| Typical Purity | 98%+ by HPLC |
|---|---|
| Key Impurity | Unconjugated UDCA |
| Test Method | HPLC-UV |
| CoA | Request batch-specific |
| CAS Number | 14605-22-2 |
| Typical Assay Range | 98.5-99.5% (HPLC) |
| Impurity Spec (UDCA) | ≤ 0.4-0.5% |
| Third-Party Test Cost | $200-500 per sample |
TUDCA raw material quality varies between suppliers, and a CoA alone does not guarantee what is in the drum. This guide covers the practical steps for verifying TUDCA purity, understanding what a Certificate of Analysis actually tells you, and spotting unreliable suppliers before placing an order.
The distinction between "supplement grade" and "pharmaceutical grade" TUDCA is not a formal regulatory classification -- it is a description of manufacturing standards and documentation. The practical differences matter for buyers.
Pharmaceutical-grade TUDCA is manufactured in a facility that complies with ICH Q7 Good Manufacturing Practice (GMP) guidelines for active pharmaceutical ingredients. This means: validated manufacturing processes with documented critical process parameters, qualified equipment and utilities, a formal quality management system with deviation and change control, stability testing program per ICH Q1A, and full traceability from starting material (bovine bile/cholic acid) through to finished TUDCA API. The CoA will typically include HPLC purity with full chromatogram, identification by IR or specific rotation, individual specified impurity levels (unconjugated UDCA, TCDCA, taurine), residual solvents by GC, heavy metals by ICP-MS or AAS, and microbial limits.
Supplement-grade TUDCA may be manufactured under less rigorous quality systems -- sometimes at facilities that are GMP-compliant for dietary supplements (21 CFR Part 111) rather than ICH Q7 for APIs. The analytical testing may be less complete: the CoA may report HPLC purity but not individual impurity levels, residual solvents may not be tested, and heavy metals testing may use older, less sensitive methods. Supplement-grade TUDCA is appropriate for supplement manufacturing in many markets, but buyers should understand the documentation limitations and decide whether they meet their quality requirements.
In practice, many Chinese manufacturers produce TUDCA at a quality level that meets pharmaceutical specifications, but market it as either supplement-grade or pharmaceutical-grade depending on the buyer's requirements and the documentation package requested. The same physical material may be sold as "pharma grade" with a full documentation package or as "supplement grade" with a basic CoA and MSDS. For buyers, the practical question is not "what grade is this?" but "what documentation package does this supplier provide, and does it meet my requirements?"
A complete TUDCA quality assessment covers six categories of testing. When reviewing a supplier's CoA, check that each is addressed.
HPLC (High-Performance Liquid Chromatography) with UV detection is the universal standard for TUDCA purity determination. Typical results from qualified manufacturers fall in the 98.5-99.5% range. A specification of 98.0% minimum is standard. The key impurity to watch for is unconjugated UDCA (ursodeoxycholic acid) -- the starting material that was not fully conjugated with taurine. Acceptable UDCA levels are 0.4-0.5% or below. Other common impurities include taurochenodeoxycholic acid (TCDCA, typically ≤0.8-1.0%), taurine residue (≤0.15-0.2%), and unspecified individual impurities (≤0.4-0.5% each). A CoA that reports only total purity without individual impurity levels provides incomplete quality information.
Heavy metals testing is critical because TUDCA's starting material (bovine bile) is of animal origin and may accumulate environmental contaminants. A standard specification is: lead (Pb) ≤10 ppm, arsenic (As) ≤2 ppm, cadmium (Cd) ≤1 ppm, and mercury (Hg) ≤1 ppm. Testing should be performed by ICP-MS or atomic absorption spectroscopy (AAS). Older "heavy metals as lead" limit tests (USP 〉231⌫) are less sensitive and are being phased out in favor of elemental-specific methods per USP 〉232⌫/〉233⌫ and ICH Q3D.
TUDCA synthesis involves organic solvents including acetone, ethyl acetate, and methanol. Residual solvent testing per ICH Q3C should be included in a complete CoA. Typical limits: acetone ≤5,000 ppm, ethyl acetate ≤5,000 ppm, methanol ≤3,000 ppm. A supplier that cannot provide residual solvent data may be using uncontrolled solvent recovery processes that leave unpredictable solvent residues in the finished product.
Standard microbial specifications for TUDCA raw material: Total Aerobic Microbial Count (TAMC) ≤1,000 CFU/g, Total Yeast and Mold Count (TYMC) ≤100 CFU/g, and absence of Escherichia coli, Salmonella, and Staphylococcus aureus (per USP 〉62⌫). These limits are consistent with USP 〉1111⌫ for non-sterile oral dosage forms. Buyers manufacturing finished capsules should also test the blended and encapsulated product, as microbial contamination can be introduced during the manufacturing process, not just by the raw material.
Appearance should be white to off-white crystalline powder. Specific rotation is a useful identity confirmation: the USP specification for UDCA is +58.0° to +62.0° (on dried basis), while TUDCA typically falls in the +41.0° to +47.0° range. Loss on drying (moisture content) should be ≤1.0% for the anhydrous form or approximately 5.0-7.0% for the dihydrate form. Confirm which form (anhydrous or dihydrate) the supplier is providing, as the molecular weight and dosage calculation differ.
