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  • 5 October 2016

    Discuss factors affecting DTA results

    Q.5. (a) Draw diagram of apparatus and give methodology of DTA. Discuss factors affecting DTA results.
    Ans.5. (a) Differential Thermal Analysis
    In differential thermal analysis (DTA), a sample and a thermally inert reference material differencebetween the sample and the reference is measured as a function of the temperature applied. Because, during transition, the sample may either absorb or evolve heat, the difference in the temperature between the sample and the standard is equivalent to the temperature of transition and can indicate if the transition is endothermic or exothermic. Usually, ΔT is plotted against the temperature, T, or as a function of time (t).
    DTA data are probably the most accurate of all thermal techniques, because the thermocouple is insert     into the sample; however, only the temperature of a transition and not the amount of heat can be measured from a DTA curve, as the area under the peak is not proportional to the amount of energy transferred into or out of the sample.
    Factors affecting the DTA curve

  • 5 October 2016
    Elaborate factors affecting electrophoretic mobility

    Q.4.(c) Elaborate factors affecting electrophoretic mobility.
    Ans.4. (c) Electrophoretic Mobility         
    The migration rate ʋ of an ion (cm/s) in an electric field is equal to the product of the field strength E (V cm-1) and the electrophoretic mobility µe (cm2V-1s-1). That is,
    ʋ = µeE
    Electrophoretic mobility, µe = E/ʋ
    The electrophoretic mobility is in turn proportional to the ionic charge on the analytic and inversely proportional to frictional retarding factors.
    Factors affecting Electrophoretic Mobility:

  • 5 October 2016
    Discuss about carrier gases, column and solid support stationary phases in GLC

    Q.4. (b)Discuss about carrier gases, column and solid support stationary phases in GLC
    Ans.4. (b) Carrier gas: For selecting a carrier gas following considerations should be taken into account:

  • 5 October 2016
    Give difference stationary phases used in different modes of HPLC

    Q.4.(a) Give difference stationary phases used in different modes of HPLC.
    Ans.4. (a)Types of Stationary Phases used in HPLC:     Various stationary phases available for HPLC are  Polystyrene/Divinylbenzene- Based Resins   In ion chromatography, the support material is polystyrene/ divinylbenzene (PS/DVB) based resin that is relatively stable with respect to pH.

  • 5 October 2016
    Differentiate between PMR and 13 CNMR

    Q.3. (b) How will you simplify complicated splitting pattern in PMR? Differentiate between PMR and 13 CNMR.
    Ans.3. (b)Introduction:
    The complete analysis of a compound is frequently made difficult, when signals overlap and as a result, useful information is often buried due to complexity of the spectrum. In a spectrum several signals may overlap as is the case, e.g., of closely related methylene groups in a molecule. In such a situation an intense, broad and compulsory unresolved signal, termed the methylene envelope may appears between δ 1-2. Another cause of complexity is where a coupling constant is comparable with the chemical shift different between the coupled protons. For these problems following techniques may use to solve them.

  • 5 October 2016
    How will you differentiate between first order and non-first order PMR spectra

    Q.3.(a) How will you differentiate between first order and non-first order PMR spectra
    Ans.3. (a)First order spectra:

    For a spectrum to be first order, the frequency difference (∆v, in Hz) between any two coupled resonances must be significantly larger than the coupling constant that relates them. A first-order spectrum has ∆v/J >  -63.
    First-order resonances have a number of helpful characteristic, some of which are related to the number individual coupling, n:

  • 4 October 2016
    How will you distinguish

    Q.2.(c)How will you distinguish
    (i) 10,20, and 30 aliphatic amines.
    (ii) 10,20,and 30 aliphatic alcohols and phenols.
    (iii) Alkane, alkene, alkyne and arene from each other. 

  • 4 October 2016
    Explain frequency shift due to inductive and mesomeric effects in IR spectroscopy

    Q.2. (b) Explain frequency shift due to inductive and mesomeric effects in IR spectroscopy
    (b)Frequency shift due to inductive:     The inductive effects solely depends upon the ‘intrinsic’ tendency of a substituent to either release or withdraw electrons- by definition, its electronegativity acting either through the molecular chain or through space. This effect usually weakens steadily with increasing distance from the substituent

  • 7 September 2013
    Pharma Analysis

    Pharmaceutical Analysis

    INTRODUCTION
    Pharmaceutical analysis is a branch of practical chemistry that involves a series of process for identification, determination, quantification and purification of a substance, separation of the components of a solution or mixture, or determination of structure of chemical compounds.

  • 22 March 2010
    APPLICATIONS OF IR SPECTROSCOPY

                APPLICATIONS OF IR SPECTROSCOPY

    Infrared spectroscopy is widely used in industry as well as in research. It is a simple and reliable technique for measurement, quality control and dynamic measurement. It is also employed in forensic analysis in civil and criminal analysis.

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