Analytical Chemistry Definition:
Analytical chemistry is the chemistry discipline concerned with the chemical composition of materials. Analytical chemistry also is concerned with developing the tools used to examine chemical compositions.
or
Analytical Chemistry Analytical chemistry is a branch of chemistry that determines the nature and identity of a substance and its composition. In the early twentieth century there were only four accepted branches of chemistry, organic chemistry, inorganic chemistry, physical chemistry and biochemistry. At that time, analysis was considered to be a service to the other four branches. Its importance grew, and in the process, absorbed techniques and skills from all other four branches so by the 1950s, analytical chemistry was finally accepted as a branch of chemistry in it own right. There are basically two types of analysis, qualitative analysis and quantitative analysis. The former identifies the nature of substance, and if it is mixture, the nature of the components present, whereas, the latter determines the elemental composition of the substance and/or the quantitative distribution of each component. Most analytical procedures start with some type of separation process, filtration, distillation, extraction, centrifugation and, what is most likely today, some form of chromatography. Chromatography, in any one of its different forms, is probably the most important technique available to the analyst. Chtromatography not only separates a mixture into its constituents, but also provide assistance in their identification and gives a quantitative estimation of the amount of each constituent present in the mixture. Any analytical laboratory devoid of any chromatographic technique would, indeed, be restricted in its scope and performance.
Analytical techniques likewise enable chemists to ensure the purity of our medicines and foods and the quality of chemical products such as plasticware, synthetic fibers, solvents, paints, polishes, cleaning fluids, lubricants, and so on.
Analytical chemistry is also central to the development of new products and medicines. Using sophisticated techniques and high-tech instruments, modern chemists can analyze the complex mixture of chemicals found in plants and other natural substances. Their aim is to ferret out those natural chemicals that may prove valuable to medicine or industry.
In the 1960s, analytical chemists revealed what was in the first Moon rocks. Since then, their techniques have likewise been used to analyze meteorites from Mars. Should we ever obtain a sample of life from another planet, analytical chemists will reveal its nature to us. Already, analytical chemistry can be used to identify an individual human being from just a few scant fragments, such as a strand of hair or Most modern analytical chemists do their work with the assistance of powerful computers and an impressive array of electronic equipment. But their field is as old as chemistry itself. Sixteenth-century chemists, for example, knew that a sample of a mineral that burned with a green flame contained copper. One that contained potassium produced a red flame, while sodium burned yellow. Then, as today, the identification of new substances and the analysis of chemical mixtures made all other chemical disciplines possible.
Classical methods
Although modern analytical chemistry is dominated by sophisticated instrumentation, the roots of analytical chemistry and some of the principles used in modern instruments are from traditional techniques many of which are still used today. These techniques also tend to form the backbone of most undergraduate analytical chemistry educational labs.
Quality and Quantity
Analytical chemistry encompasses two main branches: qualitative analysis and quantitative analysis. Qualitative analysis concerns itself with identifying the individual chemicals in unknown samples. Quantitative analysis deals with determining the amounts of various chemicals in a sample. Each of these branches uses special tests to get its results. Analytical chemistry involves both learning how to perform these tests with precision and mastering how to interpret their sometimes beguiling results. The following sections offer a brief introduction to some of the most important and widely used methods in analytical chemistry.
Paper chromatography is basically a one-dimensional process. In column chromatography, an extra dimension is added by using a cylinder of support material. A variety of different materials have been developed for the technique, each of which is suited to separation of different types of substances. Small molecules may be separable using a powdered solid such as silica gel or alumina, which is generally mixed with a solvent. This mixture is then put into a tube with a porous plate or filter at the end to prevent the support material from flowing out. As in paper chromatography, the sample components separate due to differences in their ability to dissolve in the liquid medium or adsorb to the support, as the liquid medium flows through the column. Instead of forming a one-dimensional line, as it would on paper, a single component takes the shape of a disc or cylinder as it migrates forward.
