Detector HPLC

Nuclear magnetic resonance and mass spectrometric detectors HPLC/NMR and HPLC/MS are popular techniques that combine the versatility of HPLC with the identification power of NMR or MS (see Chapters 11, 12, and 18). 

Model RR/066 351 and 352 pumps models 750/16 variable-wavelength UV monitor detector 750/11 variable filter UV detector, MPD 880S multiwave plasma detector, 750/14 mass detector 750/350/06 electrochemical detector refractive index detector HPLC columns column heaters, autosamplers, pre-columns derivatization systems, solvent degassers, preparative HPLC systems... 

ECO = electron capture detector ED = electrochemical detector FID st flame ionization detector GC = gas chromatography HECD = Hall s electrolytic conductivity detector HPLC = high performance liquid chromatography MEC = molecular emission cavity analysis MS - mass spectrometry HD = photo-ionization detector... 

CZE = capillary zone electrophoresis EC = electrochemical detector GC = gas chromatography HCD = Hall conductivity detector HPLC = high performance liquid chromatography IDMS = isotope dilution mass spectrometry MS = mass spectrometry RSD = relative standard deviation SEE = supercritical fluid extraction SPE = solid phase extraction UV = ultraviolet absorbance detection... 

Fig. 42 Reversed-phase HPLC profiles of natural (top) and rearranged (bottom) butterfat triacylglycerols as obtained with the light-scattering detector. HPLC conditions Hewlett-Packard Model 1050 liquid chromatograph equipped with a Supelcosil LC-18 column (25 cm X 0.46-cm ID) coupled to a Varex ELSD II light-scattering detector. Solvent linear gradient of 10-90% propanol in acetonitrile at 25°C over a period of 90 min (1 ml/min) recording stopped at 70 min. Peak identification by carbon and double-bond numbers of triacylglycerols.

Owing to the varied structures of various food dyes, they can often be differentiated from one another by their characteristic ultraviolet/visible absorbance spectra. Using HPLC coupled with a diode array detector (HPLC-DAD) it is possible to collect a compound s absorbance spectrum as it elutes from the HPLC column, which greatly assists in identification. At Reading Scientific Services Ltd (RSSL) this type of detector is routinely used in a range of analyses of such substances as patulin, a mycotoxin found in apple juice, and in the analysis of colours and vitamins, which allows a more certain assignment of a particular peak to a specific compound to be made. 

Any HPLC or FPLC machine containing a pump, gradient mixer, UV detector, HPLC columns, and fraction collector can be used. UV detection should be done at 215 nm. Use solvents that do not show absorbance at 215 nm (i.e., acetonitrile, water, and trifluoroacetic acid [TFA]) (see Note 10). For MicroHPLC we use a Smart HPLC system (Pharmacia). 

Detection by Mass Spectrometry The use of a mass spectrometer as a detector (HPLC-MS) can provide much information concerning the structures of the compounds being separated. Interfaces are available (see under Mass Spectrometry, p. 253). 

GC-FID gas chromatography with flame ionization detector, HPLC-UV high performance liquid chromatography with UV detector, LC-MS liquid chromatography coupled with mass spectrometry, GC-FPD gas chromatography with flame photometric detector... 

The CFF-mediated conversion of salicylate to 2,5- and 2,3-DHBA and catechol was used as a semi-quantitative assay to determine the levels of redox-active Fe/Cu, as follows in 100 pi reaction mixture, containing 50 pi CFFs and salicylate and ascorbate (1 mM, each) in KH buffer was incubated for Ih at 37 C. To terminate the incubation, ice-cold TCA (3% final concentration) was added, and the suspensions were centrifuged at 12,000g for 1 min. The supernatant was analyzed for 2,5- and 2,3-DHBA and catechol by HPLC coupled to an electrochemical detector (HPLC-ECD), as previously described [10]. 

Ultramicroelectrode Synonymous with microelectrode. Ultraviolet/visible detector, HPLC Detector for high-performance liquid chromatography that uses ultraviolet/visible absorption to monitor eluted species as they exit a chromatographic column. 

A variety of analytical methods has been used for determining trace concentrations of PAHs in environmental samples (Table 6-2). These include GC with various detectors, HPLC with various detectors, and TLC with fluorimetric detectors. Various detection devices used for GC quantification include FID, MS, Fourier transform infrared spectrometer (FT-IR), laser induced molecular fluorescence detector (LIMF), diode array detector (DAD), and gas phase fluorescence detector (GPFDA). GC/MS and HPLC with UV or spectrofluorimetric detectors are perhaps the most prevalent analytical methods for determining concentrations of PAHs in environmental samples. 

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