Chromatography 3 Flashcards
Each peak on a chromatogram represents what?
Each peak represents a separated component of the mixture
The chromatograph gives the analysts a number of important details regarding……..
the separation and identification of the components of the mixture;
What is Retention time?
The time taken for a solute to reach the detector after injection (to).
List two terms used to Determine how good the chromatographic separation is.
- Resolution
2. Efficiency
What is Resolution?
This is a measure of how well the peaks have separated.
Resolution is needed to be able to use peak area quantitatively
what is the formula for Resolution?
R = 2(tR2-tR1)/wb1 +wb2
By convention, resolution (R) = twice the distances between the two peak maxima 2(tR2-tR1) divided by the sum of base width of the two peaks (wb1+wb2).
The greater the value of R, the better the resolution of the two compounds. true/false?
true
R value of approximately 1.5 means?
good base line separation
R value of approximately 1.0 means?
resolution not fully complete (only about 90%)
R value less than 1.0 means?
the separation is really not good enough to allow the analysis to make any quantitative analysis of concentration.
The BP assay of betamethasone 17-valerate states that it must be resolved from betamethasone 21-valerate so that the resolution factor is > 1.0. Which of the following ODS columns meet the specification? SEE TABLE ON CHROMATOGRAPHY 3 LECTURE SLIDE 8
Why use an Alternative form of the resolution equation ?
Can be used if the base line is difficult to measure
What is the alternative form of the resolution equation?
Rs = 1.18 x (tR2-tR1)/Wh1 + Wh2
The retention times of the two peaks observed in the resulting chromatogram were 3.9 minutes and 4.1 minutes. The width of each peak at half height was 0.1 minutes and 0.05 minutes respectively. What is the resolution between the two peaks?
1.57
In chromatography, what does a resolution value of 0.5 between peaks tell you?
Peaks are poorly resolved