Hi I' m really stuck on this so any help is appreciated.
I am doing a project on cinchona alkaloids.
I made 4 calibration curves, one for each alkaloid standard, and used hplc data and the equation of the line to find the unknown concentration, but i need to further calculate the concentration of each alkaloid for each of my sample undiluted.
So for example, i added 0.4 grams of bark to 30 ml of solvent, and then ultrasonicated it. Then i took 1ml put in in a 10ml volumetric flask, and diluted that with mobile phase. then did hplc analysis.
So how do i use this information alongside with the concentration i found from the equation of the line, to get the real concentrations?
thank you
If your concentration (Cquant) is in [mg/mL] (and assuming recovery=100%):
(Cquant*10*30)/0,4 grams = mass of alkaloid [mg]/g of bark
regards,
GB
You must use 2 equations.
1. ug/mL Alkaloid from graph x (10 mL/1 mL x 30 mL total volume)/0.4 g
2. Since y = mx + b (linear curve), therefore
ug/mL Alkaloid = (Peak area - bias or b)/(m or HPLC detector response factor)
Usually, a previously tested sample is 'spiked' with your standard and the % Recovery or % Accuracy is calculated. It should be around 100% for all your alkaloids.
There can be several justifiable reasons for a 'low' % Recovery! An example is whether you have
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