Sulfated derivatized

Urine Acidify and heat to hydroloyze add NaOH to pH=11 extract with benzene-diethyl ether reacidify and dry with sodium sulfate derivatize with hexamethyl disilizane on GC column (PNP) GC/ECD 50 pg/L (50 ppb) 95.4 Cranmer 1970 EPA1980d... 

K. Tsuji, J. F. Goetz, W. VanMeter, and K. A. Gusciora, Normal-phase high-performance liquid chromatographic determination of neomycin sulfate derivatized with l-fluoro-2,4,-dinitrobenzene, J. Chromatogr., 775 141 (1979). 

Corticosteroids are used by some athletes and racing horses to enhance their performances. In order to prohibit drug doping, many sport organizations, e.g., International Olympic Committee, attempt to monitor the corticosteroids in urine of athletes. An example of earlier GC-MS method in steroid screen consists of procedures of deconjugation of glucuronide and sulfate, derivatization with MSTFA and GC-MS analysis [98], The more recent LC-MS/MS methods separate the corticosteroids by... 

Considers only the basic monosaccharide units. A derivatized monosaccharide unit, such as a D-galactopyranosyl 6-sulfate unit, is not considered as a unit separate from a D-galactopyranosyl unit, for example. 

Note The reagent can be employed on silica gel and cellulose layers. When derivatization is carried out from the vapor phase the detection limit for morphine is 10 ng and that for papaverine 1 ng per chromatogram zone [5]. In some cases it has been recommended that ammonium sulfate be added to the layer with subsequent heating to 150 —180 °C [1] after derivatization. It is also possible to spray afterwards with an aqueous solution of potassium iodide (1 %) and starch (1%) [2]. 

The GBR resin works well for nonionic and certain ionic polymers such as various native and derivatized starches, including sodium carboxymethylcel-lulose, methylcellulose, dextrans, carrageenans, hydroxypropyl methylcellu-lose, cellulose sulfate, and pullulans. GBR columns can be used in virtually any solvent or mixture of solvents from hexane to 1 M NaOH as long as they are miscible. Using sulfonated PDVB gels, mixtures of methanol and 0.1 M Na acetate will run many polar ionic-type polymers such as poly-2-acrylamido-2-methyl-l-propanesulfonic acid, polystyrene sulfonic acids, and poly aniline/ polystyrene sulfonic acid. Sulfonated columns can also be used with water glacial acetic acid mixtures, typically 90/10 (v/v). Polyacrylic acids run well on sulfonated gels in 0.2 M NaAc, pH 7.75. 

Derivatization Dissolve less than 1 mg of methyl or ethyl ester in 1 ml of freshly distilled pyrrolidine and 0.1 ml of acetic acid. Heat the mixture in a sealed or capped tube (able to withstand high temperatures) at 100° for 30 min. Cool the reaction mixture to room temperature and add 2 ml of methylene chloride. Wash the methylene chloride extract with dilute HC1, followed by ion exchange water. Dry the methylene chloride extract with anhydrous magnesium sulfate.1... 

The thiazolecarboxylic acid structure (40) was also guessed in a similar way, from tracer experiments. The unknown compound was converted into the thiamine thiazole by heating at 100°C and pH 2. On paper electrophoresis, it migrated as an anion at pH 4. Tracer experiments indicated that it incorporated C-l and C-2 of L-tyrosine, and the sulfur of sulfate. The synthetic acid was prepared by carboxylation of the lithium derivative of the thiamine thiazole, and the derivatives shown in Scheme 19 were obtained by conventional methods. Again, the radioactivity of the unknown, labeled with 35S could not be separated from structure 40, added as carrier, and the molar radioactivity remained constant through several recrystallizations and the derivatizations of Scheme 17. 

Two steps have been added to the original Pesticide Analytical Manual method to increase the stability of the trimethylsilyl derivatives and to clean up the final extract prior to GC analysis, namely the use of a sodium sulfate mini-column to dry the extract after derivatization and the use of a Florisil Sep-Pak cartridge to remove matrix interferences. The advantages of the current method are the simultaneous evaluation of the four analytes, reproducibility and low matrix interference. 

Prepare a chromatographic column with silica gel (5 g, deactivated with 1.5% water) packed in n-hexane. Add a 3-cm layer of anhydrous sodium sulfate on the top of the silica gel column. Drain the n-hexane down to the sodium sulfate layer. Transfer the n-hexane phases obtained from the derivatized samples into the column and let the n-hexane drain. Elute with a first fraction of n-hexane-ethyl acetate (50 mL, 9 1, v/v) and discard the eluate. Elute with a second fraction of n-hexane-ethyl acetate (50 mL, 7 3, v/v) and collect the eluate in a 100-mL evaporation flask. Concentrate the eluate to dryness with a rotary evaporator and dissolve the residue in 5 mL of toluene for GC/MS analyses. 

The most general method for the simultaneous analysis of oxyanions by gas chromatography is the formation of trimethylsilyl derivatives. Trimethylsilyl derivatives of silicate, carbonate, oxalate, borate, phosphite, phosphate, orthophosphate, arsenite, arsenate, sulfate and vanadate, usually as their ammonium salts, are readily prepared by reaction with BSTFA-TMCS (99 1). Fluoride can be derivatized in aqueous solution with triethylchlorosilane and the triethylfluorosilane formed extracted into an immiscible organic solvent for analysis by gas chromatography [685). 

Collect headspace vapor of HBr from plasma treated with dimethyl sulfate at 85°C Extract in 18% trichloroacetic acid derivatize to 1,2-dibromo-cylcohexanone Digest in KOH. Convert to bromate, then to tetrabromorosaniline... 

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