ANALYTICAL CHEMISTRY

APPLICATIONS & ITS FUTURE ASPECTS

Introduction:

Analytical chemistry is the branch of chemistry which deals with the study of separation, identification and quantitative analysis (i.e., estimation) of the chemical components of natural and artificial materials. E.g.:

1) Estimation of Ca, Fe content present in cement.2) Estimation of Fe present in water.3) To study the blending property and thermal stability of polymers.4) To study the morphology of particle size i.e., dimensions of nano sized particles

used as nano fibres, nano clays, nano composites, nano antibacterial air purifier, etc.

5) Application of sot gel method to metal oxides nano particles.6) To study the contents of clay (which is alumino-silicates) which are bricks,

building stones, rock specimens, etc.7) Determination of hardness of water i.e., estimation of Ca and Mg present in

hard water.8) Detection of adulterants in common food stuffs.

E.g.: a) Detection of starch in milk.b) Detection of yellow dye in turmeric powder.c) Detection of Khesari dal in Besan.

In analytical chemistry a chemist have to perform two important steps-

i)Qualitative analysis- It is a quite simple step which involve only the identification step methods or volumetric methods.

ii)Quantitative analysis- It is a more complicated step in comparision to qualitative analysis. It can be classified depending upon the method of analysis or can be categorized according to the scale of analysis. Qualitative analysis can be sub-divided involving classical methods like gravimetry or volumetry or there involving sophisticated instruments estimating with EDTA solution using Eriochrome Black T indicator.

For getting reproducible results, some interfering elements come in the way of quantative analysis and these problems have been solved by analytical chemists having the knowledge of sampling and excellent methods of separation such as solvent extraction, ion-exchange chromatography and other different methods of

chromatography like TLC, paper, partition, HPLC, etc. These methods have significantly helped an analytical chemist to mitigate these problems of interference, a short review of which discussed below.

I) The Isolation and Purification step during analysis involves atomic absorption spectroscopy.

II) The next step on analysis involves volumetric methods or gravimetric methods if the sample is present in milligram concentration.

III) If the sample to be analyzed is present at very low concentration then the analysis involves optical methods or spectroscopic methods like UV- visible, IR- spectroscopy.

IV) The methods principally used for illusidation of structure involved NMR and mass spectroscopy.

V) Thermo analytical and radiochemistry methods are used for quantitative works.

VI) Another important set of methods uses available electro-analytical techniques ie. Potentiometry, cyclic voltametry, Polarography, Conductometry and Coulometric methods of analysis.

Chemical analysis and analytical chemistry:

Chemical analysis establishes the qualitative and quantitative composition of materials. The constituents to be detected or determined are elements, radicals, functional groups, compounds or phases. Analytical chemistry is concerned with much broader and more general aspects of analysis, while chemical analysis is concerned with much narrower and more specific aspects of analysis. The determinatio0n of one constituent in the presence of several other similar materials is essential, e.g. the careful control of conditions such as pH, complexation, change in oxidation state, is essentials. Several advanced in analytical chemistry have been made possible due to the spectacular progress in separation methods. Analysis is generally composed of quantitative analysis and qualitative analysis. Usually qualitative analysis is carried out before quantitative analysis.

Improving the accuracy of analysis:

There are several ways of achieving accuracy in the analysis. One can use small blanks along with the sample during determination. The use of large blanks reduces the precision.

Another way is to give a correction e.g. in weighing of filter paper, or weight of precipitate unreacted or unignited. An analytical chemist should strive hard to improve the existing methods by proper combination of methods of separation and determination

to increase accuracy. Real advances can only be made by abandoning old methods and seeking newer ones. An analytical chemist should be an originator and innovator as well as a repair person.

Applications of Analytical Chemistry:

No other branch of science finds such extensive applications as analytical chemistry, purely for two reasons. Firstly it finds numerous applications in various disciplines of chemistry such as inorganic, organ, physical and biochemistry and secondly it finds wide applications another fields of sciences such as environmental science, agricultural science, biomedical and clinical chemistry, solid state research and electronics, oceanography, forensic science and space research. Hence analytical chemistry plays a very important role in enhancing the human knowledge about natural materials.

Some important methods which are used immensely in analytical chemistry are as follows-

A) CHROMATOGRAPHY- It is defined as a method of deporting a mixture of components into individual components through equilibrium distribution between two phases. The name chromatography (Greek ‘chroma’-color and ‘graphy’ writing) means color writing.

Principle: The technique of chromatography is based on the difference in the rate at which the components of a mixture move through a porous medium ( called stationary phase) under the influence of some solvent or gas ( called moving phase). In chromatography, the stationary phase may be solid or a liquid and the mobile phase may be liquid or a gas.

