2012-01-31 (Tue) 06:08:46 Shodex Technical question

Record: 512

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Category: Column Problem Product: PH-814 Sample:

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Question I am using a brand new column PH814. My mobile phase are ammonium sulfate (2M) and PBS (0.1M phosphate and 0.15 NaCl) for A and PBS for B. When flow at 0.4ml/min, 30 C, the pressure is already at 21bar. How come? The maximum pressure for this column is 25bar. How can I run at 1ml/min as in the column CofA? Anything wrong? BTW, I could not find tel# in the US for tech support. This certainly will impact my purhcase plan.     Answer As you mentioned, the maximum pressure for PH-814 is 25bar. And this usable pressure is not including the pressure for the other parts on the flow line such as tubes or detector. So, there is the case that the indicated pressure on the pump us higher than the usable pressure for the column. Could you please check the pressure of the system without the PH-814? If the flow line of the LC system does not have the higher pressure, please let us know the serial No. of the column. We will check the pressure of the column when it was shipped. Even if the pressure is higher than the usable condition of the column, the column is not damaged by the higher pressure, as long as the higher pressure comes from the upstream of the column. Because the pressure at the column is not interfered by the pressure at the upstream. That means the pressure at the upstream of the column is not limited for the column performance. However, please note that the high pressure at the downstream of the column can be the cause of column damage, because the back pressure is loaded to the bottom of the column. If there is the case that the back pressure is over the usable pressure of the column, we recommend making the back pressure lower by exchanging the tubes or decreasing the flow rate,     Additional Comments