Name: trace analysis by stripping voltammetry
Uploaded: 2024-12-05T18:31:57.000Z
Duration: 1 min 13 s
Channel: JoVE

La voltammetria di stripping comporta la deposizione di analiti di metalli in tracce sulla superficie di un elettrodo. Questo è seguito dal suo stripping (anodico, catodico o adsorbente) quando la corrente viene monitorata in funzione del potenziale applicato.
La voltammetria di stripping anodico comprende due fasi. In primo luogo, all'elettrodo di lavoro viene applicato un potenziale catodico costante, che provoca la riduzione degli ioni al corrispondente metallo depositato sull'elettrodo.
Successivamente, quando viene applicato un potenziale anodico, i metalli depositati vengono ossidati ai loro stati ionici e rimossi dalla superficie dell'elettrodo. La corrente anodica risultante misurata è proporzionale alla concentrazione dell'analita del campione.
La voltammetria di stripping catodico prevede l'ossidazione dell'elettrodo di mercurio che si combina con l'analita per depositarsi come film insolubile. Questo viene reinserito nella soluzione scansionando verso un potenziale più negativo e misurando la corrente catodica.
La voltammetria di strippaggio adsorbente prevede l'adsorbimento dell'analita sulla superficie dell'elettrodo senza sottoporlo a elettrolisi, seguito da strippaggio anodico o catodico.

voltammetria: metodi di stripping

Voltammetry: Stripping Methods

La voltammetria di stripping anodico (ASV), la voltammetria di stripping catodica (CSV) e la voltammetria di stripping adsorbente (AdSV) sono tecniche elettrochimiche che vengono usate per determinare tracce di analiti in soluzione. Questi metodi comportano l'applicazione di un potenziale a un elettrodo e la misurazione della corrente risultante.

Voltammetria di stripping anodico (ASV)

L’ASV viene usata per determinare i metalli e i metalloidi a livelli di traccia. Essa comporta due fasi: la deposizione e lo stripping. Innanzitutto, viene applicato un potenziale negativo all'elettrodo di lavoro, riducendo gli ioni analita e depositandoli sulla superficie dell'elettrodo. Dopo la fase di deposizione, il potenziale viene scansionato nella direzione positiva, causando l'ossidazione degli ioni analita depositati, e lo stripping della superficie dell'elettrodo. La corrente risultante durante questi processi viene misurata e tracciata, mostrando la relazione proporzionale alla concentrazione dell'analita.

<ul style="list-style-type: disc; display: flex; flex-direction: column; gap: 10px; padding: 0 0 0 10px;">
	<li>Condizioni ottimali: garantire una superficie dell'elettrodo pulita e ben lucidata, controllare il tempo di deposizione e mantenere un pH stabile nella soluzione.</li>
	<li>Sfide: interferenza da altri ioni, sporcamento dell'elettrodo e necessità di un controllo preciso del potenziale.</li>
</ul>

Voltammetria a stripping catodico (CSV)

Nella CSV, l'elettrodo di mercurio subisce l’ossidazione mentre interagisce con l'analita, creando una pellicola insolubile sulla sua superficie. Successivamente, il potenziale viene scansionato nella direzione negativa, riducendo e rimuovendo l'analita dalla superficie dell'elettrodo. La corrente risultante viene misurata ed è proporzionale alla concentrazione dell'analita. La CSV, di solito, è utilizzata per determinare i composti organici, come alcuni inquinanti e farmaci.

