Enzyme Solution Preparation SOP

Version: v1.0

1. Purpose

Define standardized method to prepare enzyme reagent solution ensuring activity, stability, and dispensing accuracy for glucose test strips.

2. Scope

Applies to GDHFAD Enzyme Laboratory personnel preparing production enzyme lots.

3. Responsibilities

• Lab Technician: Executes preparation, records data.
• QA: Reviews batch record, releases lot.
• Supervisor: Ensures training & deviation handling.

4. Safety

• PPE: Lab coat, nitrile gloves, safety glasses.
• Spill: Absorb with inert material, dispose as chemical waste.
• Biological hazard: If enzyme is biological origin, follow biosafety level guidelines.

5. Materials & Equipment

Item	Spec	Purpose
Enzyme powder	Approved lot (activity cert)	Active component
Buffer components	Analytical grade	pH control
Stabilizers (e.g., BSA / polymer)	Specified purity	Stability
Preservative (if used)	Conforms to formula	Microbial control
Micropipettes	Calibrated	Accurate measurement
Analytical balance	0.1 mg	Weighing
pH meter	Calibrated ±0.01	pH adjustment
Magnetic stirrer	Variable speed	Dissolution
Refrigerated storage	2–8°C	Interim holding
Filtration unit	0.22 µm	Sterile clarification
Activity assay kit	Validated	Activity verification

6. Formula (Example Template)

Component	Target Concentration	Tolerance	Notes
Enzyme	X U/mL	±5%	Define based on strip response
Buffer (e.g., Phosphate pH 7.0)	50 mM	±2%	Ionic strength
Stabilizer A	0.5% w/v	±0.05%	Protein/polysaccharide
Preservative	0.05%	±0.005%	Optional
DI Water	QS to volume	N/A	18 MΩ·cm

7. Procedure

1. Preparation Verification: Check calibration status of balance, pH meter, pipettes.
2. Cleanliness: Wipe bench with 70% IPA; assemble sterile containers.
3. Weigh Components: Record each weight directly into Batch Record (no transcription later).
4. Dissolution: Add buffer salts to ~80% final volume water; stir until dissolved.
5. pH Adjustment: Measure; adjust with 1M acid/base to target (e.g., 7.0 ±0.05).
6. Add Stabilizers: Slowly sprinkle to avoid clumping; fully dissolve.
7. Add Enzyme: Gently add; avoid foaming. Stir minimal speed.
8. Make Up Volume: Add DI water to final volume.
9. Filtration (If required): Pass through 0.22 µm PES filter into sterile amber bottle.
10. Homogenization: Invert 5 times—avoid vortexing.
11. Sampling: Take aliquots for activity assay, pH, viscosity (if applicable), appearance.
12. Labeling: Apply lot label (Format: ENZ-YYYYMMDD-XX). Include storage condition.
13. Storage: 2–8°C (record placement time). Maintain temperature log.
14. Documentation: Complete batch record; attach test results.

8. Acceptance Criteria

Test	Requirement	Method	Action if OOS
Activity	Within target ±5%	Validated assay	Rework or reject
pH	Target ±0.05	Calibrated pH meter	Adjust if possible
Appearance	Clear / slight opalescence	Visual	Investigate particulates
Microbial (if required)	< specified CFU	Plate count	Reject

9. Yield & Loss Recording

Record theoretical vs actual volume; investigate >2% loss.

10. Deviations

Log any step variance; assign deviation number; QA disposition before use.

11. Records

• Enzyme Batch Record (this SOP number referenced)
• Activity Test Report
• pH & Calibration Log snapshot

12. Change Control

Formula or method change requires validation protocol & QA approval prior to revision release.

13. Appendices

A. Sample Batch Record Template Fields: - Lot ID, Component Lots, Weights, pH Adjustments (volumes), Filter ID, Assay Results, Release Signature.

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Revision History: v1.0 Initial release.