New potentiometric sensors for creatinine

Three main types of creatinine potentiometric membrane sensors are described. They are based on the use of dibenzo-30-crown-10 (DB30C10) with potassium tetrakis(p-chlorophenyl)borate type (I), dibenzo-30-crown-10 alone type (II), and potassium tetrakis(p-chlorophenyl)borate alone type (III), incorporating in poly(vinyl chloride) matrix membrane plasticized with either o-nitrophenyl octyl ether or dioctylphthalate. The sensors are used for quantification of creatinine after soaking the membranes in 0.1 M creatinine solution for 2 days. The sensors show almost the same potentiometric response characteristics. Sensor type (I) exhibits Nernstian responses over a concentration range of 5.0 x 10(-5) mol l(-1)-1.0 X 10(-2) mol l(-1) creatinine with cationic slopes of 59.5 +/- 0.1 and 60 +/- 0.2 mV decade(-1) and detection limits of 1.1 x 10(-5) mol l(-1) and 8 x 10(-6) mol l(-1) creatinine, over the pH range of 3.5-6.5 and 3.5-7.0, for o-NPOE and DOP solvent mediators, respectively. Sensor type (II) displays Nernstian responses over a concentration range of 6.0 x 10(-5) mol l(-1)-1.0 X 10(-2) mol l(-1) creatinine with cationic slopes of 60.0 +/- 0.1 and 65.0 +/- 0.2 mV decade(-1) and detection limits of 1.5 x 10(-5) mol l(-1) and 1.4 x 10(-5) mol l(-1) creatinine over the pH range of 2.6-6.2 and 2.5-6.0, for o-NPOE and DOP solvent mediators, respectively. Sensortype (III) shows Nernstian responses over a concentration range of 7.0 x 10(-5) mol l(-1)-1.0 X 10(-2) mol l(-1) creatinine with cationic slopes of 60 +/- 0.1 and 62.0 +/- 0.2 mV decade(-1) and detection limits of 2.7 x 10(-5) mol l(-1) and 2.0 x 10(-1) mol l(-1) creatinine over the pH range of 2.5-6.0, for o-NPOE and DOP solvent mediators, respectively. The response times of the sensors for 10(-3) mol l(-1) creatinine solution are instantaneous (4-10 s). The sensors show long-term stability with life span of similar to 6 months. The sensors are used for determination of serum creatinine of rats (Rattus Norvigicus) with mean R.S.D. of 2.62\%, and the results agreed well with the Jaffe kinetic method. (c) 2006 Elsevier B.V. All rights reserved.