Jeffrey D. Weidenhamer

Trustees’ Distinguished Professor


Professor of Chemistry and Chair,

Department of Chemistry, Geology & Physics 

Ashland University | Ashland, OH 44805  | E-mail: | Phone: 419-289-5281


Current position:  I have been a member of the Chemistry faculty at Ashland since 1989, and currently

chair the Department of Chemistry, Geology & Physics.  I teach General Chemistry, courses in Analytical Chemistry,

as well as Core science courses including Science as a Cultural Force and Lead & Civilization. 

I previously served as Core Curriculum Director for six years.


Research interests:  I have focused on two main areas of research.  First, I have a longstanding interest in the

development of methods for the analysis of plant root exudates in soil.  This work has been funded by the Research

Corporation and the National Science Foundation, and we have developed a new method for soil analysis using silicone

microtubing placed directly in soil.  In addition, my students and I have conducted investigations of the contamination of

consumer products with heavy metals such as lead and cadmium.  This work has resulted in at least 14 recalls by the

Consumer Product Safety Commission involving more than 1.5 million children’s jewelry and toys, and has been cited in a

US Congressional resolution seeking a ban on US export of electronic waste.



Ashland University, B.S. in Chemistry, 1979

The Ohio State University, M.S. in Agronomy, 1983

The University of South Florida, Ph.D. in Biology, 1987

Louisiana State University, M.S. in Analytical Chemistry, 1991                 



General Chemistry (CHEM 103-104)

Quantitative Analysis (CHEM 204)

Lead and Civilization (CHEM 250)

Instrumental Analysis (CHEM 420)

Science as a Cultural Force (CHEM/PHIL 350)




          Recent Grants Received


Bergosh, R., Corbin, P., Mohney, B. and Weidenhamer, J. (Co-PI)  2009-2012.  MRI: Acquisition of a 400-MHz NMR

Spectrometer, funded by the National Science Foundation ($319,340)


Weidenhamer, J.  2005-2008. RUI: Measurement of allelochemical dynamics in the rhizosphere. 

Funded by the National Science Foundation, Division of Environmental Biology, Ecological Biology Cluster ($209,843). 


          Weidenhamer, J.  2000-2001.  Course, Curriculum and Laboratory Improvement Adaptation and Implementation Grant

from the National Science Foundation, Division of Undergraduate Education.  Drs. Michelle Jones-Wilson and Brian

Mohney were co-authors.  Instrumentation to enhance an investigative approach to chemistry. $61,298,

matched by an equal amount by Ashland University for analytical instrumentation.


Invited Presentations

Weidenhamer, J.  August 2009.  Analytical strategies for ecologically active phytochemicals.  Baltimore, MD.  Annual

meeting of the Phytochemical Society of North America


          Weidenhamer, J.  June 2008.  Lead:  An ancient but still present hazard.  Chicago, Illinois Chapter of the American

          Chemical Society.


          Weidenhamer, J.  August 2008.  Lead: Using a potent neurotoxin to teach environmental principles.

          Philadelphia, PA, National meeting of the American Chemical Society.


          Weidenhamer, J.  August 2008.  Diffusive sampling of the rhizosphere using polydimethylsiloxane sorbents.  

          Philadelphia, PA, National meeting of the American Chemical Society.


          Weidenhamer, J.  September 2008.  Measurement of allelochemical dynamics and movement with polydimethylsiloxane

          sorbents.  Saratoga Springs, NY, Fifth World Congress on the International Society of Allelopathy.


          Weidenhamer, J.  May 2007.  Diffusive sampling methods for analysis of the rhizosphere.  Invited platform presentation. 

          Presented at the Europe meeting of the Society of Environmental Toxicology and Chemistry (SETAC), Porto, Portugal.


Weidenhamer, J.  2005.  Measurement of allelochemical dynamics in the rhizosphere.  Part of a symposium on

allelopathy at the August joint meeting of the Ecological Society of America and International Congress on Ecology

in Montreal. 


