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Using Excel for generating graphs.
For our example we wish to graph the absorbance measurements of different
acetylsalicylic acid concentrations (remember aspirin determination?). In Figure 1, found
on the next page, there is an example of an Excel spreadsheet that was used to generate a
standard curve using acetylsalicylic acid concentrations and measured absorbances.
The acetylsalicylic acid (ASA) concentrations (x-values for our graph) were entered in
cells A2 through A6. The measured absorbances (at 526 nm) were entered in cells B2
through B6.
To generate a graph of the data you can either click on the Chart Wizard (see Figure1)
or highlight Chart under Insert on the tool bar.
1. Select a type of graph (e.g. XY (scatter)). Click next.
2. Enter the cell range where your data is found (e.g. $A2:$B6) or click the Data
Range box and select the cells that contain your data. Click next.
3. Type in title and axis labels (remember units where appropriate). You can
also edit chart axis, gridlines, legend and data labels at this point. Click next.
4. Place chart as new sheet or object in existing sheet. Click finish.
The chart should then appear on your spreadsheet. To insert a trendline and show an
equation:
1. Click on a single data point to highlight all the data points on the graph.
2. Under Chart on the menu bar, choose add trendline.
3. Select a Trend/Regression type (e.g. linear).
4. Click on the options button and set the y-intercept to zero (if you wish) and
choose to display the equation of the line and the R2-factor (if you wish).
Click Okay.
A trendline with an equation should appear on your graph. You can move your chart by
clicking on the chart area, holding down the left mouse button and dragging. You can
make the chart larger or smaller by clicking on your chart area and dragging the corner of
the chart while holding down the left mouse button. You can print the chart by clicking
on the chart area and choosing Print under File on the menu bar. This simple example
should give all the information you need to produce great graphs in Excel. Good Luck.
