By W. P. Cochrane (auth.), R. W. Frei, J. F. Lawrence (eds.)
The first quantity during this sequence is dedicated to derivatization innovations in chromatography, for terribly visible purposes. In gasoline chromatography (GC) chemical derivatization as an relief to extend the usefulness of the procedure has been recognized for greater than a decade and has turn into a longtime method. the 1st bankruptcy offers to a good quantity with derivatization for the aim of constructing compounds amenable to Gc. even though the dialogue concentrates on insecticides, a few usually legitimate conclusions could be drawn from this bankruptcy. Chemistry are not constrained to the separation-it may also have a reported influence at the pattern cleanup, one other subject cov ered in bankruptcy 1. because the creation of coupled GC-mass spectroscopy (GC-MS), the most important instrument, derivatization suggestions have taken nonetheless one other di rection-taking under consideration chromatographic in addition to mass spec trometric development of the compounds of curiosity. Cyclic boronates are mentioned as derivatization reagents for this function within the moment chapter.
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Each yield DMP (dimethyl phosphate), while temephos, fenthion, fenitrothion, and methyl parathion produce DMTP as product. Therefore, this approach which only characterizes the P moiety is more suited as a very good general screening method. 2. Derivatization of the Alkyl or Aryl Moiety As shown in Figure 15, parathion on hydrolysis produces p-nitrophenol, which is further derivatized with pentafluorobenzyl bromide (PFBB) to its PFB ether, which is very EC sensitive. (172,173) The further derivatization of hydrolysis-generated phenols to various ethers and esters has been previously reviewed(8,9) and a large volume of literature also exists in connection with the quantitation analysis of phenolic herbicides or metabolites.
H. 01 ppm(204) using an AFID. , the dialkyl phosphates and thiophosphates and phenyl phosphonates, involving esterification with diazoalkanes. However, another approach is via the formation of the benzyl(20S) or p-nitrobenzyl esters(206) using triazene reagents. Prior to benzylation the phosphoric acids were fully protonated by passing through a strong cation exchange resin in the H+ form. The dry acids were then refluxed for 20 min or more with 3-benzyl-l-p-tolyltriazene in sealed vials, partitioned into cyclohexane, and determined by FPD after separation on a 5% OV-210 column, temperature programmed from 170°-225°C at 16°CJmin: S(O) ----+.
Cochrane 24 L Fig. 7. Base-promoted isomerization of heptachlor epoxide (I) to the corresponding aUylic alcohol (1-hydroxy-3-chlorochlordene, J) with subsequent derivatization by chlorination and oxidation. and identity of the products from the t-BuOH/t-BuOK reaction has been investigated in some detail for heptachlor, its epoxide, and cis- and transchlordane. (69) Prior to a study of the effect of base on cis- and trans-nonachlor their exact stereochemistry had to be confirmed. The trans isomer ® @ ...