-
- Posts: 1
- Joined: Fri Jul 28, 2017 4:11 pm
Cyclohexane pressure problems
Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.
3 posts
Page 1 of 1
Working with 100% cyclohexane and n-hexane (and only then), I have observed (ternary Hitachi L-6200 pump) that the pressure drop was severely fluctuating (e.g. from 0, 10, 12 bar minimum to 80 bar maximum, every few seconds), with the column. When the column was removed, I observed the same pressure variation (naturally, smaller range 0-7 bar) and flow rate variance as well (i.e. when pressure went down to 0 there was no flow while it was at 7 the flow was too fast, almost overflowing).
-
- Posts: 517
- Joined: Thu Jul 14, 2016 12:08 pm
It seems that there's an obstruction somewhere and you already narrowed it down between the mobile phase bottle and the part that connects to the column.
I suggest to narrow it down further by decoupling more tubings step by step.
There are several possibilities, one thing i had lately that gave the same symptoms was a pump line filter frit where something got stuck.
I suggest to narrow it down further by decoupling more tubings step by step.
There are several possibilities, one thing i had lately that gave the same symptoms was a pump line filter frit where something got stuck.
-
- Posts: 6
- Joined: Fri May 11, 2018 1:01 am
peterjack wrote:
Working with 100% cyclohexane and n-hexane (and only then), I have observed (ternary Hitachi L-6200 pump) that the pressure drop was severely fluctuating (e.g. from 0, 10, 12 bar minimum to 80 bar maximum, every few seconds), with the column. When the column was removed, I observed the same pressure variation (naturally, smaller range 0-7 bar) and flow rate variance as well (i.e. when pressure went down to 0 there was no flow while it was at 7 the flow was too fast, almost overflowing).
This looks typical of a check valve problem. Happens pretty often with hexane. Was the system used in a polar solvent before? If is is the case make sure to wash with lowering polarity solvent before going to hexane, otherwise you will get check valve problems.
3 posts
Page 1 of 1
Who is online
In total there is 1 user online :: 0 registered, 0 hidden and 1 guest (based on users active over the past 5 minutes)
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm
Users browsing this forum: No registered users and 1 guest
Most users ever online was 1117 on Mon Jan 31, 2022 2:50 pm
Users browsing this forum: No registered users and 1 guest
Latest Blog Posts from Separation Science
Separation Science offers free learning from the experts covering methods, applications, webinars, eSeminars, videos, tutorials for users of liquid chromatography, gas chromatography, mass spectrometry, sample preparation and related analytical techniques.
Subscribe to our eNewsletter with daily, weekly or monthly updates: Food & Beverage, Environmental, (Bio)Pharmaceutical, Bioclinical, Liquid Chromatography, Gas Chromatography and Mass Spectrometry.
- Follow us on Twitter: @Sep_Science
- Follow us on Linkedin: Separation Science