The Arsenic Project: Chemical Measurements in Support of Studies of the Biogeochemistry of Arsenic

1
The Arsenic Project Chemical Measurements in
Support of Studies of the Biogeochemistry of
Arsenic
Julian Tyson Department of Chemistry Smith
College UMass Amherst jutyson_at_email.smith.edu
tyson_at_chem.umass.edu http//courses.umass.edu/che
mh01/
2
(No Transcript)
3
The Arsenic Project Chemical Measurements in
Support of Studies of the Biogeochemistry of
Arsenic
Analytical chemistry Application of chemical
principles for the determination of the chemical
composition of materials.Provision of reliable
information that is useful in the context of the
problem.A science that (a) underpins the
progress of many scientific disciplines, and (b)
impacts many aspects of our daily lives (e.g.
clinical analysis of blood, food and beverage
safety).Is it safe? what species/ what
concentrations/ where did it go?
4
Background to The Arsenic Project
Loughborough U. 76 - 89 UMass 89 - present
Steve Offley, "Determination of arsenic in a
nickel based alloy by flow injection hydride
generation atomic absorption spectrometry
incorporating by continuous flow matrix isolation
and stopped flow pre-reduction procedures," J.
Anal. At. Spectrom., 1992, 7, 315-322. Peter
Yehl my first student to work on issues of
environmental arsenic (from pressure-treated
wood) obtained his Ph.D. in 1996. Since then, at
least one Ph.D. student has worked on
arsenic-related topics every year.
5
Background to The Arsenic Project
Started with trying to answer the question, What
happens to the arsenic that leaches out of wood
pressure-treated with chromated copper arsenate?
Three hypotheses (1) it forms insoluble
compounds with soil, (2) it is washed away by
surface water run-off, and (3) it evaporates,
because soil bacteria convert it to volatile
methylated compounds.
Needed methods to measure the various arsenic
compounds in soils. Turned out to be very
difficult!
6
Background to The Arsenic Project
Awareness of the PTW source led to my suggestion
that tracking the arsenic from PTW as part of an
arsenic in the environment theme would be a
suitable for our GK-12 program. Started in
summer of 2002.
Needed a procedure for the determination of
arsenic to support studies by the middle-school
student participants. Issues cost, safety,
limit of detection (LOD), speed Picked the Hach
version of the Gutzeit test designed to measure
As in drinking water. But it has limitations.
7
Background to The Arsenic Project
Could we do better? This led to a research
project, supported by NSF, into the possibility
of pervaporation with visible spectrophotometry.
Started in fall 2003.
Also an interest in the general need for
inexpensive, reliable, field-deployable, simple,
technologies for the determination of arsenic at
realistic concentrations i.e. with an LOD of lt 10
ppb (or ng mL-1 or mg L-1)
Fall 2004. Creation of authentic research
experiences for first-year undergraduates--more
info at the arsenic project website
http//courses.umass.edu/chemh01/
8
Background to The Arsenic Project
Mandal and Suzuki, Arsenic around the world
Talanta, 2002, 58, 201-235.
As, element 33, a mono-isotopic (75) metalloid,
named for the yellow pigment orpiment (Latin
arsenicum), probably isolated in 1250 by Albert
Magnus. It is widely distributed in all
environments. 20th most abundant in earths
crust, 14th in seawater and it is claimed the
12th in the body (but this must be wrong).
Concn. in rocks 2 mg kg-1, slightly higher in
soils, sea water 8 µg L-1. But there is a huge
range.
9
Background to The Arsenic Project
Mandal and Suzuki, Arsenic around the world
Talanta, 2002, 58, 201-235.
Uses insecticides, herbicides, desiccant
(cotton production), wood preservative, feed
additive, medicine, poison, bullets, electronics,
glass, paints, wallpapers and ceramics.
Our quality of life is affected by the extent to
which we can (a) minimize the harmful effects of
naturally occurring chemicals, (b) exploit the
beneficial effects of chemicals with which we
choose to interact.
10
Background to The Arsenic Project
The US FOOD and Drug Administration (FDA)
considers 130 µg/person/day from all sources to
be a tolerable daily intake of arsenic and the US
Environmental Protection Agency (EPA) has set the
maximum contaminant level in drinking water at
10 µg/L. http//vm.cfsan.fda.gov/frf/guid-as.htm
l, http//www.sis.nlm.nih.gov/enviro/arsenicandhum
anhealth.html (accessed March 2007).
11
Background to The Arsenic Project
Chemical form or speciation is all
important. The most toxic are arsenite, As(OH)3,
arsine AsH3 and the methylated forms of AsIII.
MMAIII and DMAIII
These are more toxic than the corresponding 5
species, which in turn, are more toxic than
arsenate, As(O)(OH)3
12
Intake of 70 to 300 mg of arsenic trioxide may be
fatal. Death typically occurs between 12 to 48
hours but can occur within one hour. Those who
survive arsenic trioxide poisoning may develop
encephalopathy or severe peripheral neuropathies.
Symptoms of acute poisoning usually occur
within one hour of ingestion but may be delayed
for up to 12 hours, particularly in the presence
of food. The principle toxic effects are
hemorrhagic gastro-enteritis, profound
dehydration, cardiac arrhythmias, convulsions,
muscle cramps, shock and death. http//www.gettin
gwell.com/drug_info/nmdrugprofiles/nutsupdrugs/ars
_0026.shtml (accessed April 2005)
13
Toxicity from dietary intake of arsenicup to 60
µg/dayis relatively low. Intakes of higher
amounts of arsenic on a chronic basis may cause
hyperkeratosis, especially of the palms and
soles, skin pigmentation, eczematous or
follicular dermatitis, edema (especially of the
eyelids), alopecia, muscle-aching and weakness,
stomatitis, excessive salivation, anemia,
leukopenia, thrombocytopenia, jaundice,
cirrhosis, ascites, peripheral neuropathy,
paresthesias, proteinuria, hematuria and anuria.
Chronic-high arsenic ingestion has been
associated with various cancers, such as basal
cell carcinoma and bladder, liver and lung
cancers. The nail changes associated with arsenic
toxicity are known as Mees' lines or transverse
striate leukonychia.
14
(No Transcript)
15

