Chromatography

Question 1

Theoretical plate

Answer 1

N number of Segments of the stationary phase where equilibrium is reached, more theoretical plates better separation

Question 2

Height equivalent of a theoretical plate

Answer 2

HETP = L/N = A + B/v + C • v

ABC = coefficients
V = velocity of mobile phase

Smaller the HETP, the better the separation

Question 3

Detectors properties (GC)

Answer 3

1. ) sensitivity
2. ) linearity
3. ) stability
4. ) universal or selective response

Question 4

Linearity

Answer 4

Refer to the concentration range over which the signal is directly proportional to the concentration of the analyte and not distorted

Question 5

Stability

Answer 5

The extent to which the signal output remains constant with time

Question 6

Universal or selective response

Answer 6

To the components present in the mixture

Question 7

Most common detectors

Answer 7

1. ) thermal conductivity detector (TCD)

2. ) flame ionization detector (FID)

Question 8

Thermal conductivity detector

Answer 8

Uses a metal filament to sense changes in the thermal conductivity of the carrier steam, universal detector

Question 9

Flame ionization detector

Answer 9

The effluent front he column is mixed with hydrogen and burned in air to produce a flame that has enough energy to ionize solute molecules that have low ionization energy, detector = selective

Question 10

Resolution (GC)

Answer 10

R = 2(tr2-tr1)/(wb1-wb2)

2 = substance 2, 1 = substance 1, w = bandwidth