On the estimation of extra-column contributions to band broadening through measurements on an authentic chromatogram
✍ Scribed by Nilsson, O.
- Publisher
- John Wiley and Sons
- Year
- 1979
- Tongue
- English
- Weight
- 310 KB
- Volume
- 2
- Category
- Article
- ISSN
- 0935-6304
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The time constant, τ, is determined from the tail of an authentic HPLC peak through a plot of In U versus time, t, according to the relation
expected at low recorder deflexions, U. The value obtained, τ = 2.43 s, is one order of magnitude larger than an ordinary recorder time constant, which is quite normal for LC detectors. It agrees with the value, τ = 2.44 s, needed theoretically to distort a Gaussian‐shaped peak so as to obtain the experiment‐ally found second moment, σ^2^ = 11.13 s,^2^ and the experimental difference between first moment t and peak retention time t~max~, t – t~max~ = 0.78 s. The determination is therefore regarded as a demonstration of the variance addition rule
where σ is the second moment of the non‐distorted peak. The column contribution version
is also considered. This equation was appliied earlier to an estimation of extra‐column contributions to band broadening with the aid of the “abt” concept. An explicitly k‐(capacity ratio)‐dependent expression for the mass exchange contribution, σ is derived from Golay's equation for capillary columns, but the validity of the Golay equation is under discussion.