A Molecularly Imprinted Polymer-based Dye Displacement Assay for the Rapid Visual Detection of Amphetamine in Urine.

The rapid sensing of drug compounds has traditionally relied on antibodies, enzymes and electrochemical reactions. These technologies can frequently produce false positives/negatives and require specific conditions to operate. Akin to antibodies, molecularly imprinted polymers (MIPs) are a more robust synthetic alternative with the ability to bind a target molecule with an affinity comparable to that of its natural counterparts. With this in mind, the research presented in this article introduces a facile MIP-based dye displacement assay for the detection of (±) amphetamine in urine. The selective nature of MIPs coupled with a displaceable dye enables the resulting low-cost assay to rapidly produce a clear visual confirmation of a target's presence, offering huge commercial potential. The following manuscript characterizes the proposed assay, drawing attention to various facets of the sensor design and optimization. To this end, synthesis of a MIP tailored towards amphetamine is described, scrutinizing the composition and selectivity (ibuprofen, naproxen, 2-methoxphenidine, quetiapine) of the reported synthetic receptor. Dye selection for the development of the displacement assay follows, proceeded by optimization of the displacement process by investigating the time taken and the amount of MIP powder required for optimum displacement. An optimized dose-response curve is then presented, introducing (±) amphetamine hydrochloride (0.01-1 mg mL-1) to the engineered sensor and determining the limit of detection (LoD). The research culminates in the assay being used for the analysis of spiked urine samples (amphetamine, ibuprofen, naproxen, 2-methoxphenidine, quetiapine, bupropion, pheniramine, bromopheniramine) and evaluating its potential as a low-cost, rapid and selective method of analysis.

Reversed-phase chromatography of zimelidine and similar dibasic amines. I. Analysis in biological material.

Zimelidine, a new antidepressant, and its pharmacologically active metabolite, norzimelidine, have been determined quantitatively in biological material. The compounds are extracted from alkali-treated body fluid or tissue homogenate into diethyl ether-n-hexane (8:2, v/v), and re-extracted into a small volume of acidic aqueous phase (ca. 100 microliter), which is injected onto the chromatographic column. The chromatographic support is Nucleosil C18 (5 micron) and the mobile phase is phosphate buffer (pH 2)-acetonitrile (91:9, v/v) with the addition of an aliphatic amine, N,N-dimethyl-N-octylamine (4.10(-4) M), which improves the chromatographic performance. By using glass-lined stainless-steel tubes instead of the common precision-bore stainless-steel columns, peak symmetries were improved. Detection limits in plasma are in the range 2.3--4.7 nmol/1 for extractions from 1 ml. It is demonstrated that the quality of the quantitations are improved by use of an internal standard, norzimelidine E-isomer. The precisions obtained for both compounds at the concentration levels of 300 and 1500 nmol/1 are ca. 5--6% and 2% respectively for within-run variations, and 8--9% and 5% respectively for day-to-day-variations.