UV-fluorescent devices

To replicate such an UV spectrum, two laboratory devices are in common use. They are used to conduct weathering research for all types of plastics the xenon arc and UV-fluorescent devices, as shown in Fig. 10.2. 

Chromatographic methods such as HPLC and GC, coupled with different types of detection device (HPLC UV, fluorescence, MS, GC PND-, ECD-, MS), are frequently used for the measurement of biocompartment levels of small molecules. In the... 

The fluorescent UV sources are typically incorporated into fluorescent UV/condensation devices in which dark periods with condensation are alternated with periods of UV radiation. The temperature is generally controlled at different levels during each of these periods. The devices may also incorporate periodic water spray on the front surface of the samples during exposure to radiation but do not control relative humidity. Some of the modem types of these devices have capabilities for irradiance control. Procedures for exposing polymeric materials in... 

Figure 10.4 Half-life laboratoiy predictions of four geotextiles extrapolated to 20°C using UV-fluorescent weathering devices per ASTM D7238. (a) A 220-g/m woven monofilament black geotextile, (b) A 110-g/m woven sUt-film black geotextile. (c) A 130-g/m nonwoven needlepunched black geotextile. (d) A 340-g/m nonwoven heat-bonded gray geotextile (highly stabiUzed).

UV-fluorescent (ASTM-D7238) irradiance = 42.42 W/m between 250- and 400-nm wavelengths, which is a property of the incubation device, and... 

Specifications for modem detectors in HPLC are given by Hanai [538] and comprise spectroscopic detectors (UV, F, FUR, Raman, RID, ICP, AAS, AES), electrochemical detectors (polarography, coulometry, (pulsed) amperometry, conductivity), mass spectromet-ric and other devices (FID, ECD, ELSD, ESR, NMR). None of these detectors meets all the requirement criteria of Table 4.40. The four most commonly used HPLC detectors are UV (80%), electrochemical, fluorescence and refractive index detectors. As these detectors are several orders of magnitude less sensitive than their GC counterparts, sensor contamination is not so severe, and... 

Applications With the current use of soft ionisation techniques in LC-MS, i.e. ESI and APCI, the application of MS/MS is almost obligatory for confirmatory purposes. However, an alternative mass-spectrometric strategy may be based on the use of oaToF-MS, which enables accurate mass determination at 5 ppm. This allows calculation of the elemental composition of an unknown analyte. In combination with retention time data, UV spectra and the isotope pattern in the mass spectrum, this should permit straightforward identification of unknown analytes. Hogenboom et al. [132] used such an approach for identification and confirmation of analytes by means of on-line SPE-LC-ESI-oaToFMS. Off-line SPE-LC-APCI-MS has been used to determine fluorescence whitening agents (FWAs) in surface waters of a Catalan industrialised area [138]. Similarly, Alonso et al. [139] used off-line SPE-LC-DAD-ISP-MS for the analysis of industrial textile waters. SPE functions here mainly as a preconcentration device. 

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