Detector in high-performance liquid chromatography

Shelly, D. C. and Warner, I. M., Fluorescence detectors in high-performance liquid chromatography, in Liquid Chromatography Detectors, Vol. 23, Vickrey, T. M., ed., Marcel Dekker, New York, 1983, chap. 3. 

Bollet, C., Oliva, P., and Caude, M., Partial electrolysis electrochemical detector in high-performance liquid chromatography, /. Chromatogr., 149,625,1977. 

AN Masoud, Y N Cha. Simultaneous use of fluorescence, ultraviolet, and electrochemical detectors in high performance liquid chromatography-separation and identification of phenolic antioxidants and related compounds. J High Resolut Chromatogr Comm 5 299-305, 1982. 

Kollotzek D., Oechsle D., Kaiser G., Tschopel P. and Tolg G. (1984) Application of a mixed-gas microwave induced plasma as an on-line element-specific detector in high-performance liquid chromatography, FreseniuS Z Anal Chern 318 485-489. 

I. S. Krull, Recent Advances in New and Potentially Novel Detectors in High-Performance Liquid Chromatography and Flow Injection Analysis. Amer. Chem. Soc. Symp. Ser., 297 (1986) 137. 

Ultraviolet Absorption Photometers Ultraviolet photometers often serve as detectors in high-performance liquid chromatography. In this application. a mercury va >or lamp usually serves as a source, and the emission line ai 254 nm is isolated by fillers. This type of detector is described briefly in Section 28(%b. 

Recent Advances in New and PotentiaUy Novel Detectors in High-Performance liquid Chromatography and Flow Injection Analysis... 

C.N. Svendsen, Multi-electrode array detectors in high-performance liquid chromatography A new dimension in electrochemical analysis. Analyst, 1993, 118, 123-129. 

Chromatopolarography appeared to be an important method, because on a well-chosen chromatographic column, substances which had almost identical voltam-metric characteristics (half-wave potentials) could be separated, if their affinities to the column-filling material (stationary phase) were sufficiently different. After separation, they could be polarographically detected and their content determined. This method may be considered a precursor of many combined voltammetric techniques developed in forthcoming years and specifically electrochemical detectors in high performance liquid chromatography (HPLC) and microfluidics. 

Application of a mixed-gas microwave induced plasma as an on-line element-specific detector in high-performance liquid chromatography, Fresenius Z. 

Chan HK, Carr GP. Evaluation of a photodiode array detector for the verification of peak homogeneity in high-performance liquid-chromatography. Journal of Pharmaceutical and Biomedical Analysis 8, 271-277, 1990. 

It must be compatible with the analytical method. The frequent use of CS2 as a solvent is favored because CS2 produces a low response when analysis is performed by gas chromatography with flame ionization detection (GC/FID). Likewise, low UV-absorbing solvents are frequently used in high performance liquid chromatography (HPLC) to minimize solvent interference when using a UV detector. 

Figure 1 is the ultraviolet spectrum of a 10 mcg/ml solution of vitamin D3 in methanol. The spectrum was obtained using a Cary Model 219 recording spectrophotometer (Varian Instrument Co., Palo Alto, CA). Vitamin D3 and related compounds have a characteristic UV absorption maximum at 265 nm and a minimum at 228 nm. The extinction coefficient at 265 nm is about 17,500 and 15,000 at 254 nm. An index of purity of vitamin D3 is a value of 1.8 for the ratio of the absorbance at 265 to that at 228 nm. The high absorbance at 254 nm enables one to use the most common and sensitive spectrophotometric detector used in high performance liquid chromatography (HPLC) for the analysis of vitamin D3 in multivitamin preparations, fortified milk, other food products, animal feed additives etc. 

Zavitsanos, P., and Goetz, H. (1991). The practical application of diode array UV-visible detectors to high-performance liquid chromatography analysis of peptides and proteins. In High-Performance Liquid Chromatography of Peptides and Proteins Separation, Analysis,... 

Apparatus (See Chromatography, Appendix IIA.) Use a high-performance liquid chromatograph operated at room temperature with a 10-p.m particle size, 30-cm x 4-mm (id), C18 reverse-phase column (jxBondapak C18 column, Waters Corp., 34-T Maple Street, Milford, MA 01757, or equivalent). Maintain the Mobile Phase at a pressure and flow rate (typically 2.0 mL/min) capable of giving the required elution time (see System Suitability in High-Performance Liquid Chromatography). Use an ultraviolet detector that monitors absorption at 254 nm (0.2 to 0.1 AUFS range). 

Chromatographic System Use a liquid chromatograph equipped with a 254-nm detector and a 25-cm x 4.6-mm (id) column that contains 5- to 10- xm porous silica microparticles (pPorasil, or equivalent). Set the flow rate to about 1 mL/ min. Chromatograph replicate injections of the Standard Preparation, and record the peak responses as directed under Procedure. The relative standard deviation is not more than 2.0%, and the resolution, R, between (Z)-phytonadione and ( )-phytonadione is not less than 1.5 (see System Suitability in High-Performance Liquid Chromatography under Chromatography, Appendix IIA). 

In high-performance liquid chromatography (HPLC), postcolumn detection is generally used. This means that all solutes are traveling at the same velocity when they pass through the detector flow cell. In HPCE with on-capillary detection, the velocity of the solute determines the residence time in the flow cell. This means that slowly migrating solutes spend more time in the optical path and thus accumulate more area counts [3]. 

Fig. 1 The inductively coupled plasma-mass spectrometer (ICP-MS) used as a detector for high-performance liquid chromatography (HPLC). The liquid sample passes through the capillary into a nebulizer where it is changed into an aerosol. The aerosol passes through a spray chamber and into the plasma. The analytes pass into the mass spectrometer. The CE interface is not in detail in this figure.

Countercurrent chromatography (CCC) is a chromatographic method which separates solutes more or less retained in the column by a stationary phase (liquid in this case) and are eluted at the outlet of column by a mobile phase. Two treatments of column effluent have been used until now in CCC. Either the column outlet is directly connected to a detector commonly used in high-performance liquid chromatography (HPLC) (on-line detection) or fractions of the mobile phase are collected and analyzed by spec-trophotometric, electrophoretic, or chromatographic methods (off-line detection). 

Goodall, D. M. and D. K. Lloyd, A note on an optical rotation detector for high-performance liquid chromatography, in Chiral Separations (D. Stevenson and D. Wilson, eds.). Plenum Press, New York, 1988, pp.131-133. 

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