Preparation and study of a naproxen ion-selective electrode

Naproxen membrane electrodes based on different plasticizers and quaternary ammonium salt tetraoctylammonium (S)-6-methoxy-α-methyl-2-naphthaleneacetate (NAP–TOA) were prepared. The electrode response to naproxen has the sensitivity of − 59.2 mV decade− 1 over the linear range of 10− 4–10− 1 mol L− 1 and limit of detection 1.80 × 10− 5 mol L− 1. This electrode has a response time 15–20 s and can be used in the pH range 5.5–9.5. The selective coefficients were determined in relation to some organic and inorganic anions and excipients of pharmaceuticals. The notable property and attractive quality of the naproxen electrode are low cost, comfortable application and very long lifetime—about 20 months. The electrode was successfully applied for determination of naproxen in urine samples and pharmaceuticals by the calibration curve method and standard addition method. The obtained results are comparable and sometimes better than those obtained by pharmacopoeial method.