The various techniques of chromatography are summarized in the table below-

Techniques Stationary Phase Mobile Phase

i) Column Chromatography or Absorption Solid Liquidii) Partition Chromatography Liquid Liquidiii) Paper Chromatography Liquid Liquidiv) Thin Layer Chromatography (TLC) Liquid or Solid Liquidv) Gas Liquid Chromatography (GLC) Liquid Gasvi) Gas Solid Chromatography (GSC) Solid Gas

i) Applications of Column Chromatography:

a) Analytical uses- Capillaries made of glass or copper are used for analytical purposes. Glass capillaries whose internal surfaces are treated with conc. NH3 at 500*c can separate amino acid using Butanone/Pyridine/Dil. Acetic Acid or Xylose/Glucose/Maltose using Butanone/Acetic Acid/Water.b) Deportation of Geometrical Isomers- It helps to separate cis and trans isomers.c) Chromatography is also used in separation of tautomeric mixtures.

ii) Applications of Liquid-Liquid partition Chromatography:

a) Detergent removal from protein solution.b) Separation of steroids, bile acids and microtoxin. c) Removal of pesticides, phenols, incecticides.d) Trace metal concentration from aq. solution.

iii) Applications of Thin Layer Chromatography:

a) TLC is used for checking the separation procedures and purification process.

b) In organic chemistry, TLC is used in the isolation and separation of individual components of a mixture. Besides this, it is applied on checking the purity of sample, examination of reaction and for the identification of organic compounds.

c) Recently TLC has been used for separating cationic, anionic, purely covalent species and also some organic derivatives of the metals.

iv) Applications of Paper Chromatography:

These are most same as the applications of TLC.

v) Applications of Gas Liquid Chromatography (GLC)-

a) The detections of steroid drugs used by the athletes in international sports competitions and the steroids administered to animals in races are being carried out by GLC.b) Hazardous pollutants such as formaldehyde, carbon monoxide, bichloroethylene, benzene and acrylonitrile can be monitored by GLC.c) In analysis of foods, the separation and identification of

lipids,proteins,carbohydrates,preservatives, flavors, colorants and texture, GLC is frequently used.

d) It is also possible to analyze the dairy products by GLC foraldehydes and ketones, fatty acidsand milk sugar.

iv) Applications of Gas Solid Chromatography (GSC):

The apparatus and technique for GSC happen to be the same as for GLC. The only difference lies in the nature of the stationary phase and the length of the column. Information on the columns and therir applications is included in the table.

Column Deportation Gas

Carbon (Carbosieves) Light Hydrocarbons, H2 & O2.Silica (Spherosil, Parasil) Light Hydrocarbons, H2 & O2.Alumina Hydrocarbons.Molecular Sieve H2, O2, N2 and branched chain

Hydrocarbons.

B) NANOTECHNOLOGY - Nanotechnology is considered to be the key technologies for the current century. Efforts are being made worldwide to create smart and intelligent textiles by incorporating various nano particles or creating nano structured surface and intelligent textiles by incorporating various nano particles or creating nano structured surface and nano fibres which lead to unprecedented level of textile performances, such as strain resistant, self cleaning, antistatic, UV protective, etc.

There are two main techniques involved in nano technology-

i) Scanning Electron Technology (SEM)- The scanning electron microscope that images the sample surface by scanning it with a high energy beam of electrons. Conventional light microscopes use a series of glass image while the scanning electron microscope creates the magnified image by using electrons instead of light waves.

Applications of SEM:

a) The SEM shows very detailed 3D black and white images at much high magnifications (up to 300000X) as compared to light microscope (up to 10000X).

b) The surface structure of polymer nano particles and nano coating can be imaged through SEM- with great clarity.

c) SEM can be used for antibacterial air purifier.d) SEM technique can also be used to view dispersion of nano

particles such as carbon nano-tubes, nano clays and hybrid.

ii) Transmission Electron Microscope (TEM)- Transmission electron microscopy is a

Microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen and interacts as passes through the sample. An image is formed from the electron transmitted through the specimens magnified and focused by an objective lens and appears on an imaging screen.

Applications of TEM:

i. The TEM is used widely in both material science/metallurgy and biological sciences. In both cases the specimens must be very thin and be able to with stand the high vacuum present in side the instrument.

ii. The properties of nano composite depend to a large extent on successful nano level dispersion or intercalation/exfoliation of nano clays, therefore monitoring their morphology and dispersion is very crucial.

C) THERMAL METHODS - Thermal methods of anlysis may be defined as those techniques in which changes in physical and/or chemical properties of substance are measured as a function of temperature.

