الشمااااخ.pptx

Ion Selective Electerode Nooreldeen Altyeb Objective :- Define the ISE Define the potentiometery Principle of ISE Component of ISE Type of ISE Type of ion selective membrane Advantage and disadvantage of ISE...

Ion Selective Electerode Nooreldeen Altyeb Objective :- Define the ISE Define the potentiometery Principle of ISE Component of ISE Type of ISE Type of ion selective membrane Advantage and disadvantage of ISE  ion selective electerode (ISE):- Definition :- Is transducer or (sensor) that convert the activity of specific ion dissolved in a solution Into electrical potential. Potentiometry :- Definition :- Is the measurement of an electrical potential different between two electrode (( reference electrode , indicator electrode )) in electrical solution. Uses :- a.Analytical chemistry -electrolyte -body fluids like plasma ,serum , sweat b. Biochemistry or biophysical research  Type of electrode :- There are many different types of electrodes 1- Rodex electrode 2- Ion selective membrane 3- pa CO2 electrode  Principle of ISE:- Ion selective electrode consist of two electrode reference electrode , indicator electrode , in indicator electrode develops potential current due to ion exchange between the sample and the inorganic membrane (that use as type of electrode ) this potential is measured against stable reference electrode of constant potential. the potential different between two electrode will depend upon the activity of the specific ion in solution.this activity is direct propotinal to activity of ion in the sample  Types of ion selective membrane:- They are four main types of ion selective membrane used in ISE 1. Glass membrane 2. Crystaline membrane 3. Ion exchange resin membrane 4. Enzyme membrane  Glass membrane :- are made from ion exchange type of glass. Advantage of glass membrane:- Good selectivity Disadvantage of glass membrane :- Only use for several single charged cations : Mainly H+ , Na+ , Ag+.  Crystaline membrane :- Made from mono or polycrystaline of single substance. Advantage of crystaline membrane Good selectivity for both cations and anions. e.g fluride selective electrode. Ion exchange resin membrane:- Made from special polymers have ability to ion exchange. This type is most common type of ion selective electrode. e.g potassium selective electrode.  Enzyme membrane:- Not true electrode because have double reaction mechanism : Frist mechanism the reaction occurs between enzyme and specific substance the product of this reaction may be OH- or H+ Second mechanism detect the OH- or H+ by ion selective electrode. e.g glucose selective electrode.  Advantage of ISE :- 1- Simple 2- Easy to handle 3- measure both positive and negative ions 4- inexpensive 5- unaffected by sample color and turbidity Disadvantage of ISE :- 1- electrode can be block by proteins 2- interference by other ions 3- electrode are fragile.  Types of ISE :- 1- direct ion selective electrode : In this type measurement of the sample without dilutions 2- in direct ion selective electrode : In this type measurement of the sample after dilutions.  Component of ISE :- They are three main component of ion selective electrode : 1- indicator electrode 2- reference electrode 3- ion selective membrane.