<ul style="list-style-type: disc; display: flex; flex-direction: column; gap: 10px; padding: 0 0 0 10px;">
	<li>Condizioni ottimali: selezionare un elettrolita di supporto appropriato e mantenere un controllo della temperatura adeguato.</li>
	<li>Sfide: gestione dell'elettrodo di mercurio a causa della sua tossicità e garanzia che la formazione della pellicola sia riproducibile.</li>
</ul>

Voltammetria a stripping adsorbente (AdSV)

L’AdSV è una variante della voltammetria a stripping in cui le specie di analita vengono adsorbite sulla superficie dell'elettrodo prima della fase di stripping. Un potenziale viene applicato all'elettrodo di lavoro, che porta all'adsorbimento delle specie di analita. Dopo l'adsorbimento, l'analita viene rimosso dall'elettrodo modificando il potenziale e la corrente risultante viene misurata per quantificare la concentrazione dell'analita. L'AdSV è comunemente utilizzato per determinare specie sia organiche che inorganiche, inclusi i vari inquinanti, i pesticidi e i metalli pesanti.

<ul style="list-style-type: disc; display: flex; flex-direction: column; gap: 10px; padding: 0 0 0 10px;">
	<li>Condizioni ottimali: selezionare il tempo di adsorbimento, il potenziale e il materiale dell'elettrodo appropriati.</li>
	<li>Sfide: competizione per i siti di adsorbimento sull'elettrodo e sensibilità alle impurità nella soluzione.</li>
</ul>

Voltammetria: metodi di stripping

La voltammetria di stripping anodico (ASV), la voltammetria di stripping catodico (CSV) e la voltammetria di stripping adsorbente (AdSV) sono tecniche elettrochimiche utilizzate ...

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Analytical Chemistry

Chimica Analitica

Unit 1

Unità 1

Electrochemical Analyses and Redox Titration

Analisi elettrochimiche e titolazione redox

electrochemical-analyses-and-redox-titration

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

trace analysis by stripping voltammetry

Stripping voltammetry is an electrochemical method used to detect trace amounts of analytes in solution. It works by applying a potential to an electrode and measuring the current that results. The current is then used to estimate the analyte concentration.

Anodic Stripping Voltammetry, or ASV, is used for metals and metalloids at very low levels. It has two main steps: deposition and stripping. First, a negative potential reduces analyte ions and deposits them on the working electrode surface. Then the potential is scanned in the positive direction, and the deposited ions oxidize and strip off the surface. The measured current is proportional to the analyte concentration. A clean, well-polished electrode surface, controlled deposition time, and stable pH help ASV work well. Common problems include interference from other ions, electrode fouling, and the need for precise control of potential.

Cathodic Stripping Voltammetry, or CSV, uses a different stripping step. In this method, a mercury electrode is oxidized while it interacts with the analyte, which forms an insoluble film on the surface. The potential is then scanned in the negative direction, reducing and stripping the analyte from the electrode. The current that appears is proportional to analyte concentration. CSV is often used for organic compounds, including some pollutants and drugs. It works best with the right supporting electrolyte and good temperature control. Its challenges include the toxicity of mercury and the need for reproducible film formation.

Adsorptive Stripping Voltammetry, or AdSV, depends on adsorption before stripping. Adsorption means the analyte species stick to the electrode surface. After this step, the potential is changed and the analyte is stripped off, and the resulting current is measured to find the concentration. AdSV can be used for organic and inorganic species, including pollutants, pesticides, and heavy metals. The method depends on the right adsorption time, potential, and electrode material. It can also be affected by competition for adsorption sites and by impurities in the solution.

Trace Analysis by Stripping Voltammetry

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Stripping voltammetry is an electrochemical method used to detect trace amounts of analytes in solution. It works by applying a potential to an electrode and measuring the current that results. The current is then used to estimate the analyte concentration. Anodic Stripping Voltammetry, or ASV, is used for metals and metalloids at very low levels. It has two main steps: deposition and stripping. First, a negative potential reduces analyte ions and deposits them on the working electrode surface.

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key terms and concepts

Learn how ASV, CSV, and AdSV detect trace analytes by measuring current changes at an electrode, with uses, setup needs, and common challenges.

Trace Analysis by Stripping Voltammetry | JoVE K12

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Trace Analysis by Stripping Voltammetry

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