Triazines fluorescent detection

In subsequent work, Piletsky et al. [26] devised a somewhat simpler system for the fluorescent detection of the herbicide triazine. This technique was based upon the competition of the template and a fluorescent analogue (reporter) for the... 

Many reported methods for BA and AA involve pre- or postcolumn (or capillary) derivatization of these compounds before detection using 3-(4-carboxybenzoyl)-2-quinoline-carboxaldehyde," 5-(4,6-dichloro-s-triazin-2-ylamino) fluorescein, l,2-naphthoquinone-4-sulfonate," < -Phthalaldehyde (OPA), fluorescamine, and many other procedures reported in Table 30.2. OPA is disadvantageous in that it reacts only with primary amines, and the fluorescent derivatives are associated with significant instability. Dabsyl- and dansylchloride are better in this respect as they react with both primary and secondary amino groups, and provide stable derivatives. Indirect UV, indirect fluorescence detection, conductivity," and electrochemical detection have been utilized after CE separation as well as mass spectrometry Kvasnicka et al. " developed a direct,... 

Wang W, Li C, Li Y, Hu Z, Chen X (2006) Rapid and ultrasensitive determination of ephedrine and pseudoephedrine derivatizated with 5-(4,6-dichloro-s-triazin-2ylamino)fluo-rescein by micellar electrokinetic chromatography with laser-induced fluorescence detection. J Chromatogr A 1102 273-279. doi 10.1016/j.chroma.2005.10.015... 

The first work in this field was probably that of Piletsky et al. [84] that described a competitive FILA for the analysis of triazine using the fluorescent derivative 5-[(4,6-dichlorotriazin-2-yl)amino]fluorescein. The fluorescence of the supernatant after incubation was proportional to the triazine concentration and the assay was selective to triazine over atrazine and simazine. The same fluorescent triazine derivative was applied to competitive assays using atrazine-imprinted films [70]. To this end an oxidative polymerization was performed in the presence of the template, the monomer(s) 3-thiopheneboronic acid (TBA) or mixtures of 3-amino-phenylboronic acid (APBA) and TBA (10 1) in ethanol-water (1 1 v/v) where the template is more soluble. The polymers were grafted onto the surface of polystyrene microplates. The poly-TBA polymers yielded a detection limit of 8 pM atrazine whereas for the poly-TBA-APBA plates it was lowered to 0.7 pM after 5 h of incubation. However, a 10-20% decrease in the polymer affinity was observed after 2 months. 

This approach has been used primarily to study photosynthesis, for example to introduce tolerance to a variety of stress conditions. Many studies have been successful in verifying the effea of single amino acid modifications on herbicide binding affinity. High affinity binding to the D1 protein is a useful property for the detection of herbicides. A fluorescence biosensor based on mutants resistant to various herbicide subclasses was developed, it makes possible to distinguish between subclasses of herbicides (e.g., triazines from urea and phenolic type herbicides). ... 

The specificity of the whole cells and isolated photosynthetic materials was obtained by applyir the knowledge available on the relationships between herbicide binding activity and the structure of the D1 protein. For example, distinctions among classes of chemicals could be achieved through mutations in amino acid residues of D1 which can impart resistance to individual triazine herbicides. Realisation of new, sophisticated transduction systems based on printed electrodes, fluorescence and chemiluminescence as well as alternative systems such as the reconstimtion of Qp site in overexpressed DI protein utilizing chromophore quinones to enhance sensitivity and specificity for detected signals. 

Immunochemical methods have also been applied to the detection of bound pesticide residues in soil. These are formed by binding of pesticides to the organic matter of the soil, mainly humic and fulvic acids, and cannot be analyzed using common extraction and assay methods. Hahn et al. used Fab fragments labeled with a fluorescent dye to detect nonextractable residues of atrazine in soil from corn fields. The fluorescence signal obtained was related to the amount of bound atrazine in native soil samples determined by GC after supercritical methanol extraction. A noncompetitive sandwich lA for the analysis of bound residues based on HA-Ab and triazine Ab was developed by Ulrich et HA was extracted from soil, bound to the plates by the HA-Ab and the nonextractable triazine residues were detected by... 

Mass spectrometry has been used to identily complexes formed in the gas phase by reaction of oxyanions and carbanions with 1,3,5-triazine. Spectroscopic studies and DFT calculations on the species formed by reaction of ethylamine with 2,4-dinitrotoluene in DMSO indicate that transfer of a methyl proton rather than nucleophilic attack is the major interaction. Two methods for the detection of 2,4,6-trinitrotoluene (TNT) using fluorescence techniques rely on the formation of its complexes with amines. Also cobalt-doped zinc sulfide quantum dots have been used to interact with complexes formed from TNT and L-cysteine allowing detection of the nitro compound. A complex between 2,4-dinitroanisole and L-cysteine methyl ester has been identified by surface-enhanced Raman spectroscopy. ... 

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