chemical analysis

McGraw-Hill Science & Technology Dictionary:

analytical chemistry

(′an·əl′id·ə·kəl ′kem·ə·strē)

(chemistry) The branch of chemistry dealing with techniques which yield any type of information about chemical systems.

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Analytical chemistry

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The science of chemical characterization and measurement. Qualitative analysis is concerned with the description of chemical composition in terms of elements, compounds, or structural units, whereas quantitative analysis is concerned with the measurement of amount.

Analytical chemistry, once limited to the determination of chemical composition in terms of the relative amounts of elements or compounds in a sample, has been expanded to involve the spatial distribution of elements or compounds in a sample, the distinction between different crystalline forms of a given element or compound, the distinction between different chemical forms (such as the oxidation state of an element), the distinction between a component on the surface or in the interior of a particle, and the detection of single atoms on a surface. To permit these more detailed questions to be answered, as well as to improve the speed, accuracy, sensitivity, and selectivity of traditional analysis, a large variety of physical measurements are used. These methods are based on spectroscopic, electrochemical, chromatographic, chemical, and nuclear principles.

Modern analysis has also placed significant demands on sampling techniques. It has become necessary, for example, to handle very small liquid samples [in the nanoliter (10⁻⁹ liter) range or less] as part of the analysis of complex mixtures such as biological fluids and to simultaneously determine many different components. The sample may be a solid that must be converted through vaporization into a form suitable for analysis.

Spectroscopy includes the measurement of emission, absorption, reflection, and scattering phenomena resulting from interaction of a sample with gamma rays and x-rays at the high-energy end of the spectrum and with the less energetic ultraviolet, visible, infrared, and microwave radiation. See also Spectroscopy.

Lower-energy forms of excitation such as ultraviolet, visible, or infrared radiation are used in molecular spectroscopy. Ultraviolet radiation and visible radiation, which are reflective of the electronic structure of molecules, are used extensively for quantitative analysis. The radiation absorbed by the sample is measured. It is also possible to measure the radiation emitted (fluorescence). The absorption of infrared radiation is controlled by the properties of bonds between atoms, and it is accordingly most widely used for structure identification and determination. It is not widely used for quantitative analysis except for gases such as carbon monoxide (CO) and hydrocarbons. X-rays are used through emission of characteristic radiation, absorption, or diffraction. In the last case, characteristic diffraction patterns reveal information about specific structural entities, such as a particular crystalline form. Extended x-ray absorption fine structure (EXAFS) is based on the use of x-rays from a synchrotron source to reveal structural details such as interatomic distances. See also Emission spectrochemical analysis; Extended x-ray absorption fine structure (EXAFS); X-ray fluorescence analysis.

Though not strictly a spectroscopic technique, mass spectrometry is an important and increasingly applied method of analysis, especially for organic and biological samples. Among the applications are the analysis of more than 70 elements (spark-source mass spectrometry), surface analysis (secondary ion mass spectrometry and ion-probe mass spectrometry), and the determination of the structure of organic molecules and of proteins and peptides (high-resolution mass spectrometry). See also Mass spectrometry; Secondary ion mass spectrometry (SIMS).

Nuclear magnetic resonance measures the magnetic environment around individual atoms and provides one of the most important means for deducing the structure of a molecule. Atoms possessing nuclear spin are probed by monitoring the interaction between their nuclear spin and an applied external magnetic field. For large molecules these interactions are complex, and a variety of nuclear excitation techniques have been developed that permit establishment of the connectivity between the various atoms in a molecule. Since the technique is nondestructive, it can be used to monitor living systems. See also Nuclear magnetic resonance (NMR).

Several forms of spectroscopy are especially useful for surface analysis. The scanning electron microscope (SEM) involves a finely collimated electron beam that sweeps across the surface to produce an image. At the same time the surface atoms are excited to emit characteristic x-rays, thus making it possible to obtain an image of the surface along with its spatially resolved elemental composition. The resolution of this technique (electron microprobe) is in the micrometer (10⁻⁴ cm) range. Images with a resolution of angstroms (10⁻⁸ cm) have been obtained by using the techniques of atomic force microscopy (AFM) and scanning tunneling microscopy (STM), which correspond to the dimensions of individual atoms. A significant advantage of the latter two techniques is that a high vacuum is not required, so samples can be analyzed at atmospheric pressure. See also Electron-probe microanalysis; Electron spectroscopy.

