I already prepare the standard curve and read the absorbance reading for reducing sugar, then how to relate that with standard curve?
January 8, 2023
Dear Zahirudin,
I am assuming you prepared your standard curve on your computer using Excel, and that the data points of your sugar standard lie on a good straight line. The correlation coefficient (R-squared) should tell you this.
You can use the equation for the straight line to calculate the amount of reducing sugar in your unknown sample.
Equation: y = mx + b, where y is the experimentally-determined absorbance, b is the y-intercept and m is the slope of the line. x is the reducing sugar concentration you are trying to determine. Rearrange the equation: x = (y - b)/m. In this rearranged equation, insert the absorbance (y) of your unknown and the constants (m & b), then calculate the reducing sugar concentration.
I hope this information helps you.
Bill Colonna Iowa State University, Ames, Iowa, USA [email protected]
Dear W.J. Colonna
Thank you for your help. It is possible if you can share some article/research paper regarding this calculation.
1/141/23
Dear Zahirudin,
I am not aware of any specific research article describing this calculation. This is a standard and accepted way of using a calibration curve to determine the concentration of a target analyte by quantitative analysis using spectrophotometry. It is a simple algebraic approach. Before I learned how to do this, I used to do it the "old fashioned" way. After constructing the calibration curve, I would determine the absorbance of the unknown, find that data point on the standard curve, then drop a perpendicular to the x-axis to get the analyte concentration. This works, but it is "hard" on your eyes, especially if you have a lot of samples. Eventually, I found that I could get the correct results by dividing the absorbance of the unknown by the slope of the calibration curve. You might be able to find this in a textbook on quantitative analysis. Your colleagues in the lab probably know how to do this.
I hope this information helps you.
Bill Colonna Iowa State University, Ames, Iowa, USA [email protected]
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