to the detection of... 

Zhao, Q., Sannier, F., Garreau, I., Lecoeur, C., and Piot, J. M., Reversed-phase high-performance liquid chromatography coupled with second-order derivative spectroscopy for the quantitation of aromatic amino acids in peptides application to hemorphins, /. Chromatogr. A, 723, 35, 1996. 

Wagner, H. P., Pepich, B. V., Hautman, D. P., and Munch, D. J., Analysis of 500 ng/1 levels of bromate in drinking water by direct-injection suppressed ion chromatography coupled with a single, pneumatically delivered postcolumn reagent, /. Chromatogr. A, 850, 119, 1999. 

Riickert, M., Wohlfarth, M., and Bringmann, G., Characterization of protein mixtures by ion-exchange chromatography coupled on-line to nuclear magnetic resonance spectroscopy, ]. Chromatogr. A, 840, 131, 1999. 

Karuna, R. and Sashidhar, R. B., Use of ion-exchange chromatography coupled with TLC-laser scanning densitometry for the quantitation of fumonisin Bl,... 

Lederer, K., Imrich-Schwarz, G., and Dunky, M., Simultaneous calibration of separation and axial dispersion in size exclusion chromatography coupled with light-scattering, J. Appl. Polym. Sci., 32, 4751, 1986. 

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