Analytical Methods

An analytical method or analytical technique is a method to determine the concentration of a chemical compound or element in a sample.  There is a very wide variety of methods used for analysis which afford different degrees of sample preparation and instrumentation:

Content Table

Titrimetry

Titration, also known as titrimetry or volumetric analyis,[1] is a common laboratory method of quantitative chemical analysis that is used to determine the unknown concentration of a known reactant. A reagent, called the titrant or titrator,[2] of a known concentration (a standard solution) and volume is used to react with a solution of the analyte or titrand, whose concentration is not known. The reaction is generally carried out in a glass flask containing the liquid or dissolved sample. Titrant solution is volumetrically delivered to the reaction flask using a calibrated burette. Delivery of the titrant is called a titration. The titration is complete when sufficient titrant has been added to react with all the analyte. This is called the equivalence point. An indicator is often added to the reaction flask to signal by colour change when all of the analyte has reacted. The titrant volume where the signal is generated is called the end point. The equivalence and end points are rarely the same. Endpoints can also be determined by other parameters like conductivity, pH, temperature, etc. 

In the classic strong acid-strong base titration for example, the endpoint of a titration is the point at which the pH of the reactant is just about equal to 7, and often when the solution takes on a persisting solid color as in the pink of phenolphthalein indicator. 

Read more in the original Wikipedia article: Titration

Microscopy

Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy, optical, electron, and scanning probe microscopy.
Optical and electron microscopy involve the diffraction, reflection, or refraction of electromagnetic radiation/electron beams interacting with the specimen, and the subsequent collection of this scattered radiation or another signal in order to create an image. This process may be carried out by wide-field irradiation of the sample (for example standard light microscopy and transmission electron microscopy) or by scanning of a fine beam over the sample (for example confocal laser scanning microscopy and scanning electron microscopy). Scanning probe microscopy involves the interaction of a scanning probe with the surface of the object of interest. The development of microscopy revolutionized biology and remains an essential technique in the life and physical sciences. 

Read more in the original Wikipedia article: Microscopy

Chromatography

Chromatography (from Greek χρῶμα chroma "color" and γράφειν graphein "to write") is the collective term for a set of laboratory techniques for the separation of mixtures. It involves passing a mixture dissolved in a "mobile phase" through a stationary phase, which separates the analyte to be measured from other molecules in the mixture based on differential partitioning between the mobile and stationary phases. Subtle differences in a compound's partition coefficient result in differential retention on the stationary phase and thus changing the separation.
Chromatography may be preparative or analytical. The purpose of preparative chromatography is to separate the components of a mixture for further use (and is thus a form of purification). Analytical chromatography is done normally with smaller amounts of material and is for measuring the relative proportions of analytes in a mixture. The two are not mutually exclusive. 

Read more in the original Wikipedia article: Chromatography

Spectroscopy

Spectroscopy ( /spɛk’trɒskəpi/) is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative energy as a function of its wavelength or frequency. Spectroscopic data is often represented by a spectrum, a plot of the response of interest as a function of wavelength or frequency.
Spectrometry and spectrography are terms used to refer to the measurement of radiation intensity as a function of wavelength and are often used to describe experimental spectroscopic methods. Spectral measurement devices are referred to as spectrometers, spectrophotometers, spectrographs or spectral analyzers.
Daily observations of color can be related to spectroscopy. Neon lighting is a direct application of atomic spectroscopy. Neon and other noble gases have characteristic emission colors, and neon lamps use electricity to excite these emissions. Inks, dyes and paints include chemical compounds selected for their spectral characteristics in order to generate specific colors and hues. A commonly encountered molecular spectrum is that of nitrogen dioxide. Gaseous nitrogen dioxide has a characteristic red absorption feature, and this gives air polluted with nitrogen dioxide a reddish brown color. Rayleigh scattering is a spectroscopic scattering phenomenon that accounts for the color of the sky.
Spectroscopic studies were central to the development of quantum mechanics and included Max Planck's explanation of blackbody radiation, Albert Einstein's explanation of the photoelectric effect and Niels Bohr's explanation of atomic structure and spectra. Spectroscopy is used in physical and analytical chemistry because atoms and molecules have unique spectra. These spectra can be interpreted to derive information about the atoms and molecules, and they can also be used to detect, identify and quantify chemicals. Spectroscopy is also used in astronomy and remote sensing. Most research telescopes have spectrographs. The measured spectra are used to determine the chemical composition and physical properties of astronomical objects (such as their temperature and velocity). 

Read more in the original Wikipedia article: Spectroscopy

Electroanalytical Methods

Electroanalytical methods are a class of techniques in analytical chemistry which study an analyte by measuring the potential (volts) and/or current (amperes) in an electrochemical cell containing the analyte.[1][2][3][4] These methods can be broken down into several categories depending on which aspects of the cell are controlled and which are measured. The three main categories are potentiometry (the difference in electrode potentials is measured), coulometry (the cell's current is measured over time), and voltammetry (the cell's current is measured while actively altering the cell's potential).

Read more in the original Wikipedia article: Electroanalytical method

Related Publications

Urban Hydroinformatics: Data, Models and Decision Support for Integrated Urban Water Management - Roland Price and Zoran Vojinovic 
Publication Date: Jan 2011 - ISBN - 9781780401362

Water Technology: An Introduction for Environmental Scientists and Engineers - N. F. Gray 
Publication Date: Aug 2010 - ISBN - 9781843393030

References

[1]titrimetry, n. OED Second edition, 1989; online version November 2010
[2]Compendium for basal practice in biochemistry, 2008 ed.. Aarhus University

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