• Abnormal levels exist in
• Argentina, Australia, Bangladesh, Chile, China,
  Hungary, India, Mexico, Mongolia, Peru, Thailand
  and the United States of America
• Adverse health effects documented in
• Bangladesh, China, India (West Bengal), Mongolia
  and the United States of America
• Arsenic in drinking-water will cause 200,000
  270,000 deaths per year predicted from cancer
  in Bangladesh alone.
• Arsenic contaminated water revealed in 1993
• 4.5 million tube wells
• Arsenic contamination in 20 of those tested

16
Environmental Health Perspectives, 2005, 113, A379
17
(No Transcript)
18
(No Transcript)
19
Recent studies estimate that 2-100 children per
million exposed to PTW during early childhood may
develop lung or bladder cancer later in life as a
result of this exposure Consumer Product Safety
Commission (2003)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23

24

25

26
300,000 metric tons of inorganic arsenic have
been used for wood preservation since 1975.
But as of December 2003, the As-treated stuff
is no longer sold. Up till then, about 2 x 108
ft3 of wood pressure-treated with CCA was made
every year. Depending on formulation, the
material contains 4.0, 6.4 or 13 kg m-3 of CCA.
(type C has 38 As) The acute lethal oral dose
is 1 - 2.5 mg kg-1 (of body weight). For a 75 kg
adult this is 75 - 188 mg. This is, for best
case scenario, 313 cm3 or a cube 7 cm on the
side. Worst case scenario 2.3 cm cube.
27
How does this compare with arsenic as a
poison? The density of arsenic trioxide is 3.74
g cm-3. A 100 mg lethal dose is a cube of side
3 mm.
28
Some arsenic compounds are not so bad.
29
Some of the good guys
Salvarsan used to treat syphilis until the
advent of penicillin in the 1950s
30
Neoarsphenamine used in the treatment of
syphilis until the advent of penicillin in the
1950s.
31
Melarsoprol currently used in treatment of
sleeping sickness, Trypanosoma brucei rhodense
and gambiense. May also cure chromic lymphocytic
leukemia. As2O3 is used to treat acute
promyelocyte leukemia, chronic myeloid leukemia
and some cases of lymphoma or esophageal
cancer. J. Chem. Educ., 2003, 80, 497
32
Roxarsone growth promoting and antibiotic agent
in poultry. Annual emission estimated to be
900,000 kg.
4-hydroxy-3-arsanilic acid
p-arsanilic acid or 4-aminophenylarsonic acid
33
The end of the metabolic path?
trimethylarsine oxide TMAO
tetramethylarsonium iodide
34
(No Transcript)
35
arsenobetaine AsB
Present in high concentrations in seafood
arsenocholine AsC
36
Current arsenic-related research in the Tyson
group. Primary topics Fate of arsenic leached
from CCA pressure-treated wood. Study of the
transformations of arsenic compounds by
microorganisms. Study of the uptake of arsenic
by plants. Study of the in vivo interaction of
arsenic and selenium (plants and humans)
37
Graduate Student Activities
Improved procedures for the determination of
arsenic compounds in waters, soils, plants and
other biological systems. Improved against the
usual criteria cost, speed, accuracy, precision,
multi-analyte capability, detection limit,
selectivity, sensitivity, signal-to-noise ratio,
cost effectiveness, Both at high tech end (HPLC
with plasma source emission or mass spectrometry)
. . . and at the low tech end
(naked-eye detection).
38
Graduate Student Activities
Secondary Topics Mapping of As distribution in
local communities. soil, surface ground
water PTW, pesticide herbicide application
(past and present), chicken farming, cemetery
leachate Removal of arsenic from drinking
water. Solid-phase extraction, adsorption,
ion-exchange, chelation, waste biomass,
zero-valent iron, live biota Biomarkers of
arsenic exposure Hair, nails, and earthworms
39
HPLC-HG-ICP-OES
Sample flow rate 1ml/min Argon flow 0.55
l/min NaBH4 0.5 in 0.1 NaOH NaBH4 flow rate 1.5
ml/min HCl 16 M flow rate 0.05 ml/min
40
Baseline separation of four key compounds
41
Sequential extraction procedure for soils
0.2 g soil to 15 ml centrifuge tube 5 ml 0.1 M
phosphoric acid added and shake for 24
h Centrifuged for 10 min at 70 rps Supernatant
filtered through 0.45 µm filter and inject 5 ml
0.1 M sodium hydroxide was added shake for 24
h Centrifuged for 10 min at 70 rps Supernatant
filtered through 0.45 µm filter, adjust pH to 2.5
and inject.
42
(No Transcript)
43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
As and Se in human urine
Operating conditions for HPLC-ICP-MS

