O, boy. Okay here is what you do.
[ol]
[li]open your file.[/li][li]Analysis > Plot > Point[/li][li]You will get the spectrum in the plot tool window.[/li][li]zoom into the m/z region you want to substract (190 for you)[/li][li]MIDDLE BUTTON click and drag on the matrix peak. A green bar will appear over your matrix peak.(middle button might be your scroll wheel)[/li][li]An pop up window will appear. You could play around with the Analysis Mode (I use Mean) And for the Output window, pick an empty window. That’s where your mean image (in your case the matrix divisor) will go. [/li][li]You should see a new image appear in the window you speced. On the bottom you should see something like “(mean:189.3432-191.3324)[/li][li]close the spectrum “Plot tool” window[/li][li]Here is the part I get wrong all the time. Highlight the file you open in step 1. This is your numerator. [/li][li]Tools > Calculation > Divide and the divide window will pop up[/li][li]Your Reference is the window with your matrix image. Output to an empty window. [/li][li]Wait.[/li][/ol]
Hope this is what you were looking for. If it works, send beer.
KC
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