Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: wzhu on January 29, 2010, 03:17:53 PM
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I am preparing standard solutions of furan, furfuryl alcohol, phenol, and benzoic acid. I dissolved furan, furfuryl alcohol and phenol in MeOH, but found the solute content decreased significantly with time. How to prevent vaporization please?
The procedure I use is: measure MeOH with balance in a 40 mL vial, leaving no more than 1 mL headspace. Seal the vial with septa. Then pierce through the septa to inject certain amount (10 - 100 uL) of standard chemical. Measure injected chemical with balance. Then seal the vial with parafilm, and put in cold storage.
According to direct injection to GC-MS, up to 2 folds of response decrease was observed within 1 hour after freshly prepared... I have been trying different GC parameters (injection purging, split ratio, etc.), but found it was most likely caused by vaporization.
Does anyone know how to prevent this vaporization please? Thank you so much for your *delete me*
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I have been spending a whole week day and night, and found it was because of the cap. FYI, the phenolic black headspace vial cap from Supelco is not air tight enough for VOC standards. I found the green caps from Supelco much more airtight, and works well for VOC solutions.