Weidenhamer, J. 2005.  Measurement of allelochemical dynamics in the rhizosphere.  Invited plenary lecture at the

Fourth World Congress on Allelopathy, held at Charles Sturt University in Wagga Wagga, Australia. 


Weidenhamer, J. 2005.  Evaluation of the allelopathic potential of a mustard cover crop.  Invited presentation,

coauthored by Jeanne Durkalski and Warren Dick of Ohio State University.  Presented at the Fourth World Congress

on Allelopathy, held at Charles Sturt University in Wagga Wagga, Australia. 


Weidenhamer, J.  April 2004.  Ecological weed management: Lessons from the Florida scrub. 

International Conference on the Theory and Practice of Ecological Agriculture, Nanchang, China.


Weidenhamer, J.  April 2004.  Allelopathic mechanisms and experimental methodology. 

International Symposium on Allelopathy Research and Application.  Sanshui, China.


Weidenhamer, J.  April 2002.  Killing off the competition: Allelopathy in plant communities. 

Invited lecture, Department of Biological Sciences; Mississippi State University.


Weidenhamer, J.  April 2001.  Invited lecture on Chemical interference in plant communities,

Williams College (MA).


Selected Publications       Request a copy

Over 30 publications on allelopathy and chemical education, including (* indicates undergraduate co-author):


Mohney, B., Matz, T.*, LaMoreaux, J.*, Wilcox, D.*, Gimsing, A., Mayer, P. and J. Weidenhamer.  2009.  In situ silicone tube

microextraction:  A new method for undisturbed sampling of root-exuded thiophenes from marigold (Tagetes erecta L.) in soil.

In press, Journal of Chemical Ecology 35(11).  DOI: 10.1007/s10886-009-9711-8


Weidenhamer, J., Boes, P.* and D. Wilcox.* 2009.  Solid-phase root zone extraction (SPRE):  A new methodology

for measurement of allelochemical dynamics in soil.  Plant and Soil, 322: 177-186.  DOI: 10.1007/s11104-009-9905-4.


Dayan , F., Howell, J. and Weidenhamer, J.  2009. Dynamic root exudation of sorgoleone and its in planta mechanism of action. 

Journal of Experimental Botany, 60, 2107–2117.


Weidenhamer, J. 2008.  Lead contamination of inexpensive seasonal and holiday products. 

Science of the Total Environment, 407: 2447-2450.  DOI:10.1016/j.scitotenv.2008.11.031


Yost, J.* and J. Weidenhamer.  2008.  Accessible and total lead in low-cost jewelry items. 

Integrated Environmental Assessment and Management, 4:358-361. 


Yost, J.* and J. Weidenhamer.  2008.  Lead contamination of inexpensive plastic jewelry. 

Science of the Total Environment, 393:348-350. 


          Weidenhamer, J.  2008.  “Allelopathic mechanisms and experimental methodology.” 

          Pp. 119-35 In:  (R.S. Zeng, A.U. Mallik, and S.M. Luo, eds.) Allelopathy in Sustainable Agriculture and Forestry

          (New York: Springer Science and Business Media).


          Loi, R.*, Solar, M. and J. Weidenhamer.  2007.  Solid phase microextraction method for in vivo measurement

          of allelochemical uptake.  Journal of Chemical Ecology, 34:70-75.


          Weidenhamer, J. and M. Clement.  2007.  Widespread lead contamination of imported low-cost jewelry in

          the US.  Chemosphere, 67: 961-965.


          Weidenhamer, J.  2007.  New approaches for the analysis of allelochemicals in soil.  Allelopathy Journal, 

          19(1): 135-142 (Invited review).


          Weidenhamer, J.  2007.  Circuit board analysis for lead by atomic absorption spectroscopy in a course for non-science

          majors.  Journal of Chemical Education, 84:1165-1166.  Featured on cover of July issue.


