I have digested plant samples with 1 mL of 6M HCl. I am now attempting to dry the samples in a vacuum oven. I have it set at 60 deg 6, 60 mmHg and after 3-4 hours I am not seeing a reduction in the volume.
I've even put in a vial with water and I'm not seeing a reduction in that volume either. The Sigma Aldrich nomograph confirms that 6M Hcl (bp= 108 deg C) should boil at 37 deg C when at 60 mmHg. What's wrong?
How can i confirm the pressure inside of the oven? There is a dial but perhaps it is incorrect? Are there any other suggestions for getting rid of the acid when freeze-drying is not an option?
Hello, something wrong with your pump or system. Vacuum 6.6mmHg should evaporate and dry your sample even at room temperature.
For see pressure in oven you need some barometer installed on it.
How you see 6.6mmHg ?
6M HCl is very corrosive and not easy to remove, however there are many options for that. You can use anti-corrosive freeze dryer, or speedVac but it seems that you do not have any of these then heating around 40oC at vaccuum around 20 torr should remove the 6M HCl in 14-24 hours. The important questions are
1. are there any undissolved blackish or other materials in your samples?
2. How large is the surface area of the samples?
I recommend to pass all the samples through glass wool or cotton filters to remove any undissolved materials and use large surface area.
You can also neutralise the 6M HCl with NaOH use the freeze dryer however this will produce NaCl salt which can be easily removed by SPE.
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