Studies on Influence of (2-Hydroxypropyl)- $\beta$ -Cyclodextrin on Properties of a New Indomethacin Electrode

This paper examined the preparation of indomethacin membrane sensors and the effect of β-cyclodextrin on electrode characteristic, selectivity, and response time. Several plasticized poly(vinyl)chloride membranes of different composition were tested and the best electrode based on tetraoctylammonium 1-( p-chlorobenzoyl) 5-methoxy-2-methyl-3-indolylacetate with membrane plasticized with diisobutylphthalate was selected. The electrode shows the sensitivity near Nernstian (-58.7 mV decade^-1) over the linear range of 5×10^-6-1×10^-2 molL^-1 and limit of detection 2.5×10^-6 molL^-1. The present electrode exhibits clear discrimination of indomethacin ions from several inorganic, organic, and some common drug excipients. This electrode has a response time of 9 s and can be used in the pH range 5.5-10 in the period of time 2.5 months without any considerable deterioration. The notably property and attractive quality of the indomethacin sensor are high sensitivity, selectivity, low cost, and comfortable application in drugs analysis. Furthermore, it can be used even in the presence of β-cyclodextrin at a concentration below 1×10^-2 molL^-1.