A gas-phase biosensor for environmental monitoring of formic acid: laboratory and field validation.
In order to encourage more exposure measurements to be performed, a formic acid gas-phase biosensor has been developed for this purpose. In the present paper, an enzyme based biosensor has been validated with respect to analyte selectivity and on-site use. To ensure that the sampler developed measures the compound of interest the biosensor was exposed to three near structural homologues to formic acid, i.e. acetic acid, methanol and formaldehyde. These vapours were generated with and without formic acid and the only compound that was found to have an effect on the performance of the biosensor, albeit a small one, was acetic acid. The field test was performed in a factory using formic acid-containing glue for glulam products. In parallel to the measurements with the biosensor a well defined reference method was used for sampling and analysing formic acid. It was found that the biosensor worked satisfactorily in this environment when used in a stationary position. It was also shown that the biosensor could determine formic acid vapour concentrations down to 0.03 mg m(-3).
Electrochemical sensors for environmental monitoring: design, development and applications.
The advancement in miniaturization and microfabrication technology has led to the development of sensitive and selective electrochemical devices for field-based and in situ environmental monitoring. Electrochemical sensing devices have a major impact upon the monitoring of priority pollutants by allowing the instrument to be taken to the sample (rather than the traditional way of bringing the sample to the laboratory). Such devices can perform automated chemical analyses in complex matrices and provide rapid, reliable and inexpensive measurements of a variety of inorganic and organic pollutants. Although not exhaustive due to the vast amounts of new and exciting electrochemical research, this review addresses many important advances in electrochemical sensor design and development for environmental monitoring purposes. Critical design factors and development issues including analytical improvements (e.g. detection limits), microfabrication and remote communication are presented. In addition, modern environmental applications will be discussed and future perspectives considered.
Investigation of the composition of a unique efflorescence on calcareous museum artifacts
Fibrous crystals, consisting principally of calcium, acetate, chloride and nitrate ions on a number of calcareous museum artifacts worldwide, have been examined. Ion chromatography (IC) was used to determine the exact composition of the efflorescence and nuclear magnetic resonance spectrometry (NMR) was used to determine the degree of hydration associated with the salt. Of the twelve samples analysed, eleven salts had the same stoichiometry as Efflorescence X, a novel salt identified from an Egyptian limestone relief sculpture in the Burrell Collection, Glasgow, that has the composition Ca3(CH3,COO)3 Cl(NO3)2 · 7H2O.