ICP-MS

　　Amazingly, 18 years after the commercialization

　　of inductively coupled

　　plasma mass spectrometry

　　(ICP-MS), less than 4000 systems

　　have been installed worldwide. If

　　you compare this number with another

　　rapid multielement technique, inductively

　　coupled plasma optical emission spectrometry

　　(ICP-OES), first commercialized

　　in 1974, the difference is quite significant.

　　In 1992, 18 years after ICP-OES was

　　introduced, more than 9000 units had

　　been sold, and if you compare it with the

　　same time period that ICP-MS has been

　　available, the difference is even more dramatic.

　　From 1983 to the present day,

　　more than 17,000 ICP-OES systems have

　　been installed — more than four times

　　the number of ICP-MS systems. If the

　　comparison is made with all atomic spectroscopy

　　instrumentation (ICP-MS, ICPOES,

　　graphite furnace atomic absorption

　　[GFAA] and flame atomic absorption

　　[FAA]), the annual turnover for ICP-MS

　　is less than 7% of the total atomic spectroscopy

　　market — 400 units compared

　　to approximately 6000 atomic spectroscopy

　　systems. It’s even more surprising

　　when you consider that ICP-MS offers

　　so much more than the other

　　techniques, including two of its most attractive

　　features — the rapid multielement

　　capabilities of ICP-OES, combined

　　with the superb detection limits of GFAA.

　　ICP-MS — ROUTINE OR RESEARCH?

　　Clearly, one of the reasons is price — an

　　ICP-MS system typically costs twice as

　　much as an ICP-OES system and three

　　times more than a GFAA system. But in a

　　competitive world, the “street price” of an

　　ICP-MS system is much closer to a top-ofthe-

　　line ICP-OES system fitted with sampling

　　accessories or a GFAA system that

　　has all the bells and whistles on it. So if

　　ICP-MS is not significantly more expensive

　　than ICP-OES and GFAA, why hasn’t

　　it been more widely accepted by the analytical

　　community? I firmly believe that

　　the major reason why ICP-MS has not

　　gained the popularity of the other trace

　　element techniques is that it is still considered

　　a complicated research technique,

　　requiring a very skilled person to

　　operate it. Manufacturers of ICP-MS

　　equipment are constantly striving to

　　make the systems easier to operate, the

　　software easier to use, and the hardware

　　easier to maintain, but even after 18 years

　　it is still not perceived as a mature, routine

　　tool like flame AA or ICP-OES. This

　　might be partially true because of the relative

　　complexity of the instrumentation;

　　however, in my opinion, the dominant

　　reason for this misconception is that

　　there has not been good literature available

　　explaining the basic principles and

　　benefits of ICP-MS in a way that is compelling

　　and easy to understand for someone

　　with very little knowledge of the

　　technique. Some excellent textbooks (1,

　　2) and numerous journal papers (3–5)

　　are available that describe the fundamentals,

　　but they tend to be far too heavy for

　　a novice reader. There is no question in

　　my mind that the technique needs to be

　　presented in a more user-friendly way to

　　make routine analytical laboratories more

　　comfortable with it. Unfortunately, the

　　publishers of the “for Dummies” series of

　　books have not yet found a mass (excuse

　　the pun) market for writing one on ICPMS.

　　So until that time, we will be presenting

　　a number of short tutorials on the

　　technique, as a follow-up to the poster

　　that was included in the February 2001

　　issue of Spectroscopy.

　　During the next few months, we will be

　　discussing the following topics in greater

　　depth:

　　• principles of ion formation

　　• sample introduction

　　• plasma torch/radio frequency generator

　　• interface region

　　• ion focusing

　　• mass separation

　　• ion detection

　　• sampling accessories

　　• applications.

　　We hope that by the end of this series,

　　we will have demystified ICP-MS, made it

　　Figure 1. Generation of positively charged ions in the plasma.