Topic: standards

Applications

ion chromatography

Preserving eluent quality with dedicated storage protected from ambient carbon dioxide

To ensure that liquid chromatography analysis methods meet regulatory demands of retention repeatability as dictated by pharmacopoeia and the ICH guidelines, it is important to protect weakly buffered eluents from ambient carbon dioxide. The formation of carbonate species will otherwise change the pH and strength of the eluent, thus shifting retention.

ion chromatography

Determination of sulfamate and sulfate in topiramate tablets according to USP monograph

Official quality control method for the second-generation antiepileptic drug topiramate which also have shown effect against migranes. This analysis was performed according to the United States Pharmacopeia monograph and determines the degradation products sulfamate and sulfate which can be formed during storage in humid environments or at elevated temperatures.

ion chromatography

Comparing suppressed and non-suppressed ion chromatography

Suppressed ion chromatography with conductivity detection is a powerful and sensitive technique to analyse charged ionic species, especially anions of strong acids. The chemically regenerated membrane suppressor Xenoic® XAMS can enable analysis of such anions down to levels of a few microgram per litre (part per billion, ppb).

ion chromatography

Published case study of analytical quality by design method development and validation

Diduco has published a scientific peer-reviewed case study on how modern analytical method development can be performed in the pharmaceutical industry. The work was performed according to analytical quality by design (AQbD) principles to establish the design space and robust setpoint of the ion chromatography assay, and then validated according to the guidelines established by the International Council for Harmonization (ICH).

ion chromatography

Quantification of anions in water using an improved ion chromatography system

Anion analysis can be performed at several conditions, using various columns on different systems and still be able to meet official requirements. A common approach is isocratic separation with carbonate-bicarbonate eluents, and this example showcase how such analyses can be improved and streamlined with autosampler injections, continuous suppression and protected eluents.

HILIC

Separation of selected amino acids

Amino acids are the fundamental building blocks of all proteins and therefore essential constituents of many nutritional supplements and can also be present in pharmaceutical formulations. Due to the highly hydrophilic nature and zwitterionic charge at neutral pH of many amino acids and their structurally related degradation products, hydrophilic interaction chromatography is an attractive mode of separation that require no derivatization, while evaporative light scattering enables rather sensitive detection of these poorly light-absorbing compounds.

ion chromatography

Published routine method for quantification of anions in tap water and natural waters

Quantification of the seven common anions is an important part of water quality control. This published ion chromatography method is from a scientific paper that presents full validation data according to the ICH guidelines to meet the requirements of laboratories acting under the ISO 17025 accreditation.

HILIC

Separation of simple sugars and carbohydrates

Simple carbohydrates are frequent ingredients in drinks, food, dietary supplements and pharmaceutical formulations. One approach to their analysis is hydrophilic interaction chromatography combined with evaporative light scattering detection, although this might be challenging due to the possibility of reducing sugars to mutarotate and thereby change their conformation into other anomers with different retention.

ion-exclusion chromatography

Separation of organic acids by ion-exclusion chromatography

Separation of organic acids can be a challenging task due to their hydrophilic nature and structural diversity. One of the more traditional approaches to this analysis is ion exclusion chromatography, which offer complementary selectivity to other separation techniques, especially for the monovalent acids which tend to be more strongly retained in this mode.

HILIC

Separation of nucleosides and nucleobases

Being one of the basic components of all cells as building blocks of DNA and RNA, there is a high and growing need for bioanalytical methods to determine nucleosides, nucleobases and related compounds in a variety of samples. Hydrophilic interaction chromatography is one of the most suitable approaches for this, due to the hydrophilicity of these compounds as demonstrated by their negative logP and logD values.

reversed-phase

Reaction monitoring of enzyme-catalysed one-pot cascade synthesis

The move towards a more sustainable world includes sourcing functional monomers for polymer synthesis from renewable natural products rather than from fossil-based sources. This green chemistry revolution often relies on the development of new reaction procedures efficiently catalysed by enzymes to involve fewer harmful chemicals.

ion chromatography

Modernized assay for foscarnet following ICH guidelines

New preliminary assay for the antiviral medication foscarnet which is a DNA polymerase inhibitor that is used to combat herpes viruses, including drug-resistant cytomegalovirus, and to treat patients with HIV as part of salvage therapy. This method was developed by Diduco to meet the requirements in the ICH guidelines, as a contribution to the United States Pharmacopoeia initiative for modernized monograph methods.

ion chromatography

Analysis of clodronate related substances according to European Pharmacopoeia monograph

Official quality control method for the first-generation bisphosphonate clodronate, which inhibits bone resorption and is used to treat bone weakness or pain caused by cancer that has spread to the skeleton. This analysis was performed according to the European Pharmacopoeia monograph method which is used to determine related substances that could be present as impurities in the active ingredient.

ion chromatography

Generic method for isocratic separation of fifteen common pharmaceutical counterions

Many medicines and dietary supplements are bases that carry a positive charge, and consequently these small molecules are accompanied by negatively charged counterions. Such anionic excipients may influence the properties of the pharmaceutical formulation and can also influence the effect of the active ingredient since different ion pairs can have different dissolution rates or abilities to penetrate cell walls.

ion chromatography

Column screening using hydroxide gradients for ion chromatography method development

Hydroxide gradient elution is an effective approach in ion chromatography analysis due to its ability to separate organic acids and anions with a wide range of characteristics. During method development of such protocols, scouting gradients is a quick way to rapidly screen different columns and assess their potential for a certain analysis situation and sample composition.

ion chromatography

Alternative method for determination of voriconazole impurity E

Voriconazole is an antifungal medication that is included on the WHO Model list of Essential Medicines. During synthesis of the active ingredient a resolving agent for chiral amines is often used, and it is thus necessary that the quality control prove that this substance is not present at harmful levels in the final product.

ion chromatography

Isocratic separation of four small monovalent organic acids using a weak hydroxide eluent

Singly charged anions of small organic acids can be challenging to separate due to their low retention on many ion chromatography columns. During method development for their analysis several different columns often need to be compared to find a separation selectivity that is suitable for the set of compounds in question.

ion chromatography

Hydroxide gradient elution of organic acids and inorganic anions

Gradient elution is a powerful tool when aiming to separate many compounds having a wide range of different chemical characteristics. Hydroxide gradients are the most common approach in ion chromatography since they can be converted into pure water with nearly zero conductivity.

ion chromatography

Generic method for isocratic separation of ten common pharmaceutical counterions

ion chromatography

Partial separation of structurally similar organic acids at isocratic conditions

Small organic acids are an important group of chemical compounds that needs to be analysed and quantified in many different industries. This application shows ion chromatography of a variety of organic acids using a non-optimized isocratic carbonate-based eluent.

ion chromatography