Hey gulzar, just make stock solution of 200 mg per liter (you can go for small volume also) and make serial dilution according to your interest (2 times, 5 times, 10, 15, 20 etc)

@Nitesh sir is it the right way to make 20-100mg/l

• Take 2mg, 4mg, 6mg, 8mg & 10mg of Gallic acid in 100ml volumetric flask

as 2mg/100ml = 20mg/1000ml and so on...

• Measure the absorbance of each test tube at 760nm against water blank

Yes you can also do like that but if you take individual standard.. There is a chance of error and due to that u will not get proper linearity.. So better go for serial dilution..

@nitesh sir then give step by step details plz how to go serial dilution

ohhh.. once you prepare stock solution my making 20mg/100mL..

1) Take 10 ml from that and make 100 mL (2mg/100mL)

2) Take 20 ml from stock and make 100 mL (4mg/100mL)

3) Take 50 ml from stock and make 100 mL (10 mg/100mL)

By this nethod, make working concentration of standard which you want..

All d best...

Stock solution 20mg/ml means 200mg/l.

Sir explain me when we take 10ml from stock soln how it is 2mg/100ml

ohh my god. you r doing phd and dont know how to dilute standard.. even dont know about serial dilution.. such a shame. Atleast one should know about this.

Neways let i explain...

if you r taking 10 mL of stock solution 20 mg/100 mL, it means 100 ml contain 20 mg then 10 ml contain 2 mg.. right????

now this 10 ml means 2 mg you dilute to 100 ml so final concentration is 2mg/100ml... so simple...

@nitesh i know that

I know that hahahahahahhahaahah