Which gas chromatography detector would be best suited for the selective detecti
ID: 527212 • Letter: W
Question
Which gas chromatography detector would be best suited for the selective detection of low levels of chlorinated pesticides? (A) electron capture detector (B) flame-ionization detection (C) sulfur chemiluminescence detector (D) thermal conductivity detector The advantage of a packed column over a fused silica wall coated open tubular column is (A) short analysis times (B) higher sample capacity. (C) higher resolution. (D) reduced band broadening. The distribution of polymer molecular weights is often characterized by size-exclusion chromatography, what limits the range of molecular weights that can be characterized? (A) packing pore size (B) packing particle size (C) limited analyte solubility in the stationary phase (D) interactions with the surface of the stationary phase particles Increasing the flow rate of the mobile phase in chromatography would (A) increase band broadening due to greater eddy diffusion. (B) increase band broadening due to multiple paths. (C) increase band broadening due to longitudinal diffusion. (D) increase band broadening due to slow mass transfer kinetics. The use of smaller diameter stationary phase particles in liquid chromatography (A) decreases the plate height. (B) increases retention time. (C) decreases the resistance to solvent flow. (D) decreases the back pressure.Explanation / Answer
(41)
Analysis of low levels of pesticides is done using gas chromatography (GC) with a electron capture detection (ECD), Thus option (a) is the correct option.
(42)
Introducing a packed material leads to a greater area, thus giving us an option to run the experiment at a higher sample capacity. Hence option (b) is the correct option.
(43)
The amount of polymer that can pass through the size exclusion chromatography depnds on the pore size. Hence option (a) is the correct option. The amount of polymer depends on the pore size of the packing material.
(44)
option (a) is the correct option. increasing the speed of the mobile phase leads to more eddy formation, which results in a band broadening.
(45)
Decreasing the size of the stationary phase particles leads to increasing resulation. The resulation term in a chromatography is directly related to the retention time. Thus decreasing the diameter leads to increase of the retention time. Thus option (b) is the correct option.
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