High performance liquid chromatography

Method optimization to increase sensitivity in case of LOQ / LOD problems

Written by Dr. Eva Arnold on . Posted in High performance liquid chromatography

In our first blog article on increasing the sensitivity in case of limit of detection (LOD) / limit of quantitation (LOQ) problems in HPLC methods, we addressed the increase in sensitivity primarily by reducing baseline noise. Now we will look on the same topic from another perspective – with the eyes of “method optimization”. What can be optimized to increase the peak size and thus the overall signal to noise ratio (S/R)?

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Increasing the sensitivity in case of LOD / LOQ problems in HPLC methods

Written by Eva Arnold on . Posted in High performance liquid chromatography

During validation of purity testing methods of drugs or their active ingredients, sooner or later a point comes when the detection and quantification limits are needed to be determined. The limit of detection or LOD is defined as the lowest amount of an analyte in a sample that can still be detected. This is different from quantification - since the limit of quantitation (LOQ) is the lowest amount of an analyte in a sample that can still be reliably quantified.

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HPLC: What to do in case of peaks being too broad?

Written by Eva Arnold on . Posted in High performance liquid chromatography

HPLC methods are often part of routine analysis of drugs or drug substances in pharmaceutical QC laboratories under GMP conditions.

The shape of the peak of a HPLC chromatogram is extremely critical for its evaluation. Subtle changes in the shape during a quantitative measurement can lead to misleading results and in turn can ruin the entire measurements obtained throughout the experiment. Therefore, it is important to keep a watchful eye on the “peak shape”.

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The HPLC system: simply explained

Written by Eva Arnold on . Posted in High performance liquid chromatography

Not only in university laboratories, but especially in the laboratories of the pharmaceutical industry or of contract research laboratories, HPLC methods play an important role e.g. as purity tests of medicines and their active pharmaceutical ingredient during quality control. Therefore, let's take a closer look at the HPLC system.

High Pressure Liquid Chromatography (HPLC) is a technique widely used to separate various substances in solution. A HPLC system could be thought as an example of a steady flow:

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Pressure differences in HPLC systems

Written by Eva Arnold on . Posted in High performance liquid chromatography

In HPLC systems everything is associated with each other. There is not one common solution for one specific problem. Of course, pressure is completely normal for high pressure liquid chromatography (HPLC). This is the backpressure of the eluents, which are pumped through very narrow capillaries onto a tightly packed column. So, what can go wrong? Quite a lot!

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