Technical Resources
A working library for the people who have to read a certificate of analysis, challenge a limit, or qualify a second source — written from the documents, not from a brochure.
100 technical notes, grouped by the question they answer. Every note states what a test proves, where it stops proving it, and what to ask next. No supplier names, no batch numbers, no claimed pharmacopoeial conformity.
- 01Specification & Pharmacopoeia (7)
- 02Impurities & Limits (14)
- 03Analytical Methods & Testing (25)
- 04COA, Release & Documentation (18)
- 05Stability, Storage & Physical Form (11)
- 06Supplier Qualification & Compliance (20)
- 07Bile Acid Products & Applications (5)
01Specification & Pharmacopoeia
What a specification actually commits the material to, and where EP, USP and in-house limits diverge.
- Acceptance Criteria: Whether They Came From Data or Habit
- When the Pharmacopoeia Changes: What Happens to Stock
- What Does EP Grade Actually Mean on a Supplier's Page?
- How to Specify TUDCA When No Pharmacopoeia Defines It
- Dried Pig Bile Powder: The ChP Specification Explained
- Chenodeoxycholic Acid Specification: A Quick-Reference
- UDCA Specification Guide: EP vs USP Limits & COA Checks
02Impurities & Limits
Named impurities, their origins, and how the individual limits add up against the total.
- Recovered Solvents and Mother Liquors: Recycling Rules
- Cleaning Validation: The Number That Sets Your Limit
- 7-KLCA Related Substances: Where Each One Comes From
- Chiral Purity of UDCA: Epimers vs Enantiomers Explained
- Nitrosamine Risk Assessment for APIs: What Buyers Should Ask
- Elemental Impurities Under ICH Q3D: Where They Come From
- UDCA Synthesis: What the Route Does to the Impurity Profile
- Why UDCA Impurity A (CDCA) Is the Hardest to Clear
- UDCA Related Substances: How the EP Limits Actually Add Up
- Residual Solvents in UDCA: An ICH Q3C Guide for Buyers
- Lithocholic Acid: UDCA EP Impurity C Limit and Test
- Chenodeoxycholic Acid: UDCA Impurity A and Starting Material
- Ursodeoxycholic Acid EP Impurities: Complete A–I Reference
- Is 7-Ketolithocholic Acid the Same as UDCA Impurity F?
03Analytical Methods & Testing
Which method proves what, where each method stops being able to see, and how results travel between laboratories.
- Appearance Defects: Judging Colour Against a Reference
- Why Two Laboratories Disagree by More Than Their Methods
- Method Robustness and Routine Variation: Which Gap Matters
- Reference Solutions: How Long They Last and Why It Matters
- Chromatographic Integration: The Step Nobody Audits
- Not Detected, Below Limit, Zero: Three Different Claims
- When System Suitability Fails, the Batch Is Not Guilty
- The Test Is Only as Good as the Sample Behind It
- TLC and HPLC See Different Impurities: Why It Matters
- Titration or HPLC? Why the Two Assay Numbers Disagree
- Clarity and Colour: Two Visual Tests Worth Defending
- Residue on Ignition: What the Ashes Actually Tell You
- Minimum Sample Weight: The Number Behind Every Result
- Instrument Qualification: DQ, IQ, OQ, PQ in Plain Terms
- Method Validation Under ICH Q2(R2): What Each Test Proves
- Mass Balance: Why Assay, Impurities and Water Must Add Up
- Analytical Method Transfer: The Step Most Buyers Skip
- UDCA Identification Tests: What IR, TLC and Colour Prove
- UDCA Melting Range: Why 200–204 °C Is a Narrow Window
- Choosing a Third-Party Laboratory: Six Things to Check
- Microbial Limits and Endotoxin: What a Non-Sterile API Needs
- Stability-Indicating Method: Why a Passing Assay Can Mislead
- Loss on Drying vs Water Content: Why UDCA Shows Both
- Bile Acid Reference Standards: CRS, USP RS and Your Own
- UDCA Specific Optical Rotation: The +58 to +62 Degree Test
04COA, Release & Documentation
Reading a certificate line by line, spotting the internal contradictions, and knowing what a release signature covers.
