Pentafluoro benzyls

If necessary, the nucleosides can be hydrolyzed to the sugar and the base by heating in formic acid.2 Kresbach et al.3 have used pentafluoro-benzylation combined with negative Cl for the detection of trace... 

Eight benzimidazoles Animal tissues ACN extn, liq-liq partns, two SPE cleanups 24 Hewlett-Packard RP-18,5 m, with Kontron RP-18 Presat, 25-40 m, guard column O.OIM pentane-sulfonate contg 0.5% TEA, pH 3.5/ACN (50 50) UV 298 nm/ 20-50 ppb/ GC-NPD 39-87% or GC-EI-MS or GC-Pulsed PICI-NICI-MS after derivatization with methyl iodine or pentafluoro- benzyl bromide 358... 

Peroxide Bis-[ot-(4-meihoxy-letra-fluoro-anilino)-pentafluoro-benzyl]- EI0b2, 59 (Imin/Ox.)... 

Nitro-3,4,6-trifluoro- ElOa, 710 Pcntafluoro- V/3, 487 (F -> NH2) ElOa, 387/521 (Educt) E10b, 616/650 (Educt) EI0b2. 55f./58 (Educt) 60 (N = CHR - NH2), 401/438/455/458 (Educt) 2-(2,3,4,5,6-Pentafluoro-benzyl)-E10b2, 117 (Educt) N-(Pentafluoro-benzylidene)-2,3,5,6-tetrafluoro- EI0b2, 59 (Educt) Pcntafluoro-N-(pentafluoro-benzyli-dene)- E10b2, 59f. (Educt) Pentafluoro-N-phcnyl- EI0b2, 455 (F -> NH-Ar)... 

Alternatively, extract exchanged into 2-propanol derivatized with pentafluoro-benzyl bromide derivative dissolved in hexane fractionated over silica gel eluted with 15% toluene in hexane and determined by GC-ECD. 

Agemian and Chau [190] have reported a method for determining low levels of 4-chloro-2-methylphenoxyacetic acid and 4-(4-chloro-2-methylphenoxy)-butyric acid in non saline and waste waters by derivatisation with pentafluorobenzyl bromide. The increased sensitivity of the pentafluorobenzyl esters of these two herbicides over the 2-chloroethyl methyl esters as well as their longer retention times make pentafluoro-benzyl bromide the preferred reagent. 

Benzoic, oleic linoleic and undecanoic acids Chloroform — Electron capture Acids converted to pentafluoro benzyl esters [225, 226]... 

Phenoxy alkane alkanoic acids Conversion of phenoxy alkanoic acids to methyl esters with diazomethane, then GLC or derivitivisation with 2-chloroethyl and pentafluoro benzyl esters then GLC [419, 422]... 

Alkylated barbituric acids, 6-chloro-a-methylcarbazole-2-aceticacid, 1-phenylethanol, 1-phenyl-1-propanol, dimethyl, 3,4,5,6-pentafluoro-benzyl alcohol, l-(2-naphthyl)-ethanol, 1 -(p-biphenyl)-ethanol Chirasil-Dex coated column, 0.15 pm... 

Extract, clean extract, derivatized with pentafluoro-benzyl bromide... 

Product distributions have been determined for electrolyses of pentafluorobenzaldehyde, pentafluorobenzoic acid, and pentafluorobenzamide at mercury in aqueous media containing either sulfuric acid or TEABF4 [204]. Reduction of the aldehyde gives pentafluoro-benzyl alcohol and 2,3,5,6-tetrafluorobenzyl alcohol. Pentafluorobenzoic acid is initially converted to a mixture of 2,3,5,6-tetrafluorobenzoic acid (73%), pentafluorobenzyl alcohol (6%), and 2,3,5,6-tetrafluorobenzyl alcohol (20%) however, at a more negative potential, only the last two products are obtained in a 1 2 ratio. Pentafluorobenzaldehyde and... 

