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

Abstract

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.