Clavulanic Acid internal standard

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

6 posts Page 1 of 1
Helo everyone
I'm upon developing new method for analyzing clavulanic acid using Ms/Ms with ESI in the negative mode
and the problem what I have that I can't find a proper internal standard that ionized in the -ESI and match the same chromatography conditions of it
Please any suggestions?
and what is the possible m/z ions in the -ESI for the suggested internals?
hello
please can you help me ?
did u find the proper internal standard ?
because iam facing now the same porblem
First rule: NEVER re-invent the wheel!
That is, do not go the trouble of developing a method, if one is already available in the literature.
So,
1. Do a search on your favorite browser to answer your question; found a method YES or NO,
If YES, problem solved,
if NO,
2. Find structure and molecular weight of clavulanic acid (CA).
3. For the internal standard, find a chemical analogue that has similar structure & Molecular weight to CA and maintains the -COOH group.
For instance, a -CH3 instead of -CH in an alkyl chain or methylation of free -OH to -OMe is acceptable, but esterification to -COOMe is not.

I note that the -CH=CH- double bond in CA is in the Z configuration.
Does the -CH=CH- double bond in CA exist in the E configuration? If it does and is stable under your chromatographic conditions, that would make an ideal I.S.

Regards,
JMB
Or google: https://www.clearsynth.com/en/CSP03866.html
To be honest, I sometimes do reinvent the wheel when it comes to methods in literature. There are quite a few square wheels that have been successfully published over the years. But you're right, as a friend once said: "you can save yourself a good hour in the library by spending a week in the lab instead"
lmh wrote:
as a friend once said: "you can save yourself a good hour in the library by spending a week in the lab instead"


We would always review literature before developing a procedure ourselves for actives in our OTC consumer products. Most USP-type methods were for the actives themselves, not mixed into products at low levels, so not applicable. Sometimes a supplier would volunteer a procedure.

But most often we would need to develop from scratch. First we'd look at the structure of the sought-for analyte, see if it had a UV absorbance or was or could be made volatile. After we could get a good, retained peak for the analyte, we'd then look at a placebo product matrix for co-eluting peaks, sample preparation, etc. So not a slam-dunk, why I was paid accordingly.

Then the cGMP validation studies......
The trouble with literature is that so much of it is appalling. And journal editors sometimes don't know their nose from their eyeball, and some reviewers shouldn't be allowed to read the newspaper without someone there to help them with the big words.

I'm looking at the moment at a paper in Analytical and Bioanalytical Chemistry (so there's no excuse, this is an analytical journal). It's a methods paper, with a title along the lines of Quantification of Favourite Analyte in red blood cells by LC-MS", so you'd expect describing the method to be a fairly high priority.

The method claims steps of 0-0.8min 100%A; rise to 70% B in 4.8min; to 100% B in 0.1min; hold 100% B for 0.2 min; followed by a 3.5min equilibration. Then, the next sentence summarises that the overall run time was 8.5 min, with an injection volume of 5 uL. I have added up those step-times in every way I can imagine, and can I get 8.5 min? The paper has a typical chromatogram of a standard, showing the peak eluting nicely at 6.3min. Which would place it firmly in the re-equilibration part of the gradient, whether I use the gradient quoted, or the 8.5min figure. I'm guessing that actually the method is 9.5, not 8.5 (a typo) and that they dropped from 100%B to 100%A over 0.1min but missed this bit out. I'm also guessing (at least hoping) that the typical chromatogram with a 6.3min elution time came from an earlier, slower run before they optimised the gradient. The alternative is to hope that their system has a huge dead volume, because otherwise, at the very least, this target was only just eluting at 100%B, and the whole 0-70 bit was a waste of time.

If a methods paper in an analytical journal can't actually quote its gradient correctly, and none of the reviewers even notice, what is the point of having literature methods to follow? As usual, this means we can use the paper to get a rough idea of the sort of column-chemistry that might work (assuming they haven't messed that up too), and otherwise, we develop our own method.
6 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

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.

Liquid Chromatography

Gas Chromatography

Mass Spectrometry