Advances in Analytical Chemistry is a peer-reviewed research journal that is devoted to the dissemination of new and original knowledge in all branches of analytical chemistry. The journal publishes features and news articles about major advances, trends, and challenges in analytical chemistry. These articles include peer-reviewed features written by researchers and news stories that discuss novel analytical concepts and instruments.
Subject areas include, but are not limited to the following fields:
To determine when the molecules have exited the column, an ultraviolet (UV) light is placed so that it is perpendicular to the flowing stream of mobile phase. The molecules in the blood sample will absorb the UV light and create a signal at the detector. The height of the signal will be proportional to the concentration of the drug in the urine. The time between the sample injection and passage through the column is reproducible and, by comparing it to the time observed when standard samples are used, permits component identification.
Analytical chemistry is the chemistry discipline concerned with the chemical composition of materials. Analytical chemistry also is concerned with developing the tools used to examine chemical compositions.
or
Analytical Chemistry Analytical chemistry is a branch of chemistry that determines the nature and identity of a substance and its composition. In the early twentieth century there were only four accepted branches of chemistry, organic chemistry, inorganic chemistry, physical chemistry and biochemistry. At that time, analysis was considered to be a service to the other four branches. Its importance grew, and in the process, absorbed techniques and skills from all other four branches so by the 1950s, analytical chemistry was finally accepted as a branch of chemistry in it own right. There are basically two types of analysis, qualitative analysis and quantitative analysis. The former identifies the nature of substance, and if it is mixture, the nature of the components present, whereas, the latter determines the elemental composition of the substance and/or the quantitative distribution of each component. Most analytical procedures start with some type of separation process, filtration, distillation, extraction, centrifugation and, what is most likely today, some form of chromatography. Chromatography, in any one of its different forms, is probably the most important technique available to the analyst. Chtromatography not only separates a mixture into its constituents, but also provide assistance in their identification and gives a quantitative estimation of the amount of each constituent present in the mixture. Any analytical laboratory devoid of any chromatographic technique would, indeed, be restricted in its scope and performance.
Analytical techniques likewise enable chemists to ensure the purity of our medicines and foods and the quality of chemical products such as plasticware, synthetic fibers, solvents, paints, polishes, cleaning fluids, lubricants, and so on.
Analytical chemistry is also central to the development of new products and medicines. Using sophisticated techniques and high-tech instruments, modern chemists can analyze the complex mixture of chemicals found in plants and other natural substances. Their aim is to ferret out those natural chemicals that may prove valuable to medicine or industry.
In the 1960s, analytical chemists revealed what was in the first Moon rocks. Since then, their techniques have likewise been used to analyze meteorites from Mars. Should we ever obtain a sample of life from another planet, analytical chemists will reveal its nature to us. Already, analytical chemistry can be used to identify an individual human being from just a few scant fragments, such as a strand of hair or Most modern analytical chemists do their work with the assistance of powerful computers and an impressive array of electronic equipment. But their field is as old as chemistry itself. Sixteenth-century chemists, for example, knew that a sample of a mineral that burned with a green flame contained copper. One that contained potassium produced a red flame, while sodium burned yellow. Then, as today, the identification of new substances and the analysis of chemical mixtures made all other chemical disciplines possible.
Classical methods
Quality and Quantity
Analytical chemistry encompasses two main branches: qualitative analysis and quantitative analysis. Qualitative analysis concerns itself with identifying the individual chemicals in unknown samples. Quantitative analysis deals with determining the amounts of various chemicals in a sample. Each of these branches uses special tests to get its results. Analytical chemistry involves both learning how to perform these tests with precision and mastering how to interpret their sometimes beguiling results. The following sections offer a brief introduction to some of the most important and widely used methods in analytical chemistry.
Paper chromatography is basically a one-dimensional process. In column chromatography, an extra dimension is added by using a cylinder of support material. A variety of different materials have been developed for the technique, each of which is suited to separation of different types of substances. Small molecules may be separable using a powdered solid such as silica gel or alumina, which is generally mixed with a solvent. This mixture is then put into a tube with a porous plate or filter at the end to prevent the support material from flowing out. As in paper chromatography, the sample components separate due to differences in their ability to dissolve in the liquid medium or adsorb to the support, as the liquid medium flows through the column. Instead of forming a one-dimensional line, as it would on paper, a single component takes the shape of a disc or cylinder as it migrates forward.
