Title: CHE2DEV Env Water Qual Quiz 6-2

Feedback shared by this category's questions, if partly right: 1

Q: Solutes containing halogens can best be studied in gas chromatography with
- a flame ionization detector.
- an electron capture detector.
- a flame photometric detector.
A: an electron capture detector.

Q: Decreasing the thickness of the stationary phase leads to
- decreased plate height, increased retention time, and decreased capacity for the analyte.
- decreased plate height, decreased retention time, and decreased capacity for the analyte.
- decreased plate height, decreased retention time, and increased capacity for the analyte.
A: decreased plate height, decreased retention time, and decreased capacity for the analyte.

Q: Which is the most common carrier gas for gas chromatography?
- helium
- nitrogen
- hydrogen
A: helium

Q: You can improve the separation of components in gas chromatography by
- raising the temperature of the injection port.
- raising the temperature of the column isothermally.
- raising the temperature of the column programmatically.
A: raising the temperature of the column programmatically.

Q: In GC, separation between two different solutes occurs because
- the solutes have different solubilities in the mobile phase.
- the solutes volatilize at different rates in the injector.
- the solutes spend different amounts of time on the stationary phase.
A: the solutes spend different amounts of time on the stationary phase.

Q: A good technique for using a GC syringe to inject liquid sample into a gas chromatograph is
- after cleaning the syringe several times with solvent, take up air, then sample, and then more air.
- after cleaning the syringe several times with nitrogen, take up solvent, then sample, and then more solvent.
- after cleaning the syringe several times with solvent, take up air, then solvent, then air, then sample, and then more air.
A: after cleaning the syringe several times with solvent, take up air, then solvent, then air, then sample, and then more air.

Q: An on-column injection is used
- when a very small amount of analyte is present in the sample.
- when the sample decomposes above its boiling point.
- when the sample is not going to be used for quantitative analysis.
A: when the sample decomposes above its boiling point.

Q: A split injection on a gas chromatograph is normally preferred when
- the analyte is less than 0.01% of the sample.
- when the analyte is greater than 0.10% of the sample.
- the analyte contains two substances with widely different retention times. Splitting the injection allows the sample to be analyzed much more quickly.
A: when the analyte is greater than 0.10% of the sample.

Q: Compared with packed columns open tubular columns offer
- higher resolution, shorter analysis time, greater sensitivity, and larger sample capacity.
- higher resolution, shorter analysis time, greater sensitivity, and lower sample capacity.
- higher resolution, longer analysis time, greater sensitivity, and larger sample capacity.
A: higher resolution, shorter analysis time, greater sensitivity, and lower sample capacity.

Q: Typical GC detectors include
- flame ionization, thermal conductivity, electron capture, and mass spectrometer.
- ultraviolet, fluorescence, amperometric, and conductivity.
- spectrophotometer, refractive index, light scattering, and electrochemical.
A: flame ionization, thermal conductivity, electron capture, and mass spectrometer.