Optical Sensor for Gaseous Ammonia With Tuneable Sensitivity
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Teresa Grady, Thomas Butler, Brian D. MacCraith, Dermot Diamond and M. Anthony McKervey
Abstract
The detection of gaseous ammonia using an optical evanescent wave sensor coated with a PVC film containing a chromogenic calixarene (nitrophenylazophenol calix[4]arene) is described. On addition of various concentrations of ammonia gas, the absorbance maximum shifts to 500 nm, which is characteristic of deprotonation of the chromogenic group. The sensitivity of the sensor to ammonia varied depending on whether the free ligand or lithium complex was used in the membrane. Intermediate sensitivities can be generated by varying the mole ratio of lithium to calixarene. The response time of the lithium complex measured at 520 nm to a 5–50 ppm change in ammonia concentration is fast (several minutes to steady state) but the signal is slow to return to the baseline when the gas is replaced by nitrogen.
References
- A. Sharma, Z. Ali and I. J. Higgins, Environ. Proc. Monitor. Tech., 1992, 107 Search PubMed.
- M. E. Meyerhoff, Anal. Chem., 1980, 52, 1532 CrossRef CAS.
- Q. Zhou, D. Kritz, L. Bonnell and G. H. Sigel, J. Appl. Opt., 1989, 28, 2022 Search PubMed.
- P. Caglar and R. Narayanaswamy, Analyst, 1987, 112, 1285 RSC.
- R. A. Potyrailo, S. P. Golubkov, P. S. Borsuk and P. M. Talanchuk, Analyst, 1994, 119, 443 RSC.
- A. Morales-Bahnik, R. Czolk and H. J. Ache, Sens. Acutuators B, 1994, 19, 493 Search PubMed.
- S. Ozawa, P. C. Hauser, K. Seiler, S. S. Tan, W. E. Morf and W. Simon, Anal. Chem., 1991, 63, 640 CrossRef CAS.
- S. J. West, S. Ozawa, K. Seiler, S. S. Tan and W. Simon, Anal. Chem., 1992, 64, 533 CrossRef CAS.
- K. Seiler, Ion-selective Optode Membranes, Fluka, Buchs, 1993, p. 39 Search PubMed.
- O. S. Wolfbeis, in Fiber Optic Chemical Sensors and Biosensors, ed. Wolfbeis, O. S., CRC Press, Boca Raton, FL, 1991 Search PubMed.
- T. Werner, I. Klimant and O. S. Wolfbeis, Analyst, 1995, 120, 1627 RSC.
- W. Mills, L. Wild and Q. Chang, Mikrochim. Acta, 1995, 121, 225 CAS.
- A. Brandenburg, R. Edelhauser, T. Werner, H. He and O. S. Wolfbeis, Mikrochim. Acta, 1995, 121, 95 CAS.
- M. McCarrick, B. Wu, S. J. Harris, D. Diamond, G. Barrett and M. A. McKervey, J. Chem. Soc., Perkin Trans. 2, 1993, 1963 RSC.
- M. McCarrick, S. J. Harris and D. Diamond, Analyst, 1993, 118, 1127 RSC.
- M. McCarrick, S. J. Harris and D. Diamond, J. Mater. Chem., 1994, 4, 217 RSC.