Determination of Copper Ions with Different Dissolution Characteristics in Tea by Concentration Direct-Reading Method after Standard Solution Addition

doi:10.7506/spkx1002-6630-201404030

Abstract

Abstract:

A new method to detect copper ions with different dissolution characteristics in tea was established. After
sequential extraction of tea samples with water and alkali, the remaining residue was microwave-digested and detected with
a copper-selective electrode by directly reading the concentrations of copper ions. Results showed that the optimal amounts
of 1.00 mol/L potassium nitrate and 1.00 mol/L sodium fluoride added were both 5.00 mL in total ionic strength adjustment
buffer (TISAB) at pH 4.00. The conversion factor of the copper ion selective electrode was more than 93%, indicating that
the Nernst response of this electrode is quite good. Under these experimental conditions, the relative standard deviation for
11 repeated determinations of tea samples was 2.4%, the spike recoveries were in the range of 94.38%–101.22%, and the
detection limit was 1.20 × 10-6 mol/L. Satisfactory analytical results were obtained by using the method in comparison to the
national standard method.

Key words: concentration direct-reading after standard solution addition, tea, copper, dissolution characteristics

CLC Number:

TS207.3

GAO Xiang-yang1,2, WEI Jiang-mian2, ZHANG Na1. Determination of Copper Ions with Different Dissolution Characteristics in Tea by Concentration Direct-Reading Method after Standard Solution Addition[J]. FOOD SCIENCE, 2014, 35(4): 146-150.

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