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

The Arsenic Project Chemical Measurements in Support of Studies of the Biogeochemistry of Arsenic. Julian Tyson Department of Chemistry UMass Amherst MA 01003 tyson@chem.umass.edu http://courses.umass.edu/chemh01/. Outline of “The Arsenic Project” talk. Background to my involvement.

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

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  1. The Arsenic Project Chemical Measurements in Support of Studies of the Biogeochemistry of Arsenic Julian Tyson Department of Chemistry UMass Amherst MA 01003 tyson@chem.umass.edu http://courses.umass.edu/chemh01/

  2. Outline of “The Arsenic Project” talk • Background to my involvement. • Background on arsenic: environment and health • Pressure treated wood • Arsenic in water • Other sources of arsenic • Middle school and undergraduate researchers. • Measurement problems: soils and water • High tech: HPLC- HG-ICP-OES; low tech: test strips • What is research?

  3. Background to “The Arsenic Project” Loughborough U. 76 - 89: UMass 89 - present J. F. Tyson , S. G. Offley, N. J. Seare, H. A. B. Kibble and C. Fellows, "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 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.

  4. 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!

  5. Background to “The Arsenic Project” This 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.

  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” Can 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 < 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. Uses: insecticides, herbicides, desiccant (cotton production), wood preservative, feed additive, medicine, poison, bullets, electronics, glass, paints, wallpapers and ceramics. Our quality of life affected by the extent to which we can (a) minimize the harmful effects of naturally occurring chemicals, (b) exploit beneficial effects of chemicals with which we choose to interact.

  9. Update on “The Arsenic Project” “The World Health Organization (WHO) recommends a tolerable daily intake of 50 µg/kg body weight from food and no more than 20 µg/L in the drinking water (WHO, 1983).” http://www.prn.usm.my/sites/arsenic.html (accessed April 2005).

  10. Update on “The Arsenic Project” Chemical form or speciation is all important. E.g. Sodium is nasty, chlorine is even worse. But swap an electron between them and make sodium chloride, and the resulting compound is essential. Not quite the same for As, as there are no known essential compounds (in humans). But there is a very wide range of toxicities.

  11. As OH CH3 As OH CH3 CH3 OH Update on “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.gettingwell.com/drug_info/nmdrugprofiles/nutsupdrugs/ars_0026.shtml (accessed April 2005)

  13. Toxicity from dietary intake of arsenic—up to 60 µg/day daily—is 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. 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 from cancer in Bangladesh alone. Arsenic contaminated water revealed in 1993 4.5 million tube wells Arsenic contamination in 20% of those tested

  15. Environmental Health Perspectives, 2005, 113, A379

  16. 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)

  17. Some arsenic compounds are not so bad.

  18. Some of the good guys Salvarsan: used to treat syphilis until the advent of penicillin in the 1950s

  19. Neoarsphenamine: used in the treatment of syphilis until the advent of penicillin in the 1950s.

  20. 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

  21. 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

  22. The end of the metabolic path? trimethylarsine oxide TMAO tetramethylarsonium iodide

  23. Arsenosugars: Found in urine and seaweed.

  24. arsenobetaine AsB Present in high concentrations in seafood arsenocholine AsC

  25. 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/ere/ereweb/acere_synthesis_rpt.cfm (accessed April 2005).

  26. Student Activities in “The Arsenic Project” http://courses.umass.edu/chemh01/ Undergraduates: Now in 5th 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

  27. Student Activities in “The Arsenic Project” 6. Spectrophotometric Determination of Arsenic in Pressure-Treated Wood: Silver diethyldithiocarbamate 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 http://courses.umass.edu/chemh01/

  28. Student Activities in “The Arsenic Project” http://courses.umass.edu/chemh01/

  29. 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 interaction of the in vivo interaction of arsenic and selenium

  30. Graduate Student Activities • Improved procedures for the determination of arsenic and 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).

  31. Graduate Student Activities Secondary Topics Mapping of As distribution in local communities. PTW, soil and ground water Removal of arsenic from drinking water. Waste biomass Biomarkers of arsenic exposure Hair, nails, and earthworms

  32. 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: FTK vs HG-AAS vs Ag-DDTC; false negatives were as high as 68% and false positives up to 35%. 2,866 samples from previously labeled wells: HG-AAS; 45% mislabeling in the lower range (< 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.”

  33. Caldwell, et al. “Searching for an optimum solution to the Bangladesh arsenic crisis,” Social Science & Medicine, 2003, 56, 2089–2096.. “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.”

  34. Hossain “Arsenic Contamination in Bangladesh—An 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 region’s groundwater are unreliable and that many wells in Bangladesh have been labeled incorrectly”

  35. 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.”

  36. What’s the problem? A procedure capable of the reliable on-site determination of arsenic in ground water at single digit ppb concentrations is needed. Can be used on site by inexperienced operators. Costs nothing. Field deployable criterion rules out the best technique: atomic spectrometry Candidates: electrochemistry, solution spectrophotometry, and Gutzeit-type test kits

  37. Spectrophotometric methods? Two candidates: (a) molybdenum blue, and (b) silver diethyldithiocarbamate Arsenate + molybdate + acid + reducing agent gives blue color due to formation of heteropoly species containing both MoIV and MoVI. Arsenate converted to arsine, evolved and trapped in a solution of AgDDC in non-aqueous solvent containing a base. A red color forms due to colloidal silver formation

  38. Spectrophotometric methods? Two candidates: (a) molybdenum blue, and (b) silver diethyldithiocarbamate. Both have problems as basis of field deployable procedure. AgDDC complicated. Molybdenum blue has possibilities but reaction is slow and non-specific. There is current activity: e.g. Dhar et al., “A rapid colorimetric method for measuring arsenic concentrations in groundwater,” Anal. Chim. Acta, 2004, 526, 203-209

  39. Dhar et al., “A rapid colorimetric method for measuring arsenic concentrations in groundwater,” Anal. Chim. Acta, 2004, 526, 203-209 There are still some issues to be sorted out. “one peculiarity of the formation of As-molybdate complexes encountered during this study is that samples containing very little P must be spiked to at least 2 µmol L-1 P (i.e. to ~0.05 absorbance for a reduced aliquot) because of a P dependence of the rate of color development for As.” Could the method be adapted to a non-instrumental finish?

  40. Maybe. Matsunaga et al., “Naked-eye detection of trace arsenic in aqueous media using molybdenum loaded chelating resin having b-hydroxypropyl-di(b-hydroxyethyl)amino moiety” Talanta, 2005, 66, 1287-1293 The color developed fully after heating for 4 h at 40 oC. The 20-min (45% max color) detection limit was 1 x 10-6 mol dm-3 But this is only 75 ppb.

  41. Prospects: Cardwell et al. “Pervaporation flow injection determination of arsenic based on hydride generation and the molybdenum blue reaction” ACA, 2001, 445, 229-238. Determination of arsenic by pervaporation flow injection hydride generation and permanganate spectrophotometric detection,ACA 2004, 510, 225-230. 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

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