A TUDCA Certificate of Analysis is a summary document, and knowing how to read it helps buyers distinguish genuine quality data from incomplete reporting. Here is what each section means in practice.
| CoA Section | What to Check | Red Flags |
|---|---|---|
| Header / Product Info | Product name, CAS (14605-22-2), batch/lot number, manufacturing date, retest date | Missing batch number; retest date more than 2 years from manufacture date |
| Appearance | White or off-white crystalline powder | Yellow or brown discoloration (suggests oxidation or contamination) |
| Identification | IR spectrum or specific rotation matching reference standard | No identification test performed; "conforms" without method description |
| Assay (HPLC) | Purity percentage, HPLC method description, column type, detector wavelength | Purity reported without method; "99%+" without decimal precision; titration-only result |
| Related Substances | Individual impurity names and levels (UDCA, TCDCA, taurine, unspecified) | "Total impurities" only without individual levels; no impurity testing performed |
| Residual Solvents | Solvent names and levels, GC method reference | "Meets ICH Q3C" without actual values; no residual solvent testing performed |
| Heavy Metals | Element names, individual levels, test method (ICP-MS/AAS) | "Conforms" without values; "heavy metals as lead" limit test only |
| Microbial Limits | TAMC, TYMC, pathogen test results | No microbial testing performed |
| Storage | Temperature, humidity, container type | No storage conditions specified |
| Signatures | QC manager name/signature, date of testing | No signature or electronic equivalent; testing date from previous year |
A complete, credible CoA will report individual impurity levels with their chemical names (UDCA at 0.35%, TCDCA at 0.45%, other at 0.15%) rather than grouping all impurities into a single "total impurities" line. The HPLC method should be described with enough detail that a qualified analyst could reproduce the test -- column type (e.g., C18, 250 x 4.6 mm), mobile phase composition, detector wavelength (typically 210 nm for bile acids), and flow rate.
Independent laboratory testing is the most reliable way to verify TUDCA quality, and it is a regulatory requirement for US dietary supplement manufacturers under 21 CFR Part 111 (identity testing). Several types of third-party labs can test TUDCA.
ISO 17025-accredited contract labs are the gold standard. Labs such as Eurofins, SGS, Intertek, and ALS operate ISO 17025-accredited facilities in China, the US, and Europe that can perform HPLC purity, heavy metals (ICP-MS), residual solvents (GC), and microbial testing on TUDCA samples. Typical costs: $200-500 per sample for a complete analytical package, with turnaround times of 5-10 business days. Some labs offer expedited service (2-3 days) at a premium.
University and research labs with HPLC capability can perform purity testing, though they may not operate under ISO 17025 quality systems. This option can be cost-effective for initial supplier qualification when a full accredited report is not required. Budget approximately $100-300 per sample.
In-house testing by the buyer using their own HPLC equipment provides the fastest turnaround and lowest per-sample cost once the equipment is in place and the method is validated. The investment in HPLC equipment ($30,000-60,000 for a basic system) is justified for buyers purchasing more than 100 kg of TUDCA annually, where testing costs from external labs would exceed the equipment cost within 1-2 years.
For practical supplier qualification, the recommended approach is: (1) request the supplier's CoA and full analytical data package, (2) send a pre-shipment sample to an ISO 17025-accredited lab for independent testing, (3) compare results against the supplier's CoA, (4) if results match within an acceptable variance (<2% difference in HPLC purity), approve the supplier, and (5) retest at a frequency proportional to purchasing volume and the supplier's quality history.
Certain behaviors from TUDCA suppliers are reliable indicators of quality problems. These red flags come from practical sourcing experience and are worth treating as disqualifying unless the supplier can provide a reasonable explanation.
Refusing to share a CoA before the order. Some suppliers claim they can only provide a CoA after payment or after the order ships. This is not standard industry practice. A legitimate manufacturer can provide a representative CoA from a recent batch before the order. A refusal to share any CoA before payment suggests the supplier does not have documented quality data or is concealing unfavorable results.
"99% purity" claims without HPLC data. The phrase "99% pure" or "99%+ purity" without specifying the test method (HPLC vs. titration), the impurity profile, or providing a chromatogram is a marketing claim, not a quality statement. Request the full HPLC report showing integration of all peaks, with retention times and area percentages for each detected component. A supplier that cannot produce this level of analytical detail either does not perform proper testing or is unwilling to share the results.
No third-party testing available. Suppliers who refuse or discourage independent third-party testing -- for example, by claiming their in-house testing is "sufficient" or that external testing is "unnecessary" -- are often concealing quality issues. A confident supplier welcomes third-party verification because it confirms their quality claims. Resistance to independent testing is a red flag regardless of how professional the supplier appears in other respects.
Prices well below market. As of 2026, pharmaceutical-grade TUDCA API trades at approximately $600-700/kg for standard volumes. If a supplier offers TUDCA at $300-400/kg, the discount has to come from somewhere: lower purity, different manufacturing route with more impurities, no GMP overhead, or material that failed quality testing at another buyer and is being re-offered. Prices below $500/kg should prompt additional quality due diligence before ordering.
Vague pharmacopoeia references. Claims that a product "meets USP standards" or "complies with EP monograph" without specifying which monograph, which edition, and which tests were performed are meaningless. TUDCA does not have a USP or EP monograph as of 2026 -- it is not a pharmacopoeial substance. A supplier making such claims either does not understand pharmacopoeial standards or is making false statements. Either way, the quality documentation from such a supplier should be scrutinized.