Detectors for high pressure liquid

Steichen, J. C., A dual-purpose absorbance-fluorescence detector for high-pressure liquid chromatography, /. Chromatogr., 104, 39, 1975. 

In specific circumstances where there happen to be no interferences, the simple voltammetric response of an electrode can be a Very convenient monitor in process streams and effluents. Such applications, however, have little generality. An application of electrochemical celts of increasing importance is as a detector for high-pressure liquid chromatographs. Here, the chromatographic column should have already separated the components of the mixture and the ability to record complete i-E responses quite rapidly can be used to identify components and to confirm complete separation (does the curve change through a peak ),... 

Fig. lUl Electrochemical detector cells for high-pressure liquid ctiromatography. (a) Porous lectrode cell for coulometric detection in high-pressure liquid chromatography (Courtesy Coulochem). (b) Thin-layer ampcrometric detector for high-pressure liquid chromatography, (c) The Wall jet ampcrometric odl. (Courtesy EDT Research.)... 

F.E. Brinckman, K.L. Jewett, WR Iverson, K.J. Irgolic, K.C. Ehrhardt, and R.A. Stockton. Graphite furnace atomic absorption spectrophotometers as automated element-specific detectors for high-pressure liquid chromatography. The determination of arsenite, arsenate, methylarsonic acid and dimethylarsinic add. J. Chromatogr., 191, 31 (1980). 

Shultz and Mathis [39] developed an ion-selective electrode detector for high-pressure ion-exchange chromatography. The detector was based on a commercial liquid-membrane ion-selective electrode, and was sensitive to nanomole amounts of inorganic and organic species. These electrodes have much potential for the analysis of ionizable species in column effluents. 

The apparatus used for high pressure liquid chromatography was by Pye-Unicam (Cambridge), HJ-—4oll equipped with a FU-4o2o UV detector. The co-... 

Yao and Wasa (1988a) assembled modified electrodes for amino acids by crosslinking L- or D-amino acid oxidase with glutaraldehyde on silanized platinum probes. The sensors were employed as detectors in high pressure liquid chromatography. Whereas the L-amino acid oxidase electrode responded to L-tyrosine, L-leucine, L-methionine, and L-phenylalanine in amounts as low as 2 pmoles, the D-amino acid electrode measured only D-methionine and D-tyrosine. The response time in steady state measurements was only 5-10 s. 

Inc. System (two model 6000A pumps model 440 UV detector with a 254 filter model 680 gradient controller model 746 data module and a RCM 8 X 10 cm Radial Compression Cartridge Holder) was used for high pressure liquid chromatography. Injections were made with a model 7125 Rheodyne injector. 

The major application of porous, three-dimensional electrodes has been in metal removal from dilute process liquors (Chapter 7) although inorganic and organic dectrosynthesis applications continue to be explored (see, for example, the Dow-Huron cell for production in Chapter S). Many battery and l el cell electrodes utilize an active material which is (or is supported by) a porous, three-dimensional matrix (Chapter 11), while miniature porous electrodes have found use in electrochemical detector systems for high-pressure liquid chromatography analysis (Chapter 12). 

High pressure liquid chromatography (HPLC) was used for the quantitative measurement of quinones and hydroquinones in the cultures. 20 pi of supernatant were injected in a Merck-Hitachi HPLC system 655A-12 equipped with a 4.6 x 250 mm Nucleosil C18 column (5 pm, RP 18). The system was run at a flow rate of 1 ml min-1 with a methanol/water gradient (10 to 20% methanol in 15 min, then 20 to 100% methanol in 5 min). The UV detector was operated at 281 nm or 275 nm to follow the reduction of quinones 13 and 14, respectively (37). 

For the analyses discussed here, we have used Gas Chromatography-Thermal Energy Analysis (GC-TEA ) and/or High Pressure Liquid Chromatography-Thermal Energy Analysis (HPLC-TEA). The TEA has been used as the detector... 

The application of atomic spectroscopic instruments as element-specific detectors in chromatography has been reviewed by van Loon More recently, Krull has extensively reviewed their use in high pressure liquid chromatography (HPLC). Atomic spectrometry has found wide acceptance in the field of liquid chromatography because, in most cases, the fractions can be directly analysed after elution from the column. However, it is possible to use the technique for the analysis of solid samples without first dissolving the matrix. This is particularly useful after electrophoresis, where the fractions are fixed either in a gel or on paper. Kamel et al. have shown that it is possible to cut the appropriate sections and insert them into the carbon furnace for analysis. The disadvantage of this approach is that the precision is usually poorer (about 10%) and it is difficult to calibrate the instrument. Nevertheless, this approach is very useful if it is used for qualitative speciation. 

It is for these reasons that a recommendation is made to avoid, wherever possible, concentration and cleanup steps that involve "column chromatography" of this nature, that is, chromatography where an in-line detector is not involved. This distinction is made to eliminate any implied criticism of instrumented high pressure liquid chromatographic systems which have not to date been used extensively for this particular purpose. 

Thermal volumetric Liquids only 1 Measures time taken for liquid to flow between two detectors by means of a heat pulse High pressure liquid phase chromatography (Section 6.8.3 and Volume 2, Chapter 19) No moving parts. Suitable for high pressures and temperatures... 

THIS SYSTEM IS COMPOSED OF XXX SUBPROGRAMS WHICH ACQUIRE DATA FROM A DUAL BEAM MULTIPLE WAVELENGTH DETECTOR IN A CONFIGURATION FOR USE WITH A HIGH PRESSURE LIQUID CHROMATOGRAPH. 

Fig. 14.8 A thin-layer cell for use as a high pressure liquid chromatography electrochemical detector (courtesy of Bioanalytical Systems).

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