Water Purification System — Standard Operating Procedure

1. Daily Checks

• [ ] Record resistivity reading (target: ≥18.2 MΩ·cm)
• [ ] Verify TOC reading (<5 ppb)
• [ ] Check RO pressure (4–6 bar)
• [ ] Inspect for visible leaks
• [ ] Verify dispense flow rate
• [ ] Log all readings in water quality logbook

2. Usage Guidelines

Application	Water Grade	Notes
SPPS resin washing	Type 2	Freshly dispensed
HPLC mobile phase	Type 1 (18.2 MΩ·cm)	Filter through 0.22 µm
Lyophilization diluent	Type 1	—
LC-MS solvents	Type 1	TOC <5 ppb critical

3. Routine Maintenance

Interval	Task
Weekly	Sanitize dispense point with 70% IPA
Monthly	Replace 0.22 µm final filter
Quarterly	Replace carbon filter and sediment filter
Semi-annually	Replace UV lamp
Annually	Replace RO membrane and ion exchange resins

4. Out-of-Specification Response

If resistivity falls below 18.0 MΩ·cm: 1. Stop dispensing water 2. Check system display for error codes 3. Flush system for 10 min at max flow 4. If persists, call maintenance 5. Document incident