How to Read a Glass Packaging Certificate of Analysis (CoA)
Practical guide for QA managers and procurement officers: how to interpret every section of a CoA, understand test values, and recognize red flags before accepting shipments.
1. What is a Glass Packaging CoA and Why It Matters
A Certificate of Analysis (CoA) is an official quality document issued by the supplier or an accredited laboratory, containing test results for a specific production batch. For pharmaceutical glass packaging, a CoA demonstrates that the product meets agreed specifications and applicable pharmacopeial standards.
In the regulatory context, a CoA is not merely a supplementary document -- it is a mandatory requirement in batch release records. BPOM, FDA (21 CFR 211.84), and EMA require every batch of primary packaging material to be inspected and documented before production use. Without a valid and complete CoA, a packaging batch must not be released for production use.
A comprehensive pharmaceutical glass CoA covers: material identification (glass type, color, dimensions), quality test results (hydrolytic resistance, thermal shock, extractables), batch information (lot number, production date), and a conformance statement against acceptance criteria.
When to Request a CoA
Request a CoA for: (1) every new shipment batch, (2) during vendor qualification, (3) after supplier process or material changes, (4) when there are quality complaints, (5) for product registration renewal at BPOM.
2. Key Sections of a Glass CoA Explained
Every complete pharmaceutical glass CoA contains the following sections. Understanding each section helps you evaluate batch quality comprehensively.
Material Identification
This section specifically identifies the product being tested.
Batch Information
Traceability data linking the CoA to a specific production batch. Critical for recalls and investigations.
Test Results
The core section of the CoA containing actual test values. Must include: test method, result values, acceptance criteria, and pass/fail status.
Acceptance Criteria and Approval
Each test parameter must have clear acceptance criteria (upper/lower limits) and a conformance statement. The CoA must be signed by an authorized person with name, title, and date. The issuing laboratory must be identified, ideally with ISO/IEC 17025 accreditation number.
3. Reading Hydrolytic Resistance Results
Hydrolytic resistance testing is the most important test in a pharmaceutical glass CoA. This test measures how much alkali leaches from glass into water under standard conditions (121°C for 30 or 60 minutes). The lower the leaching value, the better the glass resistance.
Two types of tests are reported in the CoA:
HGB -- Surface Glass Test
Tests the intact surface of the glass container. Containers are filled with water, heated to 121°C for 60 minutes, then the volume of NaOH or HCl required for titration is measured. Results indicate the actual surface resistance that will contact the product.
| Class | Max Limit (mL 0.01M HCl) | Glass Type |
|---|---|---|
| HGB 1 | Depends on container capacity | Type I, II |
| HGB 2 | Higher than HGB 1 | Type III |
| HGB 3 | Highest | Type III |
HGA -- Powdered Glass Test
Tests the bulk glass composition (not just the surface). Glass is crushed, sieved, and a specific fraction is tested. This shows the intrinsic resistance of the glass material and is not affected by surface treatment.
| Class | Max Limit (mL 0.02M HCl/g) | Glass Type |
|---|---|---|
| HGA 1 | ≤ 0.10 | Type I |
| HGA 2 | ≤ 0.85 | Type II |
| HGA 3 | ≤ 1.50 | Type III |
When to Reject Based on Hydrolytic Results
Reject the batch if: (1) HGA/HGB values exceed limits for the claimed glass type, (2) CoA states "Type I" but HGA > 0.10 mL/g, (3) glass claims "Type II" but HGA > 0.85 mL/g, (4) no actual numerical values are provided (only "pass"), (5) test method does not reference USP <660> or EP 3.2.1.
4. Interpreting the Dimensional Analysis Section
The dimensional analysis section displays actual measurements of critical bottle dimensions compared to target specifications and accepted tolerances. This section determines whether bottles will be compatible with your filling line and closure system.
Note that a good CoA displays min/max/average values from measured samples, not just a single value. This provides a picture of production consistency within the batch.
| Dimension | Target | Tolerance | What to Check | Standard |
|---|---|---|---|---|
| Overall Height | Per drawing | +/- 1.0 mm | All values within range | ISO 8362 / 9187 |
| Body Diameter | Per drawing | +/- 0.5 mm | Ovality (max-min) | ISO 8362 / 9187 |
| Bore Diameter (Neck) | Per finish type | +/- 0.15 mm | Critical for seal | GPI / ISO 8362 |
| Thread Diameter | Per GPI spec | +/- 0.20 mm | Closure compatibility | GPI |
| Weight | Per drawing | +/- 5% | Even glass distribution | Internal spec |
| Overflow Capacity | Per drawing | +/- 3% | Fill volume accuracy | ISO 8362 / 9187 |
Tip: How to Read the Dimensional Table
- -- Verify ALL actual values fall within target +/- tolerance range
- -- Note variation (max - min) within samples: large variation indicates process instability
- -- Neck finish dimensions most critical: tighter tolerances, direct impact on seal integrity
- -- Weight below target may mean walls too thin (risk of breakage during shipping/sterilization)
5. Reading Thermal Shock Test Results
Thermal shock testing measures the ability of glass to withstand sudden temperature changes without cracking or breaking. Testing follows ISO 7459 and ASTM C149 by heating glass containers to a specific temperature, then rapidly cooling them to a lower temperature.
The temperature differential tested (e.g., 42°C for soda-lime or 120°C for borosilicate) depends on the glass type and application. Results are reported as pass/fail based on whether samples survived without cracking after a specified number of cycles.
