A calibration curve is used in analytical chemistry to figure out the concentration of a substance in a sample, by comparing the sample to a set of predetermined data. In order to build a calibration curve in Excel 2007, you should already have your experimental data formatted in a worksheet with columns (x, y) and column headers. For example, if you want to plot absorbance vs. concentration, put your absorbance values in column A and your concentration values in column B.
Highlight both columns of your data. Left-click on the top left of your data, then drag the mouse to the bottom-right of your data.
Click the "Insert" ribbon.
Click the "Scatter" button in the Charts section of the Insert ribbon. Click the bottom-right icon in the Scatter Plot drop-down list. The icon has squares with lines between them. The ribbon has now automatically switched to “Design,” and your plot has appeared on screen.
Click “Select Data,” in the Data section of the Design ribbon.
Click the list item titled “Series1,” then click "Edit" right above that.
Type “Calibration Curve” in the “Series Name” text box. Press "OK."
Press "OK" again, and you are back on your spreadsheet with the Calibration Curve plot.
“Absorbance” should be the first data column, and “Concentration” should be the second column. If they are reversed, your plot axes will also be reversed.
The calibration curve is never exact: it only gives you an estimate of the concentration. Make sure you build in an allowance for error into your calculations.