Qualitative analysis
A qualitative analysis determines the presence or absence of a particular compound, but not the mass or concentration. That is, it is not related to quantity.Chemical tests
For more details on this topic, see Chemical test.
There are numerous qualitative chemical tests, for example, the acid test for gold and the Kastle-Meyer test for the presence of blood.Flame test
For more details on this topic, see Flame test.
Inorganic qualitative analysis generally refers to a systematic scheme to confirm the presence of certain, usually aqueous, ions or elements by performing a series of reactions that eliminate ranges of possibilities and then confirms suspected ions with a confirming test. Sometimes small carbon containing ions are included in such schemes. With modern instrumentation these tests are rarely used but can be useful for educational purposes and in field work or other situations where access to state-of-the-art instruments are not available or expedient.Gravimetric analysis
For more details on this topic, see Gravimetric analysis.
Gravimetric analysis involves determining the amount of material present by weighing the sample before and/or after some transformation. A common example used in undergraduate education is the determination of the amount of water in a hydrate by heating the sample to remove the water such that the difference in weight is due to the loss of water.Volumetric analysis
For more details on this topic, see Titration.
Titration involves the addition of a reactant to a solution being analyzed until some equivalence point is reached. Often the amount of material in the solution being analyzed may be determined. Most familiar to those who have taken chemistry during secondary education is the acid-base titration involving a color changing indicator. There are many other types of titrations, for example potentiometric titrations. These titrations may use different types of indicators to reach some equivalence point.Advances in Analytical Chemistry is a peer-reviewed research journal that is devoted to the dissemination of new and original knowledge in all branches of analytical chemistry. The journal publishes features and news articles about major advances, trends, and challenges in analytical chemistry. These articles include peer-reviewed features written by researchers and news stories that discuss novel analytical concepts and instruments.
 Atomic Spectroscopy |
| Bioanalysis |
| Chemical Sensors |
| Chemometrics |
| Chromatography |
| Electrochemistry |
| Electron Spectroscopy |
| Electrophoresis |
| Environmental Analysis |
| Lab Info Management Systems |
| Miscellaneous Techniques |
| Nuclear Magnetic Resonance |
| Optical Molecular Spectroscopy |
| Radiochemical Methods |
| Sample Preparation |
| Surface Analysis |
| Thermal Methods |
| X-Ray Spectroscopy |
From Measurement to Concentration
Most modern analytical chemistry techniques are based on instrumental methods involving optical and electrical instruments. Elemental concentrations can be determined by measuring the amount of light absorbed or emitted by gas-phase atoms. Similarly, molecular concentrations are correlated with the emission or absorption of light by molecules in aqueous solutions . Electrodes, like the glass pH electrode, measure the electrical potential due to the presence of specific ions in solution. Finally, chromatographic methods separate the components of complex mixtures to determine the concentration of each component.Application
One application of instrumental methods is the determination of what drugs a person has taken twenty-four hours after the person took them. In a procedure detailed by Thomas P. Moyer at the Mayo Clinic, a 5-milliliter (0.17-ounce) sample of the patient's blood is analyzed by a technique called high performance liquid chromatography. The sample is treated and injected into a stream of water and methanol that is called a mobile phase. The mobile phase is pumped through a column of fine sand, where the particles of sand have been coated with a thin layer of an oil-like substance (octadecane). The molecules from the blood sample, including the drug, will spend part of their time adsorbed to the modified sand (stationary phase) and part of their time in the mobile phase. The molecules that spend the majority of their time in the mobile phase will it make through the column first.To determine when the molecules have exited the column, an ultraviolet (UV) light is placed so that it is perpendicular to the flowing stream of mobile phase. The molecules in the blood sample will absorb the UV light and create a signal at the detector. The height of the signal will be proportional to the concentration of the drug in the urine. The time between the sample injection and passage through the column is reproducible and, by comparing it to the time observed when standard samples are used, permits component identification.
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