What to Check
- Temperature differential tested matches the claimed glass type
- Test method references ISO 7459 or ASTM C149
- Number of samples tested meets standard requirements (minimum 10 units)
- All samples pass (0 failures) -- there is no "acceptable failure rate" for thermal shock
Pass/Fail Criteria by Type
Type I (Borosilicate)
Must withstand minimum 120°C temperature differential (ISO 7459). Some specifications require 180°C for depyrogenation applications.
Type II (Treated Soda-Lime)
Standard: 42°C differential. Surface treatment does not improve thermal shock resistance of the bulk glass.
Type III (Soda-Lime)
Standard: 42°C differential for normal wall thickness. Bottles with thicker walls may require lower differentials.
6. Red Flags in a CoA to Watch For
The following warning signs in a CoA indicate quality issues or document credibility problems. Each red flag requires follow-up action before accepting the batch.
No test methods referenced
A CoA stating only "Hydrolytic Resistance: Pass" without mentioning USP <660>, EP 3.2.1, or validated internal methods lacks technical credibility. Cannot verify how testing was performed.
Only pass/fail results without numerical values
Actual numerical values allow you to assess how far results are from limits. Batches that "barely pass" (values near limits) indicate process variation risk that could cause the next batch to fail.
No batch traceability
A CoA without batch number, production date, or test date cannot be linked to a specific shipment. This makes recalls and investigations effectively impossible.
Vague or missing acceptance criteria
Every test parameter must have clear acceptance limits. A CoA stating "within specification" without showing specific limits cannot be audited and does not meet cGMP requirements.
Outdated standard references
Check whether referenced standards are still current. Pharmacopeial standards are revised periodically. Example: USP <660> has undergone several revisions since first published. Ensure the CoA uses the current applicable version.
Incomplete dimensional data
A CoA reporting only partial dimensions (e.g., only height and diameter, without neck finish and weight) does not provide a complete picture of product quality. All critical dimensions must be measured and reported.
All results exactly at acceptance limits
In normal testing, results will show natural variation. If all parameters show values exactly at acceptance limits or exactly at target, this is highly suspicious and may indicate fabricated data.
7. Step-by-Step CoA Review Checklist
Use this checklist every time you receive a CoA from a supplier. All items must be checked before the batch is accepted for production.
1 Verify Document Identity
- Unique CoA number is listed and verifiable with supplier
- Laboratory name and accreditation are listed
- Authorized person signature with name and title
2 Match Batch Information
- Batch number on CoA matches what is printed on packaging/pallet
- Batch quantity matches the quantity received
- Product name/item code on CoA matches Purchase Order
3 Review Test Results
- All agreed parameters are tested and reported
- Actual numerical values are provided (not just pass/fail)
- All results are within acceptance criteria limits
- Test methods reference correct and current standards
4 Evaluate Trends and Consistency
- Compare with previous batch CoA -- are there significant deviations
- Check for values approaching limits (indication of unstable process)
- Document review and accept/reject decision in quality system
FAQ: Reading a Glass Packaging CoA
What is a glass packaging Certificate of Analysis (CoA) and when should it be requested?
A CoA is an official document from the supplier stating quality test results for a specific production batch. A CoA should be requested for EVERY shipment batch of pharmaceutical glass packaging, not just the first batch. BPOM, FDA, and EMA regulations require CoA documents as part of the batch release record. Without a valid CoA, packaging batches must not be used for pharmaceutical production.
How do you verify that a glass CoA meets USP <660> standards?
Verify that the CoA states: (1) the test method explicitly references USP <660>, (2) actual hydrolytic test values are shown (not just "pass/fail"), (3) acceptance criteria match USP limits for the stated glass type, (4) sample volume tested follows USP procedures, and (5) the stated glass type is consistent with HGA/HGB test results. If there is any inconsistency between the claimed glass type and test results, request written clarification from the supplier.
How long is a glass packaging CoA considered valid?
A CoA is valid specifically for the batch listed and has no formal "expiration date." However, if glass packaging is stored for more than 12 months before use, re-testing is recommended, particularly for surface hydrolytic resistance (HGB), as aging and storage conditions can affect glass surface interaction. CoAs from old batches (>2 years) should be accompanied by revalidation data.
What should be done if a CoA shows out-of-specification results?
Steps to take: (1) Do not use the batch for production, (2) Immediately contact the supplier for confirmation and root cause investigation, (3) Request re-testing by an independent third party if needed, (4) Document the non-conformance in your quality system, (5) Evaluate whether previous batches from the same supplier need re-review. Never accept a batch with an out-of-spec CoA even if values are "close to" the limit.
Can CoAs from international suppliers be accepted without local accreditation?
CoAs from laboratories accredited to ISO/IEC 17025 by ILAC (International Laboratory Accreditation Cooperation) recognized accreditation bodies are generally accepted internationally. However, for BPOM registration, additional verification may be required. Verify that the issuing laboratory has accreditation scope covering the tests performed. If uncertain, conduct verification testing at a local KAN-accredited laboratory.
How can you distinguish a genuine CoA from a falsified one?
Indicators of a genuine CoA: (1) laboratory name and accreditation details are listed, (2) wet or digital signature from an authorized person, (3) unique CoA number that can be verified with the supplier, (4) specific test method details (not generic), (5) test results show normal inter-parameter variation (all results "exactly at the limit" is highly suspicious), (6) format is consistent with previous CoAs from the same supplier. Verify by contacting the laboratory directly if in doubt.
Need Complete and Transparent CoAs?
Pharmaglass issues comprehensive CoAs for every production batch, tested at our ISO/IEC 17025 accredited laboratory. Every CoA includes complete numerical values, test methods, and full traceability.