Research Interests

My research interests fit broadly into two categories; sample introduction methods for atomic spectrometry and the measurement of trace metals in the environment.
 
 

Sample Introduction Methods for Atomic Spectrometry

Sample introduction has been the archilles heal of atomic spectrometry methods for several decades. Traditionally, sample materials are converted to liquids prior to analysis of elemental composition by atomic spectrometry. This ensures homogeneity of the sample components and ease of transport to the instrument. Common atomic spectrometric techniques use a flame or plasma to achieve atomization. The problems come when trying to introduce a liquid into a flame or plasma. Normal liquid sample introduction is extremely inefficient usually allowing only a small proportion of the sample to enter the spectrometer as small droplets while the rest goes to waste. I have been interested in a couple of possible methods for increasing the efficiency of sample introduction for atomic spectrometry.

Desolvation

Desolvation is method for reducing the amount of solvent introduced into an atomic spectrometer.  The general principle is to heat an aerosol of the sample in order to evaporate the solvent, then remove the solvent vapor using a condenser or drier. This essentially introduces a dry aerosol of the sample into the spectrometer.  Desolvation should allow a much larger percent of the sample material to be analyzed.  Most desolvation methods, however, are not as efficient as expected and suffer from problems such as memory effects and pressure fluctuations.  One attractive alternative to thermal heating is the use of microwave energy.  Microwave methods would be expected to heat more efficiently and evenly than thermal methods due to the direct heating of aerosol droplets. (Fig. 1).  Experimental results have been disappointing because of the inefficient coupling of microwave energy with small droplets.

Projects:
 

"Numerical Analysis of Sprayed Sample Enrichment via Microwave Heating." - Kevin Douglass, Undergraduate Project, Marist College (2001).
Presented at Mid-Hudson Section ACS Undergraduate Research Symposium, New Paltz, NY (April 2001) and FACSS Conference, Detroit, MI (October 2001).
"Feasibility of a Desolvation System based on Direct Microwave Coupling with an Aqueous Aerosol"- Kevin Douglass, Neil Fitzgerald, Bradley Ingebrethsen and Julian F. Tyson, Spectrochim. Acta Part B. (in preparation).
 

Chemical Vapor Generation (Fig.2)

An alternative to liquid sample introduction is to chemically produce a volatile form of the analyte that can be introduced to a spectrometer in the gas form without introducing solvent.  This can be achieved efficiently for some elements (such as arsenic, selenium, tin, and lead) by formation of the volatile hydride.  Mercury is known to produce a volatile elemental form in reducing conditions and has been used as a standard method for mercury analysis for many years.  Recently, cadmium has been found to produce an atomic vapor allowing detection in the low parts per trillion (ng/L) although the reaction mechanism remains unclear.  Evidence is also beginning to emerge to suggest that other elements (such as gold, platinum, palladium and rhodium) may be determined at low levels using similar techniques.

Projects:

"Trace Level Determination of Cadmium in Environmental Samples by Cold Vapor Atomic Absorption Spectrometry" - Rebecca Wack, Undergraduate Project, Marist College (completed May 2002).
Presented at the Mid-Hudson Section ACS Undergraduate Research Symposium ,New Paltz, NY (April 2002) and FACSS Conference, Providence, RI (October 2002).
 
 

Trace Metals in the Environment

Many trace elements in the environment are responsible for toxicity and have significant environmental impact.  The study of trace metals can also give useful insight into the chemistry and physical process in environmental systems.  I have recently been involved in two areas of study of trace metals in the environment.
 

Toxicity and Analysis of Metals Deposited from Automobile Catalytic Converters

This is a project performed in collaboration with Dr. Gagnon (Marist College) looking at toxicity and levels of platinum, palladium and rhodium in the environment.  Several researchers have observed an increase in the levels of these metals (although levels are currently very low) particularly in roadside soil due deposition from catalytic converters.  As there does not seem to be a natural sink for these metals, it can be expected that concentrations will continue to rise.  Questions remain as to the ability of metals to become mobile and absorbed into the food chain and the toxicity of metal species to plants and animals (Fig. 3).  There also appears to be an increasing need to reliably measure and monitor these elements with relatively low cost, common instrumentation.

Projects:

"Study of Accumulation and Bioavailability of Platinum Group Metals in Tomato Plants and Sphagnum" - Carrie Shapiro and Julie Gosewisch, Undergraduate Project, Marist College (completed, May 2002)
Presented at the Eastern Colleges Science Conference, Niagara Falls, April 27th 2002
 
 

Study of Trace Metal Variations in Streams (Fig. 4)

The concentrations of trace metals in streams are strongly dependent on local conditions such as acidity, temperature, recent weather events (rainfall, snow melt, drought) and chemical composition.  These variations can often be explained by simply chemical concepts such as solubility, and chemical reactivity.  Many metals also have significant impact on the environment due to their toxicity (e.g. aluminum, lead, and cadmium).  The study of trace metals variations in different stream types can, therefore, provide much useful information about the chemical and physical mechanisms involved.

Projects:

"Study of Trace Metal Variations in Buffered and Poorly Buffered Streams in the Mohonk Reserve as a Function of Acidity and Temperature" - Neil Fitzgerald, Marist College, in collaboration with Kathleen Weathers and Denise Schmidt (Institute of Ecosystem Studies, Millbrook, NY), and Dr. Feldman (Marist College), funded by the John S. Eaton Fellowship (expected completion June 2002).

· "Benthic Ecology and Chemistry of the Coxing Kill and Tributary in the Shawangunk Mountains" Richard Feldman, Vincent Porzio, Ryan Streck and Neil Fitzgerald, poster presentation, The Northeast Natural History Conference, SUNY Albany, April 25th 2002