- The Six Things a Technical Confirmation Email Must State
- Batch Numbering: What the Batch Number Can and Cannot Prove
- One Drum, Four Documents: Where Discrepancies Start
- Batch Blending: Uniformity Is Not the Same as Consistency
- Who Signs a Batch Release, and What Each Signature Means
- The First-Order Pack: Nine Files Buyers Actually Need
- Data Integrity in a COA: Can the Raw Data Be Produced?
- OOT Trends and Batch History: Reading a Supplier's Data
- OOS Investigation: What a Buyer Should Receive, and When
- The 30-Second COA Check: Five Failures Buyers Spot First
- Your Spec vs Ours: Building a Gap Table That Works
- A Result on the Limit: Trend, Method Precision, or Reject?
- Assay vs Purity in 7-KLCA: Why Both Numbers Matter
- No Method on the COA: What to Ask Before You Accept It
- Assay Above 100%: Why It Happens and When It Is Fine
- Batch-to-Batch Consistency: Reading Three Consecutive COAs
- How to Read a UDCA COA: What Each Line Actually Proves
- Incoming Testing of an API: Why Every Container Matters
05Stability, Storage & Physical Form
Re-test periods, crystal form, particle size, transport and the packaging variables that decide whether a drum arrives as it left.
- Stability Chambers: The Records Nobody Reads Until an Audit
- Retention Samples vs Ongoing Stability: Two Promises
- Temperature Excursions: When a Spike Still Means Release
- Zone IVb Stability: Why 30 °C/75% RH Changes the Answer
- Photostability of Bile-Acid APIs: What ICH Q1B Requires
- Bulk Density and Flow: What It Costs on a Tableting Line
- Hygroscopicity and Packaging: Why Bags Clump in Transit
- UDCA Solubility: Why the Profile Line Shapes Your Process
- Does UDCA Have Polymorphs? What Milling Actually Changes
- Re-test Period vs Shelf Life: What a COA Date Really Means
- UDCA Particle Size Distribution (D90) and Tabletability
06Supplier Qualification & Compliance
The documentary side of a second source: certificates, regulatory roles, origin, and the questions an audit leaves open.
- Thirty Questions Before You Qualify a Bile Acid Supplier
- Non-Conforming Material: Return, Replace or Downgrade
- Remote or On-Site: What an Audit Can Actually Verify
- Annual Product Quality Review: What a Good One Answers
- Rework and Reprocessing: One Word Changes the File
- Deviation Classification: What a Buyer Is Entitled to Know
- Seven Quality Clauses That Decide an API Supply Dispute
- Complaint Handling for APIs: What a Closed Loop Looks Like
- Change Notification for API Supply: Whose Clock Is Running
- HS Classification for Bile Acids: Why the Code Matters
- GDP for API Distributors: What an Audit Does Not Show
- Halal and Kosher Claims for Bile Acids: Where the Line Is
- REACH and Bile-Acid Imports: What EU Buyers Must Confirm
- How to Verify a CEP or GMP Certificate: A Buyer's Check
- Is There a Non-Animal Route to UDCA? What Origin Claims Mean
- Adding a Second API Source: What Your QA Department Will Ask
- Dried Pig Bile Powder: Origin, BSE/TSE and Traceability
- UDCA Dual Sourcing: What Supply Concentration Actually Costs
- CEP, DMF or Written Confirmation: Which One You Need
- How to Verify a Bile Acid Supplier Before You Order
07Bile Acid Products & Applications
How the molecules relate to each other, and what each one is bought for.
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If a document you have received does not answer a question raised here, send the question and the redacted document. We reply with the test, the limit, and the reason the two may not match.
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