Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: LabRat1017 on August 09, 2013, 11:21:55 PM
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Im working on the USP Maleic acid monograph testing for Limit of Fumaric Acid. I am having an issue with my TLC plate when i am finished and viewing under UV light. There are diamond shaped spotsa ll over my plate. Has anyone done this test or had this issue with anything else?
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Could you elaborate on the test?
Don't copy it verbatim but give the plate type, mobile phase and any visualisation method (i.e. pre-treatment before UV)
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Plate: Silica Gel GF 250um
MP : Heptane:Butanol:Chloroform:Anhydrous Formic Acid: (44:36:16:16)
Unsaturated chamber, run about 3/4 length of plate and then dried 100C for 15 min and viewed under UV at 254nm
Plate is predried at 105/30min
Its completed verbatum from USP monograph for Maleic Acid see link :
http://www.pharmacopeia.cn/v29240/usp29nf24s0_m442.html
When viewed under the UV light there are all of these diamond shaped spots all over the plate so you can not see the spots of interest. At first i thought something was sprayed on the plate but we tried 2 more times and same issue. If anyone can help?
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Have you checked have you tried with fresh solvents?
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I have tried fresh solvents, a new plate.