NEW PLASTIC MEMBRANE ION-SELECTIVE ELECTRODE FOR DETERMINATION OF TRIMETHOPRIM

Trimethoprimium-phosphomolybdata, (TM)3PM, was used as an ion-exchange r in the construction of a TM-responsive plastic membrane electrode. T he calibration graph slope of the electrode is 56.5 mV per TM concentr ation decade when preconditioned by soaking in water, over a concentra tion range of 2.3 x 10(-6)-10(-2) M with instantaneous response. The e lectrode has a life span of 24 h when soaked in 10(-3) M TM solution a nd 5 days when soaked in distilled water. The working pH and temperatu re ranges of the electrode are 1.6-6.2 and 30-65-degrees-C, respective ly. The isothermal coefficient of the electrode is 0.00091 V-degree-C- 1. The electrode is highly selective for TM towards inorganic cations, sugars and amino acids. It can be employed as a potentiometric sensor for determination of TM in pure solution and in tables.