Biopolymer Metal Binding and ETVICPMS

1
Biopolymer Metal Binding and ETV-ICPMS
The Bonded-Phase Ion-Exchange System
ICP-MS is the cutting edge technology for atomic
spectrometry. It can offer part per trillion
detection limits, over 5 orders of magnitude of
linear response, and works for almost all
elements in the periodic table. It uses an
inductively coupled plasma (8,000 K) as the
ionization source. Our ICP-MS uses a time of
flight system for mass analysis. Though many
labs rely on solution nebulization for sample
introduction, this is not always the best
technique. It can be problematic for some
matrices (e.g. salty solutions, organic
solutions, and solids or slurries). An
alternative is electrothermal vaporization (ETV).
This uses a carbon tube to vaporize the sample
before introduction to the ICP-MS. Vaporization
temperatures of up to 3,000o C can be achieved in
a controlled manner. It can handle a wide variety
of sample types, and generally has higher sample
introduction efficiency than nebulizers.
For the past several years, one of the primary
focuses of our research group has been the
development of novel ion-exchange systems for the
purpose of metal remediation from aqueous
systems. Expanding on hints from Mother Nature,
we chose to explore the metal chelation abilities
of proteins and, in particular, their constituent
amino acids. In order to simplify these
ion-exchange systems, short-chain homopolymers
consisting of repeating monomers of a specified
amino acid residue have been used. These systems
exhibit many of the characteristics for an ideal
ion-exchanger strong binding fast, efficient
release and structural stability. These
biologically-based systems also have the added
benefit of being environmentally friendly, unlike
many traditional exchange systems which require
harsh extraction agents.
Sample
To ICP-MS
Developing Fluorescence-based Sensors
Exploring a Combinatorial Approach
Creating Chemical-free Remediation Systems
ETV-ICP-MS for Isobars and Isotopes
Internal Standards for ICP-TOF-MS
Graphical Illustration of RSD
By definition, a small change in the ratio
between two elements as a condition changes, is
indicative of a good analyte-IS pair. The RSD
of these ratios is used as a quantitative measure
of internal standard compatibility.
One problem with ICP-MS is elements of the same
nominal mass (isobaric interference). ETV can be
used to separate some problematic elements based
on their differing volatilities. Rb and Sr can be
separated to remove the isobar at mass 87.
Determining the Relationship Between RSD and
Chemical Properties
Each point on the scatter plots illustrated in
the example plot above represents a ratio of 238U
and one of approximately 100 IS considered.
Analyte-to-IS mass separation typically offered
the strongest and most consistent relationship to
RSD for all conditions.
The time of flight design is able to offer
excellent isotope ratio precision as a result of
simultaneous ion extraction from the plasma.
However, difficulties have been encountered with
ratio accuracy. Factors that cause this and
possible fixes are actively being researched.
Questions? Email Haley. hjf244_at_mail.utexas.edu
Questions? Email Ram. ramk_at_mail.utexas.edu
Questions? Email Shelly. slcascaito_at_mail.utexas.ed
u
Questions? Email Carina. cgunder_at_mail.utexas.edu
Questions? Email Adam. adamrowland_at_mail.utexas.edu
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