-
- Posts: 1
- Joined: Thu Jan 15, 2015 1:22 am
Hello,
I have noticed an issue at my institute where a sample is run as part of a bracketing standard USP test method that yields areas low enough to generate a failing result. However, if the same sample prep is run on the same system (either a new vial is prepared or the same vial is used) with the same column, mobile phase, standards etc. the sample passes with expected area counts.
The system consists of an auto-injector, heated mobile phase, column heater and refractive index detector. The retention times of all standards and samples were very consistent and the area counts of the failing samples and the standards had very little variation (probably around 0.2% RSD).
My question is: why would the sample areas be low enough to give a failing result while in a subsequent run the area count for the sample is high enough that it would pass on the second analysis?
During first run, sample areas are low and fail. During second run, sample areas are high and sample passes. Nothing is changed from run 1 to run 2 (same column, mobile phase, detector, system, vials, etc.). Why does this happen?
I have noticed an issue at my institute where a sample is run as part of a bracketing standard USP test method that yields areas low enough to generate a failing result. However, if the same sample prep is run on the same system (either a new vial is prepared or the same vial is used) with the same column, mobile phase, standards etc. the sample passes with expected area counts.
The system consists of an auto-injector, heated mobile phase, column heater and refractive index detector. The retention times of all standards and samples were very consistent and the area counts of the failing samples and the standards had very little variation (probably around 0.2% RSD).
My question is: why would the sample areas be low enough to give a failing result while in a subsequent run the area count for the sample is high enough that it would pass on the second analysis?
During first run, sample areas are low and fail. During second run, sample areas are high and sample passes. Nothing is changed from run 1 to run 2 (same column, mobile phase, detector, system, vials, etc.). Why does this happen?
