Rapid determination of trace level copper in tea infusion samples by solid contact ion selective electrode

Should include Mn & Al data for clarity

Details


Summary:

A new copper selective solid-state electrode based on o-xylylenebis(N,N-diisobutyldithiocarbamate) ionophore has been described. It has been developed for selectively measuring the copper levels found in the tea infusion samples. Robust, cheap and fast determination of copper by using solid contacts is the highlight of this work.

Observations:

  • Scale of samples: Four samples were brought from market for preparing the tea infusion samples. A better adaptability of the system can be judged with at least 10 initial samples.
  • pH adjustment: The most commonly used acid for pH adjustment is sulphuric acid. But here, use of nitric acid for adjusting the pH seems to have an impact on the detection of copper ions. Using nitric acid induces a chemical environment similar to Cu(NO3)2 used for standardisation. So, using sulphuric acid instead of nitric acid is a more potent approach for pH adjustment as well as prevents interaction of Cu2+ with nitrate ions which increases its detection. Another observation regarding pH adjustment is that, it should have been checked for success at pH around 7.0 or mildly acidic conditions. It suffers from the low window for pH sensitivity.
  • Selectivity against interferent: It was interesting to note that the selectivity coefficients excluded any data on Al3+ and Mn2+ which are known to be present in major concentrations across different varieties of tea.

Recommendations:

  • As the described procedure involves use of nitric acid for adjusting the pH, it suffers from the bias of interaction of nitrate with copper ions. So, the pH adjustment is recommended using sulphuric acid.
  • Presence of Al3+ and Mn2+ which are known to be present in major concentrations is to be included for a comprehensive assessment.


Leave a Comment