field portable methods for the determination of arsenic in environmental samples

199 Pages·2010·2.15 MB·English

by  James Kearns

FIELD PORTABLE METHODS FOR THE DETERMINATION OF ARSENIC IN
ENVIRONMENTAL SAMPLES

A Dissertation Presented
by
JAMES K. KEARNS

Submitted to the Graduate School of the
University of Massachusetts Amherst in partial fulfillment
of the requirements for the degree of

DOCTOR OF PHILOSOPHY
September 2010
Department of Chemistry
© Copyright by James Kalman Kearns 2010

All Rights Reserved
FIELD PORTABLE METHODS FOR THE DETERMINATION OF
ARSENIC IN ENVIRONMENTAL SAMPLES

A Dissertation Presented

by

JAMES KALMAN KEARNS

Approved as to style and content by:
____________________________________

Julian F. Tyson, Chair

____________________________________

Edward G. Voigtman Jr., Member

____________________________________

Paul Dubin, Member

____________________________________

David Reckhow, Member

_________________________
Craig Martin, Department Head
Department of Chemistry
DEDICATION

To my parents
ACKNOWLEDGMENTS
First of all, I would like to express my sincere gratitude and thanks to Dr. Julian F.
Tyson professor of chemistry in the analytical division at the University of Massachusetts
at Amherst who has been my advisor during my time as PhD. Student. He provided me
with direction, a knowledge base, and acted as true role model.
I would also like to express my appreciation to Dr. Peter C. Uden, professor emeritus
who made valuable suggestions about the admissions process and the direction of my
professional development.
Special gratitude goes to Dr. Edward Voigtman for providing me with the statistical
and instrumental background as well as insightful suggestions regarding data analysis and
experimental ideas.
To my parents, thank you! To the Five College Woodsy Club, The UMass Juijitsu
Club, the staff of Prince-Crampton, thank you. To my Smith College mentors Dr. Lale
Aka Burk and Dr. Rebecca Mae Thomas, thank you for teaching me the ―Have fun and
go for it!‖ attitude.
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ABSTRACT
FIELD PORTABLE METHODS FOR THE DETERMINATION OF ARSENIC
IN ENVIRONMENTAL SAMPLES
JAMES K. KEARNS, B.S., UNIVERSITY OF MASSACHUSETTS AMHERST
M.S., UNIVERSITY OF MASSACHUSETTS AMHERST
Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST
Directed by: Professor Julian F. Tyson
Arsenic contamination of the environment is a worldwide health hazard. This
research project focused on four areas: development and testing of low cost, field
portable devices capable of measuring levels of arsenic at 10 g L-1 or less; specific
chemical techniques for such testing; creation of educational tools and techniques to
allow operators who lack advanced chemistry training to perform accurate testing; and
the determination and use of a biomarker in DNA as a cancer predictor in individuals
exposed to environmental arsenic.
The analytical techniques explored include: (1) the Gutzeit method of arsenic
determination though arsine gas production, which was investigated in three experiments:
measuring arsenic levels in soil samples, using Gutzeit-based kits using silver nitrate as a
reactant for arsine gas, and sensitivity comparison of three commercial test kits over
varying time periods up to twenty-four hours. (2) The molybdenum blue method,
technologically quantified through three different experiments: digital photographic
analysis, spectroscopic analysis, and flow injection. (3) Filtration of arsenic contaminated
water with wood-ash, sand, ferric oxide, and commercially available steel wool; and the
construction of a filtering device constructed of recyclable discarded soda bottles.
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Further, single nucleotide polymorphisms in the DNA of arsenic exposed individuals
were studied to determine what immune response genes might be implicated in arsenic
susceptibility.
The major conclusions of this research were: digital image analysis used with the
Gutzeit method improves precision and accuracy; silver nitrate proved to be a better
measurement tool at low concentrations of arsenic than mercuric bromide; and the
Gutzeit method can be applied to soils in the Hach kit.
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TABLE OF CONTENTS
ACKNOWLEDGMENTS ................................................................................................. iii
ABSTRACT .................................................................................................................... iv
CHAPTER 1: INTRODUCTION ........................................................................................1
1.1 Field Portable Methods For the Determination of Arsenic in Environmental
Samples ......................................................................................................................................................... 1
1.2 Gutzeit Method: The Spectrophotometric Determination of Arsenic Using Hydride
Generation ................................................................................................................................................... 6
1.2.1 The Chemistry of the Determination of Arsenic as a Hydride ......................................... 6
1.2.2 Chemistry of the Gutzeit Method ................................................................................................. 7
1.2.3 Challenges of Accuracy in the Determination of Arsenic Using Hydride
Generation ...................................................................................................................................... 10
1.3 The Chemistry of the Molybdenum Blue Method ....................................................................... 10
1.3.1 The Spectrophotometric Determination of Arsenic with the Molybdenum Blue
Method ............................................................................................................................................. 10
1.3.2 Uses of Heteropolyoxometallates .............................................................................................. 12
1.3.3 Analytical Applications .................................................................................................................. 12
1.3.4 History of Molybdenum Blue ....................................................................................................... 13
1.3.5 Chemistry of Molybdenum Blue ................................................................................................. 13
1.3.6 Different Formulations of Molybdenum Blue and Current Research ......................... 16
1.3.7 Flow Injection and Molybdenum Blue Chemistry .............................................................. 17
1.3.8 Stoichiometric Measurement of the Elemental Composition of Molybdenum
Blue With ICP-OES....................................................................................................................... 20
1.3.9 Naked-Eye and Photographic Determination of Arsenic with the Molybdenum
Blue Method ................................................................................................................................... 20
1.4 Color Measurement .................................................................................................................................. 21
1.4.1 Color Measurement and Tristimulus ....................................................................................... 21
1.4.2 Theory of Reflectance Spectroscopy ........................................................................................ 24
1.4.3 The Absorption Process................................................................................................................. 24
1.4.4 Causes of Absorption: Electronic Processes ......................................................................... 25
1.4.5 The Scattering Process ................................................................................................................... 25
1.4.6 Kubelka Munk Background .......................................................................................................... 26
1.5 Chemical Education and Field Portable Methods ....................................................................... 26
1.6 The Determination of Single Nucleotide Polymorphisms in the DNA of Arsenic
Exposed Humans and Its Use as a Biomarker for Cancer Prediction ................................ 28
1.7 Toxicology of Arsenic .............................................................................................................................. 29
1.8 References .................................................................................................................................................... 29
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CHAPTER 2: IMPROVING THE ACCURACY AND PRECISION OF AN
ARSENIC TEST FIELD KIT: INCREASED REACTION TIME AND
DIGITAL IMAGE ANALYSIS ................................................................37
2.1 Introduction ................................................................................................................................................ 37
2.2 Experimental ............................................................................................................................................... 41
2.2.1 Field Kit ................................................................................................................................................ 41
2.2.2 Reagents ............................................................................................................................................... 42
