A new high sensitivity deep-UV LED photometric detector with a z-type flow cell (45 nL or 180 nL) for miniaturised and portable capillary liquid chromatography (LC) was designed and fabricated to overcome sensitivity limitations due to short pathlength in on-capillary detectors. The new detector has a 10 mm geometric pathlength and uses high intensity light-emitting diodes (LED) as light sources in the deep-UV range (254 nm and 280 nm). No optical reference was necessary due to the low drift in the signal. Stray light was minimized by the use of an adjustable slit with a 0.5 mm pinhole. The direct relationship between absorbance and concentration was obtained using dichromate to evaluate the sensitivity and the linearity range of the detector. Performance of the miniaturised version was compared with that obtained from a commercial benchtop detector for capillary LC under the same conditions using the same optical z-cell. The miniaturised version exhibited a superior performance across all parameters, including 3 times higher effective pathlength, 4 times higher upper limit of detector linearity, and 2–5 times lower stray light levels. An application of the new detector was shown with the detection of l-dopa, l-tyrosine, norfenefrine, phenylephrine and tyramine, separated using capillary LC. The baseline noise level recorded was as low as 3.9 μAU. Further, the detector was applied in a miniaturised capillary LC for the indirect detection of common inorganic anions. In comparison to an on-capillary LED detector applied under similar chromatographic conditions, there was a 50 times higher signal to noise (S/N) ratio.

Item Type:	Refereed Article
Keywords:	Deep UV LED, high-sensitivity z-cell, absorbance detector, capillary liquid chromatography, portable liquid chromatography
Research Division:	Chemical Sciences
Research Group:	Analytical chemistry
Research Field:	Separation science
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the chemical sciences
UTAS Author:	Li, Yan (Mr Yan Li)
UTAS Author:	Nesterenko, PN (Professor Pavel Nesterenko)
UTAS Author:	Stanley, RA (Professor Roger Stanley)
UTAS Author:	Paull, B (Professor Brett Paull)
UTAS Author:	Macka, M (Professor Mirek Macka)
ID Code:	151518
Year Published:	2018
Funding Support:	Australian Research Council (FT120100559)
Web of Science® Times Cited:	17
Deposited By:	Chemistry
Deposited On:	2022-08-01
Last Modified:	2022-09-01
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