Carbohydrates evaporative light-scattering detection

Bruns, A., Waldhoff, H., and Winkle, W., Application of HPLC with evaporative light-scattering detection in fat and carbohydrate chemistry, Chro-matographia, 27, 340, 1989. 

Wei Y, Ding MY. Analysis of carbohydrates in drinks by high-performance liquid chromatography with a dynamically modified amino column and evaporative light scattering detection. Journal of Chromatography A 904, 113-117, 2000. 

Sugars Common carbohydrates are monosaccharides (glucose, fructose), disaccharides (sucrose, maltose, lactose), trisaccharides (raffinose), and polysaccharides (starch). HPLC offers a direct, quantitative method for simple sugars, which requires a specialty cationic resin-based column and refractive index or evaporative light scattering detection.7,8 UV detection at low wavelengths (195 nm) can be used but is more prone to interferences.8... 

Alltech Application Note 0054E The use of acetone in the mobile phase to speed up run times for carbohydrates in beer by reversed phase HPLC and evaporative light scattering detection is described, March 29, 2004. 

Evaporative light scattering is gaining popularity due to its ability to detect analytes on a nonse-lective basis. Basically, this detector works by nebulizing the column effluent, forming an aerosol that is further converted into a droplet cloud for detection by light scattering. This type of detector has been applied to studies of small molecule combinatorial libraries [13,14], carbohydrates [15], and lipids [16,17]. 

Also known as the mass detector, this is an evaporative analyzer in which the mobile phase is removed by nebulization and evaporation prior to the determination of nonvolatile carbohydrates by light scattering (44). Unlike the refractive index detector, it allows gradient elution (eluent is removed before detection) and is more sensitive. The detection limit can go up to a few tens of nanograms injected. 

The evaporative light-scattering detector (ELSD) is a near universal detector suitable for the determination of (mainly) neutral compounds that are less volatile than the mobile phase used for the separation [151,152]. Primary uses include the detection of compounds with a weak response to the UV detector, especially carbohydrates, lipids, surfactants, polymers and petroleum products. Its greater sensitivity and ease of use in gradient elution separations makes it preferable to the refractive index detector for these applications. The ELSD is compatible with most volatile solvents used for normal and... 

The equipment widely used for the detection of carbohydrates in the HPLC method is the differential refractive index (RI) detector. The principle involved in this detection depends on the continuous measurement of the variation of the RIs of the mobile phase containing the samples with little or no chromophores such as carbohydrates, lipids, and other polymer compounds that do not absorb UV light. RI detection method presents high degree of reproducibility and is very convenient for the analysis of polysaccharides. However, other detectors such as evaporative light scattering detector and pulsed amperometric detector have been used for the detection of polysaccharides [100]. 

Conductivity, direct absorbance or a differential refractometer are the most common forms of detection for lEC, PAD and ELSD. A pulsed amperometric detector (PAD) or, more recently, an evaporative light-scattering detector (ELSD) is appropriate for detection of carbohydrates. Both non-suppressed and suppressed conductivity have been used extensively. The need to incorporate a low concentration of a strong acid into the eluent has been an impediment to direct conductivity detection. 

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