How to Make Calcium-Sensitive Minielectrodes

Abstract

In this protocol we describe how to make and use minielectrodes for measuring [Ca²⁺] in small volumes of solution. The minielectrodes are ∼2 mm in diameter and have sufficiently low resistances to be used with a standard pH meter. They are made by dipping polyethylene or borosilicate glass tubes (∼5 cm long) in a membrane solution. Although the chemicals used to make these Ca²⁺-sensitive minielectrodes are expensive, they can be used to make hundreds of electrodes, each with a useful life of several months.