Neurosteroids are steroids that are synthesized de novo in the central nervous system (androsterone, dihydrotestosterone, testosterone, allopregnanolone, isopregnanolone, and pregananole). After extraction of plasma and cerebrospinal fluids, using solid-phase extraction (SPE), and derivatization with carboxymethoxime, pentafluoro-benzyl, and trimethylsilyl, the derivatized samples were injected into a GC-MS system for quantitative evaluation with a selected ion monitoring (SIM) method. Details of the method have been described in Ref. [25]. 

Carboxylic acids can be reacted with pentafluoro-benzyl bromide after extraction as ion-pairs with symmetrical quaternary ammonium ions at pH 7-9 [62,63]. The same process can be applied to phenols extracted at more alkaline pH values [26,27]. Xanthine derivatives... 

As outlined above (Sections 2 and 3), methyl ester formation with diazomethane is still often employed for analysis of these labile compounds, including thromboxanes and leukotrienes. For high sensitivity analyses by negative ion electron capture GC-MS, pentafluoro-benzyl esters have proved to be very useful [168-170], with low pg sensitivities being obtained. For 6-keto-... 

The formation of cyclic isoxazolinones on reaction of organic acids with hydroxylamine hydrochloride [13] is utilized for the derivatization of succinylacetone (2,4-dioxoheptanoic acid). After stabilization of the keto groups by isoxazole formation in this way, the remaining carboxylic acid group is esterified with pentafluoro-benzyl bromide for GC—MS assay in El [193] or NlCl [194] mode. The latter mode is required to measure the low levels present in amniotic fluid. 

The condensation reaction of carbonyl compounds with halogen-containing derivatization chemicals (so-called elec-trofoiic reagents like pentafluorophenyl hydrazine, 2,4,6-trichlorophenyl hydrazines) and, especially, pentafluoro-benzyl hydroxylamine that has been consid-... 

For nonpolar and volatile compounds, GC-MS is indeed one of the best online detection techniques, which ideally combines the advantages of the high separation efficiency of capillary GC with high sensitivity and selectivity of the MS detector. GC-NPD and GC-MS techniques have been applied to determine a few HCAs, which require a derivatization step prior to the analysis. A number of derivatizing agents, such as acetic, trifluoroacetic, pentafiuoro-propionic, and heptafiuoro-butyric anhydrides, pentafluoro-benzyl bromide, 3,5-bistrifiuoro-methylbenzyl bromide, and 3,5 bistrifluoro-methylbenzoyl chloride have been tested for the analysis of some HCAs [116],... 

Fig. 6. Methane chemical ionization negative ion mass spectra of pentafluoro benzyl ABA upper with insert of unlabelled material) and dipentafluoro benzyl ODA lower). The compounds were isolated from tomato shoots supplied with 40% -H. >O for six days, then severely wilted. M/z-263 = molecular ion — 1 mass unit after the loss of the pentafluorobenzyl residue +H.M/Z 377 = molecular ion of dipentafluorobenzyl ODA-1 mass unit after the loss of one pentafluorobenzyl residue +H. Ordinate. relative intensity abscissa, mass numbers...

Application of the Extractive Alkylation Technique to the Pentafluoro-benzylation of Morphine and Surrogates, with Special Reference to the Quantitative Determination of Plasma Morphine Levels Using Mass Fragmentography... 

Pentafluoro benzyl alcohol 362 for fenfluthrin can be prepared according to Reaction scheme 244. 

Chlorophenols Capillary column Electron capture Chlorophenols derivitivised by alkylation with pentafluoro-benzyl chloride, then GLC, recovery 70% ng L- [632]... 

Phenols, carboxylic acids Electron capture Phenols and carboxylic acids alkylated with pentafluoro-benzyl bromide, then GLC l-IOpg L [647]... 

Monosaccharides converted to trimethyl silyl derivatives Acrolein brominated to acrolein-o-methyloxime Converted to pentafluoro-benzyl esters prior to GLC Polar volatile analysis... 

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