%0 Journal Article
%T Determination of ammonium on an integrated microchip with LED-induced fluorescence detection
%A Shuhua Xue
%A Katsumi Uchiyama
%A Hai-fang Li
%A <br>Shuhua Xue
%A Katsumi Uchiyam
%A Hai-fang Li
%J 环境科学学报(英文版)
%D 2012
%I 
%X A simply fabricated microfluidic device integrated with a fluorescence detection system has been developed for on-line determination of ammonium in aqueous samples. A 365-nm light-emitting diode (LED) as an excitation source and a minor band pass filter were mounted into a polydimethylsiloxane (PDMS)-based microchip for the purpose of miniaturization of the entire analytical system. The ammonium sample reacted with o-phthaldialdehyde (OPA) on-chip with sodium sulfite as reducing reagent to produce a fluorescent isoindole derivative, which can emit fluorescence signal at about 425 nm when excited at 365 nm. Effects of pH, flow rate of solutions, concentrations of OPA-reagent, phosphate and sulfite salt were investigated. The calibration curve of ammonium in the range of 0.018-1.8 μupg/mL showed a good linear relationship with R2 = 0.9985, and the detection limit was (S/N = 3) 3.6 × 10-4 μupg/mL. The relative standard deviation was 2.8% (n = 11) by calculating at 0.18 μupg/mL ammonium for repeated detection. The system was applied to determine the ammonium concentration in rain and river waters, even extent to other analytes fluorescence detection by the presented device.
%K microfluidic chip
%K light emitting diode
%K o-phthaldialdehyde
%K fluorescence
%K ammonium<br>microfluidic
%K chip
%K light
%K emitting
%K diode
%K o-phthaldialdehyde
%K fluorescence
%K ammonium
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=3FF3ABA7486768130C3FF830376F43B398E0C97F0FF2DD53&cid=A7CA601309F5FED03C078BCE383971DC&jid=6CB1530875F53489BF1E81BD87B7F5E6&aid=7D4B0212F9173E1ABB86A9B4D7DDF694&yid=99E9153A83D4CB11&vid=B91E8C6D6FE990DB&iid=38B194292C032A66&sid=2497388423811B81&eid=18F040DBCB74FFF9&journal_id=1001-0742&journal_name=Journalofenvironmentalsciences(China)&referenced_num=0&reference_num=35