Stephen Brown
Associate Professor
Environmental
Department of Chemistry
Chernoff Hall, CHE404 (office)
Department of Chemistry
90 Bader Lane
Queen's University
Kingston, Ontario K7L 3N6
Research Interest
The main goal of my research group is the development of new methods of environmental analysis, with emphasis on detecting small organic compounds in aqueous samples. This requires development of instruments and chemical/biochemical assays to provide sensitive and selective measurement of a particular contaminant. Developing a complete analysis procedure occurs in three main steps:
- Design of the instrument;
- Development of the chemistry and biochemistry to detect the contaminant;
- Combination of the detection method with the instrument.
1) We mainly use optical signals for the analysis, so major components of the instrument design are lasers, fibre-optics and light detectors. Our signal of choice is fluorescence (compounds which absorb u.v. light but then emit visible light), because of its sensitivity. The basic design of the instrument (see diagram) uses a laser radiation source, a single optical fibre, a monochromator for separating the different laser and sample wavelengths, and a photomultiplier light detector. A ‘perforated’ mirror (small hole in center) is used to redirect the signal emerging from the optical fibre toward the detector. For different analysis methods, the optimum components (laser type, wavelength, optical fibre material, etc.) must be determined using various criteria. Since these instruments are generally not available ‘off the shelf’, we must also do custom assembling, electronics, computer interfacing and programming.
2) For some environmental contaminants, there are simple chemical methods for detection using coloured or fluorescent reagents. In these cases, we can adapt the standard methods for remote or on-line measurements. Often, however, a method is not available, and we must identify a scheme which will work for a sample of interest. The unique approach which our group uses is the application of enzymes as selective catalysts for environmental analysis. Currently, a great deal of research is proceeding in the characterization of enzymes which degrade contaminants in the environment. As these enzymes are isolated and purified, we can then develop biochemical enzyme assays which detect similar contaminants. In methods which we have already developed, chlorinated phenols and polycyclic aromatic hydrocarbons (PAHs) were detected, with the enzymes providing selectivity and increased sensitivity to the analysis.
3) Combining steps 1) and 2) involves advancing from remote detection using the environmental analysis methods to development of true fibre-optic chemical sensors. This requires incorporating the detection method into the optical fibre light-guiding process. For enzyme-based methods, this means immobilizing the enzyme (and possibly other reagents) onto the optical fibre surface. There are many immobilization schemes available, but the best one for a particular enzyme must be identified and possibly modified, considering optical properties, enzyme stability and response. Working sensors can then be tested on real samples for a final evaluation of overall performance.
- B.Sc., 1985, Dalhousie University;
- M.Sc., 1988, University of Toronto;
- Ph.D., 1992, University of Toronto.
Recent Publications
Barnes, J.A., Brown, R.S., Cheung, A.H., Dreher, M.A., Mackey, G., Loock, H.-P. (2010) Chemical sensing using a polymer coated long-period fiber grating interrogated by ring-down spectroscopy, Sensors and Actuators B-Chemical, 148, 221-226.
Brown, R.S., Macotte, E.J.-P., Dunkinson, C.E., Aston, W.P., Gallant, P.J., Wilton, D. (2010) An Automated Detection Technology for Onsite E.coli and Coliform Bacteria Monitoring, Water Environment Laboratory Solutions, 17(6), 1-5.
Byer J.D., Alaee M, Brown R.S., Backus S., Keir M., Pacepavicius G., Lebeuf M., Casselman J., Kennedy S., Hodson P.V. (2010) Dioxin contaminants in American ell: a likely cause for their decline?, Organohalogen Compounds, 72, 1213-1216.
Byer, J.D., M. Alaee, RS Brown, M. Lebeuf, S. Trottier, S. Backus, S. Blunt, M. Keir, M. Konefal, G. Pacepavicius, P.V. Hodson. (2010) Brominated Flame Retardants in American Eel: a Reason for the Eel’s Decline?, Proceedings of the Fifth International Symposium on Brominated Flame Retardants (BFR 2010), Kyoto, Japan, April 2010.
