Chih-Wei Wu This email address is being protected from spambots. You need JavaScript enabled to view it.1 and Yi-Lung Lee1

1Department of Mechanical & Mechatronic Engineering, National Taiwan Ocean University, Keelung, Taiwan 202, R.O.C.


Received: February 9, 2007
Accepted: April 14, 2007
Publication Date: June 1, 2007

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Nitrite ion has recently attracted a great deal of attention because of its potential roles in diverse fields of our lives. This work shows an innovative PDMS-based liquid core waveguide (LCW) to determine the concentrations of nitrite in nature water. A 1 cm straight and Teflon AF 1601S coated polydimethylsiloxane (PDMS) microchannel (600 m width and depth) replicated from a SU8 master was sealed with a glass slide with the same coating. This formed a low index of refraction microchannel in which a high index aqueous solution was flowed. Light generated by a fiber-coupled tungsten halogen lamp propagated by total internal reflection to the end of the channel where the light was detected using a CCD array spectrometer. There is a dramatic difference between channels with and without the Teflon coating. The absorbance response of this PDMS-based LCW varies linearly with concentration and adheres to Beer’s law. Additionally, calculations of absorbance using this LCW are in excellent agreement with a commercial spectrometer (JASCO, V-530). This innovative PDMSbased LCW provides a low-cost and high efficient approach to fill the inspection technology gap between in-situ and laboratory analyses. It has greater potential for development and commercialization and will be mass-produced in the future.

Keywords: Liquid Core Waveguide, Nitrite, Teflon AF 1601S


  1. [1] Zafiriou, O. C., Ball, L. A. and Hanley, Q., “Trace Nitrite Oin Oxic Waters,” Deep Sea Res., Vol. 39, pp. 13291347 (1992).
  2. [2] Motomizu, S., Mikasa, H. and Toei, K., “Fluorometric Determination of Nitrite in Natural Waters with 3- Aminonaphthalene-1, 5-disulphonic Acid by FlowInjection Analysis,” Talanta, Vol. 33, pp. 729732 (1986).
  3. [3] Cox, R. D., “Determination of Nitrate and Nitrite at the Parts Per Billion Level by Chemiluminescence,” Anal. Chem., Vol. 52, pp. 332335 (1980).
  4. [4] Garcide, C., “A Chemiluminescent Technique for the Determination of Nanomolar Concentrations of Nitrate and Nitrite in Seawater,” Mar. Chem., Vol. 11, pp. 159167 (1982).
  5. [5] Kieber, R. J. and Seaton, P. J., “Determination of Subnanomolar Concentrations of Nitrite in Natural Waters,” Anal. Chem., Vol. 67, pp. 32613264 (1995).
  6. [6] Waterbury, R. D., Yao, W. and Byrne, R. H., “Long Pathlength Absorbance Spectroscopy: Trace Analysis of Fe(II) Using a 4.5 m Liquid Core Waveguide,” Anal. Chim. Acta, Vol. 357, pp. 99102 (1997).
  7. [7] Steimle, E. T., Kaltenbacher, E. A. and Byrne, R. H., “In Situ Nitrite Measurements Using a Compact Spectrophotometric Analysis System,” Mar. Chem., Vol. 77, pp. 255262 (2002).
  8. [8] Datta, A., Eom, I. Y., Dhar, A., Kuban, P., Manor, R., Ahmad, I., Gangopadhyay, S., Dallas, T., Holtz, M. and Temkin, H., “Microfabrication and Characterization of Teflon AF-Coated Liquid Core Waveguide Channels in Silicon,” IEEE Sens. J., Vol. 3, pp. 788 795 (2003).
  9. [9] Manor, R., Datta, A., Ahmad, I., Holtz, M., Gangopadhyay, S. and Dallas, T., “Microfabrication and Characterization of Liquid Core Waveguide Glass Channels Coated with Teflon AF,” IEEE Sens. J., Vol. 3, pp. 687692 (2003).
  10. [10] Dress, P., Belz, M., Klein, K. F., Grattan, K. T. V. and Franke, H., “Physical Analysis of Teflon Coated Capillary Waveguides,” Sens. Actuator B-Chem., Vol. 51, pp. 278284 (1998).