ELSD检测器的选择和主要的应用介绍.ppt

* Since carbohydrates are non-volatile samples, sensitivity is lost when analyzing them in impactor on mode. * Glucopyranosides are non-volatile samples and splitting the mobile phase decreases the detection sensitivity. Impactor Off mode is ideal for this sample because the mobile phase is mostly organic and the sample is not volatile Weve talked about two examples for impactor off, so lets move on to impactor on * Parabens are a classic example of impactor on analysis because they are semi-volatile, especially the lower molecular weights. Analysis in impactor on mode reduces the amount of mobile phase entering the drift tube and ultimately allows low temperature operation. Sensitivity is increased in impactor on * Sucrose is a common application for RI and ELSD detectors. In this example the ELSD is more sensitive and has better baseline stability. Throughout the presentation, the ELSD conditions are listed, but I wont be taking the time to read them to you. Most of the applications from this seminar were performed on the Model 500, and Melissa will be talking about the differences you can expect when comparing methods done on the 500 to those on the 2000. * The top chromatogram shows the isocratic elution of carbohydrates, and the bottom one shows gradient elution. The gradient compatibility of the ELSD achieves improved resolution and faster separation * Only detects chromophoric - any compound less volatile Detection based on extinction coeff. - based on concentration Gradient Baseline drift at low wavelength - little or no solvent front interference - no response from solvents solvent limited by uv cutoff- compatible w/ BPless than 100 * Here is a steroid conjugate example The sample has 100 ng estrone sulphate, 100 estradiol, and 220 pregnane diol glucuronide ELSD shows greater mass related response. * Here is a steroid conjugate example The sample has 100 ng estrone sulphate, 100 estradiol, and 220 pregnane diol glucur