Refractive index detector high-performance liquid chromatography

The refractive index is another very rapid analytical method for determining purity and identity of a substance. It is uniquely useful for quality control monitoring of raw materials and finished products. Many students encounter a refractometer first as a universal detector for high-performance liquid chromatography. 

The determination of the molecular weight of nanoparticles is performed by gel permeation chromatography (GPC). The experimental setup consists of a high performance liquid chromatography system with a size exclusion column and a refractive index detector. The nanoparticles are usually freeze-dried and dissolved in tetrahydrofuran for analysis on the system. Poly(styrene) or poly(methylmethacrylate) standards are used to calibrate the column, to enable the determination of number average molecular weight (Mn), as in... 

Analytical Method Development for TRIS. The detection of brominated compounds of very low volatility such as TRIS posed special analytical problems. Since TRIS has no recognizable chromophore, the detection systems which are commonly used with high performance liquid chromatography (hplc), such as refractive index or short wavelength (<220 nm) uv detectors, are too non-specific to be of much practical use for the analysis of environmental samples. Furthermore, the sensitivities available with these detection methods are generally inadequate. 

While lactose may be determined by gas liquid chromatography, high performance liquid chromatography (HPLC), using a refractive index detector, is now usually used. 

High-performance liquid chromatography (HPLC) system with refractive index detector and HPLC column (e.g., Aminex HPX-87H, Bio-Rad) fitted with suitable guard column... 

Fig. 4.3. High performance liquid chromatography (HPLC) of the monosaccharides obtained from a partially purified preparation of microbubble glycopeptide surfactant from forest soil. Following hydrolysis (in 2 N HC1 for 6 hr at 100°C) and filtration, the carbohydrate mixture was charged on a Bio-Rad HPX-87 cation exchange column. For comparison, part A shows the chromatogram (using the same HPLC column) of a standard solution, which contained 4 pg of each of three different monosaccharides (i.e., the last three peaks shown are glucose, xylose and fiicose, in the order of increasing retention times). Part B shows the chromatogram obtained from hydrolysis of the partially purified (see text) microbubble surfactant (approximately 30 pg). All other experimental conditions were identical in the two cases, i.e., water eluent, 0.5 ml/min flow rate, 85°C, refractive index detector attenuation -2x. (Taken from ref. 322.)...

Virtually every type of high-performance liquid chromatography (HPLC) detector can be combined with SCIC refractive index, UV absorbance (direct and indirect), electrochemical, and so forth. 

High-performance liquid chromatography (HPLC) of the bile alcohols was carried out on a Waters Associates ALC 201 system employing a Waters model 401 refractive index detector and a Waters 4-mm ID x 30-cm p Bondapak Cjg column (Waters Associates Inc., Milford, MA). The solvent system was 80 % Me0H/H20 (v/v) with a flow rate of 1.5 mL/min. 

Xylose, xylitol, and ethanol were analyzed using LC-IOAD high-performance liquid chromatography (Shimadzu, Japan), equipped with an HPX-87H Aminex column (Bio-Rad) and a RID-IOA refractive index detector. The column was maintained at 55 °C and eluted with 5 mmol/L H2SO4 at a flow rate of 0.4 mL/min. 

TLC RCP methods may not be sufficient to identify all the compounds that are present in a product. High-performance liquid chromatography (HPLC) has a higher sensitivity and resolving power than simple TLC methods. Gamma emitters are detected using a well scintillation counter connected to a rate meter. Other detectors (ultraviolet or refractive index) can be connected in series allowing simultaneous identification of compounds. 

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