In order to maintain the quality if their packaged products,the UWA tea and coff

Question

In order to maintain the quality if their packaged products,the UWA tea and coffee company regularly conducts HPLC analysis of their raw ingredients to determine the levels of centain antioxidants and the caffeine content.Due to a fault in the HPLC software,results from analyses are being displayed as a data table instead of an easy to read chromatogram

a)Are the peaks for compound 4 and 5 resolved and show how can you prove your answer?

b)A UV-visible detector can be used to detect caffeine due to its strong chromophore.Describe a detector,including how it works,that could be used to detect a non-charged organic compound that does not have a UV-visible chromophore.

Explanation / Answer

Solution:
a) Retention time (tR) is the time it takes a solute to travel through the column. The retention time is assigned to the corresponding solute peak.Theoretical plates numbers are an indirect measure of peak width for a peak at a specific retention time. Columns with high plate numbers are considered to be more efficient (i.e., higher column efficiency) than columns with lower plate numbers. A column with a high number of plates will have a narrower peak at a given retention time than a column with a lower number of plates.

Separation factor (a);

The separation factor (a) is a measure of the time or distance between the maxima of two peaks.

a = k2 / k1

k1 = retention factor of first peak

k2 = retention factor of second peak

a = 28/26.3 = 1.06 min

b) Photoionization detector (PID) is a type of gas detector.

It is a battery-operated detectors are widely used in military, industrial, and confined working facilities for safety.

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