M. Mohamadkhani, 2013
This research introduces the design of new PVC membrane electrodes for analysis of two abuse drugs.
In the first part of this work, the construction and electrochemical response characteristics of polyvinyl chloride (PVC) membrane sensors for the determination of morphine is described. An ion–pair of morphine–sodium tetraphenyl borate was used as an electroactive material and dibutyl phthalate (DBP) as an anion excluder in a PVC matrix in the percentage ratio of 2.60:62.51:35.10 (w/w). This potentiometric sensor exhibits a linear response to morphine in a concentration range of 1.0 × 10–3 to 2.0 × 10−6 M with a limit of detection of 2.3 × 10−6 M and with a slope of -58.62 ± 1.7mV decade–1 over the pH range 3.4 – 6.2. The selectivity coefficients of the sensor for morphine relative to a numbers of potential interfering compounds were investigated. The sensor is highly selective for morphine over a large number of similar compounds. The sensor showing a fast response time of 25 s and was used over a period of 2 month with a good reproducibility. The sensor was successfully applied to determine morphine in pharmaceutical, urine, and blood serum samples with satisfactory results.
In the part two of this research a new PVC membrane sensor is described as a potentiometric sensor for methadone. The sensor having methadone-sodium tetra phenyl phthalate (ion pair) as an electro active material and dioctyl phthalate (DOP) as an anion excluder in PVC matrix in the percentage ratio of 2.8:64.6:32.8 (ion-pair: DOP: PVC) (w/w). The membrane sensor exhibit suitable response to methadone in a concentration range of 6.0×10–6-1.0×10−2 M with a limit of detection of 4.37 µg/ml. The slope of the system was -59.88± 1.8 mv/decade. Selectivity coefficient for methadone relative to a numbers of potential interfering substances were investigated. The sensor was highly selective for methadone over a large number of similar compounds. The sensor showing a fast response time of 20 s and was used over a period of 2 months with a good reproducibility. The sensor was successfully applied to determine Methadone in real sample such as human urine, tablets and other pharmaceutical product with satisfactory results.