Category: Resource Library

Limit of Quantitation: Does it Matter?

Defined as “the  lowest amount of analyte  in a  sample which  can be quantitatively determined with  suitable precision and  accuracy” in ICH Q2(R1), limit of quantitation (or ‘quantitation limit’ in the ICH terminology) is an important method performance characteristic which is typically demonstrated during analytical method validation. Although the concept of limit of quantitation (LOQ) […]

Drafts of ICH Q2(R2) and Q14 on Public Consultation

Draft versions of the revision of ICH Q2, Validation of Analytical Procedures, and also the new guideline Q14, Analytical Procedure Development, were published on the 24th March 2022. The deadline for comments is 31st July 2022. You can view the draft guidelines, and also a presentation from ICH about the guidelines, using the following links: […]

How Long to Equlibrate an HPLC Column?

This is a question commonly asked by HPLC analysts, particularly those relatively new to the technique. The range of currently available column dimensions means that a ‘one size fits all’ approach is not appropriate. The amount of mobile phase which should be flushed through a column before it is ready to use is usually expressed […]

HPLC Mobile Phase Expiry Dates

Question: What is the typical (the industrial ‘norm’) for the expiration date of mobile phases for HPLC, i.e. with buffer and without buffer. Also, what should you do (e.g., measure the pH or run and verify the retention time) if you need to extend the expiration date in extenuating circumstance e.g. shortage of acetonitrile or […]

Replicates in Analytical Methods: When and How Many?

Do you prepare your samples/standards in duplicate without really thinking about it? If challenged on why, would your answer be something like, “it’s good practice, isn’t it?” The use of replicates in analytical procedures is commonplace but it is important to understand why you are doing it and also what the results are telling you. […]

How Much Forced Degradation in a Stress Study?

Question: When I forcibly degrade my drug or drug product to create degradation products, how much degradation should I aim for? Answer: The aim of a forced degradation study is to generate degradation products from a drug which are both realistic and representative, typically for the purposes of assessing degradation pathways, or to create suitable […]