Leiden researchers have developed a sample preparation technique that rare metabolites quickly thickens to a measurable concentration. Even if the original sample volume is very small, they report in Analytical Chemistry.
Last author Peter Linden Burg cites the example of the cerebrospinal fluid of a labmuis: sodium hydroxide if you want the animal survives there, you can at most a microliter of bleeding, and that volume is too small to work nice.
His method comes down to electro-extraction, translated to a lab on a chip. Those electro-extraction is a variation on liquid-liquid extraction, supplemented with a strong electric field. The trick here is that this first phase is an organic liquid and a second aqueous phase which conducts electricity much better. Thus, the field strength is concentrated in the organic phase; charged molecules that are in there are to be forcibly drawn into the water phase, but once they pass the interface are immediately the momentum from there.
In the original form which was electro-extraction batch process, but the Leiden chip makes a continuous process of it. In addition, the aqueous phase is stopped, while the organic phase is flowing over it. The result is that you can handle a much larger volume of organic phase which, without that the liquid layer is so thick that the metabolites take too long to do in order to reach the interface. Where the batch process stopped sodium hydroxide at 10 to 100 microliters, can with the current chip within 20 minutes to process a whole milliliter.
The Leiden researchers have tried it with acylcarnitines, which serve as biomarkers for problems with the fatty acid oxidation. They mixed by urine, which they then dispersed in a large excess of ethyl acetate. Which cocktail they sent by the chip, after which they rsterende water layer from the chip analyzed by liquid chromatography. sodium hydroxide Indeed, they found not only the added acylcarnitines sodium hydroxide back, but also traces of other variants which were present in much lower concentrations in the urine already sodium hydroxide used.
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