Turbulence as a Source of Excessive Baseline Noise during High-Speed Isocratic and Gradient Separations Using Absorption Detection
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- 作者：Deirdre Cabooter ; Fré ; dé ; ric Lynen ; Pat Sandra ; Gert Desmet
- 刊名：Analytical Chemistry
- 出版年：2008
- 出版时间：March 1, 2008
- 年：2008
- 卷：80
- 期：5
- 页码：1679 - 1688
- 全文大小：323K
- 年卷期：v.80,no.5(March 1, 2008)
- ISSN：1520-6882
文摘
The occurrence of turbulent flow conditions in the connection tubing or at the entrance of the detection flow cellhas been identified as a potential source of excessivedetector noise in the signal of the diode array UV-absorption detector flow cell of a commercial HPLCsystem used to perform high-speed separations on wide-bore columns (4.6 mm i.d.). This excessive noise wasfound to occur abruptly if the flow rate is increased beyonda certain critical value or during gradient runs, if themobile phase viscosity falls below a certain critical value.Several detector cells of different dimensions werestudied to investigate the dependency of the effect on thedetector cell design and the system tubing. Evidence forthe turbulent flow origin of this noise is that its onsetalways occurred at a given fixed value of the Reynoldsnumber. This critical Reynolds number could also be usedto predict the onset of detector noise during gradientelution runs. Second, evidence for the turbulent floworigin of the noise was that it could be reliably eliminatedusing a flow splitter after the column to reduce the flowrate below its critical value before entering the detector.The loss in separation efficiency and detection sensitivityaccompanying this flow splitting solution was found to beso small that it does not weigh up against the hugeadvantage of the possibility to eliminate the excessivedetector noise.