Concentration unit used is mg/L (it is same as microgram per mL). Dilutions generally made are: 75, 100, 150, 250, 500, 550, 600, 700, 750 mg/L.

@Dildar

At this high concentration more chances of deviation from linearity

Hi Raghad,

To prepare a standard calibration curve of Gallic acid it is better to take different concentrations of Gallic acid (10 to 100 μg/ml) in methanol, it may be 10, 20, 30, 40, 50 μg/ml and so on.

Good luck!

My research group used this concentration range many a time and got straight line. However, more dilute solutions can be used.

different ranges of gallic acid concentration lead to different regression equations and different answers for total phenol content !!!

@ Manju Tembhre ,

Can we prepare the gallic acid standard solution in deionized water in place of methanol ?