• HPLC Pump SP8810 precision isocratic pump
• Injector Rheodyne 7010
• ICP-MS Perkin-Elmer Elan 6100 DRC-e
• Isocratic mode
• Mass As 75, Se78
• Column Waters Symmetry C-8 (4.6 x 250 mm, 5 ?m)
• Ion-pairing reagent 13 mM tetrabutylammonium
  hydroxide (TBAH)
• Mobile phase 1.3 MeOH, pH adjusted with malonic
  acid
• Flow rate 1.0 mL/min
• Injection volume 50 ?L
• Column and sample temperature Room temperature

48
Calibration Arsenic compounds
49
Calibration Arsenic compounds
As75 (5-fold diluted syn-urine)
Concentration, ppb
50
Calibration selenium compounds
51
Gutzeit test? Arsenate zinc acid produces
AsH3. Soluble in water to 780 mg/L, but
dissolved salts and H2 evolution transferAsH3
into head space. AsH3 reacts with mercuric
bromide impregnated test strip. Yellow-brown
color produced after set time is compared with
preprinted chart.
52
Rahman et al.,Effectiveness and Reliability of
Arsenic Field Testing Kits Are the Million
Dollar Screening Projects Effective or Not? Env.
Sci. Technol, 2002, 36, 5385-5394.
290 samples false negatives were as high as 68
and false positives up to 35. 2,866 samples
from previously labeled wells 45 mislabeling
in the lower range (lt 50 ppb), for 70 - 600 ppb,
4 - 10 mislabeled
Millions of dollars are being spent without
scientific validation of the field kit method.
Facts and figures demand improved,
environmentally friendly laboratory techniques to
produce reliable data.
53
Caldwell, et al. Searching for an optimum
solution to the Bangladesh arsenic crisis,
Social Science Medicine, 2003, 56, 20892096..
The reason for caution about precipitating a
great suspicion of tubewells or a rapid turning
against them is that no alternative source of
water may prove very satisfactory.
the most urgent need is not changing the source
of water but comprehensive national water testing
providing essential information to households
about which wells are safe and which are not . .
. all progress depends on nationwide testing and
retesting of all tubewells, a process that has
hardly started.
54
Hossain Arsenic Contamination in BangladeshAn
Overview,, Agriculture, Ecosystems and
Environment, 2006, 113, 1-16 2.5
million tube wells, 128 million people
No-one has devised practical methods of ground
water remediation, most studies and actions have
focused on testing tube well water for arsenic.
Field kits used to measure As in the regions
groundwater are unreliable and that many wells in
Bangladesh have been labeled incorrectly
55
Melamed, Monitoring As in the environment a
review of science and technologies with the
potential for field measurements, Anal. Chim.
Acta, 2005, 523, 1-13.
Accurate, fast measurement of arsenic in the
field remains a technical challenge.
Technological advances in a variety of
instruments have met with varying success.
However, the central goal of developing field
assays that reliably and reproducibly quantify
arsenic has not been achieved.
56
Prospects
Our approach Pervaporation into an acceptor
solution containing iodate and permanganate with
detection by visible spectrophotometry.
Performance was superior to those of procedures
based on (a) the molybdenum blue chemistry, which
requires on-line heating, and (b) pervaporation
into permanganate alone. LOD 0.5 ppb
57
Modifications to Hach Test

Field test kits offer the only plausible
approach for mass screening Kinniburgh Kosmus,
Talanta, 2002, 58, 165-180.

