Elemental analysis is a core component to the work undertaken by our Chemical Analysis team and the technique is used for a wide range of products – from packaging to pharmaceutical ingredients. We caught up with a Smithers expert to find out more about elemental analysis, why it’s so important for the pharmaceutical industry, and how the team use ICP-OES for drug products, excipients and packaging.

What is elemental analysis?

Elemental analysis is an analytical technique which allows us to identify and quantify the various elements within a sample. We can do this for elements which may only be present at trace levels in the material.

Why is elemental analysis so important for pharmaceutical products?

Elemental analysis allows us to quantifiably measure the presence of impurities within the sample, whether it’s the product, excipient or packaging. Contaminants can be toxic, cause side effects, or affect the shelf-life or drug stability. Therefore, all impurities are closely monitored and there are clear guidelines and regulations on the limits allowed for each component.

What methods do you use for elemental analysis?

We use ICP-OES (inductively coupled plasma-optical emission spectroscopy), as recommended in ICH Q3D and USP <232>.  

How does ICP-OES work?

ICP-OES uses emission spectroscopy/spectrometry to quantify the levels of elements in a sample. An inductively coupled plasma excites the elements, as ions or atoms, in the sample and these emit electromagnetic radiation at characteristic wavelengths for each particular element. The intensity of emission is related to the concentration of the element within the sample.

How many elements can ICP-OES detect?

The ICP-OES is able to detect over 70 elements; it is a sensitive piece of equipment, and whilst typical limit of detections vary for each element it is able to detect parts per million (ppm) levels for the majority of elements and even parts per billion (ppb) levels in some cases.

How are the samples prepared for ICP-OES?

Typically, samples are prepared to give an acidified aqueous matrix, prior to being analysed. The analysis of elements in complex matrices, e.g. a rubber stopper, often involves digestion in a combination of strong acids and then dilution. However, when the samples have a less complex matrix, simple acidification of the sample may be sufficient.

The ICP-OES at Smithers also allows the direct analysis of organic solvents. This can reduce or eliminate time-consuming preparation steps for samples which consist of an organic matrix or are soluble in an organic solvent. 

What would be the first step of an ICP-OES testing program? 

One of our current offerings for elemental analysis is a semi-quantitative screening method. Focusing on a selection of elements which may be of toxicological concern, this includes elements specified in USP <232>, ICH Q3D, and the EMA guideline on limits for metal catalyst or metal reagent residues. This process covers over 30 elements and is a good starting platform for most clients. The benefit of this method is that a large range of elements are analysed in a cost effective manner and in a short time. 

How would this differ if there was a known element of interest?

Semi-quantitative analysis as described above is, in some instances, just the starting point for a program of analysis and an ICH Q2(R1) validated method may be required for selected elements.

When specific elements of interest have been selected for analysis in a sample, a method development and validation program, following ICH Q2(R1), can be undertaken for analysis over a specified concentration range. Such programs are typically executed to quantify the elements of concern in a drug or other product. Specific sample preparation methods, based on the sample matrix, can be developed and the method appropriately validated for accuracy, precision, repeatability, linearity, limits of detection and quantification (LOD, LOQ) and so forth.  

What accreditation does Smithers have for this work? 

Analysis can also be undertaken in accordance with the principles of cGMP as per your requirements. 

Smithers is accredited by the UK Accreditation Service (UKAS) in accordance with the recognised International Standard, BS EN ISO/IEC 17025:2005. 

Find out more about the elemental characterization services we offer.