Abstract: An example sensor includes a conductive electrode and an ion-selective membrane over the conductive electrode. The ion-selective membrane includes an ionophore that is selective for ionized magnesium (iMg) and at least two types of anionic lipophilic salts. The at least two types of anionic lipophilic salts may include one or more fluorinated borate salts and one or more chlorinated borate salts.

Abstract: Method and system for detecting and/or quantifying ?9-tetrahydrocannibinol (THC) in exhaled breath. In one embodiment, the method involves providing an electrochemical sensing element, the electrochemical sensing element including a working electrode, and also providing a filter that traps THC in exhaled breath. Next, a subject exhales onto the filter, whereby at least some of the THC, if present, is trapped in the filter. Next, the filter is washed with an eluent, whereby at least some of the THC trapped in the filter is eluted in an eluate. Next, the eluate is deposited onto the working electrode of the electrochemical sensing element, and the eluate is dried, whereby any THC present is immobilized on the working electrode. Next, an electrolytic solution is delivered to the electrochemical sensing element, and the THC immobilized on the working electrode is directly electrochemically detected and/or quantified using a pulse voltammetry technique, such as square-wave voltammetry.

Abstract: Method and system for detecting and/or quantifying ?9-tetrahydrocannibinol (THC) in a saliva sample. In one embodiment, the method involves providing an electrochemical sensing element, the electrochemical sensing element including a working electrode, a counter electrode, and a reference electrode, all of which are screen-printed. A saliva sample is then deposited directly on the working electrode. Next, the deposited saliva sample is treated with a fluid that includes one or more alcohols and water in an alcohol/water ratio of 50/50 to 100/0 (v/v), the fluid optionally also including a surfactant. Next, the treated saliva sample is dried, whereby any THC present in the treated saliva sample is immobilized on the working electrode. Next, an electrolytic solution is delivered to the electrochemical sensing element, and the THC immobilized on the working electrode is directly electrochemically detected and/or quantified using a pulse voltammetry technique, such as square-wave voltammetry.