QC for Glycol Analysis

[sohaib1]

Can anybody suggest how to prepare QC samples. I am analyzing Ethylene and Propylene Glycol. Can i prepare QC from Stock Calibration solution or it has to be diffrent. I need help in QC Please. Thank you in advance

[James_Ball]

It depends on what agency you are reporting data to.

Most require that a calibration curve be validated by a QC sample that is prepared from a source separate from that of the calibration curve standards, but ongoing QC can be from either source. If you do not have two sources of ethylene and propylene glycols, then make two separate preparations of a stock dilution standard from the original compounds. This will show at least that there is no problems with the preparation.

[sohaib1]

It depends on what agency you are reporting data to.

Most require that a calibration curve be validated by a QC sample that is prepared from a source separate from that of the calibration curve standards, but ongoing QC can be from either source. If you do not have two sources of ethylene and propylene glycols, then make two separate preparations of a stock dilution standard from the original compounds. This will show at least that there is no problems with the preparation.

So are you suggesting i make separate QC from pure Ethylene Glycol and Propylene Glycol. Like lets say make 50 PPM Ethylene Glycol and 50 PPM Propylene Glycol?

[HPLC chemist]

Why not just obtain a previously tested QC sample and spike it with various concentrations of Glycol and EO?

[James_Ball]

It depends on what agency you are reporting data to.

Most require that a calibration curve be validated by a QC sample that is prepared from a source separate from that of the calibration curve standards, but ongoing QC can be from either source. If you do not have two sources of ethylene and propylene glycols, then make two separate preparations of a stock dilution standard from the original compounds. This will show at least that there is no problems with the preparation.

So are you suggesting i make separate QC from pure Ethylene Glycol and Propylene Glycol. Like lets say make 50 PPM Ethylene Glycol and 50 PPM Propylene Glycol?

If you have a pre-made mixture from a supplier then you can use that also. We normally order a solution from one supplier to use for making the calibration curve and another solution from a different supplier to do a QC standard. Restek, AccuStandard, Ultra, or any of the many other suppliers will probably have what you need for about $35.

[sohaib1]

It depends on what agency you are reporting data to.

Most require that a calibration curve be validated by a QC sample that is prepared from a source separate from that of the calibration curve standards, but ongoing QC can be from either source. If you do not have two sources of ethylene and propylene glycols, then make two separate preparations of a stock dilution standard from the original compounds. This will show at least that there is no problems with the preparation.

So are you suggesting i make separate QC from pure Ethylene Glycol and Propylene Glycol. Like lets say make 50 PPM Ethylene Glycol and 50 PPM Propylene Glycol?

If you have a pre-made mixture from a supplier then you can use that also. We normally order a solution from one supplier to use for making the calibration curve and another solution from a different supplier to do a QC standard. Restek, AccuStandard, Ultra, or any of the many other suppliers will probably have what you need for about $35.

OH ok thank you. So what QC will i need to make. The results will be reported to an internal department.