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By Christy on Wednesday, August 18, 2004 - 03:32 am:
Dear all,
In my lab, we have to share the same HPLC system (Agilent 1100 with PDA detector). We just bought a new fluorescent detector to develop a new method. Unfortunately, when we inject the blank (H20), it shows a peak at the same retention time with the interested peak. This peak is not big (peak height is about 0.2) but we also want to analyse at very low concentration (down to 3-5ng/ml) so it really interferes. We did try some works to eliminate the cause of this peak and at last we suspected that the system was contaminated from previous works so we want to wash the system. Could anyone suggest the good procedure to wash?
Thank you in advance!
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By zetto on Wednesday, August 18, 2004 - 04:56 am:
Hi Christy
Bypass your column,flush the system (including the injector loop and other valved tubing) with 50 ml water. Run 50 ml of 20%v/v nitric acid (make sure you separate the waste from your ''regular'' waste if it contains solvent that migh react with the HNO3) Flush again with 50 ml of water...and voilà ! it works 99% of the time
Bye
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By christy on Wednesday, August 18, 2004 - 05:23 am:
Thanks zetto! I 'll try your suggestion. However still wonder if the contaminator is an organic cpd so can HNO3 help?
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By A on Wednesday, August 18, 2004 - 11:12 am:
The previous suggestion is about as agressive as you can get. I would first try a flush with IPA first, if that does not work, then 30% H3PO4, if that does not help then passivate with the nitric. If you have to share this system, it is probable that you will have to do this often so taking a less agressive route might be better. Also, in my experience, it takes many more volumes of water to fully wash out the volume of nitric used in these flushes.
Dear all,
In my lab, we have to share the same HPLC system (Agilent 1100 with PDA detector). We just bought a new fluorescent detector to develop a new method. Unfortunately, when we inject the blank (H20), it shows a peak at the same retention time with the interested peak. This peak is not big (peak height is about 0.2) but we also want to analyse at very low concentration (down to 3-5ng/ml) so it really interferes. We did try some works to eliminate the cause of this peak and at last we suspected that the system was contaminated from previous works so we want to wash the system. Could anyone suggest the good procedure to wash?
Thank you in advance!
-------------------------------------------------------------------------------------------------------
By zetto on Wednesday, August 18, 2004 - 04:56 am:
Hi Christy
Bypass your column,flush the system (including the injector loop and other valved tubing) with 50 ml water. Run 50 ml of 20%v/v nitric acid (make sure you separate the waste from your ''regular'' waste if it contains solvent that migh react with the HNO3) Flush again with 50 ml of water...and voilà ! it works 99% of the time
Bye
-------------------------------------------------------------------------------------------------------
By christy on Wednesday, August 18, 2004 - 05:23 am:
Thanks zetto! I 'll try your suggestion. However still wonder if the contaminator is an organic cpd so can HNO3 help?
-------------------------------------------------------------------------------------------------------
By A on Wednesday, August 18, 2004 - 11:12 am:
The previous suggestion is about as agressive as you can get. I would first try a flush with IPA first, if that does not work, then 30% H3PO4, if that does not help then passivate with the nitric. If you have to share this system, it is probable that you will have to do this often so taking a less agressive route might be better. Also, in my experience, it takes many more volumes of water to fully wash out the volume of nitric used in these flushes.