The methods of thermal analysis have been widely accepted in analytical chemistry.

The various techniques of thermal analysis are summarised in the table below-

NAME OF THE TECHNIQUE

ABBREVIATION OF THE TECHNIQUE

INSTRUMENT EMPLOYED

PARAMETERS MEASURED

DRAWING OF THE CURVE

THERMO-GRAVITY TG THERMO-BALANCE

MASS Mass V/S Temperature or Time

DERIVATIVE THERMOGRAVIMETRY

DTG THERMO-BALANCE

dm/dt dm/dt V/S Temperature

DIFFERENTIAL THERMAL ANALYSIS

DTA DTA APPARATUS

∆T ∆T V/S Temperature

DIFFERNTIAL SCANNING CALORIMETRY

DSC CALORIMATERY dH/dt d H/dt V/S Temperature

I) THERMOGRAVIMETRY (TG)- It is a technique whereby the weight of a substance in an environment heated or cooled at a controlled rate, is recorded as a function of time or temperature.

Applications of Thermogravimetry-i) It helps in determining purity and thermal stability of both the

primary and secondary standard.ii) It helps in determining the composition of alloys and mixtures.iii) In analytical chemistry use- analytical reagents especially those used

in titrimetric analysis as primary standards e.g, sodium carbonate, sodium tetraborate and potassium hydrogen phthalate have been examined.

iv) Building materials- one of the intresting examples in cement is the study of a ternary compound in the system CaO-Al2 O3 –SiO2.

v) One of the most important applications of TG is in examining the thermal stability of polymers. TG is also capable of giving informations concerning polymer’s identity.

II) DERIVATIVE THERMOGRAVIMETRY(DTG)- In DTG curve, the first derivative of the TG curve is plotted with respect ot eithr temperature or time.

This is produced electronically from the TG trace by the computer and represents the dm/dt or occasionally the dm/dt as a function of time or T.

Applications of DTG-i) The magnitude of DTG signal is directly proportional to the rate of reaction, it

allows the comparision of reaction rates and ii) The DTG curve separates overlapping reactions more clearly than the TG

curve.

III) DIFFERTIAL THERMAL ANALYSIS(DTA )- DTA though often considered an adjunct to TG is infact far more versatile and yields data if a considerably more fundamental nature. This technique is simple as it involves the techniques of recording the defference in temperature between a substance and a reference material against time or temperature.

Applications of DTA-i) Thermal diffusivity- DTA has been used to determine the thermal diffusivities

by measuring the temperature difference, ∆Ts, between the centre and surface of the sample, heated at a uniform rate.

ii) Analytical chemistry use-

a) DTA has become an established technique for the identification of clays.b) In a reaction the products are identified by this specific DTA curve.c) An melting point can be easily determined by DTA.d) DTA technique has been widely used for the quality control of a large no. Of

substaces like cement, glass, soil, catalysts, textiles, resins etc.iii) Miscellaneous applications- DTA has been made to detect energy changes

occuring during melting, polymorphic transitions, and second order transitions.

IV) DIFFERENTIAL SCANNING CALORIMETRY(DSC)- It is a thermal method whereby the energy necessary to establish a zero temperature difference between a substance and a reference material is recorded as a function of temperature or time.

Applications of DSC-i) DSC provides a rapid yet reliable method for determining the purity of

materials.ii) Using DSC calorimeter a blend containing Nylon66, orlon and vycron polyester

can be determined.iii) DSC can be used to determine calcium sulphate hydrates in cement.iv) DSC can be used to study the no. and the temperature range of polymorphs.

Since each polymorphic transition causes an energy change that may also be detected by DSC.

CONCLUSION- From the above discullion it can be concluded that the analytical chemistry is an important tool in the hands of an analytical chemist for the quantitative as well as qualitative analysis of a compound accurately. Analytical chemistry has various aspects in the different fields of study. Now a days a chemist can not think of analysis of substances used in our daily life and also which are naturally abundant without analytical chemistry. In near futhre it is going to be the capstone of all the branches of chemistry. All the materials used in our daily life i.e, hags, clothes, chair, aeroplane, fans etc. belong to polymer family and the thermal stabiliyty of these po;ymers is a part of analytical chemistry,. Now a days nano science and technology is growing in the field of chemistry. The morphology i.e, size,dimensions, surface structure of the nanoparticles used as nanofibres, nonocoatings, nanopolymers, nanocomposites etc. can be dermined by tools and techniques which is an integral part of analytical chemistry. So, the analytical chimistry is essential and integral part for the development of the future prospects of the world.