HPLC

Retention-time drift, temperature control and broad peaks from a new column are the topics of this month's discussion.

This article will shed some light on recent developments of micro-LC and the possibility of applying fast separations while reducing toxic and costly solvent waste.

The Column spoke to Martin Giera of Leiden University Medical Centre, Leiden, The Netherlands, about developments in biomarker discovery.

The article investigates the ELSD response variation with supercritical carbon dioxide-based mobile phases and compares the response with HPLC.

What do you do when the peak shape changes?

The use of interactive liquid chromatography using porous graphite as a stationary phase and gradients of long chain alcohols and chlorinated aromatics to separate olefin-based elastomers according to their chemical composition is discussed.

A method for the assay of an active pharmaceutical ingredient (API) and five known and unknown impurities was developed in accordance with Quality by Design (QbD) principles.

A novel "green chromatography" method for analysing melamine in milk is described. The method uses 100% water as the eluent and in the sample preparation stage and is reported to be a reliable and cost-effective method for laboratories in developing countries.

Will an internal standard always improve data quality?

What happens when the same method gives different retention times on different instruments?

In this review, the most recent LC–MS approaches are discussed, as well as the technical requirements for linking an LC system to a mass spectrometer. The advantages of on-line 2DLC in the "comprehensive" mode are also illustrated and selected applications for the analysis of common foodstuffs, such as triacylglycerols, carotenoids and polyphenols, are described. Finally, future trends for LC–MS in food analysis are reported.

On-line heart-cut LC–GC and, more recently, comprehensive LC–GC (LC?GC) are very powerful analytical techniques because of the combination of the selectivity features of LC with the high efficiency of GC. This article presents an overview of the most recently used interfacing systems, as well as applications in the food analysis.

What do you do when an unexpected peak appears in the chromatogram?

Triple quadrupole LC/MS analysis of aflatoxins in food samples eliminates the need for expensive immuno-affinity cleanup columns and reduces the probability of false positives to almost zero.

This application note describes the use of triggered Multiple Reaction Monitoring (tMRM) for the analysis of pesticide residues applied to chamomile and ginger extracts. The analysis is performed using the Agilent 1290 LC system coupled to a 6460 Triple Quadrupole LC/MS with tMRM acquisition.

Wine is a beverage produced and consumed throughout the world and is a highly valued commodity. Its classification and authenticity can be very important.

More than 1000 pesticides are currently used worldwide in the treatment of soil and crops. Many countries have established allowable levels of those pesticides in food to protect consumers. While these maximum residue levels (MRLs) vary, the default tolerance is 10 parts per billion (ppb).

What happens when the same method gives different retention times on different instruments?

What happens when the same method gives different retention times on different instruments?

How ethylene-bridged hybrid inorganic–organic (BEH) particles are prepared and how their special qualities can be used to improve separations

Some of the newer hydrophilic interaction liquid chromatography (HILIC) columns are reviewed, and experiments performed to categorize columns for optimized separations are described.

Monolithic columns feature both high column efficiency and high column permeability. This article discusses their preparation, applications, and future prospects.

A proof-of-concept application for detecting abused steroids in urine samples collected from an antidoping surveillance program

Changing to a "better" liquid chromatography column may not always produce the expected results.

No matter where LC is used, it is never immune to problems.

The results of a recent survery on stationary phases used in high performance liquid chromatography (HPLC) are revealed.

A mysterious autosampler problem is solved.

A systematic way to develop HPLC methods consists of building up and running a useful set of experiments (DOE, design of experiments) to evaluate the influence of several factors or method conditions on the selectivity of a chromatogram. The crucial part here is the peak tracking between the chromatograms.

Liquid chromatography is never immune to unexpected problems.

The 23rd International Symposium on Chiral Discrimination (Chirality 2011) was held in Liverpool, UK, this past July.