Potentiometry is the most widely applied electrochemical technique, since it includes a variety of ion-selective electrodes, the most important of which is the glass electrode used to measure pH. Other important ion-selective electrodes measure ions of sodium, potassium, calcium, sulfide, chloride, and fluoride. When the electrodes are used in conjunction with gas-permeable membranes, gases such as ammonia, carbon dioxide, and hydrogen sulfide can be measured. See also Electrochemistry; Ion-selective membranes and electrodes; pH; Polarographic analysis.

Separation techniques include the various forms of chromatography and electrophoresis. They are based on the separation of a mixture of species in a sample due to differential migration. Two forces act in opposition: a stationary phase acts to retard a migrating species, while the mobile phase tends to promote migration. The mobile phase may be liquid (liquid chromatography) or gaseous (gas chromatography), while the stationary phase may be a solid or a solid covered with a thin film of liquid. The stationary phase is typically packed in a column through which the mobile phase is pumped. High-performance liquid chromatography (HPLC) has become especially important for the separation of complex mixtures of nonvolatile materials. Separations may often be accomplished in a matter of several minutes. The stationary phase can preferentially interact with the migrating species according to charge, size, hydrophobicity, or in some cases because of the special affinity which a species has for the stationary phase (affinity chromatography). The stationary phase can also be a thin layer of solid support deposited on a plate (thin-layer chromatography). See also Chromatography; Gas chromatography; Liquid chromatography.

Alternatively, the driving force for separation will be the migration of charged species in an electric field (electrophoresis). The stationary phase may be a gel on a plate or in a tube, or a solution maintained in a capillary through which the analytes move. The important techniques in this area are capillary electrophoresis, isotachophoresis, and isoelectric focusing. See also Electrophoresis.

Thermal methods are based on the heating of a sample over a range of temperatures. This approach may result in absorption of heat by the sample or in evolution of heat due to physical or chemical changes. Thermogravimetry involves the measurement of mass; differential thermal analysis involves a detection of chemical or physical processes through a measurement of the difference in temperature between a sample and a stable reference material; differential thermal calorimetry evaluates the heat evolved in such processes. A variety of calorimetric techniques are used to measure the extent of reactions that are otherwise difficult to evaluate. See also Calorimetry.

Columbia Encyclopedia:

chemical analysis

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chemical analysis, the study of the chemical composition and structure of substances. More broadly, it may be considered the corpus of all techniques whereby any exact chemical information is obtained. There are two branches in analytical chemistry: qualitative analysis and quantitative analysis. Qualitative analysis is the determination of those elements and compounds that are present in a sample of unknown material. Quantitative analysis is the determination of the amount by weight of each element or compound present. The procedures by which these aims may be achieved include testing for the chemical reaction of a putative constituent with an admixed reagent or for some well-defined physical property of the putative constituent. Classical methods include use of the analytical balance, gas manometer, buret, and visual inspection of color change. Gas and paper chromatography are particularly important modern methods. Physical techniques such as use of the mass spectrometer are also employed. For samples in the gaseous state, optical spectroscopy provides the best technique for determining which atomic and molecular species are present.

Wiley Dictionary of Flavors:

Analytical Chemistry

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The branch of chemistry that deals with the testing and analysis of substances. In analytical food chemistry, gas chromatographic (GC) analysis, high pressure or high performance liquid chromatography (HPLC), and mass spectroscopy (MS) analysis are some of the techniques employed.

