Derivatizing reagent

Table 1. Analyte Functional Groups and Chiral Derivatizing Reagents...

Fluorescent derivatizing reagents with benzofuran skeleton for HPLC with spec-trometric detection 98YZ483. 

The derivatives have an optimum fluorescence at an excitation wavelength of 340 nm and an emission wavelength of 455 nm. The adduct is relatively stable at a pH of 9-11 but it rapidly degrades to a non-fluorescent residue at low pH values. Consequently, when used as a pre-column derivatizing reagent the pH of the mobile phase should be kept fairly high, o-phthalaldehyde has been employed for derivatization in the analysis of dopamine (29), catecholamines (30) and histamines (31). 

Reports on the use of fluorescent derivatives abound (5). Some reagents have become widely used. The dansyl group is probably the most thoroughly studied. Dansyl chloride has been widely used as a fluorescent derivatizing reagent for HPLC (6,7). It reacts readily with primary and secondary amino groups (7) and with phenols (8), but forms derivatives of alcohols very slowly (9). The lower detection limit for dansyl derivatives of aliphatic amines is in the range of 300 femtomoles per injection. 

We inferred that these properties might be exploited in a series of unique derivatizing reagents designed specifically for trace analysis of organic compounds using HPLC separation and fluorescence detection. The use of these pyridones for the analytical purposes reported here is based on their acidic properties. Treatment of a lH-2-pyridone with a base converts the pyridone to its salt. 

Synthesis of a more specific fluorescent acid chloride derivatizing reagent. 

Pyridone Acid Chlorides as Fluorescent Derivatizing Reagents. A second derivatizing reagent, a fluorescent acid chloride, was synthesized from the sodium salt of 3-phenyl-2(lH)pyridone (IV). 

Synthesis of Derivatizing Reagent III. We placed 50 mL of methanol, which had been previously dried over 4-S molecular sieves, in a 100-mL round-bottom flask and added 6.0 g of 2-hydroxynicotinic acid and 3 mL of boron trifluoride etherate. The solution was heated to reflux for 24 h and the solvent was removed under reduced pressure. The residue was dissolved in 50 mL of 0.1-ff sodium hydroxide and extracted with 60 mL of chloroform. The chloroform extract was concentrated under reduced pressure and the residue crystallized from isopropyl alcohol. The yield of 3-carbomethoxy-2(lH)pyridone was 5.0 g mp 152.5-154°C NMR (CDCI3) 6 3.85 (s, 3, -CH3), 6.34 (t, 1,... 

A whole series of derivatization reagents contain 4-(dimethylamino)-benzaldehyde as a fundamental component. They differ in the type and concentration of the mineral acid components used in their preparation. Other components of the reagent generally play a minor role. 

Finally, Chapter 7 discusses the use of selected fluorescence and pH indicator detection reagents, nniversal charring methods, and selective derivatization reagents that produce colored zones. 

TYPICAL HOMOCHIRAL DERIVATIZING REAGENTS FOR GAS CHROMATOGRAPHIC SEPARATION OF ENANTIOMERS... 

Manufacturer Derivatizing Reagent Percent Silanol Groups Reacted Carbon Loading ( ) Average Particle Size ( )... 

Solvent removal.. Lzurge amounts of solvents and excess derivatizing reagents, etc., can be excluded from the main separation column. Prevents column deterioration and improves the performance of sensitive, selective detectors. 

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