Research Interests


 

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 dryer. 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 FACSS Conference, Detroit, MI (October 2001).
"Desolvating the sample aerosol with microwave radiation: further theoretical and experimental insight into the significance of such approach"- Kevin Douglass*, Neil Fitzgerald, Bradley Ingebrethsen and Julian F. Tyson, Spectrochim. Acta Part B. vol.59, 261 (2004)
 

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.  Recently UV light has been shown to be capable of reducing some species to volatile products as a replacement for chemical vapor generation.

Projects:

"Mercury Determination by Cold Vapor Atomic Absorption Spectrometry Utilizing UV Photoreduction" Ryan Bendl*, Jeremy Madden*, Allison Regan, Neil Fitzgerald, Talanta, vol. 68, 1366 (2006).  Project presented by Ryan Bendl* at FACSS, Portland, OR, 2004 (awarded outstanding student poster award) and Jeremy Madden* and Lauren Jackson* at PITTCON, Orlando, FL, 2006.

"The Use of a Modified Multimode Sample Introduction System (MSIS) for the Simple and Rapid Determination of Cadmium by Chemical Vapour Generation Atomic Absorption Spectrometry" Eric. Ritschdorff*, Neil Fitzgerald, Roger McLaughlin, and Ian Brindle, Spectrochim. Acta Part B, vol 60, 139 (2005) and presented at PITTCON, March 2004.

"Trace Level Determination of Cadmium in Environmental Samples by Cold Vapor Atomic Absorption Spectrometry" - Rebecca Wack*, Undergraduate Project, Marist College (completed May 2002) and presented at FACSS, Providence, RI (2002)
 
 
 
 

Study of Trace Metal Variations in Streams (Fig. 3)

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).

"Comparison of Trace Metal Variations in a Buffered and Poorly Buffered Stream in the Shawangunk Mountain Range" - Neil Fitzgerald and Kathleen Weathers, Northeastern Geology and Environmental Science, vol. 27, 113 (2005)

"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
 
 
 
 

Bioremediation of a PAH Contaminated Site

A site in Westchester County has been identified as hazardous due to leakage of oil containers into the surrounding soil.  Oil contains Polycyclic Aromatic Hydrocarbons (PAHs) that are known carcinogens.  Previous remediation methods have proved unsuccessful as PAH appear to be contained in the water layer and are recontamining the fill soil.  An alternative approach is to use bacteria or fungi to breakdown the PAHs into non toxic substances.  In this study we are interested in identifying and investigating bioremediation methods.  The research consists of adding bacteria and fungi to PAH contaminated soil and determining the PAH concentrations by a Soxhlet extract HPLC method after various time intervals.  This work is a collaboration with Dr. Andy Ryder (biology), Dr. Elisa Woolridge (biochemistry) and Roger Basin (E3 Inc.)

Project:

"Investigation of Bioremediation Techniques for the Removal of PAHs from a Contaminated Site" - Randy Drevland*, Presented at PITTCON, Chicago, March 2004.

 

* Marist undergraduate student