Absorption photometric determination of vulcanization accelerator tetramethylthiuram disulfide by cobalt complexation

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  • ゴム加硫促進剤テトラメチルチウラムジスルフィドのコバルト錯体化‐吸光光度法による定量
  • ゴム カリュウ ソクシンザイ テトラメチルチウラムジスルフィド ノ コバルト
  • ゴム加硫促進剤テトラメチルチウラムジスルフィドのコバルト錯体化-吸光光度法による定量

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Description

Tetramethylthiuram disulfide (TMTD) formed in organic solvents a yellow-green cobalt (II) complex (Co-DMDC; DMDC, dimethyldithiocarbamate) in the presence of aqueous sodium thiosulfate. The complex showed absorption maximum at 245 nm, 268 nm, and 323 nm and the absorption at 323 nm was constant in the pH range 5.010.0. These findings were applied to the extraction spectrophotometric determination of TMTD. The recommended procedure is as follows: To 10 ml chloroform solution of 0.5 × 10-4 M TMTD in a 50 ml volumetric flask were added 10 ml of 1 × 10-2 M aqueous sodium thiosulfate and 10 ml of 0.5× 10-3 M ethanolic cobalt (II) chloride. The mixture was stirred for 60 min at 25°C and allowed to stand for 10 min. The organic phase was separated and the absorbance at 323 nm was measured against the reagent blank. The calibration curve obeyed Beer's law overthe concentration range from 1 × 10-6 M to 7.5 × 10-6 M TMTD. The molar absorption coefficient of the complex was 1.17 × 104dm3 cm -1 mol-1. The combining ratio of cobalt to DMDC in the complex was 1 : 1. The determination was not interfered by the presence of other vulcanization accelerators such as mercaptobenzothiazol and dibenzothiazyl disulfide. By this method, 5× 10-5 M TMTD in chloroform could be determined with the variation coefficient 0.22 % for 7 determinations. The method was applied to the determination of TMTD in vulcanized and unvulcanized rubbers.

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 31 (10), 583-588, 1982

    The Japan Society for Analytical Chemistry

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