March 28, 2024, 11:30:24 AM
Forum Rules: Read This Before Posting


Topic: LOQ issues in ion exchange chromatograpy  (Read 6223 times)

0 Members and 1 Guest are viewing this topic.

Offline CT101

  • Regular Member
  • ***
  • Posts: 11
  • Mole Snacks: +0/-1
LOQ issues in ion exchange chromatograpy
« on: October 12, 2007, 10:51:29 PM »
The goal is to validate an LOQ of 0.025% of a nominal concentration of 0.25 mg/ml. The compound is an oglionucleotide. A is a phosphate buffer at pH 7.9. B is A + 1.25M NH4Cl. Both A and B contain 10% ACN.  % recovery is ~65% on a good day. I need it to be at least 80%.

I suspect that NH4Cl is not a strong enough salt for trace analyte concentrations. Any one out here have any ideas?

Offline CT101

  • Regular Member
  • ***
  • Posts: 11
  • Mole Snacks: +0/-1
Re: LOQ issues in ion exchange chromatograpy
« Reply #1 on: October 14, 2007, 09:38:33 AM »
I should add that the signal to noise ratio so far is ~25.

Offline JGK

  • Chemist
  • Full Member
  • *
  • Posts: 738
  • Mole Snacks: +66/-19
  • Gender: Male
Re: LOQ issues in ion exchange chromatograpy
« Reply #2 on: January 18, 2008, 09:16:04 AM »
You can calculate theoretical LOQs using a vareity of methods including signal/noise ratio as described in the ICH validation document

http://www.emea.europa.eu/pdfs/human/ich/038195en.pdf

try these and follow up with testing to determine if it works.
Experience is something you don't get until just after you need it.

Sponsored Links