Compendial Techniques

 Home / Capabilities / Techniques / Compendial Techniques

Some of the more common compendial tests are discussed here:

General Identification Tests

Many of the compendial identification tests require a wide range of properly prepared and documented test solutions and a careful attention to detail. Not only do these tests require the utmost of care, but also demand senior chemists with the experience to produce consistently reliable data. GPA’s analytical team averages over 20 years’ experience per analyst, providing our clients with quality results for these tests, as well as the ability to seamlessly transition into more complex identification testing.


Spectroscopy is the study of the interaction between matter and radiated energy. When a beam of waves having the whole range of wavelengths is passed through a sample, the electrons in the bonds of these materials absorb certain photons from the beam. Although in non-monochromatic techniques photons of various energies are emitted, only photons with certain energies get absorbed. In monochromatic techniques, where photons of fixed energies are used, techniques leverage the known quantum mechanical properties of the target material. Thus, spectroscopic techniques use the emitted and absorbed spectrums of materials to provide information about the material itself.

Several common spectroscopic techniques are used within the pharmaceutical industry for identification or quantitation. The three most common techniques, infrared spectrometry (IR), mass spectrometry (MS), and ultraviolet-visible spectrometry (UV-VIS) are offered by Global Pharma Analytics.

IR Spectroscopy

Infrared Spectroscopy, or IR Spectroscopy, can be a powerful analytical tool for identification, as well as some quantitative analysis. The absorption of IR radiation by materials occurs as a result of the rotation and vibration of atoms engaged in chemical bonding within molecules. Because each molecule will have a unique combination of absorbed radiation, the IR spectrum is often referred to as a fingerprint spectrum.

GPA has retained a team of analysts proficient in this technique, as well as the instrumentation needed, to provide high quality results. GPA has amassed a sizable spectroscopic library and can utilize this to identify many compendial materials, as well as some unknowns. With the use of an ATR attachment, GPA can analyze material without destroying it, as well as achieve a high throughput of sample analysis.

UV/Vis Spectroscopy

Ultraviolet/Visible Spectroscopy, or UV/Vis Spectroscopy, is another widely used technique within the regulated industries. The types of electrons forming bonds within a molecule will determine the UV absorption characteristics of that molecule. For instance, a saturated hydrocarbon exhibits no UV-Vis absorbance because more energy is needed to dislodge the tightly bound electrons than is available in waves within the UV/Vis spectrum. On the other hand, a loosely bound electron in a nitrite group is easily knocked off by energy within this spectrum. Materials with this moiety, or functional groups, are classified as chromophores. Therefore, UV/Vis spectroscopy can provide a significant amount of information about the target materials.

Many of the wet chemical assay methods and identification tests performed by GPA require the use of a UV/Vis Spectrometer. Measurement of a spectrum in the UV or visible light ranges requires light emission and detection within the wavelength region from 200nm to 800nm. GPA possesses state-of-the art instrumentation to carry out these analyses. Our analysts are well trained in the use of this instrumentation, as well as the technique for sample preparation. Furthermore, GPA has developed a number of reliable UV/Vis spectrometric methods for clients. Thus, GPA’s clients feel confident in the results of UV/Vis spectrometry methods performed at GPA.

Residual Testing

In order to determine purity with a high degree of accuracy, it is often necessary to have accurate residual data. From a simple loss on drying test to a more complex residual solvent analysis by GC headspace, GPA will deliver accurate results documented with the highest quality standards.

Melting Range or Temperature

Melting Range or Temperature can also be indicative of the purity of a substance. Each element or molecule in nature exhibits a specific melting point at which a change of state occurs from solid to liquid. A highly pure material may undergo an instantaneous transition. Since almost every sample contains some level of impurity, the transition of most samples will be a blend of the energy necessary for the state transition of the various components of the sample and will exhibit a melting range rather than a melting point.

Melting range analyses rely on the concept that the fewer impurities present in a material, the tighter the melting range. Impurities may decrease or increase the melting temperature as well as broaden the temperature range across which a state transition occurs. For this reason, melting range analyses are often used to confirm purity of a sample. GPA routinely performs melting range and other temperature-associated testing. We offer our clients a team of trained analysts to proficiently perform these techniques using our qualified instrumentation.

Particulate Matter in Injections

Particulate Matter in injections and parenterals consist of inappropriate mobile, undissolved particles, other than gas bubbles, that are unintentionally present in the solutions. In the US, solutions almost uniformly must be tested for particulate matter if the solution will be used for intramuscular or subcutaneous injection. Strict compendial specifications are set for the allowed number of particles in these products. The most common technique uses an automated counter which examines the amount of light blocked by particles within a given sample. Because GPA regularly supports clients who need particulate matter in injections testing, GPA conducts this testing on a routine basis. With our experience, our clients can feel confident in the particulate matter in injections testing performed at Global Pharma Analytics.

Limit Tests

A significant number of compendial monographs require the performance of Limit Tests, such as Heavy Metals, Arsenic, Iron, and Lead. Because proper execution of these tests is critical to the generation of meaningful results, having limit tests performed by experienced analysts is extremely important. GPA’s team of highly skilled analysts are very proficient in Limit Tests, as well as many others not listed here.

Optical and Specific Rotation

Many pharmaceutical substances are optically active and exist as enantiomers, or chiral substances that are identical save for the fact that they rotate plane polarized light in opposite directions to the same extent. Enantiomers often exhibit profound differences in pharmacology and toxicology, but are otherwise identical in their results for analytical testing. Optical and specific rotation can differentiate these enantiomers and is therefore a powerful analytical tool. Also, some enantiomers can exist in differing amounts in the same compound, or in equal amounts, resulting in racemates that have a null optical rotation. The physical properties of racemates may differ from those of the component enantiomers. Therefore, optical and specific rotation may be used as both a qualitative test to determine the chirality of a substance, as well as quantitative to determine the mix of enantiomers. GPA has the state of the art instrumentation and the appropriately experienced analysts necessary to produce accurate optical results to meet the stringent needs of regulated industries.

Osmolality and Osmolarity

Osmosis is the penetration of solvent molecules, but not solute molecules, across a semipermeable membrane. Osmotic pressure is an important quantitative measure of the properties of a solution. The most common use to clients in the pharmaceutical industry is to determine the dilution ratios necessary in order to produce a solution which is iso-osmotic relative to whole blood. Highly accurate results are critical to the safety and efficacy of injectable solutions. Because clients can rely upon GPA’s highly-skilled analytical team to deliver the highest quality results, clients who value safety and efficacy should trust GPA with osmolality and osmolarity testing.

Thin Layer Chromatography

Our analysts are also adept at performing some of the more complex TLC methods required in many compendial monographs.

Ready to send samples? If so, please click here for ordering information. Place Order
CompuBrain Phenomenal