2.2.3 Digital Image Analysis .................................................................................................................... 42
2.2.4 Procedures .......................................................................................................................................... 42
2.2.5 Method Development ..................................................................................................................... 43
2.2.6 Data Analysis ...................................................................................................................................... 43
2.3 Results and Discussion ........................................................................................................................... 43
2.3.1 Results of Digital Image Analysis ............................................................................................... 43
2.3.2 Standard Run Time Versus Extended Time........................................................................... 45
2.3.3 The Results of Increasing Reaction Temperature .............................................................. 46
2.3.4 Precision and Misclassification .................................................................................................. 46
2.3.5 Accuracy and Misclassification ................................................................................................... 47
2.3.6 Kubelka Munk Calculations .......................................................................................................... 47
2.4 Conclusions .................................................................................................................................................. 49
2.5 References .................................................................................................................................................... 49
CHAPTER 3: DETERMINATION OF ARSENIC IN SOILS USING THE GUTZEIT
METHOD ..................................................................................................53
3.1 The Hach Kit: Testing Arsenic in Soil ................................................................................................ 53
3.1.1 Introduction........................................................................................................................................ 53
3.1.2 Arsenic and Health ........................................................................................................................... 54
3.1.3 Sources of Contamination ............................................................................................................. 55
3.1.4 Techniques to Measure Soil Levels of Arsenic ..................................................................... 55
3.1.5 Arsenic Speciation............................................................................................................................ 56
3.1.6 The Hach Kit ....................................................................................................................................... 56
3.2 Methods......................................................................................................................................................... 57
3.2.1 Standards and Soil Preparation .................................................................................................. 57
3.2.2 Preparation for Reaction and Test Variables ........................................................................ 57
3.2.3 Colors Analysis .................................................................................................................................. 58
3.3 Results ........................................................................................................................................................... 60
3.4 Discussion and Conclusion .................................................................................................................... 65
3.5 References .................................................................................................................................................... 66
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CHAPTER 4: METHOD FOR DETERMINATION OF ARSENIC USING SILVER
NITRATE ..................................................................................................69
4.1 Introduction ................................................................................................................................................ 69
4.2 Quantification Methods .......................................................................................................................... 70
4.3 Material and Methods ............................................................................................................................. 70
4.3.1 Chemicals ............................................................................................................................................. 70
4.3.2 Equipment ........................................................................................................................................... 71
4.3.3 Initial Testing of Hach Kit with Silver Nitrate ...................................................................... 71
4.4 Experimental Design ............................................................................................................................... 73
4.4.1 Optimization of Test Strip Design ............................................................................................. 73
4.4.2 Preparation and Testing of Strips.............................................................................................. 74
4.4.3 Experimental Procedure Initial Strip Testing....................................................................... 75
4.5 Analysis of Digital Images ...................................................................................................................... 77
4.5.1 Software Used for Analysis .......................................................................................................... 77
4.5.2 Hardware ............................................................................................................................................. 78
4.5.3 Initial Analysis with Colors.exe .................................................................................................. 79
4.5.4 Analysis of Batch Test with Photoshop ................................................................................... 80
4.6 Results and Discussion ........................................................................................................................... 80
4.6.1 Results of Initial Analysis with Colors.exe ............................................................................. 80
4.6.2 Results of Batch Test Analysis with Photoshop ................................................................... 82
4.6.3 Statistical Analysis of Batch Test Results ............................................................................... 85
4.7 References .................................................................................................................................................... 87
CHAPTER 5: DETERMINATION OF ARSENIC WITH MOLYBDENUM BLUE
CHEMISTRY ............................................................................................89
5.1 The formulation of Molybdenum Blue ............................................................................................. 89
5.1.1 Introduction........................................................................................................................................ 89
5.1.2 Experimental Temperature ......................................................................................................... 89
5.1.3 Selecting a Method ........................................................................................................................... 97
5.1.4 Results.................................................................................................................................................. 99
5.1.5 Discussion......................................................................................................................................... 102
5.1.6 Conclusion ........................................................................................................................................ 102
5.1.7 Future Work ................................................................................................................................... 103
5.2 Molybenum Blue Method for As(V) Determination Using Flow Injection ..................... 104
5.2.1 Introduction..................................................................................................................................... 104
5.2.2 Experimental Apparatus ............................................................................................................ 105
5.2.3 Results ................................................................................................................................................ 107
5.2.4 Discussion......................................................................................................................................... 107
5.2.5 Conclusion ........................................................................................................................................ 108
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