Republication or reproduction of this report or its storage and/or dissemination by electronic means is Selectivity in analytical chemistry (IUPAC Recommendations 2001)Abstract: The correct use of the term "selectivity" and its clear distinction from the term "specificity" are discussed. A definition of selectivity is given, and it is recommended that the use of this term be promoted and that the use of the term "specificity" be discouraged.

Instrumental techniques such as atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) determine only the total vanadium content of a sample, unless the tetravalent and pentavalent forms are first separated. Neutron activation analysis (NAA) is a very sensitive technique, but its use for the determination of trace amounts of vanadium is complicated by the short half-life of 52V (3.75 min) and by the masking of 52V activity by 24Na present in the matrix.* Electron paramagnetic resonance (EPR) spectrometry3 and 51V nuclear magnetic resonance (NMR) spectrometry have been used to determine Vtv and Vv, respectively, but are plagued by non-routine instrumental requirements4Vanadium is ranked tenth in abundance of 29 trace metals in soils, but in surface waters in the USA it was found in only 54 out of a total of 1500 samples.5 The highest concentration of vanadium in surface waters is found in rivers that drain from ore deposits. Air samples from cities that bum large amounts of vanadium-containing fossil fuels contain the highest airborne vanadium levels. Nakano et aZ.6 found that Vtv was the predominant species in samples of natural water, whereas Hirayama et a1.7 found equivalent levels of Vw and Vv in river and sea-water samples. Vanadium(1v) is the major form encountered in mammals.4Paper 3l01292A

Flow-based methods of analysis such as flow-injection analysis and sequential-injection analysis are being used increasingly in the automation of laboratory methods and for process analysis. Full exploitation of these techniques in automated modes of operation necessitates computer control and data acquisition. Although most commercial systems are microprocessor driven, flexibility is seldom built into the software, thereby severely limiting the ingenuity of the analysts in the use of these instruments in novel and imaginative applications. A software package is described which allows for 79 80 MARSHALL AND VAN STADEN easy automation of flow-based analysis systems. The emphasis in the design of this package has been on flexibility, with numerous user-selected options and a wide variety of features. Applications to laboratory and plant analysers are described.

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