Premium
Differential pulse cathodic stripping voltammetric determination of manganese( II ) and manganese( VII ) at the 1‐(2‐pyridylazo)‐2‐naphthol‐modified carbon paste electrode
Author(s) -
Khoo Soo Beng,
Soh Ming Koon,
Cai Qiantao,
Khan Miriam R.,
Guo Si Xuan
Publication year - 1997
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140090111
Subject(s) - chemistry , manganese , detection limit , cathodic stripping voltammetry , stripping (fiber) , metal ions in aqueous solution , analytical chemistry (journal) , carbon paste electrode , polarography , metal , electrode , voltammetry , nuclear chemistry , inorganic chemistry , electrochemistry , cyclic voltammetry , chromatography , materials science , organic chemistry , composite material
A carbon paste electrode modified with 1‐(2‐pyridylazo)‐2‐naphthol was fabricated and used to preferentially accumulate Mn( II ) at open circuit. After medium exchange, the accumulated Mn( II ) at the electrode surface was electrochemically oxidized. The hydrated MnO 2 thus formed was then cathodically stripped using differential pulse voltammetry. Various factors influencing the accumulation and stripping were studied. An optimized procedure was then developed for the determination of Mn( II ). Mn( VII ) could also be determined by chemical conversion to Mn( II ) using acidified H 2 O 2 . Following this, the Mn( VII ) concentration could be obtained by subtraction. Under optimum conditions, a detection limit of 6.9 × 10 −9 M Mn( II ) (0.38 ppb) was found for 200s accumulation. For 8 determinations, each of Mn( II ) concentrations of 1.00 × 10 −6 M, 1.00 × 10 −7 M and 1.00 × 10 −8 M, relative standard deviations of 2.90%, 4.46% and 7.20% were obtained, respectively. Selected metal ions were tested for interferences and it was found that, when determining 1.00 × 10 −6 M Mn( II ) (150s accumulation), Co( II ), Hg( II ) and Fe( II ) at 1.00 × 10 −5 M interfered. These interferences were readily eliminated by masking with complexing agents such as sodium citrate and sodium diethyldithiocarbamate. The developed method was tested using a certified sample and then applied to the determination of manganese in seawater.