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Ultraviolet absorbance detector based on a high output power 235 nm surface mounted device-type light-emitting diode
journal contribution
posted on 2023-05-21, 10:29 authored by Lam, SC, Coates, LJ, Vipul GuptaVipul Gupta, Wirth, H-J, Gooley, AA, Paul HaddadPaul Haddad, Brett PaullBrett PaullA new miniaturised capillary flow-through deep-UV absorbance detector has been developed using a microscale surface mounted device- type light-emitting diode (LED) (Crystal IS OPTAN 3535-series), emitting at 235 nm and with a half-height band width of 12 nm, and a high-sensitivity Z-shaped flow-cell. Compared with a previously reported TO-39 ball lens LEDs emitting at 235 nm, the new generation LED produced a 20-fold higher optical output and delivered up to 35 times increase in external quantum efficiency (EQE). The Z-cell was based on a reflective rectangular optical path with cross-sectional dimensions of 100 x 100 µm and a physical optical pathlength of 1.2 mm. Inclusion of UV transparent fused-silica ball lenses, between the SMD and the Z-cell, improved light transmission by a factor of 9 and improved the detector signal-to-noise ratio by a factor of 2.2, at the same input current. The detector was housed within an Al-housing fitted with a cooling fan and demonstrated excellent linearity with stray light down to 0.06%, and an effective pathlength of 1.1 mm (92% of nominal pathlength). The resultant detector was fitted successfully into a briefcase-sized portable capillary HPLC system, and practically demonstrated with the detection of a mixture of 13 test compounds at the sub-mg L−1 level in <5 min using gradient elution.
History
Publication title
Journal of Chromatography AVolume
1631Article number
461540Number
461540Pagination
1-6ISSN
0021-9673Department/School
School of Natural SciencesPublisher
Elsevier Science BvPlace of publication
Po Box 211, Amsterdam, Netherlands, 1000 AeRights statement
© 2020 Elsevier B.V. All rights reserved.Repository Status
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