One Year of the 2025 Chinese Pharmacopoeia: The "Test Solution / Titrimetric Solution" Changes in the Volume IV General Chapters — Is the QC Lab Transition Smooth?
The 2025 edition of the Chinese Pharmacopoeia (ChP) has been in force since October 1, 2025 [1]. Over the past year, companies have focused mostly on switching the monographs in the product-specific chapters, while the 8000 series (test solutions, buffer solutions, indicator solutions and titrimetric solutions) — because the changes "look minor" — often ends up with SOPs revised only in version number while the content is never checked line by line. This article covers just three things: what changed, how laboratories should catch up, and what exporters need to watch.
Key Takeaways
① What changed: 8002–8006 all add definitions or general requirements. The most consequential is 8006, which writes "after preparation and standardization, store under the [Storage] conditions specified" into the general requirements; in addition, 5 test solutions, phosphate buffer solution (pH 6.0) and ethanolic sodium hydroxide titrimetric solution are among the newly added items [2].
② How laboratories should catch up: run a self-check on four fronts — old batch numbers, method comparison, record updates and personnel training — with priority on completing storage records after standardization of titrimetric solutions; even items whose monographs are unchanged must be assessed [3].
③ What exporters need to watch: ChP, EP, USP and JP differ in their requirements for concentration tolerance, precision and restandardization intervals of titrimetric solutions. When one bottle of solution serves several pharmacopoeias, design the records to the stricter criteria.
1. What Changed in the 8000 Series?
General Chapter | 2025 Additions and Revisions | Impact on QC |
|---|---|---|
8002 Test Solutions | Definition added; 5 test solutions added (specific items subject to the official text) | Add preparation SOPs for the new items |
8004 Buffer Solutions | Definition, use and composition added; phosphate buffer solution (pH 6.0) added | Manage by "composition" rather than pH; the same pH with a different composition is not interchangeable |
8005 Indicator Solutions | General requirements added; preparation methods of some indicator solutions revised | Batches made by the old method must be compared or discontinued |
8006 Titrimetric Solutions | Definition added; storage requirements after preparation and standardization added; ethanolic sodium hydroxide titrimetric solution and others added | Storage conditions must be recorded and traceable |
0631 pH Value | Scope changed to "low ionic strength solutions"; equilibration time may be extended or saturated KCl added | Update the pH measurement SOP |
0822 Arsenic | Atomic fluorescence spectrometry added; the standard arsenic solution may be prepared from an arsenic single-element standard solution instead of arsenic trioxide | Priority switch for highly toxic substance management |
Also: 8001 Reagents revised its general technical requirements, key quality indicators and items, and 8003 Test Papers added a definition. Source: Chinese Pharmacopoeia Commission [2]
Why Do the 8006 Storage Requirements Deserve the Most Attention?
The 2025 edition of 8006 adds a definition and writes "after preparation and standardization, store under the [Storage] conditions specified under this general chapter" into the general requirements (both the 2024 ChP Commission consultation draft and the summary of additions and revisions explicitly mention this) [2][4]. Storage conditions have been elevated from a "note under individual items" to a "general requirement", so an inspector can ask directly: has this bottle of titrimetric solution been stored as required ever since standardization, and is there a record? If the laboratory records the container and light-protection conditions only once, on the day of preparation, a record gap is created.
2. Transition-Period Self-Check List
Dimension | What to Do |
|---|---|
Old batch numbers | Inventory the solutions in use and mark the edition under which they were prepared; those whose preparation method is unchanged may be used until expiry, while those with a changed method need a switch-over date; restandardize titrimetric solutions whose post-standardization storage cannot be demonstrated |
Method comparison | Compare endpoints between the old and new preparation methods for indicator solutions; run a parallel comparison between the old and new preparation methods for the standard arsenic solution; check purchased ready-made titrimetric solutions against 8006 before use and record the result |
Record updates | Add the new items to preparation SOPs; add fields for storage conditions, container and location to standardization records; state the general chapter number, pharmacopoeia edition and expiry on labels, and the composition for buffer solutions; synchronize LIMS master data |
Personnel training | Train staff with a table of differences between the old and new texts, focusing on the boundary between test solutions and titrimetric solutions and on the 0631 low ionic strength solution procedure; file the training records |
3. Exporters: How Do ChP, EP, USP and JP Differ?
Item | ChP 2025 | EP | USP–NF | JP |
|---|---|---|---|---|
Concentration tolerance | 0.95–1.05 of nominal* | ±10%[5] | No unified tolerance | Factor f 0.970–1.030 |
Standardization precision | 3 replicates each for initial and repeat standardization, relative mean deviation ≤0.1%* | RSD ≤0.2%[5] | No unified value | Per individual monograph |
Restandardization interval | Use within 3 months* | Specified for certain items | In principle, re-determine frequently; the specific interval is set by the laboratory based on stability data [6] | Per individual monograph |
Storage requirements | Written into the general requirements | Specified for certain items | General notices give principle-level guidance (e.g., protect from light); see individual monographs for details | Specified for certain items |
*Values marked with an asterisk in the ChP column reflect the inspection practice commonly used in China ("Standard Operating Procedures for Drug Inspection in China") and are not clauses in the body of general chapter 8006. The requirements of each pharmacopoeia are subject to the current official text.
