I have prepared standard curve using gallic acid concentration (20-100mg/L= 20-100µg /mL=0.02-0.1mg/mL). After evaporation of alcohol and then freeze drying, I took 0.01 g of sample and dissolved in 20 ml alcohol, i.e. concentration = 0.5mg/mL = 500mg/L= 500µg/mL). From this, 0.3 ml extract was mixed with 1.5 ml F-C reagent (10 fold dilution) and 1.2 ml (7.5% Na2CO3) and then kept for 30 min at room temperature. The absorbance value of the sample is 0.883 and the regression equation is y= 0.0107x. I have tried calculation in different ways. But I am not sure which one is correct. I got higher value when I calculated. Please kindly help me to calculate correctly.