1 ) Why should not mobile phases with pH above 8 be used with silica based columns?
- The silica dissolves at high pH so that the column deteriorates.
- The mobile phase becomes flammable at high pH.
- The pressure becomes too high.
- The analytes degrade at high pH.
2) Which organic modifiers are most common in reversed phase chromatography.
- Isopropanol and toluene.
- Methylenechloride and chloroform.
- Methanol and acetonitrile.
- Ether and acetone.
3) Chromatographic retention is due to:
- Different injection times by the autosampler.
- Adsorption of the analyte to the stationary phase.
- Differences in absorbance in the UV detector.
- Deviations in the flow from the pump.
4) Generally, how do you make a calibration curve?
- By using a RI-detector and sucrose as analyte.
- Injecting a known amount of analyte and determine the peak area.
- Accurately measure the flow rate.
- Setting the detector response to zero.
5) What is characteristic of gradient chromatography?
- The detector scans over a wide range of wavelengths.
- The mobile phase is unbuffered.
- A gradient of flow velocity is created.
- A gradient of mobile phase composition is created.
Comments or questions?
Send an e-mail to studyhplc.com
Copyright 2010 studyhplc.com. All rights reserved.