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AQUAMETRY - THE MOISTURE CONTENT DETERMINATION

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  • www.wjpps.com Vol 4, Issue 08, 2015.

    566

    Sandhya et al. World Journal of Pharmacy and Pharmaceutical Sciences

    AQUAMETRY - THE MOISTURE CONTENT DETERMINATION

    P.Sandhya Rani*, G.Nagasowjanya, A.Ajitha, Dr.V. Uma MaheswarRao

    Department of Pharmaceutical Analysis and Quality Assurance CMR College of

    Pharmacy, Kandlakoya (v), Medchal(m), Hyderabad-501401,T.S.India.

    ABSTRACT

    A small amount of a liquid (such as water) that makes something wet

    or moist. Moisture is simply water diffused in a relatively small

    quantity. Nearly all materials contain at least a diminutive volume of

    moisture as a component of the molecular makeup. It is the quantity of

    water contained in a material. Moisture content express the amount of

    water present in a moist sample.Moisture content can be expressed on

    wet or dry basis. Moisture content on dry basis is the amount of water

    per unit mass of dry solids in the sample. Moisture content on wet

    basis is the amount of water per unit mass of moist - or wet sample.

    Moisture content analysis is a critical component of material quality

    and essentially a function of quality control in most production and

    laboratory facilities. The moisture content influences the physical

    properties of a substance such as weight, density, viscosity, Refractive

    index, electrical,Conductivity and many more.

    KEYWORDS: Infrared drying, Karl Fischer titration, Infrared spectroscopy, Refractometry,

    Drying oven withbalance, NMR, Conductivity.

    AQUAMETRY ---- THE MOISTURE CONTENT DETERMINATION

    MOISTURE

    A small amount of a liquid (such as water) that makes something wet or moist. Moisture is

    simply water diffused in a relatively small quantity. Nearly all materials contain at least a

    diminutive volume of moisture as a component of the molecular makeup.

    Water content or moisture content

    It is the quantity of water contained in a material. Moisture content express the amount of

    water present in a moist sample, Moisture content can be expressed on wet or dry

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    Article Received on

    10 June 2015,

    Revised on 30 June 2015,

    Accepted on 19 July 2015

    *Correspondence for

    Author

    P.Sandhya Rani

    Department of

    Pharmaceutical Analysis

    and Quality Assurance CMR

    College of Pharmacy,

    Kandlakoya (v),Medchal(m),

    Hyderabad-501401,

    T.S.India.

  • www.wjpps.com Vol 4, Issue 08, 2015.

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    Sandhya et al. World Journal of Pharmacy and Pharmaceutical Sciences

    basis.Moisture content on dry basis is the amount of water per unit mass of dry solids in the

    sample Moisture content on wet basis is the amount of water per unit mass of moist - or wet

    sample.

    WHY MEASURE WATER OR MOISTURECONTENT?

    Most natural products contain moisture.Excessive or deficient moisture content of a

    substance can adversely impact the physical properties of a material .The water content

    present is seldom of interest. Rather, it shows whether a product intended for trade and

    production has standard properties such as,

    Storability

    Agglomeration in the case of powders

    Microbiological stability

    Flow properties, viscosity

    Dry substance content

    Concentration or purity

    Commercial grade (compliance with quality agreements)

    Nutritional value of the product

    Legal conformity (statutory regulations governing food)

    MOISTURE CONTENT DETERMINATION

    Moisture content analysis is a critical component of material quality and essentially a

    function of quality control in most production and laboratory facilities. From biological

    research organizations, pharmaceutical manufacturers, to food producers and packers,

    moisture content control greatly influences the physical properties and product quality

    ofnearly all substances and materials at all stages of processing and final product existence.

    Methods for moisture determination

    Gravimetric Chemical Spectroscopic other methods

    methods methods methods

    Infrared drying Karl Fischer titration Infrared spectroscopy Density determinationHalogen

    drying Calcium carbide Microwave spectroscopy Refractometry Drying oven withNMR

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    Sandhya et al. World Journal of Pharmacy and Pharmaceutical Sciences

    ConductivitybalanceGas chromatography Microwave drying Phosphorous pentoxyd

    Distillation.

    TABULATED OVERVIEW OF THE METHODS FOR MOISTURE

    DETERMINATION

    Method Method

    type Measurement principl

    Typical

    measur

    emnt

    range

    Typical

    measure

    mnt

    accuracy

    Water

    selecti

    ve

    Drying oven Tg Heating by convection Mass determination before

    and after drying

    0.5

    100%

    0.10.5%

    no

    Infrared drying Tg

    Heating by absorption of IR radiation

    Continuous determination of the mass during

    drying

    0.5-99% 0.10.5% no

    Halogen drying Tg

    Heating by IR radiation with halogen

    radiatorContinuous determination of the mass

    during drying

    0.5-99% 0.10.5% no

    Microwave

    drying Tg

    Heating by absorption of microwavesMass

    determination before and after drying 2-99% 0.10.5% no

    Distillation T

    Usually azeotropic distillation with insoluble

    Usually volumetric determination of the water

    content

    3-70% 1% yes

    Karl Fischer

    titrations

    coulometric

    volumetric

    EC

    C

    Electrochemical production of iodine,ppmyes

    which reacts with an equivalent amount of water.

    Indication by voltage measurement at constant

    current

    Titration of water with iodine solution. Indication

    by voltage measurement at constant current

    1100%

    ppm

    0.05

    0.5%

    yes

    yes

    Ca carbide

    method C

    Titration of water with iodine solution.Titration

    of water with iodine solution. Indication by

    voltage measurement at constant current

    Indication by voltage measurement at constant

    current

    1100% 0.05

    0.5% yes

    Infrared

    spectroscopy SP

    Volume/pressure measurement of acetylene

    formed 180% 0.31% yes

    Microwave

    spectroscopy SP

    Measurement of absorption/reflection of

    microwave radiation 270% 0.31% yes

    NMR

    spectroscopy SP

    Measurement of nuclear magnetic resonance

    (spin) 015% 0.1% yes

    Gas

    chromatography CR

    Separation on a gas chromatographic column

    Detection of the fractions using thermal

    conductivity

    0.11%

    15%

    0.01%

    0.1%

    yes

    Conductometry EL Measurement of the conductivity >3% 0.51% no

    Refractometry OP Measurement of the refractive index 050% 0.51% no

    Dichtemessung PH Messung der Dichte 298% 0.51% no

    TG= Thermogravimetry

    T= Thermal

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    Sandhya et al. World Journal of Pharmacy and Pharmaceutical Sciences

    EC= Electrochemical

    C= Chemical

    SP= Spectroscopic

    CR= Chromatographic

    OP= Optica

    SELECTION OF THE SUITABLE MEASUREMENT METHOD

    The selection of a suitable measurement method essentially depends on the following

    quantities:

    Requirements regarding accuracy, measurement range, repeatability, sensitivity

    Type of bonding of the water

    Desired information: water or moisture content

    Measurement speed

    Amount of sample

    Physical properties of the sample (e.g. decomposition temperature)

    Budget

    Simplicity (operation or functionality)

    Statutory regulations (reference methods)

    Automation capability

    Calibration capability

    Currently, many moisture analysis methods are available for commercial purposes. The

    moisture content influences the physical properties of a substance such as weight, density,

    viscosity, Refractive index, electrical, Conductivity and many more. Over the years, a wide

    range of methods has been developed to measure these physical quantities and express them

    in the form of the moisture content. The measurement methods ca

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