1 University of Massachusetts at Amherst Department of Chemistry Project 3: Silver Nitrate Detection of the Arsine Gas produced from the Gutzeit Reaction Goal: To improve the limits of detection for the standard Gutzeit reaction by using silver nitrate as a reagent. Measurement Method: digital image analysis of the reaction products on the surface of the strip. Objectives: Design an appropriate strip and optimize the silver nitrate solution used on test strips.

2 University of Massachusetts at Amherst Department of Chemistry Materials and Methods: Strip Preparation 1. Solution: 0.2% AgNO 3 (m/v) in 1% HNO Strip Preparation: 10 μL to 1 cm x 1.2 cm piece of #3 filter paper. 3. Drying Procedure: oven dry at 70 0 C for 30 minutes. 4. Strip Support: Dried strips were applied to the same plastic backing used by Hach strips using double-sided tape and are stored in an opaque container with desiccant packet.

3 University of Massachusetts at Amherst Department of Chemistry Experimental Design  Goals: to test a wider concentration range µg L -1 (ppb), use different software for analysis, and collect large sample sizes for each concentration for statistical analysis.  Targeted concentrations: 0, 2.5, 5, 10, 20, 40, 50, 60, 80, 100 µg L -1 (ppb).  Analysis: again by computer software.

4 University of Massachusetts at Amherst Department of Chemistry Plot of blue pixel value versus concentration of arsenic in water in µg L -1 with the measurement of arsine gas with silver nitrate as a reagent. Images of 2.5, 5, 10, 20 and 50 µg L -1 test results in increasing order for comparison.

5 University of Massachusetts at Amherst Department of Chemistry Results and Statistical Evaluation  T-test: to see if there is a statistically significant difference between the component values as the concentration increases.  Using 95% confidence ( = 0.05), the difference between the average blue pixel value, values from 0, 2.5, 5, 10 and 20 µg L -1 (ppb) are considered statistically significant.

6 University of Massachusetts at Amherst Department of Chemistry Conclusion for the Silver Nitrate Determination of As(III)  This strip: offers much more visibly clear results at low arsenic concentrations (<20 µg L -1 [ppb]) in comparison to the Hach kit.  Advantages: Eliminates the use of mercury Could be engineered to have a greater linear working range than mercuric bromide. Improved color formation over a wider range of concentrations.  Factors such as reaction time and AgNO 3 concentration should be studied.  Portable scanners could be used.

7 University of Massachusetts at Amherst Department of Chemistry Project 4: Determination of Arsenic using Mol-Blue and Cameras Goal: To develop a field portable technique for measurement of As (V) using Molybdenum Blue. Measurement Method: digital camera. Quantification technique: Color analyzing software.

8 University of Massachusetts at Amherst Department of Chemistry Project 5: Determination of Arsenic by Flow Injection R1R1 R2R2 Detector 895nm waste Injection valve Reaction coil 2 2 mL/min R 1 : Acidic molybdate solution R 2 : Ascorbic Acid Retention time ~5 minutes Frenzel, W., Titzenthaler F., Elbel,S. Talanta, 1994, 41,

9 University of Massachusetts at Amherst Department of Chemistry Project 6: Determination of the Stoichiometry of the Molybdenum Blue Polymer Goal: To Determine the Ratios of Mo, P, and As in the molybdenum blue polymer. Measurement Method: ICP-OES Gouzerh, P.; Proust, A. Main-group element, organic, and organometallic derivatives of polyoxometalates. Chem. Rev. 1998, 98, 77.

10 University of Massachusetts at Amherst Department of Chemistry Project 7: Study of Single Nucleotide Polymorphisms in the Promoter Regions of Cytokine Genes of Arsenic Exposed Population in West Bengal, India The study was conducted on 20 arsenic-exposed individuals with skin lesions (symptomatic) and 20 arsenic-exposed individuals without skin lesions (asymptomatics) in Murshidabad, a highly affected district where arsenic content in drinking water ranges from  g L -1. Medical histories were taken and smokers were eliminated from the sample population. Marshal Science SNP Web Site, THFR%20SNP%20Page.html, (accessed August, 2010) THFR%20SNP%20Page.html

11 University of Massachusetts at Amherst Department of Chemistry Publication Plans and Conclusion  Digital Image Analysis of Gutzeit Method to Improve Precision, a document in process; targeted publication is Royal Society of Chemistry journal Analytical Methods.  Determination of Arsenic in Soils with Gutzeit Chemistry.  The Use of Silver Nitrate as a Reagent for the Measurement of Arsenic.  Single Nucleotide Polymorphisms in the Promoter Regions of Cytokine Genes of Arsenic Exposed Populations in West Bengal, India. Potential Targets: Journal of Clinical Immunology, Carcinogenesis, and Mutation Research.

12 University of Massachusetts at Amherst Department of Chemistry Thank You and Questions Dr. Julian F. Tyson Members of the Committee Members of the Tyson Research Group The undergraduate researchers The Rise Fellowship The National Science Foundation Staff of the University of Massachusetts Chemistry Program