Sparging-based
methods have long been used to liberate volatile
organic compounds (VOCs) from liquid sample matrices prior to analysis.
In these methods, a carrier gas is delivered from an external source.
Here, we demonstrate “catalytic oxygenation-mediated extraction”
(COME), which relies on biocatalytic production of oxygen occurring
directly in the sample matrix. The newly formed oxygen (micro)bubbles
extract the dissolved VOCs. The gaseous extract is immediately transferred
to a separation or detection system for analysis. To start COME, dilute
hydrogen peroxide is injected into the sample supplemented with catalase
enzyme. The entire procedure is performed automaticallyafter
pressing a “start” button, making a clapping sound,
or triggering from a smartphone. The pump, valves, and detection system
are controlled by a microcontroller board. For quality control and
safety purposes, the reaction chamber is monitored by a camera linked
to a single-board computer, which follows the enzymatic reaction progress
by analyzing images of foam in real time. The data are instantly uploaded
to the internet cloud for retrieval. The COME apparatus has been coupled
on-line with the gas chromatography electron ionization mass spectrometry
(MS) system, atmospheric pressure chemical ionization (APCI) MS system,
and APCI ion-mobility spectrometry system. The three hyphenated variants
have been tested in analyses of complex matrices (e.g., fruit-based drinks, whiskey, urine, and stored wastewater). In
addition to the use of catalase, COME variants using crude potato
pulp or manganese(IV) dioxide have been demonstrated. The technique
is inexpensive, fast, reliable, and green: it uses low-toxicity chemicals
and emits oxygen.