To calculate the concentration of an unknown protein sample from the standard protein curve in a Bicinchoninic acid assay, you will first need to create a standard curve from protein solutions of known concentration.

To create a standard curve, use graphing software or excel. Label the X-axis standard concentrations, the Y-axis absorbance, and plot your points accordingly. You should get a linear line or something close to linear. Now use the equation of a line and solve for the slope (m) and the y-intercept (b). Equation of a line:

Where:

• y = absorbance
• m = slope
• x = concentration
• b = y-intercept

If you are using excel, create your standard curve using a Scatter plot and then add a trendline, excel will automatically calculate the values of ‘m’ and ‘c’ for you. Once you have the values plug them into the equation of a line and solve for ‘x’:

To calculate the concentration of an unknown protein sample, measure its absorbance using a spectrophotometer and then plug it in to the above equation and solve for ‘x’.