Cadmium determination in natural water samples with an automatic multisyringe flow injection system coupled to a flow-through screen printed electrode

Talanta ◽  
2012 ◽  
Vol 96 ◽  
pp. 140-146 ◽  
Author(s):  
C. Henríquez ◽  
L.M. Laglera ◽  
M.J. Alpizar ◽  
J. Calvo ◽  
F. Arduini ◽  
...  
Keyword(s):  
Flow Injection ◽  
Natural Water ◽  
Water Samples ◽  
Injection System ◽  
Screen Printed Electrode ◽  
Cadmium Determination ◽  
Natural Water Samples ◽  
Flow Injection System ◽  
Flow Through ◽  
Screen Printed

scholarly journals Detection of Total Phenol in Green and Black Teas by Flow Injection System and Unmodified Screen Printed Electrode

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Ivanildo Luiz de Mattos ◽  
José Heraclito Zagal
Keyword(s):  
Phenolic Compounds ◽  
Flow Injection ◽  
Surface Cleaning ◽  
Total Phenol ◽  
Injection System ◽  
Screen Printed Electrode ◽  
Edta Solution ◽  
Phenol Determination ◽  
Flow Injection System ◽  
Screen Printed

A flow injection system using an unmodified gold screen-printed electrode was employed for total phenol determination in black and green teas. In order to avoid passivation of the electrode surface due to the redox reaction, preoxidation of the sample was realized by hexacyanoferrate(III) followed by addition of an EDTA solution. The complex formed in the presence of EDTA minimizes or avoids polymerization of the oxidized phenols. The previously filtered tea sample and hexacyanoferrate(III) reagent were introduced simultaneously into two-carrier streams producing two reproducible zones. At confluence point, the pre-oxidation of the phenolic compounds occurs while this zone flows through the coiled reactor and receives the EDTA solution before phenol detection. The consumption of ferricyanide was monitorized at 360 mV versus Ag/AgCl and reflected the total amount of phenolic compounds present in the sample. Results were reported as gallic acid equivalents (GAEs). The proposed system is robust, versatile, environmentally-friendly (since the reactive is used only in the presence of the sample), and allows the analysis of about 35–40 samples per hour with detection limit = 1 mg/L without the necessity for surface cleaning after each measurement. Precise results are in agreement with those obtained by the Folin-Ciocalteu method.

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