Improve accuracy and precision by increasing the
time to 24 h? Read color by scanning and
interrogating the RGB values of image
pixels? Mathews et al, Quantitative assay for
starch by colorimetry using a desktop scanner,
J. Chem. Educ. 2004, 81, 702-704.
58
(No Transcript)
59
(No Transcript)
60
Background to The Arsenic Project
According to a recent NSF report About 80 of
school students decide, by the time they enter
high school, that they are not interested in
science. And environmental topics improve
student interest, attitude, achievement and
attendance. Can be applied at all stages of the
curriculum from K-21. S. Pfirman and the
AC-ERE Environmental Education in the Complex
Environmental Systems Synthesis for Earth, Life
and Society in the 21st Century, A report
summarizing a 10-year outlook in environmental
research and education for the National Science
Foundation, 2003, p. 44. http//www.nsf.gov/geo/er
e/ereweb/acere_synthesis_rpt.cfm (accessed April
2005).
61
Other students in The Arsenic Project
Awareness of the PTW source led to my suggestion
that tracking the arsenic from PTW as part of an
arsenic in the environment theme would be a
suitable for our GK-12 program. Started in
summer of 2002.
Fall 2004. Creation of authentic research
experiences for first-year undergraduates--more
info at the arsenic project website
http//courses.umass.edu/chemh01/ Currently
funded by a grant from the Dreyfus Foundation
(Special Program in the Chemical Sciences)
62
Other students in The Arsenic Project
Fall 2006 STEMRAYS. NSF-funded research
academies for young scientists Division of
Elementary, Secondary and Informal education.
After-school program with 6 teachers and 50
students.
63
Student Activities in The Arsenic Project
Participants in the one-credit, semester-long
arsenic project.
Semester No. of groups General Chem. Upper level Total Cum Total
Fall 04 6 17 6 23 23
Spring 05 10 25 17 42 65
Fall 05 11 60 12 72 137
Spring 06 11 36 9 45 182
Fall 06 8 35 12 47 229
Spring 07 6 23 6 29 258
http//courses.umass.edu/chemh01/
64
Student Activities in The Arsenic Project
Final reports from fall semester 2006 1. Arsenic
Accumulation in Lumbricus Terrestris 2. The use
of Molybdenum to Determine Arsenic Levels in
Wood 3. The Removal of Arsenic from Water using
Sand and Ash 4. Biomethylation of Arsenic by E.
coli Bacteria
65
Student Activities in The Arsenic Project
Final reports from fall semester 2006 5.
Arsenic Contamination in Soil Near Pressure
Treated Wood 6. Do microorganisms convert
inorganic arsenic to volatile arsenic? 7.
Analyzing Possible Improvements to Arsenic Field
Test Kits 8. Arsenic in Food how much do we
eat?
http//courses.umass.edu/chemh01/
66
Student Activities in The Arsenic Project
Chemistry 108 (Environmental Chemistry) Spring
2007 1. 2. 3. 4.
67
Grads,Iindependent Study, REU Participants in the
arsenic project.
68
Student Activities in The Arsenic Project
http//courses.umass.edu/chemh01/
69
The arsenic project acknowledgements
NSF awards DUE 0139272 Graduate Students in GK-12
Education (GK-12) STEM Connections, June 2002
to May 2006 NSF CHE-0316181 Integrating Research
and Education tracking arsenic from
pressure-treated wood started in July
2003. UMass Center for Teaching Faculty Grant
for Teaching. Sept 2005. Camille and Henry
Dreyfus Foundation Special Grant Program in the
Chemical Sciences. Feb 2006.
70
Student Activities in The Arsenic Project
Undergraduates Now in 7th semester. Each group
has 2-3 freshmen and 1-2 juniors and a graduate
student mentor.
Final reports from spring semester 2006. 1.
Removal of Arsenic from Drinking Water Chemical
Means Arsenic Removal by Iron Precipitation in
Alkaline Solutions 2. Arsenic (III) Removal from
Water via Coagulation with an Iron Species 3.
Measurement of Arsenic in Hair and Nails 4.
Spectrophotometric Determination of Arsenic in
Water Flow injection molybdenum blue method 5.
Spectrophotometric Determination of Arsenic in
Plants The Molybdenum Blue Method
71
6. Spectrophotometric Determination of Arsenic in
Pressure-Treated Wood Silver diethyldithiocarbama
te method 7. Determination of arsenic in wood by
inductively coupled plasma mass spectrometry
using oxalic acid extraction the mapping of
copper chromated arsenate wood on the University
of Massachusetts Amherst Campus 8. Metabolism of
Arsenic in E. Coli 9. Analyzing the spatial
distribution of arsenic in soil using the Hatch
Test Kit and soil from the Amherst area 10.
Effectiveness of Solvents in the Removal of
Arsenic from Soil 11. Evaluating and Improving a
Commercial Test Kit for the Determination of
Arsenic in Drinking Water