🧪 Glassware Verification

The analytical balance used must meet minimum resolution requirements strictly based on the nominal volume of the glassware (flask, pipette, or burette) under test.

1. Visual inspection: Verify cleanliness, inner surface condition (no frosting, scratches or chemical etching), and inscription legibility.
2. Ensure the flask is completely dry internally. Wear lint-free gloves to prevent transferring oils and heat from hands.
3. Place the empty, dry flask on the calibrated balance. Record the empty weight ($M_{E}$).
4. Fill the flask carefully with deionized water (equilibrated to room temperature) until about $1 \text{cm}$ below the graduation mark.
5. Use a dropper to add water drop-by-drop until the lowest point of the meniscus exactly touches the top edge of the graduation line (read at eye level).
6. Ensure no water droplets adhere to the inside of the neck above the meniscus line. Wipe with lint-free paper if necessary.
7. Record the water temperature ($T_{W1}$) in the dispensing container before testing.
8. Place the filled flask on the balance and record the filled weight ($M_{F1}$).
9. Empty the flask, wash, and dry it completely. Repeat steps 3–8 for readings 2 and 3 ($M_{F2}, M_{F3}$).
10. Record the final water temperature ($T_{W2}$) after testing is complete. The temperature drift must be $\le 0.5^{\circ}\text{C}$.

1. Place a receiving vessel (e.g., Erlenmeyer flask with a small amount of water to humidify it and covered with a watch glass) on the balance. Tare the balance.
2. Fill the bulb pipette with deionized water slightly above the graduation mark. Dry the outside of the tip with lint-free tissue.
3. Adjust the meniscus so the lowest point touches the upper edge of the graduation line.
4. Hold the pipette vertically and allow the water to drain freely by gravity into the receiving vessel.
5. When the continuous flow stops, rest the tip of the pipette against the inner wall of the vessel for approximately 5 seconds.
6. Draw the tip upwards along the wall to detach any hanging drop. Do NOT blow out the remaining liquid in the tip.
7. Record the mass of the dispensed water. Tare the balance.
8. Repeat for a total of 5 consecutive measurements.

1. Mount the burette perfectly vertically. Fill it with deionized water to slightly above the zero mark.
2. Open the stopcock to fill the tip completely (ensure no air bubbles are trapped).
3. Adjust the meniscus exactly to the zero mark. Remove any hanging drop at the tip.
4. Place the tared receiving vessel under the burette.
5. Fully open the stopcock and dispense water into the vessel until the meniscus is approximately $5 \text{mm}$ above the target test volume graduation.
6. Wait for exactly 30 seconds for drainage from the burette walls.
7. Carefully adjust the meniscus to exactly touch the target graduation mark. Touch the tip to the vessel wall to remove any hanging drop.
8. Record the dispensed mass.
9. Repeat steps 1-8 for a total of 5 measurements at the required points (e.g., $10 \text{mL}$, $25 \text{mL}$, $50 \text{mL}$).

The apparent mass of the water must be converted into volume at the reference temperature (usually $20^{\circ}\text{C}$) using the $Z$-factor.

• • $M_{Water}$: True mass of water (for Ex methods, this is simply the dispensed mass)
• • $Z$-factor: Correction factor accounting for the density of water at the measured temperature and air buoyancy (sourced from ISO 4787 standard tables).
• • $V_{20}$: Calculated true volume at reference temperature ($20^{\circ}\text{C}$).

• ⚠️ If the absolute error exceeds the MPE limit → repeat the verification process (must be done by a different analyst).
• ❌ If the second verification also fails → the volumetric glassware is deemed inaccurate and must be permanently removed from quantitative use.
• 🏷️ Label the failed glassware as "OUT OF SERVICE / FOR QUALITATIVE USE ONLY".
• 📋 Record results in PKK/048 and apply the UPM Temperature Correction Worksheet.

• 📋 PKKK/200/008 — Prosedur Verifikasi Alat Radas di Makmal
• 📋 UPM Temperature Correction Worksheet
• 📖 ISO 4787 — Glassware volumetric instruments