Electrocatalytic and voltammetric determination of sulfhydryl compounds through iron nitroprusside modified graphite paste electrode
Iron nitroprusside Fe(II)NP was incorporated into a carbon paste electrode and the electrochemical studies were performed with cyclic voltammetry. The cyclic voltammogram of Fe(II)NP exhibits two redox couple with formal potential (E0')1 = 0.24 e (E0')2 = 0.85 V vs SCE attributed to Fe(II)/Fe(II) and Fe(II)(CN)5NO / Fe(III)(CN)5NO, respectively. The redox couple with (E0')2 = 0.85 V presents an electrocatalytic response for sulfhydryl compounds. The electrocatalytic oxidation of sulfhydryl compounds by the mediator has been used for the determination of L-cysteine and N-acetylcysteine. The modified graphite paste electrode gives a linear range from 9.2 ×10-4 <FONT FACE=Symbol>-</FONT> 2.0 ×10-2; 9.6 × 10-4 <FONT FACE=Symbol>-</FONT> 1.4 × 10-2mol L-1 for the determination of L-cysteine and N-acetylcysteine, respectively, with detection limit of 1.9 ×10-4 mol L-1; 1.5 × 10-4 mol L-1 and relative standard desviations ± 5% and 1.5 × 10-3 mol L-1 ± 4% (n=3). The amperometric sensitivities are 0.024 and 0.027 muA/mumol L-1 for L-cysteine and N-acetylcysteine, respectively. The application of this electrode was tested and a commercial pharmaceutical product (Fluimucil) has been determined.
| Main Authors: | , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedade Brasileira de Química
2003
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532003000400019 |
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| Summary: | Iron nitroprusside Fe(II)NP was incorporated into a carbon paste electrode and the electrochemical studies were performed with cyclic voltammetry. The cyclic voltammogram of Fe(II)NP exhibits two redox couple with formal potential (E0')1 = 0.24 e (E0')2 = 0.85 V vs SCE attributed to Fe(II)/Fe(II) and Fe(II)(CN)5NO / Fe(III)(CN)5NO, respectively. The redox couple with (E0')2 = 0.85 V presents an electrocatalytic response for sulfhydryl compounds. The electrocatalytic oxidation of sulfhydryl compounds by the mediator has been used for the determination of L-cysteine and N-acetylcysteine. The modified graphite paste electrode gives a linear range from 9.2 ×10-4 <FONT FACE=Symbol>-</FONT> 2.0 ×10-2; 9.6 × 10-4 <FONT FACE=Symbol>-</FONT> 1.4 × 10-2mol L-1 for the determination of L-cysteine and N-acetylcysteine, respectively, with detection limit of 1.9 ×10-4 mol L-1; 1.5 × 10-4 mol L-1 and relative standard desviations ± 5% and 1.5 × 10-3 mol L-1 ± 4% (n=3). The amperometric sensitivities are 0.024 and 0.027 muA/mumol L-1 for L-cysteine and N-acetylcysteine, respectively. The application of this electrode was tested and a commercial pharmaceutical product (Fluimucil) has been determined. |
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