# ELISA standard curves and computer programs - (Mar/06/2006 )

Hello

I wonder If anyone could help me. I have been using Excel (and sometimes Minitab) to analyse data from ELISA. From each ELISA i use a series of standards of known protein concentration. I plot these against absorbance to give me a curve. I can then use this curve to find protein concentrations for measured absorbances from my samples.

My problem is that I am using a very antiquated method of reading the graph (actually printing out the excel line graph and drawing lines with a ruler at each measured absorbance and another line to give me concentration)

Is there a faster way I can do this (using either Excel or minitab)?

So to recap: i need a way to read (or interpolate i think i have heard it described as) values on a line graph in a fast and efficient way, within the capabilities of excel, minitab, or other (free) software.

All the best

Ewan

Make standard curve as "X-Y plot" but put absorbance on X-axis and protein concentration on Y-axis. Add linear trend line and show equation on graph. Put your absorbance in equation to get protein concentration. Check R^2 to see if your curve fits your data.

OR

Use linear regression function with your known X (abs) and Y (prot.conc.) and unknown X (abs).

OR

Use linear regression function with your known X (abs) and Y (prot.conc.) and unknown X (abs).

Thankyou

Would this work if my line is not straight (a curve)

thankyou very much for your prompt reply

All the best

Ewan

You could add a polynomial trendline and it should fit the curve and give you a quadratic equation.

Take my advice - when using polynomial (or any other non-linear) trend line/curve, don't belive what exel shows you, make new line using equation and see if it looks same good. I got tricked once...