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Boardwalk :: Forum List Forum Category GC Troubleshooting
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 Headspace GC Question - 2005/11/28 18:26 I am developing a headpsace residual solvent method and due to solubility limitations, I have to use DMSO as the sample solvent. When using water, most methods I have come across use an oven temperature of 80 C. When using DMSO, is it common to use a higher temperature since DMSO boils at approximately 189 C? I have tried to find a reference that lists the vapor pressures of common solvents at various temperatures so that I can compare with water but this has been unfruitful. Other than the risk of bursting the vial and sample degradation, is there any reason not to use DMSO at elevated temperatures (> 150)? I consulted Static Headspace Gas Chromatography by Bruno Kolb and DMSO as a solvent is not addressed. Also, any information regarding a supplier of high purity DMSO would be helpful. Volatile components present in the DMSO that I have used thus far are causing selectivity problems. Thanks in advance for your help.
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 Headspace GC Question - 2005/11/28 18:27 I don't know what solvnts you are trying to quantitate. I also have a method for determinog volatile components in printed samples of paer/plastic, and I use triacetine to make the calibration solution. I dilute all the solvents I want to quantitate in triacetine. Untill now, it has diluted all tha solvents I know.
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 Headspace GC Question - 2005/11/28 18:27 If I understand correctly, you are looking for other organic components dissolved in DMSO. I would try heating to 80 C to see if recovery is adequate. The vapor pressure of the analytes is the key factor, not that of the solvent. You should get reasonable recoveries using the same conditions used for aqueous samples.

DMSO purity is a real issue for this type of work. DMSO is very efficient at dissolving organics from the room air, so the solvent must be isolated from organic vapors during sample prep.
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 Headspace GC Question - 2005/11/28 18:28 DMSO is useful at 80°C in headspace work.

Be vigilant for DMS and DMDS peaks.

Recoveries are about 1/3 of those from water for many common organic solvents at 80-85°C.

NOTE: Heating DMSO at higher temperatures can drive unwanted reactions with the solvents of interest and the sample matrix, so be careful.

Unless you are looking for semivolatiles there is no reason to use higher temperatures.

Have you tried water/DMAc combinations for your dissolution solvent instead of DMSO, or perhaps methyl cellusolve?

Good luck.
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Boardwalk :: Forum List Forum Category GC Troubleshooting

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