Two recommendations: when one bottle of titrimetric solution serves several pharmacopoeias, design the records to the stricter criteria (precision satisfying both the ChP relative mean deviation and the EP RSD requirements, and taking the shorter restandardization interval); prepare buffer and indicator solutions according to the recipe of the pharmacopoeia being applied — the same name and the same pH do not mean the same composition.
4. CPRM Product Index (Representative Specifications)
For items where in-house preparation is costly, standardization is labor-intensive, or no procedure has yet been established after the addition, commercial ready-to-use solutions can be used directly. CATO's CPRM series is prepared in accordance with the corresponding general chapters of Volume IV of the 2025 Pharmacopoeia and is supplied with supporting quality documentation.
Catalog No. (click the number for details) | Product Name | Specification |
|---|---|---|
Titrimetric Solutions (8006) | ||
Ethanolic sodium hydroxide titrimetric solution | 0.1 mol/L | |
Ethanolic sodium hydroxide titrimetric solution | 0.01 mol/L | |
Perchloric acid titrimetric solution | 0.1 mol/L (glacial acetic acid) | |
Sodium nitrite titrimetric solution | 0.1 mol/L | |
Iodine titrimetric solution | 0.1 mol/L | |
Test Solutions (8002) | ||
Ammonium molybdate test solution | 100 g/L | |
Thioacetamide test solution (kit) | Solution A 50 mL + Solution B 250 mL | |
Silver nitrate test solution | 0.1 mol/L | |
Buffer Solutions (8004) | ||
Phosphate buffer solution | pH 6.8 | |
Acetate buffer solution | pH 3.5 | |
Ammonia–ammonium chloride buffer solution | pH 10.0 | |
Indicator Solutions (8005) | ||
Phenolphthalein indicator solution | 1 g/L (ethanol) | |
Crystal violet indicator solution | — | |
Starch indicator solution | 1 mg/mL |
💡 All products are prepared according to the General Notices of the Chinese Pharmacopoeia; other specifications are available on request. The CPRM series covers 217 test solutions, 169 titrimetric solutions, 95 buffer solutions and 77 indicator solutions SKUs. For the full catalog, sample quality documents and the availability of newly added items such as phosphate buffer solution (pH 6.0), please contact CATO technical support.
Frequently Asked Questions
Q: Can titrimetric solutions prepared under the 2020 edition still be used?
If the preparation method is unchanged, the solution is within its expiry period, and you can demonstrate that it has been stored under the [Storage] conditions since standardization, it may be used until expiry; if there is no storage record, restandardization is recommended. Purchased ready-made titrimetric solutions should be managed according to the concentration, expiry and storage conditions stated in their quality documents, with a check before use.
Q: No preparation procedure has been established for the newly added items yet, and restandardizing titrimetric solutions is a heavy workload — is there an easier way to get through the transition?
Newly added items, and solutions used in large volumes or prone to deterioration, can be switched to purchased ready-made products. At acceptance, focus on four points: whether the stated general chapter number and pharmacopoeia edition are the 2025 edition, the batch number and expiry, the specified storage conditions, and the accompanying quality documents. Take the CATO CPRM series as an example: the newly added ethanolic sodium hydroxide titrimetric solution comes in two concentrations, 0.1 mol/L (CPRM3041) and 0.01 mol/L (CPRM5318); the buffer and indicator solutions commonly used under 8004 and 8005 are prepared according to the 2025 clauses; for exporters, pH standard solutions are available in versions complying with ChP, USP and EP respectively, so you can choose according to the pharmacopoeia you follow. Once a titrimetric solution arrives, perform the pre-use check by the method specified in 8006 and record it, and it can go straight into laboratory management.
References
[1] National Medical Products Administration, National Health Commission. Announcement on the Promulgation of the 2025 Edition of the Pharmacopoeia of the People's Republic of China (No. 29 of 2025).
[2] Chinese Pharmacopoeia Commission. Overview of Additions and Revisions to the General Physicochemical Analysis Requirements of Volume IV of the 2025 Chinese Pharmacopoeia (Part 2). China Pharmaceutical News, 2025-08-06.
[3] Questions and answers from provincial drug regulatory authorities on the implementation of the 2025 Chinese Pharmacopoeia (compilation). 2025.
[4] Chinese Pharmacopoeia Commission. Public consultation draft of the revised 8006 Titrimetric Solutions (first round). 2024-01.
[5] European Pharmacopoeia, 4.2.2 Volumetric Solutions.
[6] USP–NF, Reagents: Volumetric Solutions (General text).