Calibration with Openlab CDS using Amount and Calibration

I want to calibrate the MSD by using the information related to our 17034 solution standard and I wonder how I can add the concentration in the process method that will be able to take my dilution into account and how many I put into the headspace vial. 

We have certified concentration in ug/mL (ppm). 

Since we use Headspace, we want to calibrate based on the amount of analyte added to the vials. 

Can I used the concentration and dilution factor to automatically calculated the amount in ug used for the calibration curve. 

Here an example to put this more in context: 

I have a commercial solution of ethanol at 5012 ppm (ug/mL)

I prepared my working solution by diuting 5 time the solution at 5012 (dilution factor). 

I also take 20 uL of this working solution to put into headspace vial for analysis (can be considered as multiplier here). 

So in fact, we add 5012ug/mL /5 mL * 0.02 mL = 20 ug of ethanol in the vial. 

The concentration may be susceptible to change since we will order different batches of 17034 standard solution. So we will need to enter the concentration of the commercial solution each time we process a batch. 

The dilution factor and the 20 uL added to the vial will be constant.  

How can I used program the software so it can use the 20 ug of ethanol calculated with the concentration of the commercial solution, the dilution factor and also the multiplier.

Thank you for your help. 

  • Hello,

    At this time, you cannot do any calculations that affect the calibration curve. The curve will always be built with the compound area or other selected value and the amount from the calibration table. All multipliers, dilution factor, compound multipliers, and custom calculation are applied to the calculated amounts from the curve. 


  • OK so I will need to change those compound_calibAmount manually. thank you again for your help. I am planning to use the % mass  and concentration value to report the amount ug of any residual solvents with the sample weight option so we can have a result of ug/g. 

    I will ask analyst to enter sample weight in the sequence table in milligram. 


    And we this % mass calculation we have this formula: 

    The amount will be calculated with the curve and will be ug, the sample weight in mg will only be value for samples. Since the formula already has a 100 as multiplier, I will have to adjust the other multiplier to have my result in PPM (ug/g). 

    Since I would need to change my sample weight entered in mg to g, the conversion is 1000. But since my formula already used 100, I will only use a multiplier 10 to complete this 1000 fold conversion and the final result with than become PPM (ug residual solvent/ g of sample)

    I hope it will work fine. ;-) 

  • Hi Martin I confirm that my calculation works. I can calculate directly the ppm of solvent in the sample bu using % Concentration and a multiplier used to convert % in PPM. The ug is calculated from the curve and divided by the sample weight entered in mg. 

    thank you again for your precious help. I am getin better because of you. 

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