ETR has independently developed an integrated vacuum pump unit composed
of a water-ring vacuum pump, a gas-water separator, a vacuum solenoid valve,
pipe fittings and an electrical control system.
It is a simple, safe and reliable device that continuously serves the
wards all day long, without occupying the ward space. The negative pressure is
sourced from the vacuum pump unit.
Vacuum Suction Unit Vacuum Suction Unit,Vacuum Suction Machine,Negative Pressure Suction Machine,Medical Machine Hunan Eter Electronic Medical Project Stock Co., Ltd. , https://www.centralgas.be
The derivatization reaction of the silylation-derived reagent silylating agent with the sample compound is carried out by substituting a silane group for the active hydrogen of a hydroxyl group, a carboxyl group, a mercapto group, an amino group and an imino group. The product of the derivatization reaction is a silyl ether or a silicon ester. Almost all compounds containing these active hydrogens can be derivatized with a silylating agent in the order of reaction: alcohol > phenol > carboxylic acid > amine > amide.
The silylation-derived reagent includes a trimethylsilation derivatization reagent such as hexamethyldisilazane, trimethylchlorosilane, N-methyl-N-trimethylsilylacetamide, N-methyl-N-trimethylsilyl Fluoroacetamide, N,O-bis(trimethylsilyl)acetamide, N,O-bis(trimethylsilyl)trifluoroacetamide, N-trimethylsilyl imidazole, etc.; halogenated silyl-derived reagents such as chlorine Dimethylsilyl chlorosilane, iodomethyldimethylsilyl chlorosilane, chloromethyldimethylsilyldisilazane, iodomethyldimethylsilazane, pentafluorophenyldimethylsilyl Chlorosilane, tert-butylpentafluorophenylsilyl chloride, pentafluorophenylisopropylsilylchlorosilane, and the like.
The alkylation-derived reagent produces a reaction of the alkylated derivative which is a nucleophilic substitution reaction which derivatizes the acid hydrogen of the alkyl-substituted compound of the reagent. The products obtained by the derivatization reaction are ethers, esters, thioethers, thioesters, N-alkylamines, N-alkylamides.
The alkylation-derived reagents include diazo alkanes such as diazomethane; alkyl halides such as pentafluorobenzyl bromide, iodoacetonitrile, etc.; quaternary ammonium salts such as dimethylphenylbenzylamine fluoride , trimethylphenylamine hydroxide; alcohols, such as 1,1,1,3,3,3-hexafluoroisopropanol; alkyl chloroformate, such as trichloroethyl chloroformate, etc. .
The essence of the acylation-derived reagent acylation derivatization reaction is the active hydrogen in the acyl-substituted polar compound of the derivatizing reagent. Such reagents can be used for the derivatization of compounds such as alcohols, phenols, thiols, amines, amides, sulfonamides and the like.
The acylating agent is mainly an acid halide such as 4-ethylhexyl hexafluorobutyryl chloride, perfluorooctanoyl chloride or the like; an acid anhydride such as acetic anhydride, etc.; an acyl imidazole and an amide such as perfluoroacetylimidazole and N-methylditrifluoro Acetamide.
Other derivatizing reagents form cyclic derivative reagents, such as cyclic boronic esters formed by the reaction of boric acid and cis 1,2-diol, carbonyl-containing compounds and heterocyclic derivatives formed by suitable diamines, etc.; chiral derivatization reagents Such as S-(-)-heptafluorobutyryl glutamyl chloride, R-(+)-2-methoxy-2-phenyl-3,3,3-trifluoropropionyl chloride, etc. 
Derivatization reagent in gas chromatography
Derivatization reagent in gas chromatography
The main functions of chemical derivatization in gas chromatography are: 1 to improve the volatility of the sample, 2 to improve the peak shape of the sample, 3 to improve the separation of the sample, and 4 to improve the detection sensitivity of the compound.