Gas assisted micro liquid-liquid extraction: a simple and efficient technique for high throughput bioanalysis

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The article that we highlight today describes a new, simple, efficient and automated extraction technique for high throughput bioanalysis. It has been published in Analytical Chemistry under the title "Gas Pressure Assisted Microliquid–Liquid Extraction Coupled Online to Direct Infusion Mass Spectrometry: A New Automated Screening Platform for Bioanalysis" (1). It is interesting to note that we have described another article from the same research group in a previous post (Three phase electroextraction).

According to the title, Gas Pressure Assisted Microliquid–Liquid Extraction (GPA-µLLE) is based on the thorough mixture of an aqueous biological sample (donor phase) and a organic solvent (acceptor phase) by means of a gas stream. However, the potential of this technique goes beyond this simple description for many reasons, among which the following are of note:
  • The technique is developed in a multi-plate platform and therefore it can process a high number of samples in parallel which is essential in bioanalysis.
  • It allows the extraction of non-polar or moderate polar compounds from biological samples in an efficient way.
  • The final phase is cleaner, avoiding the co-extraction of proteins or salts, and therefore completely compatible with direct infusion mass spectrometry.
  • It can be applied to different biological matrices such as plasma or dried blood spots.


Readers may wonder how GPA-µLLE works. The technique is performed in a 384-well plate platform where the sample (previously diluted) and the organic solvent are located in adjacent wells. A robotic sampler takes a defined volume of sample and dispense it on the organic solvent plate. Afterwards, a gas stream is applied by means of a pipette tip from the bottom of the plate inducing the complete mixture of both phases. Finally, the phases are led to stand and a defined volume of the extractant is taken for its direct infusion in the mass spectrometer. That is just the theoretical description but you can view a movie, published as supplementary information and free available on internet, in this link where the performance of the technique is demonstrated using crystal violet as proof of concept analyte.

We have enjoyed the reading of the manuscript and we are sure that our readers will find this article interesting. In the original manuscript you will discover all the technical considerations, the optimization of the procedure as well as the final bioanalytical application. Just visit the Analytical Chemistry article and enjoy the reading.

Reference
(1) Gas Pressure Assisted Microliquid–Liquid Extraction Coupled Online to Direct Infusion Mass Spectrometry: A New Automated Screening Platform for Bioanalysis. Link to the article

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