Acid Value of Fats - A determination of the free fatty acids (FFA) in a fat. The more critical test is the report of FFA
Active Oxygen Method (AOM - AOCS Cd 12-57) - Measures oxidative stability of an oil by bubbling air into a fat at a certain temperature.
Alkaline Soaps (AOCS Cc 17-95) - Measures the reactivity of metals on fats in water to determine the relative instability of a fat.
Anisidine Value (AOCS Cd 18-90) - Measures the aldehyde content of a fat, a measure of the degree of partial oxidation.
Arsenic, Lead, and Heavy Metals (FCC III) Third Ed. - An analytical to determine the presence of trace lead, arsenic, and other heavy metals and subsequent food grade status.
Ash (FCC III) - Flamed oxidation test of acid soluble, acid insoluble ash, and total ash.
Curcumin Test (FCC III) - Spectrophotometric assay of the coloring principle of turmeric.
Enzyme (Alpha Amylase Titrametric Test using Iodine/Starch reaction) and others (pages 479 to 499 FCC 111).
Fatty Acid Methyl Esters (FAME AOCS Ce 1-62) - Determines the fatty acid composition of a glyceride.
Fiber Tests - Total Dietary Fiber: AOAC 985.29 AACC 32-05; Insoluble Fiber: AOAC 991.42, AACC 32-21; Soluble Fiber: AOAC 991.19, AACC 32-21; Total Fiber: AOAC 991.43, AACC 32-07; Polydextrose: AOAC 2000.11; Fructans: AOAC 997.08, AACC 32-23; Beta D Glucans: AOAC 992.28 and 995.16, AACC 32-22 and 32-23.
Free Fatty Acids (FFA AOCS Ca 5a-40) - Measures by titration, the non-attached fatty acid ratio in an oil.
GLC Profile (FCC - EOA Method) - Uses relative retention time and internal standards for the identification and separation of volatile materials by GC.
Infrared Photospectrometric Method (FCC III) - A match of an unknown material to a standard fingerprint pattern. Also called Ramen Profile.
Iodine Value (AOCS Cd 1-25) - Measures the degree of unsaturation of an oil and therefore the degree of potential instability due to oxidative rancidity.
Kjeldahl Nitrogen Assay - Determines the amount of nitrogen present (mostly from amino acids and proteins).
Karl Fischer Determination - Pyridine based titration used to detect small amounts of water. (See Number 17, Loss on Drying below.)
Loss on Drying (FCC III) - A sample heated to constant weight (water driven off), analytically weighed, and calculated.
Oil Stability Index (OSI AOCS Cd 12b-92) - Measures the content of formic acid present as a measure of the degree of oxidation of an oil.
Optical Rotation - An instrumental analysis indicating the degree of rotation of polarized light by an optical active chemical. A clockwise rotation is a dextrorotatory (d or +) and a counterclockwise rotation is laevorotatory (l or -). A substance that has both dextro- and laevo- rotatory species in equal amounts is called racemic (dl). Substances that share the same structural and chemical formulae but are different by optical isomerism are called enantiomers of each other.
Peroxide Value (PV AOCS Cd 8b-90) - Measures the degree of peroxides present as a measure of the amount of partial oxidation of an oil.
Piperine Test (FCC III) - Spectrophotometric analysis of piperine in black pepper oleoresin.
pH (FCC III) - The determination is usually done by electrode, pH paper, or titration, although electrode is far more accurate and more prevalent.
Polar Materials (TPM AOCS Cd 20-91) - Considered one of the most important tests for the determination of the degree of oxidation of an oil. It measures the total amount of non-lipid compounds in a fat system.
Polymers (AOCS Cd 22-91) - Includes dimers, trimers, and tetramers, or dark shellacs of oils formed on surfaces of ovens, etc., indicating the degree of oil degradation other than polar compounds.
Refractive Index - An instrumentally measured test that determines the degree of change of the angle of incidental light as it passes through a substance (also can be used as an indication of purity).
Saponification Value - Amount of sodium hydroxide to neutralize free fatty acids.
Scoville Heat Units (FCC III) - A dilution/comparison taste test to determine the heat principle, capsaicin, present in oleoresin of capsicum.
Solidification Point (FCC III) (or Melting Point) - This test can be run by an instrument that slowly lowers the temperature of a known sample until solidification is reached.
Spray Dried Efficiency - (Entrapped Oil) = Total Oil - Surface Oil/Total Oil.
Surface Oil (Spray Dried Material) - Using ethyl ether or other non-aqueous solvent, gently mix powder and evaporate analytically. The surface oil is then weighed.
Thiobarbituric Acid (TBA AOCS Cd 19-90) - A spectrophotometric test of TBA reacted oxidation products present in a fat.
Total Oil (Spray Dried Materials) - Add water to powder. Extract oils with solvent. Evaporate and weigh. Consider water soluble fraction.
Viscosity (FCC III) - Ubbelohde Glass Bored Viscometer measures the time a thickened liquid travels from one point to another.
Viscosity (FCC III) (Brookfield Viscometer) (Model LVG) - An instrument that measures the degree of friction-based obstruction of a rotating disk due to the viscosity of a liquid in which it is immersed.
Volatile Oil Content (FCC III) - Distillation method with a V.O. (Clevenger) trap.
Water Determination (FCC III) - Karl Fischer Titrametric Determination. This is a fairly accurate determination for water using a methanol, a pyridine, and an iodine titrametric indicator called Karl Fischer Reagent. Other moisture methods include loss on drying and the toluene method.

