Impurity Standards
Impurity standards supplier — specified and unspecified related substances
Characterised impurity standards for related-substance chromatographic methods, limit testing and analytical method validation under ICH Q3A and Q3B control strategies.
How impurity standards supplier are characterised and released
Impurity standards are the reference materials a laboratory needs to prove that a related-substance method actually resolves and quantifies what it claims to. Without a characterised marker, a peak at a given retention time is an assumption, not an identification.
Each impurity standard supplied here is released against a documented HPLC purity specification with identity confirmed by 1H-NMR and LC-MS. Typical use is as a retention-time marker in related-substance methods, for relative response factor determination, and as the spiked analyte during method validation for accuracy, linearity and limit-of-quantitation work.
Purity specifications for impurity standards are lower than for API standards by design — a marker material is characterised for identity and assigned content, not manufactured to drug-substance purity.
Released standards in this category
3 materials
| Losartan Azido Impurity Standard (Impurity D) | 138401-24-8 | C22H23ClN10 | ≥ 98.5% | $96.00 |
| Losartan Impurity Standard K | 114798-36-6 | C22H23ClN6O | ≥ 98.2% | $105.00 |
| Valsartan Related Compound A (Impurity Standard) | 137863-17-3 | C14H12N4 | ≥ 98.5% | $118.00 |
Frequently asked
- Why is the purity specification lower than an API standard?
- Impurity markers are characterised for identity and assigned content rather than manufactured to drug-substance purity. The Certificate of Analysis states the determined value, which is what the method calculation uses.
- Can these be used for relative response factor determination?
- Yes. Each lot ships with an assigned chromatographic purity so a response factor can be calculated against the parent standard on the same system.
- Are pharmacopoeial impurity designations used?
- Where a compendial designation exists it is stated in the product name and synonyms. The material is supplied as a research-grade characterised standard, not as an official pharmacopoeial reference standard.