650 M. Dubernet
Automated methods frequently exhibit remarkable performance not only in terms
of sample throughput and cost, but in relation to the quality of results, especially in
relation to repeatability and reproducibility. Several systems are currently available
that enable simple automation of manual gestures; these include automatic titra-
tors, pH-meters with a circulating cell, etc., and involve approaches that are not
fundamentally different to the corresponding manual method. These techniques are
not, however, described in this chapter,nor are gas and liquid chromatography and
capillary electrophoresis, automated techniques, that may be present but are not
routinely used in oenological laboratories.
Four major families of automated analysers are routinely used today in oenology:
Flow injection analysers
Sequential analysers
NIR (near infra-red) analysers
FTIR (Fourier transform interferometer) analysers
For each of these families, the general principles, the particularities and limits of
their applications will be presented.
Note: The methods presented below are described in the OIV green document
Nā¦1276ā2008 (Dubernet 2008).
12.2 Flow Injection (FIA) Analysers
The earliest studies on the automation of chemical analysis in oenology by FIA were
carried out by Sarris et al. (1970). However, it was only from 1974 onwards that this
technique started to become widely used in routine oenological determinations with
the development of reliable and repeatable analytical methods.
12.2.1 Composition and Principle of an FIA Analyser
FIA analysers are composed of separate modules, each of which has a specific
function.
12.2.1.1 The Sample Distributor
This module consists of a tray that can generally hold between 20 and 60 sample
vials whose volume is usually between 1 and 3ml. A pivoting arm to which is a
needle is attached aspirates an aliquot of each sample with a rinse step between each
sampling step. The needle is linked to the analytical circuit via a PVC tube. The
rinsing liquid, the sample, the rinsing liquid and the next sample are successively
aspirated by the needle. The rate of analysis is determined by the sample distributor.