Arsenic Detection (Rodeostat, Openvoltam)

Required before start

✔ Electrode conditioned (see Conditioning Cheat Sheet) ✔ Reagents prepared (sample + standards) ✔ Preconfigured arsenic method available ✔ Minimum: 3 runs planned

• Sample 
• Standard addition 1 
• Standard addition 2
• ✔ Recommended: 4 repetitions per run 

STEP 1 — CREATE / OPEN SAMPLE

1. Open OpenVoltam 
2. Click New Sample or Open Sample 
3. Enter metadata: 
   • Location 
   • Date 
   • Operator name 
4. Save sample workspace 

STEP 2 – SAMPLE PREPARATION

1. Prepare your sample (x mL sample + x mL DI + 4 mL 1 M HCl = 40 mL total)
2. Load into electrochemical cell

STEP 3 — SAMPLE MEASUREMENT

Click New Run 

1. Select:
   • Method: Arsenic Detection 
   • Device: Rodeostat 
2. Run type: Sample 
3. Enter: 
   • Sample volume 
   • Total cell volume 
4. Set repetitions: 4 (recommended) 
5. Click: 
   • Ready to Run 
   • Begin Run 

STEP 4 — STANDARD ADDITION 1

1. Right click on previous Run 🡪 Select Start from from config
2. Change run type: Standard Addition 
3. Enter: 
   • Volume added 
   • Standard concentration 
4. Add clear note: Example: Well_A + 2.5 ppb As 
5. Repetitions: 4 recommended 
6. Run measurement 

STEP 5 — STANDARD ADDITION 2

Repeat Step 4 with higher spike:

• Example note: Well_A + 5 ppb As 

STEP 6 — PEAK ANALYSIS

After EACH run:

1. Click Analyze Results 
2. Verify automatically selected: 
   • Peak region (-0.2 V to +0.1 V typical) 
   • Baseline 
3. Adjust baseline if needed: Drag marker carefully 
4. Confirm: Full peak included 
5. Click: Accept & Next 
6. Repeat for all replicates 
7. Click: Save All 

QUALITY RULES 

Accept data only if:

✔ Clear single peak shape ✔ No saturation ✔ Consistent peak position across replicates ✔ Baseline is stable and reproducible

Reject or redo if:

• Peak shifts significantly 
• Noise dominates signal 
• Baseline selection changes between reps 

STEP 7 — CALCULATION

1. Go to sample environment 
2. Select: 
   • Sample + both standard additions 
   • (CTRL + click) 
3. Click: Calculate 

Recommended method

Use: Peak height over baseline 

STEP 8 — FINAL RESULT CHECK

Verify:

✔ Linear regression looks correct✔ No clear outliers✔ Confidence interval reasonable (95% default)

Software outputs:

• Concentration (µg/L = ppb) 
• Confidence interval 
• Dilution-corrected result 

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