Fluorescence with triethanolamine

In situ quantitation The chromatogram was immersed twice for ca. 1 s with brief intermediate drying in a mixture of chloroform — liquid paraffin and triethanolamine (60 -H 10 + 10) to stabilize the fluorescence (for ca. 24 h) and increase its intensity (by a factor of ca. 3). The analysis was made in UV light... 

The microspheres—synthesised via a two-step process (acid-catalysed hydrolysis and condensation of 3-mercaptopropyltrimethoxysilane (MPS) in aqueous solution, followed by condensation catalysed by triethanolamine)—have a narrow size distribution (Figure 5.16) and are considerably more stable than polystyrene divinylbenzene microspheres as shown in phosphoramidite oligonucleotide synthesis by the excellent retention of fluorescence intensity in each of the reagent steps involved in phosphoramidite DNA synthesis (Figure 5.17, in which the organo-silica microsphere free thiol groups are derivatized with ATTO 550 maleimide coupled to the entrapped dye). 

With fluorescent substances, this is usually very satisfactorily achieved by the use of fluorescence intensifiers (FlTs). Vol. la of the reagent books of Jork et al. gives tables of lipophilic FITS (mainly mineral oils) and hydrophilic FlTs such as polyethylene glycols, triethylamine, triethanolamine and especially Triton X-100, including areas of use. Treatment by spraying and dipping in various solvents is recommended. In gen-... 

Detector F ex 320 em 390 following post-column reaction. The column effluent mixed with 12% triethanolamine (for fluorescence enhancement) pumped at 0.5 mL/min and flowed through aim reaction coil to the detector. 

The addition of hexanesulfonate (H) to a y-CD-16 solution in which the dimeric complex (y-CD-16-16-y-CD) is present led to the formation of a three-component complex y-CD-16-H [124], as shown by the decrease of the excimer fluorescence and the biphasic monomer fluorescence decay. The species with the longest lifetime (i.e., the three-component complex with T = 220 ns) was quenched by triethanolamine with lower than 3 X 10 dm mol" s" and by Oj with fc, = 4 x 10 dm mol" s" . For all other forms of the CD-16 complex studied in [124], the corresponding kq are higher, that is, the best protection against the quenching is offered to 11 by the three-component complex. 

Sulfonamides are used for the prevention and treatment of human infectious diseases and also as growth promoters in swine. It is necessary to monitor pork products for drug residues of sulfonamides. Various sulfonamides were separated on Whatman LKCigF layers in a methanol-0.5 M NaCl (50 50) mobile phase spots were detected with UV light (366 nm) after spraying with fluorescamine reagent followed by 0.5% triethanolamine in chloroform to stabilize fluorescence. The Rp values of the sulfonamides were as follows sulfabromomethazine, 0.19 sulfadimethoxine, 0.39 sulfamethazine, 0.59 sulfathiazole, 0.76 sulfaguanidine, 0.90 (Whatman TLC Technical Series, Volume 3). 

More recent developments focused on isocratic separation of the B vitamers. Hamaker et al. used an isocratic method for the analysis of human milk (143), while Edwards and coworkers reported an isocratic method suitable for the determination of the six B vitamers and 4-PA in human plasma (144,145). Edwards and coworkers used a 4.6 X 250 mm LKB analytical column packed with 5-p.m particles of reversed-phase (TSK ODS-120T) material, and the separation was achieved within 23 min. The eluent was a 75-mM NaH2P04 buffer containing 75 mM NaC104, 0.85% acetonitrile, and 0.05% triethanolamine with pH adjusted to 3.4 with concentrated HCIO4. Postcolumn sodium bisulfite addition and fluorescence detection were used to quantify the B vitamers. 

Curiously, the azacrown ether imparts little if any additional stability to the complex on binding. Nevertheless, binding at the azacrown ether is a prerequisite of generating a fluorescent response as it directly participates in PET, the system requiring both recognition units to complex for fluorescence to be restored. The observed stability constants (. fobs) for sensors 94 and 95 with d-glucosamine were 18 and 17 respectively, in 33.2 wt% ethanol/water at pH 7.18 (triethanolamine buifer). 

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