INDEX molecular masses

CAS 77-58-7 Dibutylbis((1-oxododecyl)-oxy) stannane RTECS WH7000000 Dibutylbis(lauroyloxy)tin UN 2788 3146 (C Hg)2Sn(00C(CH2)i(jCH3)2/C32He404Sn EC ANNEX 1 INDEX Molecular mass 631.6 EC/EINECS 201-039-8 ... 

A protein with the innocuous name p53 is one of the most frequently cited biological molecules in the Science Citation Index. The "p" in p53 stands for protein and "53" indicates a molecular mass of 53 kDa. The p53 protein plays a fundamental role in human cell growth and mutations in this protein are frequently associated with the formation of tumors. It is estimated that of the 6.5 million people diagnosed with one or another form of cancer each year about half have p53 mutations in their tumor cells and that the vast majority of these mutations are single point mutations. 

No. Refrigerant Chemical Formula Molecular Mass Boiling Pt. (NBP) at 14.693 psia, °F Freezing Point, op Critical Temperature, op Critical Pressme, psia Critical Voliune, ftVlb Refractive Index of Liquid S ... 

CAS 818-08-6 Dibutyltin oxide RTECS WH7175000 Dibutyloxostannane UN 3146 Dibutyloxotin EC ANNEX 1 INDEX CgH gOSn / (C4Hg)2SnO EC/EINECS 212-449-1 Molecular mass 248.9 ... 

Ferritin is another protein that is important in the metabolism of iron. Under normal conditions, it stores iron that can be called upon for use as conditions require. In conditions of excess iron (eg, hemochromatosis), body stores of iron are greatly increased and much more ferritin is present in the tissues, such as the liver and spleen. Ferritin contains approximately 23% iron, and apoferritin (the protein moiety free of iron) has a molecular mass of approximately 440 kDa. Ferritin is composed of 24 subunits of 18.5 kDa, which surround in a micellar form some 3000-4500 ferric atoms. Normally, there is a little ferritin in human plasma. However, in patients with excess iron, the amount of ferritin in plasma is markedly elevated. The amount of ferritin in plasma can be conveniently measured by a sensitive and specific radioimmunoassay and serves as an index of body iron stores. 

LG j8-Lact< obulin LGL Large granular lymphocyte LH Luteinizing hormone LHRH Luteinizing hormonereleasing hormone LI Labelling index LIS Lateral intercellular spaces LMP Low molecular mass polypeptide... 

Figure 14 shows the results for Wp, the mode-dependent relaxation rate, for the different molecular masses as a function of the mode index p. For the smallest molecular mass Mw = 2000 g/mol relaxation rates Wp are obtained which are independent of p. This chain obviously follows the Rouse law. The modes relax at a rate proportional to p2 [Eq. (17)]. If the molecular weight is increased, the relaxation rates are successively reduced for the low-index modes in comparison to the Rouse relaxation, whereas the higher modes remain uninfluenced within experimental error. 

A measure of the breadth of the molecular mass distribution is given by the ratios of molecular mass averages. The most commonly used ratio Mw/Mn — H, is called the polydispersity index. Wiegand and Kohler discuss the determination of molecular masses (weights) and their distributions in Chapter 6. 

The development of mass spectroscopic techniques such as matrix assisted laser desorption (MALDI) and electrospray mass spectrometry has allowed the absolute determination of dendrimer perfection [7,8], For divergent dendrimers such as PAMAM and PPI, single flaws in the chemical structure can be measured as a function of generation to genealogically define an unreacted site of or a side reaction producing a loop at a particular generation level. Mass spectromet-ric results on dendrimers, not only demonstrate the extreme sensitivity of the technique, but also demonstrate the uniformity of the molecular mass. The polydispersity index of Mw/Mn for a G6 PAMAM dendrimer can be 1.0006 which is substantially narrower than that of living polymers of the same molecular mass [7],... 

