Traditionally, detection of traces of compounds from various types of samples has involved several steps such as compound preconcentration using an extractant, collection of the extractant after preconcentration by centrifuging, and separation of the collected extractant. In addition, if the samples contain solids particles, there is an additional need for the separation of the solids by filtration. In this project, we have developed an alternative in order to simplify the process of trace compound detection from environmental samples. The alternative involves the use of small droplets prepared inside a capillary tube. These droplets enable the preconcentration of the trace compounds as the sample flows through the tube. The technology developed in this project was able to detect < 1 ppm of fluorescent molecules, Nile red, as model analyte. The solid particles, however, do not become extracted by the droplets but they are expelled from the tube with the sample during flow. Similar detection sensitivity was obtained from samples with and without solid particles. In fact, we could detect the model analyte from an oilsand wastewater sample which contain a myriad of other components including sand, bitumen, and other hydrocarbons. Additionally, the minimum volume of the sample that the capillary can hold is close to 50 µL suggesting the possibility of detecting chemicals from saliva as well.
In conclusion, the technology developed in this project provides an easy and fast detection of trace compounds from various types of samples without the need of complicated steps involved in the traditional method. Currently, we are developing the technology further to enhance the extraction efficiency, speed up the detection time, and make the device fully portable. We believe the technology will facilitate the detection of trace compounds for various purposes such as environmental monitoring, drug screening, and personal diagnostics.
