Analytical Chemistry, Chemistry tutorial

Introduction:

Chemistry is basically the study of matter, comprising its composition and structure, its physical properties and its reactivity. There are numerous ways to study the chemistry; however we traditionally divide it into five fields: inorganic chemistry, organic chemistry, biochemistry, physical chemistry and analytical chemistry. However, this division is historical and perhaps, arbitrary-as witnessed via current interest in interdisciplinary areas like bio-analytical chemistry and Organometallic chemistry, these five fields remain the simplest division spanning the stream of chemistry.

What is Analytical Chemistry?

The whole thing is made up of chemicals. Analytical chemistry finds out what and how much. In another words analytical chemistry is mainly concerned with the separation, identification and determination of the relative amounts of the components making up the sample.

Analytical chemistry is mainly concerned by the chemical characterization of matter and the answer to two vital questions what it (qualitative) is and how much is it (quantitative). Analytical chemistry answering for fundamental questions regarding a material sample:

  • What?
  • Where?
  • How much?
  • What arrangement, structure or form?

Analytical science connects a number of scientific disciplines comprising chemistry, physics, biochemistry, mathematics and engineering. It is a science of measurement and at last of metrology when all the variables are comprehended and controlled. The analytical chemistry includes:

a) Qualitative analysis recognizes the elements, species and compounds in a sample.

b) Quantitative analysis finds out the absolute or relative amounts of elements, species and compounds in the sample.

c) Structural analysis finds out the spatial arrangements of atoms or recognizes the functional groups.

Applications of Analytical Chemistry:

Analytical chemistry is utilized in numerous fields:

1) In medicine, analytical chemistry is the base for clinical laboratory tests that assist physicians in diagnosis the disease and chart progress in recovery.

2) In industry, analytical chemistry gives the means of testing raw materials and for reassuring the quality of finished products whose chemical composition is vital. Most of the household products, paints, fuels, pharmaceuticals and so on are analyzed by the procedures developed via analytical chemists prior to being sold to the consumer.

3) Environmental quality is frequently evaluated by testing for suspected contaminants by employing the methods of analytical chemistry.

4) The nutritional value of food is found out by chemical analysis for main components like carbohydrates and protein and trace components like vitamins and minerals. Certainly, even the calories in a food are often computed from the chemical analysis.

5) Forensic analysis - analysis associated to criminology; DNA, finger print detection and blood analysis.

6) Bio-analytical chemistry and analysis- detection and/or analysis of biological components (that is, proteins, RNA, DNA, carbohydrates, metabolites and so on).

History:

The Analytical chemistry starts in the late 18th century by the work of French chemist Antoine-Laurent Lavoisier and others; the discipline was further expanded in the 19th century by Carl Fresenius and Karl Friedrich Mohr. As a pharmacist's apprentice in Frankfurt, Germany, Fresenius build up an extensive qualitative analysis scheme that, when it was later published, served as the first text-book of the analytical chemistry. He built a lab at his house which opened in the year 1848. Here he trained students in gravimetric methods which he had developed. Mohr developed laboratory devices like the pinch clamp burette and the volumetric pipette. He as well devised a colorimetric end-point for silver titrations. It was his book on titrimetry, in the year 1855, Lehrbuch der Chemisch-Analytischen Titromethode that generated widespread interest in the method.

The Scope of Analytical Chemistry:

Analytical chemistry has bounds that are amongst the broadest of any technical discipline. An analyst should be capable to design, carry out, and interpret his measurements in the context of the basic technological problem by which he is presented. The selection and utilization of appropriate chemical procedures needs a broad knowledge of chemistry, even as familiarity with and the capability to operate a varied range of instruments is necessary. At last, an analyst should encompass a sound knowledge of the statistical treatment of experimental data to allow him to gauge the meaning and reliability of the outcomes that he obtains.

Whenever an examination is limited to the recognition of one or more constituents of sample, it is termed as the qualitative analysis, whereas an examination to find out how much of a particular species is present comprises a quantitative analysis. At times information relating to the spatial arrangement of atoms in a molecule or crystalline compounds is needed or confirmation of the presence or position of some organic functional groups is sought. Such examinations are illustrated as structural analysis and they might be considered as more detailed forms of analysis. Any species which are the subjects of either qualitative or quantitative analysis are acknowledged as anlayte.

