Chromatography Forum

Hi ,

I have apple tubers. I would like to test their peel for existence of compound A. This compound A remains 98% on its peel. So taking the peel is enough

Method:

Tubers weight= 0.5 kg ( this is total from many tuber not only one )
Weight of total peel = 50 g
weight of peel sample that I took = 5 g

so I extract this 5 g by 40 ml solvent ( soaking 24 hours then filter and measure by HPLC ).

Now, how much ( mg/kg) of compound A in the whole tuber?.


My answer:

concentration in extract ( the one I made by 5 g plus 40 ml after filtration) = 1 microgram/ml
multiply this by 40 to get 40 microgram in 5 g peel
so in 50 g this will be 400 microgram/ 50 g
in 500 g ( 0.5kg) this will be 4000 microgram/500g
divide 4000/500
so in the whole tuber will be 8 mg/kg

my colleagues said use this formula but it did not give like my answer. It gave 0.8 while mine is 8

Also I am worry why we have to include tuber weight while we depend only on the tuber peel ( 5 g ) and how much compound A is in there

this formula is

concentration in tuber mg/kg = ( conc. in extract* vol 40 ml* wight of total peel )/ ( weight of peel sample*weight of tuber)

Is my answer correct, if you provide me with more practice thats will be very excellent

thanks

Hi ,
Method:
Tubers weight= 0.5 kg ( this is total from many tuber not only one )
Weight of total peel = 50 g
weight of peel sample that I took = 5 g
so I extract this 5 g by 40 ml solvent ( soaking 24 hours then filter and measure by HPLC ).
Now, how much ( mg/kg) of compound A in the whole tuber?.

My answer:
concentration in extract ( the one I made by 5 g plus 40 ml after filtration) = 1 microgram/ml
multiply this by 40 to get 40 microgram in 5 g peel
so in 50 g this will be 400 microgram/ 50 g
in 500 g ( 0.5kg) this will be 4000 microgram/500g
divide 4000/500
so in the whole tuber will be 8 mg/kg

my colleagues said use this formula but it did not give like my answer. It gave 0.8 while mine is 8

Also I am worry why we have to include tuber weight while we depend only on the tuber peel ( 5 g ) and how much compound A is in there

in 500 g ( 0.5kg) this will be 4000 microgram/500g
this would be correct if you have 500g of peel. But from this 500g of tubers you took the 50g of peel with almost 100% of your compound in it.
so you still have only 400 microgr. of compound A from all of your sample.

So these 400 microgramms are contained also in the 500 g of tubers, which then gives 400µg/500g = 0.8mg/kg

Perfect!, thanks Hollow