An automated titration for the Winkler method is presented for measuring primary productivity in the ocean. The system is based on a microcomputercontrolled titration with potentiometric endpoint detection. By the use of 0.005-N sodium thiosulfate as a titrant and a program designed to shorten the time for measuring, the method achieves a precision of 0.04% coefficient of variation with a range...

The macrocyclic ligands 3,8,12,17-tetramethyl-2,18,9,11-bipyridyl-1,4,7,10,13,16hexaazacyclooctadecanetetrahydro bromide has been synthesized and explored as suitable ionophores for chloride selective membrane sensors. It displays Nernstian behavior (59.2 mV decade-1) across the range of 4.1 × 10-8 to 1.0 × 10-2 M. The detection limit of the electrode is ~ 15 nM and the response time and life t...

A potentiometric immunosensor for the detection of human IgG has been developed using an asymmetric, ion-selective membrane with immobilized adenosine deaminase and IgG. A protein A-alkaline phosphatase conjugate binds to the immobilized IgG, creating a bienzymatic catalytic layer. In the presence of sample IgG, the conjugate does not bind to the membrane. Instead, the intermediate in the two-s...

A simple, precise, rapid and low-cost potentiometric method for diclofenac determination in pharmaceuticals is proposed. A new diclofenac-sensitive electrode was constructed by incorporating the diclofenac ion pair complex with butyl rhodamine B into graphite matrix. The electrode exhibited a linear response over the concentration range of 1 × 10-4 – 5 × 10-2 mol L-1, a detection limit of 3.9×1...

In order to study the Cu(II) ion selective electrode, an optimized membrane was prepared by mixing of 30 mg of PVC powdered, 5 mg of considered ionophore, 60 mg of plasticizer and 5 mg of additive. The sensor showed a near Nernstian response for Cu(II) ions over a concentration range from 1.0×0-6 –1.0×0-2 M with a slope of 28.90.5 mV per concentration decade with a working pH range of 3.5-6.3. ...

We found that dibenzo-18-crown-6 (DB18C6) can be used as an ionophore to make a tin (II)-ionselectivemembrane electrode. The electrode exhibits a near Nernstian response for Sn2+ ions over aconcentration range from 1.0× 10-6 – 1.0× 10-2 M with a slope of 27.5 ± 0.6 mV per concentration decadein an acidic solution (pH=1). The limit of detection was 8.0× 10-7 M. It has a response time of < 20s an...

a new cesium ion selective pvc membrane based on parent calix [4] arene was developed for potentiometric determination of cesium in environmental samples. the electrode based on p-5,11,17,23tetra(tertbutyl) 25,26,27,28-tetrahydroxy calix[4]arene(thc) as ionophor ,dibutyl phthalate (dbp)as plasticizer ,sodium tetra phenyl borate(natpb)and oleic acid as lipophilic salt and additive showed the bes...

Simple methods are described for the analysis of sulphate, sulphite and dithionate mixtures by potentiometric titration with lead perchlorate (and use of a lead ion-selective electrode). The error and precision are both about 2-5% for the sulphate concentration range 3 x 10(-3) -6 x 10(-4)M. The sulphur content in fuels derived from refuse was determined by potentiometric titration after bomb-c...

we found that dibenzo-18-crown-6 (db18c6) can be used as an ionophore to make a tin (ii)-ionselectivemembrane electrode. the electrode exhibits a near nernstian response for sn2+ ions over aconcentration range from 1.0× 10-6 – 1.0× 10-2 m with a slope of 27.5 ± 0.6 mv per concentration decadein an acidic solution (ph=1). the limit of detection was 8.0× 10-7 m. it has a response time of < 20s an...