Various liquid chromatographic techniques have been frequently employed for the purification of commercial dyes for theoretical studies or for the exact determination of their toxicity and environmental pollution capacity. Thus, several sulphonated azo dyes were purified by using reversed-phase preparative HPLC. The chemical strctures, colour index names and numbers, and molecular masses of the sulphonated azo dyes included in the experiments are listed in Fig. 3.114. In order to determine the non-sulphonated azo dyes impurities, commercial dye samples were extracted with hexane, chloroform and ethyl acetate. Colourization of the organic phase indicated impurities. TLC carried out on silica and ODS stationary phases was also applied to control impurities. Mobile phases were composed of methanol, chloroform, acetone, ACN, 2-propanol, water and 0.1 M sodium sulphate depending on the type of stationary phase. Two ODS columns were employed for the analytical separation of dyes. The parameters of the columns were 150 X 3.9 mm i.d. particle size 4 /jm and 250 X 4.6 mm i.d. particle size 5 //m. Mobile phases consisted of methanol and 0.05 M aqueous ammonium acetate in various volume ratios. The flow rate was 0.9 ml/min and dyes were detected at 254 nm. Preparative separations were carried out in an ODS column (250 X 21.2 mm i.d.) using a flow rate of 13.5 ml/min. The composition of the mobile phases employed for the analytical and preparative separation of dyes is compiled in Table 3.33. 

Fig. 3.114. The names, molecular masses, colour index numbers and structures of the azo dye used in this study. Reprinted with permission from M. Chen et al. [171].

The degree of polymerization depends on the duration of the process. After 7 min, the molecular mass is equal to 9400 (the polydispersity index is 5.30). When the reaction is carried out for 15 min, the molecular mass of the polymer increases to 37,000 and the polydispersity index reaches 7.31 (Bauld et al. 1996). Depending on whether cation-radical centers arise at the expense of intramolecular electron transfer or in a stepwise intermolecular lengthening, polymerization can occur, respectively, through a chain or a step-growth process (Bauld and Roh 2002). In the reaction depicted in Scheme 7.17, both chain and step-growth propagations are involved. 

The most commonly used detector is the differential refractometer. For polymers, the variation in the refractive index is usually independent of molecular mass. Other detectors, like photometric detectors in the UV or IR range, can also be used besides the refractometer to measure specific properties of macromolecular solutions (Fig. 7.4). 

Fig. 3 Chromatogram of a red wine using Shodex S-801/S and S-802/S columns at 75°C with a mobile phase of water at a flow-rate of 1 ml/min and using a refraction index detector. Peaks A = compounds with the highest molecular mass and with an acid character 1 = glucose 2 = fructose 3 = glycerol 4 = butan-2,3-diol (= 0.8 g/L added to the initial wine) 5 = ethanol. (Reprinted from Ref. 30 with the kind permission of Elsevier Science—NL, Sara Burgerhartstraat 25, 1055 KV Amsterdam, The Netherlands.)...

Relative molecular mass Melting point Boiling point Refractive index (20°C)... 

Modifier Temp. (°C) Pressure (atm) Molecular mass Dielectric constant at 20 °C Polarity index ... 

As P(0) —> 1 for 6 —> 0, Zimm (1960) suggested a plot of Kc/Rq against sin2(0/2) + kc (where k is a constant, dependent of the dimension of the concentration, to choose in such a way that clear figures will be created). Thus one obtains a grid which allows extrapolation to c = 0 and 0 = 0 (see Fig. 10.5). The intercept on the ordinate then gives 1/MW, and the two slopes provide values to calculate A2 (take care of the constant k at the x-axis ) and R2.. By this method polymer molecular masses of the order of 104 - 107 g/mol can be measured. In order to find the quantity K, the refractive index of the solution n, and the so-called specific refractive index increment (dn/dc), require experimental determination. Because the solutions to be measured are very dilute, the value of n may be replaced by ns the refractive index of the solvent. 

The Eight-Peak Index of Mass Spectra published by the Mass Spectrometry Data Centre of the Royal Society of Chemistry is a popular printed index of mass spectral data that now contains some 81000 spectra of over 65000 different compounds [4], These spectra are published in the shape of lists of the eight main peaks. The complete data are sorted in three different ways to allow easy identification of unknown compounds by (i) molecular weight subindexed on molecular formula, (ii) molecular weight subindexed on m/z value and (iii) m/z value of the two most intense ions. 

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