Does any body know a mathematical formula which allows replication of chromatograph peaks? I saw one years ago in GC/LC magazine but unfortunately no longer have the article.

If you want to cheat and do it in Excel, the normal distribution is built-in:
NORMDIST(x,mean,standard_dev,cumulative)

X is the value for which you want the distribution (for a chromatographic peak, this would be time).

Mean is the arithmetic mean of the distribution (for a chromatographic peak, this is the retention time).

Standard_dev is the standard deviation of the distribution (for a chromatographic peak this is 1/4 of the baseline width).

Cumulative is a logical value that determines the form of the function. If cumulative is TRUE, NORMDIST returns the cumulative distribution function; if FALSE, it returns the probability mass function (to draw peaks, you want FALSE here).

Just set up your time values in one column, calculate Normdist in the second column, and do a line graph of the second column. Add additional columns and sum them for multiple peaks.

If you really want to get cute, you can apply a scaling factor to each peak, add random "noise" and systematic drift . . .

Hmmm -- this might replace actual chromatography (and all the peaks would be perfectly symmetrical, too)! :-)

-- Tom Jupille / LC Resources