There are over one hundred thousand chemicals currently in use but this represents only a small fraction of those that are known. In fact, the total number of chemical substances registered with the Chemicals Abstract Service is over 18 million and new ones arrive at a rate of over 300 per hour. With this number of different chemicals, and the need for each one to be completely distinguishable from the rest of the crowd, comes a problem of naming.

Systematic approaches for naming chemical compounds have to be used but, all too frequently, this presents us with names that are virtually unusable in written and spoken communications. Try this one in discussion and it's by no means one of the complicated ones N,N'-1,2-ethanediylbis[ N-(carboxymethyl)glycine]tetrasodium; it is usually called EDTA tetrasodium. So where does this abbreviation EDTA come from? That is from an earlier naming system: ethylenediaminetetraacetic acid. Unfortunately for the chemist of today there are frequently many names for the same substance.

A look in the Merck Index for our EDTA, which puts it under the heading Edetate Sodium, gives many other names. In addition to systematic names there are trivial names, common names and, if that were not complex enough, commerce comes in with a whole string of trade names. Thus, for the EDTA we have, from the Merck Index: ethylene bis(iminodiacetic acid) disodium salt, edetic acid disodium salt, edathamil disodium, tetracemate disodium, Cheladrate, Chelaplex III, Sequestrene NA, Sodium Versenate. And...