Pharmaceutical Identity Test — Ph. Eur. / FTIR / HPLC

What Is Identity?

The identity test is a set of tests proving the substance in the specimen is the declared substance. Monographs usually require more than one identity test: matching FTIR spectrum against the reference, matching HPLC retention time to the reference, UV maxima and substance-specific chemical reactions are among them.

Purpose of Identity

The purpose is to prevent mix-up and adulteration. Manufacturing with the wrong substance is one of the most serious errors in the pharmaceutical sector; identity testing is therefore mandatory on every batch.

Which Products Is Identity Applied To?

Active pharmaceutical ingredients
Excipients
Finished dosage forms
Herbal drugs and extracts
Reference standards

In Which Sectors Is Identity Used?

PharmaceuticalsBiotechnology

Standards Related to Identity

Ph. Eur. 2.2.24 (infrared absorption spectrophotometry)
Ph. Eur. 2.2.25 (ultraviolet and visible absorption spectrophotometry)
Ph. Eur. 2.2.29 (liquid chromatography)
Ph. Eur. 2.2.27 (thin-layer chromatography)
USP <197> and <621>

Identity Conditions

Reference: Pharmacopoeia reference standard or a qualified working standard
Number of tests: The monograph requires more than one identity test; all are applied
Spectrum comparison: Per the criterion for matching the reference spectrum

Equipment for Identity

FTIR spectrometer
HPLC (with DAD detector)
UV/Vis spectrophotometer
Thin-layer chromatography setup
NIR spectrometer (for rapid identification)

Sample Requirements for Identity

Sufficient representative specimen
Reference standard information must be provided
Batch number and monograph reference must be provided
The specimen must be sent per its storage condition

Duration of Identity

Identity tests are quick and usually completed in a short time; duration extends somewhat for monographs including chromatographic identity.

Identity Procedure

1The monograph and identity tests to apply are determined.
2The reference standard is prepared.
3The FTIR spectrum is taken and compared against the reference.
4In chromatographic identification, retention times are compared.
5The chemical reactions in the monograph are applied.
6The results of all tests are assessed together.

Identity Acceptance Criteria

The acceptance criterion is not given on this page: for every active substance and every product, the limit comes from the relevant pharmacopoeia monograph or the approved specification in the marketing authorisation dossier. The pharmacopoeia's general chapter defines the method; the monograph sets the limit.

Evaluation of Results

A single identity test is not sufficient: substances of similar structure can give the same retention time or a similar spectrum. The monograph therefore requires multiple tests based on different principles, and all must pass.

Identity Report

Specimen identification and batch information
Monograph and identity tests applied
Result and comparison for each test
Reference standard used
Spectra and chromatograms

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

2001/83/EC Directive on Medicinal Products for Human Use
GMP Guide (EudraLex Volume 4)

Pharmaceutical Analysis — What Does This Testing Field Cover?

The section below describes the field that the Identity test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Pharmaceutical analysis determines the identity, purity, quantity and behaviour of an active substance and of the finished product. What sets this family apart is that the methods are largely defined in PHARMACOPOEIAS: the European Pharmacopoeia (Ph. Eur.) and the United States Pharmacopeia (USP) give both the method and the acceptance framework together.

The binding nature of the pharmacopoeial method shapes how the field works. In other sectors a laboratory can choose a suitable method, whereas here the method in the monograph governs; if an alternative method is to be used, its equivalence must be demonstrated. This is what makes results comparable worldwide.

Analyses are carried out in several groups. Identity and assay (HPLC, UV, titration) show what the product is and how much active substance it contains. The impurity profile and residual solvents look for unwanted compounds arising from the manufacturing process. Elemental impurities address metals originating from catalysts and equipment. Dissolution and disintegration behaviour is the most important in vitro indicator of how the drug will be released in the body.

The DISSOLUTION TEST is one of the most critical measurements in the field. It is not enough for a tablet to contain the right amount of active substance; that substance must dissolve at a suitable rate. The dissolution profile is used to assess the effect of formulation changes on bioavailability and holds a central place in generic drug licensing.

METHOD VALIDATION is a mandatory step in this family. If a pharmacopoeial method is used, it is verified that the method works properly under that laboratory's conditions. If an in-house method has been developed, it is validated against parameters such as linearity, precision, accuracy, specificity, limits of detection and quantification, and robustness. A result produced with an unvalidated method cannot be used in a licence dossier.

Stability studies determine shelf life and are the longest-running work in the field. The product is held under defined temperature and humidity conditions, analysed at set intervals, and the results become the basis of the shelf life and storage condition claims. Accelerated conditions give preliminary information but real-time data is what counts.

The microbiological side is a separate body of work: microbial enumeration, testing for specified microorganisms, sterility testing for sterile products and the bacterial endotoxin test. For sterile products, packaging integrity and sterilisation validation also come into play.

Data integrity has moved to the centre of inspections in recent years. It is not enough for the result to be correct; the raw data must be traceable, unalterable and auditable. Validation of electronic record systems has therefore become an inseparable part of analysis.

Method groups in this field

Identity and assay
HPLC, UPLC, UV-Vis spectrophotometry, titration, identity confirmation by FTIR.
Impurities and residues
Related impurities, degradation products, residual solvents (GC headspace), nitrosamine screening.
Elemental impurities
Determination of elemental impurities by ICP-MS and ICP-OES and the associated risk assessment.
Physicochemical
Dissolution and disintegration, hardness, friability, uniformity of dosage units, water content (Karl Fischer), particle size.
Microbiological
Microbial enumeration, specified microorganisms, sterility, bacterial endotoxin, preservative efficacy.
Stability
Real-time and accelerated stability studies; photostability and in-use stability.

Commonly confused in this field

The pharmacopoeial method is binding; an alternative method may be used only by demonstrating its equivalence.
A result produced without method validation cannot be used in a licence dossier.
Accelerated stability does not replace real-time data; shelf life is supported by real-time results.
The dissolution profile is sensitive to apparatus type, agitation rate and medium; the conditions must be complete in the report.
A shortcoming in data integrity produces a non-conformity in an inspection even when the result is correct.
A change of formulation or supplier requires analytical comparison and, where necessary, a new stability study.

Which decisions these results support

The licence dossier and batch release
Determining shelf life and storage conditions
Method transfer and method validation
Incoming raw material acceptance control from suppliers
Assessing the effect of a formulation change on bioequivalence

Related Tests

Frequently Asked Questions About Identity

Is rapid NIR identification accepted?

It can be, but the method must be validated and defined in the marketing authorisation dossier. NIR is common for rapid identity verification of containers; replacing the monograph tests is a separate approval matter.