spectrometers and chromatographs often allow for the analysis of a number of analytes in sequence,
with a computer controlling the adjusting of instrument settings according to a predetermined program.
The condition of the various components of an instrument can be continuously monitored by in-built
self-diagnostic software so that any deterioration in performance can be brought to the attention of the
operator and malfunctions reported as they arise.
Data Recording and Storage
One feature of modern developments in analysis has been the increasing speed with which
measurements can be made. This trend is well exemplified by the changes which have taken place in
obtaining and presenting spectra. Manual plotting of a series of wavelengths or frequencies and
corresponding detector responses was replaced by the use of x/t and x/y plotters. Currently, fast Fourier
transform and other software allow the rapid display on a VDU screen of a complete spectrum in a
matter of seconds. In the sequential spectrochemical analysis referred to earlier, ten or more elements
may be determined in a few minutes. To provide for the rapid acquisition and storage of this data a
computer with a considerable amount of memory is essential. Selected information may then be
extracted quickly, or a complete spectrum recalled in a few seconds.
Data Processing and Data Analysis (Chemometrics)
Rarely will it be possible to draw conclusions directly from the raw data of analytical measurements
and it is usual for some refinement of the data to be carried out. In its simplest form this could merely
comprise background corrections, but it is often much more complex, requiring corrections for a
number of factors as in mass spectrometry, X-ray fluorescence and electron probe microanalysis. More
complex routines made available by computers include spectrum smoothing, stripping one component
from a spectrum or making peak area measurements from chromatograms.
Data reduction and interpretation are much aided by computer methods and the high speed of current
microcomputers facilitates the 'real-time' processing and display of data. The principle of extracting as
much information as possible from analytical measurements through the application of statistical and
other mathematical methods, usually with the aid of appropriate computer software, is known as
chemometrics (p. 13).
The subject has been given considerable impetus by the rapid growth in the power of computers and in
the sophistication and speed of graphic routines. Among the more useful branches of chemometrics are
statistics, signal processing, optimization, modelling, factor analysis, image analysis, pattern
recognition, cluster analysis and library searching. Some of the most impressive examples are found in
molecular spectrometry where MS, NMR or IR spectra are used extensively as qualitative tools. A
computer library can store a large number of reference spectra which are available for rapid