Reagent Reagents have been used to target a wide group
of functionalities, including ketones (using p-nitrobenzene diazonium
fluoroborate as the diazo reagent),159 hydroxyl groups, as in
1-hydroxy-2-imidazol-1-yl-phosphonoethyl phosphoric acid (zoledronic acid), in
urine and blood samples (using trimethylsilyl diazomethane under multiple
methyl ester formation),160 the antidepressant reboxetine (RBX) in human plasma
(using 7-flouro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-F) reagent),130 isomeric separation
of fatty acids from lipids (using methylation with diazomethane in diethyl
ether),161 and for amines, e.g., erythromycyclamine (using
7-chloro-4-nitro-benzo-2-oxa-1,3-diazole (NBD-Cl)).
Extraction
Techniques and Applications: Food and Beverage G. Dugo, ... M. Saitta, in Comprehensive
Sampling and Sample Preparation,
2012 4.22.6 Purity of
the Reagents The reagents for
analytical use are commercially available in varying degrees of purity: for the
analysis of trace elements, it is appropriate that they are of the highest
possible degree of purity; pure reagents for the analysis of trace elements are
controlled from the manufacturer and the main impurities detected and their
relative amounts are listed on the container. It is therefore essential, not
only that the impurities are present in the least possible amount but also that
it is such as to avoid influencing the outcome of analysis. Even high-purity
grade reagents can be a source of contamination, especially when working at
very low concentration levels, and it may be necessary to test those that are
used for impurities; when impurities are detected in reagents such as nitric or perchloric acid, it should be better to distil them in a quartz distiller
before use. It is essential that the water used to dilute the samples is of the
highest purity too: it must have a very low conductivity and should be checked constantly; when the de-ionized
water used is not suitable, it can be prepared from the de-ionized water by
double distillation in a quartz distiller.1–3 Synthesis
and Biochemical Evaluation of Fluorinated Monoamine Oxidase Inhibitors Kenneth L. Kirk,
... Günter Haufe, in Fluorine
and Health, 2008 3.4 Allyl
hydrazines as SSAO inhibitors Carbonyl reagents,
such as semicarbazide and phenelzine (27),
are inactivators of SSAO. In a strategy that includes two inactivating
structural motifs (allylamine and hydrazine), a series of allyl hydrazines including
the series 28a–c as well as the fluoroallyl analogue 29 were
prepared. Compounds 28a‐c were potent irreversible inhibitors of SSAO, and
compounds 28a,c had particularly good selectivity with respect
to MAO inhibition. The presence of the vinyl fluoride in 29 had
little effect on potency but did result in a loss in selectivity [82]. RADIOCHEMICAL
METHODS | Overview K. Buchtela, in Encyclopedia
of Analytical Science (Second Edition), 2005 Radio Reagent Method In radio reagent methods
a radioactive species is used in a quantitative reaction and the change in
activity of that species in the course of the reaction is measured. The
radioactive species may be a labeled reagent or the analyte. After separation from excess reagent by any suitable
chemical separation method like liquid–liquid distribution, chromatography, etc., the mass or concentration of this product is
determined from activity measurement. The
advantage of radio reagent methods over classical analytical techniques arises from
the high sensitivity of the activity measurements that are not subject to
interference by other substances. The principle of the radio reagent method can
be adapted to various procedures. What is Limiting Reagents? The reactant that is entirely used up in a reaction is called as
limiting reagent. Limiting reagents are the substances that
are completely consumed in the completion of a chemical reaction. They
are also referred to as limiting agents or limiting reactants. According to
the stoichiometry of chemical reactions, a fixed amount of
reactants is required for the completion of the reaction. Let us consider the
following reaction of formation of ammonia: 3H2 +
N2 → 2NH3 In the reaction given above, 3 moles of
Hydrogen gas are required to react with 1 mole of nitrogen gas to form 2 moles of ammonia. But what if,
during the reaction, only 2 moles of hydrogen gas are available along with 1
mole of nitrogen. In that case, the entire quantity of nitrogen
cannot be used (because the entirety of nitrogen requires 3 moles of hydrogen
gas to react). Hence, the hydrogen gas is limiting the reaction and is
therefore called the limiting reagent for this reaction.
