Fluorimetric analysis analytical procedure

In analytical procedures with two immiscible aqueous phases, the traditional organic solvents used in LLE can be replaced by nontoxic, nonflammable and nonvolatile solvents [154,155,197], The feasibility of implementing aqueous biphasic extraction in flow analysis was recently demonstrated by the fluorimetric determination of lead by reaction with 8-hydroxyquinoline-5-sulfonic acid [198]. The flow system was rugged and the interface formed between the different aqueous plugs acted as an extraction (enrichment) and reaction interface. This innovation is environmentally friendly as it relies on the utilisation of two immiscible phases that are intrinsically aqueous. 

Analytical procedures for foods are generally based on extraction with purified solvents following saponification with alcoholic potash. Purification of the extracts by chromatography on column or plates is followed by analysis of the purified extract using TLC, GLC or HPLC. Spectrophotometric or spectrofluorimetric methods may be used for quantitation of the hydrocarbons a collaborative study of a spectrophotometric method showed it to be applicable at the 2 fig/kg level. HPLC techniques using spectrofluorimetric detection have been described for which improved levels of detection are claimed. Benzo(a)pyrene produces substitution products with nucleic acids. Hydrocarbon deoxyribonucleoside adducts may be isolated from DNA by gel permeation chromatography, and the formation of hydrocarbon epoxides by mammalian enzyme reaction has also been demonstrated . The limit of detection of spectrophotometric and fluorimetric methods has been improved by three orders of magnitude by the use of laser-induced fluorescence procedures for the... 

In a recent publication, Lindroth and Mopper (1979) have presented a method for precolumn derivatisation followed by separation on reversed phase packing materials with subsequent fluorimetric detection of the amino acid-derivatives. The method has been applied for the analysis of small volumes (100 jul or less) of seawater with separation of up to 25 amino acids within 25 min at sensitivities in the femtomolar (lO M) range. The speed of analysis together with the sensitivities attainable on a routine basis and the simplicity of the analytical instrumentation and procedure, makes the technique eminently suitable for real-time analysis in the field (Garrasi et al., 1979). It is certain that this approach is an exciting development in marine analytical organic chemistry and sets the standard for discovery of equivalent techniques to detect and quantify other biochemical compounds. 

Analytical quantification of BAs may be difficult due to the complexity of some food matrices and the low concentrations of BAs generally encountered in the majority of foodstuffs. In addition, the low volatility of these compounds and the lack of chromophores for most of the BAs, does not allow the rapid direct detection by ultraviolet and visible (UV and vis) spectrometric or fluorimetric (FL) methods. In general, in order to obtain an optimal analysis, extraction, clean-up, concentration, and derivat-ization procedures are required. Extraction methods usually based on liquid-liquid or solid-phase extraction with C18 or ion-exchange cartridges can be applied to improve selectivity and sensitivity (Giannotti et al., 2008 Pena-Gallego, Hemdndez-Orte, Cacho, Ferreira, 2009). Alternative approaches, such as solid-phase microextraction... 

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