MTS Helpdesk 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 […]
Author: MTS
Replicates in Analytical Methods: When and How Many?
MTS Helpdesk Question: What is the purpose of preparing replicates in analytical methods? Answer: 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 […]
How Much Forced Degradation in a Stress Study?
MTS Helpdesk 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 […]
HPLC Autosampler Vials: Dos and Don’ts
MTS Helpdesk Question: Can you provide some dos and don’ts related to HPLC vials? Answer: The HPLC vial is a seemingly minor component of an HPLC system but it has the potential to create major problems. This is particularly true for quantitative analysis. The following list of dos and don’ts will help you to avoid […]
Do I Have to Revalidate a Method if the HPLC Column is Changed?
MTS Helpdesk Question: I would like to have a ‘back-up’ column for my HPLC method so that I am not reliant on one supplier, but how can I choose one that will be suitable and do I need to validate the method fully on the replacement column? Answer: My preference is to develop a new […]
What is Mass Balance in a Forced Degradation Study?
MTS Helpdesk Question: What is the ‘mass balance’ for an analytical method and is it critical that I investigate it as part of method development or method validation? Answer: When used in the context of an analytical method, the term ‘mass balance’ relates to its ability to analyse the degradation products of a drug molecule. […]