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Silver diethyldithiocarbamate

Silver diethyldithiocarbamate is a chemical compound, with formula AgS2CN(CH2CH3)2. It is the silver salt of diethyldithiocarbamic acid;[2] the latter is a well-known chelator of heavy metals. In most of its applications, silver diethyldithiocarbamate resembles the cheaper sodium diethyldithiocarbamate, but it is uniquely insoluble in water. That property makes it a useful analytical reagent for determining arsenic concentrations.

Silver diethyldithiocarbamate
Names
IUPAC name
Silver diethylcarbamodithioate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.014.549 Edit this at Wikidata
EC Number
  • 216-003-7
UNII
  • InChI=1S/C5H11NS2.Ag/c1-3-6(4-2)5(7)8;/h3-4H2,1-2H3,(H,7,8);/q;+1/p-1
    Key: NSVHDIYWJVLAGH-UHFFFAOYSA-M
  • CCN(CC)C(=S)[S-].[Ag+]
Properties
C5H10AgNS2
Molar mass 256.13 g·mol−1
Appearance Greenish-yellow solid
Melting point 175 °C (347 °F; 448 K)
Insoluble
Solubility Soluble in pyridine
Hazards[1]
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Preparation

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Silver diethyldithiocarbamate can be prepared by mixing a solution sodium diethyldithiocarbamate with a solution of silver nitrate. A precipitate forms immediately and can be filtered to isolate from the rest of the mixture.[3] The solid should then be rinsed with hot water in order to remove the residual acid salt that will be present.[4]

Application

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Silver diethyldithiocarbamate can be applied to introduce the diethyldithiocarbamato ligand to a coordination compound. Silver diethyldithiocarbamate can also be used to detect Nitrogen monooxide in the brain and other tissue. These applications are similar to the applications of sodium diethyldithiocarbamate, which is more practical to use from a synthetic and toxicological perspective.[5]

Determination of arsenic concentration

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Figure 1: arsenic tris(diethyldithiocarbamate)
 
Figure 2: diethyldithiocarbamate; another possible product

The solubility of silver diethyldithiocarbamate, compared to sodium diethyldithiocarbamate, allows it to be used to determine arsenic concentrations in water. Silver diethyldithiocarbamate dissolved in pyridine appears as an intensely yellow-colored solution. Arsenic ions are transferred to an arsine generating flask and diluted with water. Sulfuric acid, potassium iodide solution, and stannous chloride dihydrate are diluted in a solution of concentrated hydrochloric acid and mixed. The apparatus is plugged loosely with lead acetate wool, which acts as a scrubber. The pyridine and silver diethyldithiocarbamate solution is added to the tube and serves as the absorber solution. Granulated zinc is added to the arsine generator flask, which will result in the production of hydrogen because of the presence of acid. The arsine is carried through the tube by the generated hydrogen gas. The arsine reacts with the silver diethyldithiocarbamate solution and forms red-colored products (535 nm). Ultraviolet-visible spectroscopy can be used to determine the concentration of arsenic can be calculated based on Beer's Law.[6][7]

The red product is a result of arsine bubbling through the silver diethyldithiocarbamate solution and there are two likely products responsible for the color change. One is arsenic substituting the silver in diethyldithiocarbamate, resulting a coordination compound in which three diethyldithiocarbamate ligands are bound to an arsenic atom (Figure 1). The other product is a result of the reduction of silver diethyldithiocarbamate (Figure 2).

This method for determination of arsenic concentration is applicable to not only waste water and mineral water but also petroleum, the human body,[8] various foods and ores,[9] and pyrolysis gasses.[10] There have been reports of silver diethyldithiocarbamate being modified into an electrode to be used for similar purposes.[11][12]

This method of determining arsenic levels in water is compared to the Gutzeit procedure and has the advantages of faster hydrogen gas absorption and more objective color interpretation.[8]

References

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  1. ^ https://www.fishersci.com/store/msds?partNumber=AA1189809&productDescription=SLVR+DIETHLDITHIOCARBAMATE+10G&vendorId=VN00024248&countryCode=US&language=en[full citation needed]
  2. ^ "Arsenic and its compounds. Silver diethyldithiocarbamate method". American Industrial Hygiene Association Journal. 33 (3): 197. June 4, 2010. doi:10.1080/0002889728506630. ISSN 0002-8894. PMID 5074677. S2CID 232194544.
  3. ^ Budesinsky, B. W. (1979-03-01). "Arsenic colorimetry with silver diethyldithiocarbamate". Microchemical Journal. 24 (1): 80–87. doi:10.1016/0026-265X(79)90041-9. ISSN 0026-265X.
  4. ^ "Method 200.7, Revision 4.4: Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma-Atomic Emission Spectrometry" (PDF). United States Environmental Protection Agency. 1994. p. 59. Retrieved 2023-01-01.
  5. ^ "Silver diethyldithiocarbamate". Sigma-Aldrich.
  6. ^ Fischer, Daniel Carl (1989). Colorimetric determination and speciation of arsenic with silver diethyldithiocarbamate (Thesis). p. 30. doi:10.25669/5x8m-gu68.
  7. ^ "Silver Diethyldithiocarbamate". ACS Reagent Chemicals. 2017. doi:10.1021/acsreagents.4321.20160601. ISBN 978-0-8412-3046-0.
  8. ^ a b Bäumler, J.; Obersteg, J. Im; Shafer, R. (1968). "Determination of the level of arsenic in human bodies (population of Basle)". Deutsche Zeitschrift für die gesamte gerichtliche Medizin. 64 (2): 56–61. doi:10.1007/BF00586806. PMID 5710954. S2CID 25563058.
  9. ^ Zhou, Zi-hong (2011). "Determination of Trace Arsenic in Phosphorus Ore". Guangzhou Huagong. 39 (6): 113.
  10. ^ Tong, Ling; Gao, Rui-feng (2012). "Determination of arsenic content in pyrolysis by using silver diethyl dithiocarbamate spectrophotometric method". Shihua Jishu Yu Yingyong. 30 (5): 454.
  11. ^ Lian, Kaoqi; Kang, Weijun; Li, Shan (2009). "二乙基二硫代氨基甲酸银修饰电极法测定大米中的微量硒(IV)" [Method for determination of trace element Se (IV) content in rice by silver diethyl dithio carbamate-modified electrode]. Weisheng Yanjiu (in Chinese). 38 (1): 123–124. doi:10.19813/j.cnki.weishengyanjiu.2009.01.039.
  12. ^ Zhao, Shi-hao; Zhang, Ping-Ping; Chen, Li-Yan (2009). "Determination of chloride ion in selenium(IV) system with silver-diethyldithocarbamate modified electrode". Asian Journal of Chemistry. 21 (8): 6265–6270.
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