By Jaime on Monday, June 14, 2004 - 01:26 pm:

Greetings to all...
Our lab recently purchased an HPLC 1100 series and I'm still learning how to navigate around the chemstation software. I have made varying concentrations of our sample (50, 100 ppm, etc) in hopes of creating a standard curve as a reference for future runs. My goal is to run future samples and have the method automatically use the absorbance value to calculate the concentration based on the std curve.
Is there a way to do this?

Thanks for your time.

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By Consumer Products Guy on Monday, June 14, 2004 - 03:34 pm:

Verify linearity of your analyte. You'll want to run at least a one point (cal level one) standard each time you run samples. Chemstation can do %ESTD (external standard percent) automatically, which is parts per hundred, so we use a factor of 10000 in the multiplier field of the sample table to change results to ppm. Of course, the heading will still say %, but we can change that in Notepad.

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By jaime on Tuesday, June 15, 2004 - 09:56 am:

thanks! I'll give it a try

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By Tim on Wednesday, June 16, 2004 - 06:13 am:

You can set the calibration table in the Method to use multiple level standards - just put add additional levels to each named compound for the different concentrations and it will determine the best fit for you. You will need to specify in your Sequence what level each standard being injected is at and this will establish the "Response Factor" in the method that is used to work out results.

When you inject samples in future, you must ensure you don't have any Calibration sample types specified in the sequence, so that the RF is changed.

As indicated by CPG, verifying you linearity first will mean you can just run a single level standard and do this in everyrun (though of course you can still run multi level standards in a run).

You can change the result column heading to whatever you want in the ChemStation software - check in Calibration Settings.

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By jaime on Wednesday, June 16, 2004 - 02:39 pm:

I was able to set up a multi-level calibration using the same retention time for the same compound and the graph gave a linear relationship. Now, I'm running my std samples disguised as unknown samples to see if it can calculate close to the ppm value.
thanks again.