BS 7310:1990 pdf free.Ion-selective electrodes, referenceelectrodes,combination electrodesand ion-selective electrode meters fordetermination ofions insolution.
BS 7310 sensitized ion-selective electrodesthese are categorized as follows
a)Gas sensing electrodes.These are sensorscomposed of an indicator and a reference electrode and use a gas-permeable membrane oran air-gap to separate the sample solution from athin film of an intermediate solution that is eitherheld between the gas membrane and the ion-sensing membrane of the electrode or placedon the surface of the electrode using a wettingagent (e.g.air-gap electrode).This intermediatesolution interacts with the gaseous species in such a way as to produce a change in a measuredvalue (e.g. pH) of the intermediate solution.Thischange is then sensed by the ion-selective electrode and is proportional to the partialpressure of the gaseous species in the sample.NOTE Gas-sensing electrodes are in fact whole electrochemical cells.
b) Enzyme substrate electrodes In these an ion-selective electrode is covered with a coatingcontaining an enzyme which causes the reactionof an organic or inorganic substance (substrate)to produce a species to which the electrode responds.Alternatively, the sensor could be covered with a layer of substrate that reacts withthe enzyme to be assayed.An example is anammonium ion-selective electrode coated withurease for urea determination.
internal reference electrode (of anion-selective electrode) electrode, e.g.silver-silver chloride, electricallyconnected to the screened input cable to the meter,and in contact with the internal filling solutionNOTE In all-solid-state electrodes the material of the referenceelectrode is deposited directly on to the membrane and the internal filling solution is unnecessary.
internal filling solution (of an ion-selectiveelectrode) aqueous electrolyte solution, which may be gelled,containing a fixed concentration of ion x and a fixedconcentration of the ion to which the inner referenceelectrode is reversible,e.g.chloride ion in the case ofsilver-silver chloride or calomel electrodes.
screened cable coaxial shielded cable connecting the ion-selectiveelectrode internal reference electrode system to aplug for input to the measuring instrument (ISEmeter)BS 7310 pdf download.