Adsorption-Desorption Phenomena of Vitamins at a Mercury Electrode by Measuring the Differential Capacity-Time Curves with a Flow Injection Method.

• SAWAMOTO Hiromiti

  Faculty of Education, Kochi University

Bibliographic Information

Other Title

• フローインジェクション法を用いる微分容量‐時間曲線測定によるビタミンの水銀電極への吸着‐脱着挙動
• フローインジェクション法を用いる微分容量-時間曲線測定によるビタミンの水銀電極への吸着-脱着挙動
• フローインジェクションホウ オ モチイル ビブン ヨウリョウ ジカン キョクセン ソクテイ ニ ヨル ビタミン ノ スイギン デンキョク エ ノ キュウチャク ダッチャク キョドウ

Abstract

The adsorption of vitamins at a mercury electrode was investigated by measuring differential capacity-time curves with a flow injection method, differential capacity-potential curves and cyclic voltammograms at a hanging mercury drop electrode. An experiment to measure the differential capacity-time curves was done as follows. A supporting electrolyte solution (0.05 M Na₂SO₄) was placed in a reservoir. Teflon tubing was used to connect the detector to a peristaltic pump and an injection valve. Solutions of vitamins were introduced via the injection valve. The adsorption of vitamins was almost irreversible. The adsorption of riboflavin and its reduced form (leucoflavin) was irreversible except at -0.25 V and -0.7 V. The less adsorption of leucoflavin i.d.fferential capacity-time curves is interpreted as follows. In the experiment involving the flow injection method, the molecules of riboflavin carried to the electrode are adsorbed and reduced to leucoflavin. Because the adsorption structures of riboflavin and leucoflavin are different, it takes time for the leucoflavin molecules to be adsorbed. During this time a part of the leucoflavin is carried away from the electrode. The adsorption of Vitamin B₁₂ is irreversible between -0.1 V and -1.4 V. Vitamin B₁₂ is considered to be one of the strongly adsorbed molecules at a mercury electrode. In the differential capacity-time curves between -0.4 V and -1.0 V, kinks are observed. The kinks are considered to be due to the different adsorption structures (flat and perpendicular) of vitamin B₁₂. The reduced form of thioctic acid i.d.sorbed. In the differential capacity-time curves, two adsorption structures are found. One is reversible adsorption with (CH₂)₄COOH to the electrode and the other is irreversible adsorption with S atms to the electrode. It is considered that the irreversible adsorption of vitamins is favorable for adsorptive stripping voltammetry.

Journal

• BUNSEKI KAGAKU

  BUNSEKI KAGAKU 51 (12), 1159-1164, 2002

  The Japan Society for Analytical Chemistry

Keywords

• reversible adsorption
• irreversible adsorption
• vitamins
• flow injection method
• differential capacity

Details

• CRID: 1390001204052282752
• NII Article ID: 110002905030
• NII Book ID: AN00222633
• DOI: 10.2116/bunsekikagaku.51.1159
• COI: 1:CAS:528:DC%2BD38XpslCgu7o%3D
• NDL BIB ID: 6405874
• ISSN: 05251931
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I6405874
• Web Site: http://www.jstage.jst.go.jp/article/bunsekikagaku/51/12/51_12_1159/_pdf
• Web Site: http://dl.ndl.go.jp/info:ndljp/pid/10895383
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • NDL-Digital
  • CiNii Articles
• Abstract License Flag: Disallowed