Before starting any measurements, it is important to ensure that all required equipment, consumables, and chemicals are available. Some items are essential, while others are optional but strongly recommended for data reproducibility and ease of use.
3.1 Required equipment
Equipment
Purpose / description
Notes
Rodeostat potentiostat
Electrochemical controller used to apply voltages and record currents.
Includes USB cable, electrode cables, dummy cell, and small screwdriver depending on package.
Gold microwire working electrode
Surface where arsenic is deposited and measured.
Typical specification: 30 µm diameter, approximately 5 mm length. Handle carefully; it can break.
Filled with 3 M KCl. Check for bubbles, low filling solution, or salt crystals.
Counter electrode
Completes the current path.
Iridium or platinum wire recommended. 200 µm diameter and should be longer than the working electrode
Magnetic stirrer plate and stir bar
Mixes solution during deposition.
A small laboratory stirrer with a relatively weak magnetic coupling is recommended. During method development, compact stirrers such as the IKA Topolino provided more stable operation than larger, more powerful stirrers. Excessive magnetic force or overly vigorous stirring can destabilize the electrochemical cell, cause electrode movement, and reduce measurement reproducibility.
Computer
Runs OpenVoltam.
Windows 10 or 11 operating system.
Electrochemical cell with lid
Container holding the measurement solution and electrodes.
The lid should position working, reference, and counter electrodes without contact between them.
Adjustable pipettes
To prepare the measuring solution, add standard additions and prepare reagents
Recommended ranges: 1-10 mL and 100-1000 µL.
Pipette tips
To facilitate the above.
Use clean tips and change tips between standards/samples to avoid contamination.
3.2 Recommended equipment and consumables
Item
Purpose / recommendation
Laboratory clamp
Useful to stabilize electrodes and cables.
Deionized water squeeze bottle
Used for rinsing glassware and electrodes.
Plastic storage containers
For storing acid solutions and standards. Opaque containers are recommended for As(III) solutions.
Volumetric flask (100 mL)
For reagent preparation
Labels and permanent marker
Essential for sample IDs, standards, acids, waste, and dates.
pH meter
Recommended but not strictly required if solutions are prepared carefully from high-quality reagents.
Spare gold microwires
Strongly recommended. The working electrode is fragile and may need replacement.
3.3 Required chemicals
Chemical / consumable
Purpose
Notes
Hydrochloric acid (HCl) to prepare 1 M solution
Used as supporting electrolyte for arsenic measurements and for sample acidification.
Concentrated HCl is corrosive and can produce fumes.
Sulfuric acid (H2SO4) to prepare 0.5 M solution
Used for electrode conditioning via cyclic voltammetry.
Used for cleaning/conditioning, not sample analysis.
Certified arsenic standard solution (1000 ppb)
Used for calibration, linear range testing, and standard addition measurements.
Strongly recommended for most users. Avoids handling solid arsenic compounds.
Potassium chloride (KCl)
Used as electrolyte in the reference electrode
Prepare a 3M solution from the salt
Deionized water
Used for solution preparation, dilutions, rinsing, and blanks.
Use laboratory-grade DI water where possible.
Nitrile gloves and safety glasses
Personal protection when handling acids and arsenic-containing solutions.
