Formulae isotopic labelling

B5 (pantoflienic acid), formula Isotopically labeled elution wifli (a) 0.1% aqueous with a 0.1 M pH=2 ... 

Isotopically Labeled Compounds. The hydrogen isotopes are given special names H (protium), H or D (deuterium), and H or T (tritium). The superscript designation is preferred because D and T disturb the alphabetical ordering in formulas. 

Isotopic labeling studies, 21 137-139 Isotopic mixtures, hydrogen, 13 765 Isotrate ER, molecular formula and structure, 5 110t Isotretinoin, 25 789... 

In the case of the reaction of Mn(CO)5CH3 shown above, isotopic labelling studies (with 14CO) show that the CO molecule inserted into the Mn-CH3 bond is onp of the five CO groups already coordinated, and not the external CO shown in the stoichiometric formula. It appears that an equilibrium is set up between the Mn(CO)5CH3 and a five-coordinate, 16-electron (i.e. coordinatively-unsaturated) acyl complex ... 

An isotopically labeled compound is a mixture of an isotopically unmodified compound with an analogous isotopically substituted compound or compounds. Isotopically labeled compounds may be specifically labeled or selectively labeled. To indicate isotopic labeling, the number and symbol (and locants if needed) are enclosed in square brackets closed up to the compound name or formula. 

IR-4.4.3.2 Formal treatment as coordination compounds IR-4.4.3.3 Chain compounds IR-4.4.3.4 Generalized salt formulae IR-4.4.3.5 (Formal) addition compounds IR-4.4.4 Figand abbreviations IR-4.5 Isotopically modified compounds IR-4.5.1 General formalism IR-4.5.2 Isotopically substituted compounds IR-4.5.3 Isotopically labelled compounds IR-4.5.3.1 Types of labelling IR-4.5.3.2 Specihcally labelled compounds IR-4.5.3.3 Selectively labelled compounds IR-4.6 Optional modibers of formulae IR-4.6.1 Oxidation state IR-4.6.2 Formulae of radicals IR-4.6.3 Formulae of optically active compounds IR-4.6.4 Indication of excited states IR-4.6.5 Structural descriptors IR-4.7 References... 

IR-4.5.1 General formalism The mass number of any specific nuclide can be indicated in the usual way with a left superscript preceding the appropriate atomic symbol (see Section IR-3.2). When it is necessary to cite different nuclides at the same position in a formula, the nuclide symbols are written in alphabetical order when their atomic symbols are identical the order is that of increasing mass number. Isotopically modified compounds may be classified as isotopically substituted compounds and isotopically labelled compounds. 

A chemical substance which is to be recorded by machine processing in the CAS Chemical Registry System is described in terms of a set of topological characteristics. The structural data necessary include a molecular formula, the basic relationship of the atoms present, and other data to allow complete and unambiguous identification of the substance. Each substance registered is represented in the system by a unique record, with four components 1) the connection table topology, which is a detailed inventory of the atoms and bonds that comprise the basic structure of the substance and more recently the stereochemical information 2) an isotopic labeling component which identifies any labeled atoms in the structure 3) a derivative component, which indicates that the substance is a salt or a complex of the substance defined by the first two components of the record and 4) a text descriptor component,... 

Isotopic designators in chemical formulas These generally follow common usage, which is to place a superscript number before the atom to indicate the mass of the isotope that replaces the natural isotope at that position, regardless whether it replaces the natural isotope in all molecules (isotopic substitution) or only some molecules (isotope labeling). 

Other key Issues in zinc absorption which will be studied with stable Isotopes are the bloavailablllty of zinc to human Infants from breast milk and formulas and comparison of the availability of Intrinsic and extrinsic zinc labels. 

The use of direct calorimetry is not a convenient technique, since it requires a specially constructed room and the confinement of human subjects for a day or longer in the room. The doubly labeled water technique offers a convenient alternative, providing that one has a machine to perform isotope ratio mass spectrometry. The doubly labeled water technique is used to measure the rate of total CO2 production in the body. This number alone is not sufficient to allow one to calculate the total energy expenditure. But the value for COj production (moles COi/day), along with the RQ, allows one to calculate the oxygen consumption using the following formula ... 

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