Analysis of Propionic and Acrylic Acids by Reversed Phase HPLC with Anion Suppression and Conductivity Detection
A liquid chromatographic method for the determination of propionic and acrylic acids in aquatic mixtures was developed by combining three techniques: HPLC reversed-phase separation, anion suppression and conductivity detection. This combination yields a similar response for both acids allowing their determination at ppm level and was found to be applicable to samples containing other organic compounds. These substances were chosen because of their environmental relevance and because of the increasing interest related to their involvement in different chemical and biological processes. Reproducibility, accuracy, sensitivity and linearity of this method were evaluated under optimized conditions, showing that suppressed conductivity detection combined with a reversed-phase column improves the separation and detection of both carboxylic acids when compared with non-suppressed UV detection.
Optimization of Analytical Methods Using Factorial Designs
Part 1: An Introduction
The conventional approach for optimizing analytical methods in the laboratory is the one-factor-at-a-time approach, where each experimental factor or parameter is optimized separately and independently of other factors. In contrast, factorial designs involve simultaneous optimization of all factors at once. Factorial designs offer a simple, efficient, and statistically valid method for optimizing analytical methods. In this article, the first of a three-article series, we will take an introductory look at factorial designs and its benefits to the analytical laboratory.
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Implementing Robustness Testing for HPLC Methods
This is the second article in a series about robustness testing for HPLC analytical methods. Previously, an overview of the steps involved in investigation of robustness was described. The first step is to decide which factors are going to be studied. In this article the selection of appropriate robustness factors and factor levels relating to the mobile phase will be discussed and in particular, the volume fraction of the organic solvent in the mobile phase for reversed phase HPLC.
Method Transfer and Routine-Use Study of the USP Impurities Method for Donepezil Tablets
In this article we investigate some of the sample-matrix related issues encountered when transferring a long drug final formulation separation method to a faster, more sustainable LC method. The geometrically-scaled gradient method presented in this article is 80% faster than the original compendial HPLC method and consumes 92% less mobile phase.
How to Analyse Unknown Samples by Pyrolysis GC/MS?
Although GC/MS and LC/MS are very powerful analytical techniques, they generally lack the ability to analyse and characterize insoluble materials, such as polymers and other high molecular weight products. An elegant approach to cope with this type of samples involves a combination of thermal decomposition and online chromatographic analysis of the released breakdown products. This approach is called analytical pyrolysis.
How Fittings Can Impact Chromatographic Results
Anyone who has been involved in chromatography has likely struggled with things like band broadening, split peaks, carryover, and loss of sample. Typically, when these challenges are encountered, it’s normal for chromatographers to suspect degradation of the column’s stationary phase or issues with the mobile phase, or even mechanical problems with primary system components (e.g., the injection valve, the pump, etc.). However, after investing hours and precious financial resources towards “fixing” or replacing the suspected components, it’s entirely possible that the initial challenges may still be present, leaving many a chromatographer puzzled and frustrated.
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