Function of Analytical Chemistry:

Some of the main areas of application are described below.

a) Fundamental research:

The primary steps in unraveling the details of an unknown system often comprise the identification of its constituents through qualitative chemical analysis. Follow up investigations generally need structural information and quantitative measurements. This pattern seems in such diverse areas as the formulation of new drugs, the examination of meteorites and studies on the results of heavy ion bombardment via nuclear physicists.

b) Product development:

The design and expansion of a new product will often based on establishing a link between its chemical composition and its physical properties or the performance. Typical illustrations are the growth of alloys and of polymer composites.

c) Product quality control:

Most of the manufacturing industries need a uniform product quality. To make sure that this requirement is met, both the raw materials and finished products are subjected to extensive chemical analysis. On the other hand, the essential constituents should be kept at the optimum levels; whereas on the other impurities like poisons in foodstuffs should be kept beneath the maximum allowed by law.

 d) Monitoring and control of pollutants:

Remaining heavy metals and organo-chlorine pesticides exhibit two renowned pollution problems. Sensitive and accurate analysis is needed to allow the distribution and level of a pollutant in the environment to be evaluated and routine chemical analysis is significant in the control of industrial effluents.

e) Assay:

In commercial dealings with raw materials like ores, the value of ore is set by its metal content. Large amounts of material are over and over again involved, in such a way that overall small differences in concentration can be of considerable commercial importance. Accurate and reliable chemical analysis is therefore necessary.

f) Medical and Clinical Studies:

The level of different elements and compounds in body fluids are significant indicators of the physiological disorders. High sugar content in urine pointing out a diabetic condition and lead in blood are probably the most renowned illustrations.

Common classification of analytical methods:

1) Gravimetric analytical method:

Gravimetric analysis that by definition is mainly based on the measurement of mass can be generalized into two kinds; precipitation and volatilization. The quantitative determination of the substance by the precipitation process of gravimetric analysis comprises isolation of an ion in solution via a precipitation reaction, filtering, washing the precipitate free of contaminants, transformation of the precipitate to a product of acknowledged composition, and lastly weighing the precipitate and finding out its mass by difference.  From the mass and known composition of the precipitate, the amount of the original ion can be found out.

For successful determinations the given criteria should be met: The desired substance should be fully precipitated. In most of the determinations, the precipitate is of such low solubility that losses from dissolution are negligible. The additional factor is the 'common ion' effect; this further decreases the solubility of the precipitate. Whenever Cl- is precipitated out by addition of Ag+

Ag+ + Cl- → AgCl(s)

The (low) solubility of AgCl is decreased still further via the surplus of Ag+ which is added, pushing the equilibrium to the right. We can further reduce the solubility by decreasing the temperature of the solution by employing an ice bath.  The weighed form of the product must be of known composition. The product must be 'pure' and simply filtered. This is generally difficult to get a product that is 'pure', that is, one which is free from impurities however careful precipitation and adequate washing helps decrease the level of impurity.

2) Volumetric analytical method:

Volumetric analysis is the analytical procedure or method for working out the titre or concentration of an analyte in a solution. This is done via measuring the volume of a standard solution of a suitable reagent whose accurate concentration is already known. The method is based on the reaction between the solution termed to as the titrant and the analyte which is termed to as the titrant. The most general way of carrying out this method is to put the unknown solution in an Erlenmeyer flask and then, by utilizing a burette, slowly add the titrant to it. This method is termed as titration.

3) Spectrometric analytical method:

An early illustration of a colorimetric analysis is Nessler's process for ammonia, which was introduced in the year 1856. Nessler found that adding an alkaline solution of HgI2 and KI to a dilute solution of ammonia generates a yellow to reddish brown colloid, having the colloid's color based on the concentration of ammonia. By visually comparing the color of a sample to the colors of a series of standards, Nessler was capable to find out the concentration of ammonia.

Calorimetry, in which a sample absorbs visible light, is one illustration of a spectroscopic method of analysis. At the end of 19th century, spectroscopy was restricted to the absorption, emission and scattering of ultraviolet, visible and infrared electromagnetic radiation. As its introduction, spectroscopy has expanded to comprise other forms of electromagnetic radiation like microwaves, X-rays and radio waves and other energetic particles like electrons and ions.

As these methods utilize optical materials to disperse and focus the radiation, they often are recognized as optical spectroscopes. For ease we will use the simpler word spectroscopy in place of optical spectroscopy; though, you must understand that we are considering only a limited portion of a much wider area of analytical methods.

In spite of the difference in instrumentation, all the spectroscopic methods share some common characteristics.

4) Electrochemical analytical method:

Analytical methods that utilizes a measurement of potential, charge or current to find out an analyte concentration or to characterize the analyte's chemical reactivity. Collectively we state this area of analytical chemistry electrochemistry as it is originated from the study of the movement of electrons in the oxidation-reduction reaction.

In spite of the difference in instrumentation, all the electrochemical methods share some common characteristics.

5) Chromatographic analytical method:

Chromatography from the Greek means: chroma + graphia, literally 'Colour writing'

A method for analyzing mixtures of gases, liquids and solutes by exploiting the differences in their distribution between a stationary and a mobile stage.

Chromatography is the basic method for the separation, detection, recognition and quantization of chemical species. This comes in two fundamental formats: planar and column chromatography. Chromatographic methods can as well be categorized according to whether they are being employed for recognition and measurement (that is, analytical, for micro scale to trace quantities of analyte) or as a purification step (that is, preparative, for semi micro to macro scale quantities of analyte). Nowadays, chromatographic methods are necessary tools in areas like chemistry, medicine, forensic science, biology, manufacturing and the environment and are arguably the most broadly employed of any family of the analytical methods.

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