Keyword: isocratic elution

During isocratic elution, the mobile phase elution strength within the column is constant throughout the entire separation process. This is how most liquid chromatography quality control methods are designed and it contrasts with gradient elution.

Naturally, any unintended changes of eluent composition will affect the retention. In ion chromatography, which often use hydroxide eluents or carbonate-bicarbonate eluents that has very limited buffer capacity, it is therefore often important to protect the eluent solution from contamination by foreign ions. Glass bottles, which have a tendency of releasing ions from it surfaces, may therefore often not be a suitable choice for eluent storage. In addition, these eluents often need to be protected from carbon dioxide in the air to avoid contamination by carbonate species.

To learn more, browse the application examples below or contact Diduco to discuss your specific analysis.

Applications

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 quality by design (QbD) 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).

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Tartrate in dietary supplements
Ion chromatography

Analysis of dietary supplement capsules with carnitine using a generic method for counterions

Oral L-carnitine is a dietary supplement that has been shown to reduce fatigue in elderly people with low muscular endurance, but its effects on athletes during physical activity are not well-supported. Although this endogenous compound is well-known for its involvement in the mitochondrial oxidation of long-chain fatty acids, no scientific evidence has been found that carnitine in isolation enhances fat-burning.

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Ion chromatography of five inorganic anions with and without XAMS suppressor formatted
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).

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Simple carbohydrates by HILIC-ELSD and Luna Omega Sugar
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.

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Nucleosides and nucleobases on ZIC-cHILIC column and Agilent system
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.

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Separation of twelve organic acids by ion exclusion chromatography
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.

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Cannabinoids in hemp using Raptor ARC-18
Reversed-phase

Analysis of cannabinoids in dried industrial hemp after methanol extraction

The legislation in many countries allow cultivation of industrial hemp provided that the strains do not produce high amounts of tetrahydrocannabinol (THC) and other psychoactive cannabinoids classified as narcotic substances. These strains of cannabis sativa are instead typically rich in compounds such as cannabidiol (CBD) and cannabidiolic acid (CBDA).

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Cascade reaction monitoring
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.

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Foscarnet assay calibration with XAMS suppressor and ASUREX-A200
Ion chromatography

Modernized assay for foscarnet following ICH guidelines

New 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 assay 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.

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Pharamaceutical counterions with XAMS suppressor and ASUREX-A200
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.

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Alternative method for voriconazole impurity E
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.

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Pharamaceutical counterions with XAMS suppressor and ASUREX-A200
Ion chromatography

Generic method for isocratic separation of ten 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.

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Talk to us

Get in contact
I’ll be happy to answer any questions you might have regarding our products and services.

Tobias Jonsson
CEO, PhD in chemistry
Mobile: +46 705783490
E-mail: tobias@diduco.com

Diduco is a leading provider of professional services in high performance liquid chromatography and manufacturer of the Xenoic® XAMS chemical suppressor and ASUREX automatic regenerator for ion chromatography. 

Diduco AB
Tvistevägen 48C
90736 Umeå
Sweden

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