Barnes, J., Dreher, M., Plett, K., Brown, R.S., Crudden, C.M., Loock, H.P. (2008) Chemical sensor based on a long-period fibre grating modified by a functionalized polydimethylsioloxane coating. Analyst, 133, 1541-1549.
Douma, M.D., Kerr G.M., Brown R.S., Keller B.O., Oleschuk R.D. (2008) Mass spectrometric detection of proteins in non-aqueous media - The case of prion proteins in biodiesel. Canadian Journal of Chemistry, 86, 774-81.
Jack A. Barnes, R. Stephen Brown, Judy Cipot-Wechsler, Cathleen M. Crudden, Jenny Du, Hans-Peter Loock, Krista Plett (2008) Long-Period Gratings in Chemical Sensing. Proc SPIE 7099, 70992C-1.
Cai, X., R.S. Brown, P.V. Hodson, and V. Snieckus (2004) Regiospecific synthesis of alkylphenanthrenes using a combined directed ortho and remote metalation - Suzuki-Miyaura cross coupling strategy, Can. J. Chem. 82, 195-205.
Y. Kiparissis, P. Akhtar, P.V. Hodson, R.S. Brown (2003) Partition Controlled Delivery (PCD) of Toxicants: A Novel In Vivo Approach for Embryotoxicity Testing, Environmental Science and Technology, 37, 22622266.
Ramsay, J.A.; Li, H.; Brown, R.S.; Ramsay, B.A., Naphthalene and anthracene mineralization linked to oxygen, nitrate, Fe(III) and sulphate reduction in a mixed microbial population. Biodegradation 14, 321-329 (2003).
Kiparissis, Y.; Akhtar, P.; Hodson, P.V.; Brown, R.S., Partition-controlled delivery of toxicants: A novel in vivo approach for embryo toxicity testing. Environmental Science and Technology 37, 2262-2266 (2003).
Brown, R.S.; Hussain, M., The Walkerton tragedy - issues for water quality monitoring. Analyst 128, 320-322 (2003).
Brown, R.S.; Kozin, I.; Tong, Z.; Oleschuk, R.D.; Loock, H.P., Fiber-loop ring-down spectroscopy. Journal of Chemical Physics 117, 10444-10447 (2002).
Hawkins, S.A.; Billiard, S.M.; Tabash, S.P.; Brown, R.S.; Hodson, P.V., Altering cytochrome p4501a activity affects polycyclic aromatic hydrocarbon metabolism and toxicity in rainbow trout (Oncorhynchus mykiss). Environmental Toxicology and Chemistry 21, 1845-1853 (2002).
Pang, J.; Marcotte, E.J.P.; Seward, C.; Brown, R.S.; Wang, S.N., A blue luminescent star-shaped Zn-II complex that can detect benzene. Angewandte Chemie - International Edition 40, 4042 (2001).
Brown, R.S.; Akhtar, P.; Akerman, J.; Hampel, L.; Kozin, I.S.; Villerius, L.A.; Klamer, H.J.C., Partition controlled delivery of hydrophobic substances in toxicity tests using poly(dimethylsiloxane) (PDMS) films. Environmental Science and Technology 35, 4097-4102 (2001).
Goring, G.L.G.; Brown, R.S.; Horton, J.H., The adsorption of benzo[k]fluoranthene on self assembled films of octadecyltrichlorosilane. Journal of Materials Chemistry 11, 2282-2286 (2001).
Buncel, E.; Mailloux, N.L.; Brown, R.S.; Kazmaier, P.M.; Dust, J., Synthesis and characterization of [3,3]- and [3,4]-perinophane. Tetrahedron Letters 42,: 3559-3562 (2001).
Fragoso, N.M.; Hodson, P.V.; Kozin, I.S.; Brown, R.S.; Parrott, J.L., Kinetics of mixed function oxygenase induction and retene excretion in retene-exposed rainbow trout (Oncorhynchus mykiss). Environmental Toxicology and Chemistry 18, 2268-2274 (1999).
Brown, R.S., Classic confusion. Photonics Spectra 32, 12-12 (1998).
Brennan, J.D.; Brown, R.S.; Krull, U.J., Transduction of analytical signals by supramolecular assemblies of amphiphiles containing heterogeneously distributed fluorophores. Analytical Sciences 14, 141-149 (1998).