Light scattering detector. HPLC

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.

Thin-layer chromatography (TLC) is used both for characterization of alcohol sulfates and alcohol ether sulfates and for their analysis in mixtures. This technique, combined with the use of scanning densitometers, is a quantitative analytical method. TLC is preferred to HPLC in this case as anionic surfactants do not contain strong chromophores and the refractive index detector is of low sensitivity and not suitable for gradient elution. A recent development in HPLC detector technology, the evaporative light-scattering detector, will probably overcome these sensitivity problems. 

Mengerink et al. [243] describe for the analysis of ether carboxylic acids and mixtures thereof with ethoxylated alcohols an HPLC method with the use of a evaporative light-scattering detector (ELSD). 

Trathnigg, B., Kollroser, M.J. (1997). Liquid chromatography of polyethers using universal detectors V. Quantitative aspects in the analysis of low-molecular mass poly(ethylene glycols) and their derivatives by reversed-phase HPLC with an evaporative light scattering detector. J. Chromatogr. A 768, 223-238. 

The evaporative light scattering detector (ELSD) may have a role in this field. The response is highly dependent upon the size of analyte particles formed during evaporation of the mobile phase in the interface with the HPLC. Hence, it is hard to predict how sensitive it will be for a specific compound. Furthermore, volatile... 

Fang LL, Wan M, Pennacchio M, Pan JM. Evaluation of evaporative light-scattering detector for combinatorial library quantitation by reversed phase HPLC. Journal of Combinatorial Chemistry 2, 254-257, 2000. 

Chudy MR, Wilcox MJ. The use of volatile mobile phase modifiers for HPLC methods and evaporative light scattering detectors. Alltech Application Notes 2000. 

An evaporative light scattering detector was coupled with a UV spectrophotometer, and was applied to HPLC for the quantitative determination of cholesterol oxides in edible oils and fats. 

Fig. 11 Separation of phenacyl esters of the isomeric octadecenoic acids, petroselinic acid (6-18 1), oleic acid (9-18 1), and vaccenic acid (11-18 1) by HPLC on silver ion column (Nucleosil 5SA) loaded with silver ion eluted with dichloromethane-dichloroethane-acetonitrile 50 50 0. 25 (vol vol) detection light-scattering detector. (From W.W. Christie, Analusis 26 M38 (1998), reproduced with permission.)...

Ruiz-Sala et al. (129) described a reversed-phase HPLC method with a light-scattering detector for the analysis of TGs in milk fat. The identification of TGs was carried out by a combination of HPLC and gas-liquid chromatography (GLC), and was based on the equivalent carbon numbers and retention times of different standard TGs. Finally, quantitation of peak areas from HPLC chromatograms was carried out after applying a deconvolution program to the parts of chromatograms with poor resolution. 

Fig. 45 Reversed-phase HPLC of autoxidized trilinolenin (peroxide value = 236.4 meq/kg). Nova-Pak C18 cartridge column (Waters, Milford, MA) (3.9 X 150 mm, 60 A, 4 yam), mobile phase acetonitrile/ dichloromethane/methanol (80 10 10). Ultraviolet (UV) detector (235 nm) and evaporative light-scattering detector (ELSD). Primary oxidation products, double peak at 3.6 min secondary oxidation products elute before primary oxidation products.

WS Letter. A rapid method for phospholipid class separation by HPLC using an evaporative light scattering detector. J Liq Chrom 15 253-266, 1992. 

SL Melton. Analysis of soybean lecithins and beef phospholipids by HPLC with an evaporative light scattering detector. J Am Oil Chem Soc 69 784-788, 1992. 

RD Plattner. Detection of fumonisins produced in Fusarium moniliforme cultures by HPLC with electrospray MS and evaporative light scattering detectors. Nat Toxins 3 294-298, 1995. 

Purity measured by HPLC/ELSD (evaporative light scattering detector). Yield based on weight of crude extract from the resin. 

Analysis of Tween 80 was performed using a Hewlett Packard 1100 series HPLC equipped with a Sedex 55 Evaporative Light Scattering Detector (ELSD). The mobile phase consisted of 80% acetonitrile and 20% water. Duplicate injections (5 pL) of each sample were evaluated by HPLC. Potassium iodide, used for the 1-D column and 2-D box tracer studies, was analyzed with a continuous flow Isco V4 variable UV wavelength absorbance detector equipped with an EZChrom Chromatography data acquisition system. 

The advent of the use of mass spectrometers as detectors and new mass detectors such as the charged aerosol detectors (CAD) and evaporative light scattering detectors (ELSD) should provide high-sensitivity detection of compounds that do not absorb UV light. The only problem with most of these is that they are expensive and, therefore, not readily available. When prices come down, they should finally eliminate the use of derivatives in HPLC analysis. 

Kibbey CE, Quantitation of combinatorial libraries of small organic molecules by normal-phase HPLC with evaporative light-scattering detector, Molec. Diversity., 1 247-258, 1995. 

Anklam, E., Lipp, M. and Wagner, B. (1996) HPLC with light scatter detector and chemometric data evaluation for the analysis of cocoa butter and vegetable fats. Fett Lipid, 98(2), 55—59. 

Current IPC detectors are on-stream monitors. HPLC detectors range from (1) non selective or universal (bulk property detectors such as the refractive index (RI) detector), characterized by limited sensitivity, (2) selective (discriminating solute property detectors such as UV-Vis detectors) to (3) specific (specific solute property detectors such as fluorescence detectors). Traditional detection techniques are based on analyte architecture that gives rise to high absorbance, fluorescence, or electrochemical activity. Mass spectrometry (MS) and evaporative light scattering detectors (ELSDs), can be considered universal types in their own right... 

Although tocopherols and tocotrienols can be detected by UV absorbance at 280 nm, fluorescence detection (excitation 294 nm and emission 326 nm), as shown in Figure 11.3, has proven to be a much more sensitive method. Electrochemical detection such as pulsed amperometric and coulometric (Uspitasari-Nienaber, 2002) has also proven to be sensitive and potentially valuable for the quantitative analysis of tocopherols and Tocotrienols (Abidi, 2000), especially for tocol analysis in blood and serum samples. HPLC mass detectors such as flame-ionization detectors, evaporative light-scattering detectors, and charged aerosol detectors have proven to be valuable for the quantitative analysis of many types of lipids, but because tocols have... 

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