Calibration curve by changing injection volume, validation?

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

17 posts Page 2 of 2
At least this is how I would look at it from an auditor's perspective - how can you prove that your system is precise at all of the various injection volumes? That would be the biggest question to answer if you were to do it your way - in my opinion.
The same way you prove that your dilutions are precise: by examining the linearity of the calibration plot. In any case this should be done routinely as part of PQ ("Performance Qualification", for the uninitiated).

What it boils down to is: can you prepare your calibrators more accurately / precisely than the autosampler can make its injections?

By the way, I prefer to keep injection volume constant to minimize possible matrix effects, but either approach can be validated.
-- Tom Jupille
LC Resources / Separation Science Associates
tjupille@lcresources.com
+ 1 (925) 297-5374
Thank you, Tom!! My thoughts precisely. By varying the injection volume you run into a host of problems that you don't have to deal with using a fixed injection volume, including transfer time to the head of the column, refocusing, matrix effects (especially with MS!!), etc.

As James points out, in a regulatory environment (be it USEPA, ICH, AOAC or other) you are normally limited to a controlled injection, i.e.., a fixed volume injection.
Mark Krause
Laboratory Director
Krause Analytical
Austin, TX USA
17 posts Page 2 of 2

Who is online

In total there are 2 users online :: 1 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: Google [Bot] 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