Lab in a bottle, open-source technologies for the design of affordable environmental samplers integrating on-site extraction

Access to clean water, a Sustainable Development Goal, can only be accomplished worldwide using affordable technologies. In the analytical chemistry realm, developing cheap devices capable of on-site extraction results in a helpful tool. This article presents a new device based on open-source technologies for the on-site extraction of isoflavones from environmental waters as a proof of concept. The device is wholly operated by an Arduino microcontroller that also integrates sensors (temperature and conductivity) to provide on-site information. The extraction unit stirs into the sample, using a small motor, a planar sorptive phase consisting of Mixed-mode Anionic Exchange particles (MAX). After the on-site extraction, the sorptive phase is transported to the lab for its final analysis by liquid chromatography coupled with mass spectrometry. The analytical method provided detection limits of 1.5 ng L-1 (biochanin A and formononetin) and 15 ng L-1 (daidzein and genistein). The precision, expressed as relative standard deviation, was evaluated at three concentration levels providing results better than 9.8 %. The accuracy, with relative recoveries in the 85-119 % ranges, supports the application of the method. The relevance of isotopically labeled compounds to normalize the effect of some variables on the extraction of the analytes is also discussed in detail.

Automated summary

This article presents a new device based on open-source technologies for on-site extraction of isoflavones from environmental waters. The device is operated by an Arduino microcontroller and integrates sensors to provide real-time information. The extraction unit utilizes a planar sorptive phase and the samples are analyzed in the lab using liquid chromatography coupled with mass spectrometry. The method shows good precision and accuracy, and the importance of isotopically labeled compounds for normalizing extraction variables is discussed.