          Weidenhamer, J. and M. Clement.  2007.  Leaded electronic waste is a possible source material for lead-contaminated

          jewelry.  Chemosphere, 69: 1111-1115.


Weidenhamer, J. and M. Clement.  2007.  Evidence of recycling of lead battery waste into highly leaded jewelry. 

Chemosphere, 69:1670-1672.


Weidenhamer, J.  2006.  Distinguishing allelopathy from resource competition: The role of density.

Pp. 85-103 in Allelopathy: A physiological process with ecological implications, edited by Manuel Reigosa,

Nuria Pedrol and Luís González, published by Springer.  (Invited review chapter).


Weidenhamer, J.  2005.  Biomimetic measurement of allelochemical dynamics in the rhizosphere. 

Journal of Chemical Ecology.   31(2): 221-236.


Weidenhamer, J. and J. Romeo.  2005.  “Allelopathy as a mechanism for resisting invasion: The case of

Polygonella myriophylla.”  Pp. 167-177 In:  (Inderjit, ed.) Invasive Plants: Ecological and Agricultural Aspects

(Switzerland: Birkhauser-Verlag AG).


Lane, N., J. Weidenhamer and J. Romeo.  2004.  Zapoteca formosa (Mimosaceae): sulfur chemistry and

phytotoxicity.  Journal of Chemical Ecology 30(2): 425-437.


Weidenhamer, J and J. Romeo.  2004.  Allelochemicals of polygonella myriophylla: chemistry and soil

degradation.  Journal of Chemical Ecology 30(5): 1067-1082.


Weidenhamer, J.  2001. Chapter 2: Nuevas Metodologías para el Estudio de la Alelopatía. Pp 69‑97.

In: A.L. Anaya, F.J. Espinosa‑García, and R. Cruz‑Ortega, editors. Relaciones químicas entre organismos:

aspectos básicos y perspectivas de su aplicación. Instituto de Ecología, UNAM y Plaza y Valdés,

S.A. de C.V. México.


Delaney, K.R., Bissett, N., Weidenhamer, J., 1999, "A new species of Carphephorus (Asteraceae; Eupatorieae)

from peninsular Florida", The Botanical Explorer, 1:1-15  (Rachel Lerebours* was acknowledged as a

contributor to this work).


Romeo, J. and J. Weidenhamer.  1998.  Bioassays for Allelopathy in Terrestrial Plants.  Pp. 179-211

In K.F. Haynes and J.G. Millar (eds.), Methods of Chemical Ecology, Volume 2: Bioassay Methods. 

Kluwer Academic Publishers, Norvell, MA.             


Weidenhamer, J.D.  1996.  Distinguishing resource competition and chemical interference: Overcoming

the methodological impasse.  Agronomy Journal, 88(6):866-875.


Martin, J.* and J.D. Weidenhamer.  1995.  Potassium deficiency increases thiophene production in Tagetes erecta. 

In Phytochemicals and Health, ed. D.L. Gustine and H.E. Flores.  Current Topics in Plant Physiology, Vol. 15


Thijs, H.*, J.R. Shann and J.D. Weidenhamer.  1994.  The effect of phytotoxins on competitive outcome in a

model system.  Ecology, 75(7):1959-1964.


Weidenhamer, J., F. Macias, N. Fischer and G. Williamson.  1993.  Just how insoluble are monoterpenes? 

Journal of Chemical Ecology, 19(8):1827-1835.


Weidenhamer, J. and J. Romeo.  1989.  Allelopathic properties of Polygonella myriophylla: Field evidence

and bioassays.  Journal of Chemical Ecology, 15(7):1957-1970.


Williamson, G. and J. Weidenhamer.  1990.  Bacterial degradation of juglone: Evidence against Allelopathy? 

Journal of Chemical Ecology, 16(5):1739-1741.


Weidenhamer, J., D. Hartnett and J. Romeo.  1989.  Density-dependent phytotoxicity: Distinguishing

resource competition and allelopathic interference in plants.  Journal of Applied Ecology, 26(2):613-624.