Note: AOAC (American Association of Analytical Chemists); FCC (Food Chemicals Codex); AACC (American Association of Clinical Chemists).

See Wet Analysis, Instrumental Analysis.

Oxford Dictionary of Biochemistry:

analytical chemistry

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the branch of chemistry concerned with analysing materials by chemical (or physical) methods.

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Wikipedia on Answers.com:

Analytical chemistry

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For the journal, see Analytical Chemistry (journal).

Analytical chemistry is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials.^[1] Qualitative analysis gives an indication of the identity of the chemical species in the sample and quantitative analysis determines the amount of one or more of these components. The separation of components is often performed prior to analysis.

Analytical methods can be separated into classical and instrumental.^[2] Classical methods (also known as wet chemistry methods) use separations such as precipitation, extraction, and distillation and qualitative analysis by color, odor, or melting point. Quantitative analysis is achieved by measurement of weight or volume. Instrumental methods use an apparatus to measure physical quantities of the analyte such as light absorption, fluorescence, or conductivity. The separation of materials is accomplished using chromatography or electrophoresis methods.

Analytical chemistry is also focused on improvements in experimental design, chemometrics, and the creation of new measurement tools to provide better chemical information. Analytical chemistry has applications in forensics, bioanalysis, clinical analysis, environmental analysis, and materials analysis.

History

Gustav Kirchhoff (left) and Robert Bunsen (right)

Analytical chemistry has been important since the early days of chemistry, providing methods for determining which elements and chemicals are present in the object in question. During this period significant analytical contributions to chemistry include the development of systematic elemental analysis by Justus von Liebig and systematized organic analysis based on the specific reactions of functional groups.

The first instrumental analysis was flame emissive spectrometry developed by Robert Bunsen and Gustav Kirchhoff who discovered rubidium (Rb) and caesium (Cs) in 1860.^[3]

Most of the major developments in analytical chemistry take place after 1900. During this period instrumental analysis becomes progressively dominant in the field. In particular many of the basic spectroscopic and spectrometric techniques were discovered in the early 20th century and refined in the late 20th century.^[4]

The separation sciences follow a similar time line of development and also become increasingly transformed into high performance instruments.^[5] In the 1970s many of these techniques began to be used together to achieve a complete characterization of samples.

Starting in approximately the 1970s into the present day analytical chemistry has progressively become more inclusive of biological questions (bioanalytical chemistry), whereas it had previously been largely focused on inorganic or small organic molecules. Lasers have been increasingly used in chemistry as probes and even to start and influence a wide variety of reactions. The late 20th century also saw an expansion of the application of analytical chemistry from somewhat academic chemical questions to forensic, environmental, industrial and medical questions, such as in histology.^[6]

Modern analytical chemistry is dominated by instrumental analysis. Many analytical chemists focus on a single type of instrument. Academics tend to either focus on new applications and discoveries or on new methods of analysis. The discovery of a chemical present in blood that increases the risk of cancer would be a discovery that an analytical chemist might be involved in. An effort to develop a new method might involve the use of a tunable laser to increase the specificity and sensitivity of a spectrometric method. Many methods, once developed, are kept purposely static so that data can be compared over long periods of time. This is particularly true in industrial quality assurance (QA), forensic and environmental applications. Analytical chemistry plays an increasingly important role in the pharmaceutical industry where, aside from QA, it is used in discovery of new drug candidates and in clinical applications where understanding the interactions between the drug and the patient are critical.

Classical methods

The presence of copper in this qualitative analysis is indicated by the bluish-green color of the flame.

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.

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 college chemistry 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.

Instrumental methods

Main article: Instrumental analysis

Block diagram of an analytical instrument showing the stimulus and measurement of response

Spectroscopy

For more details on this topic, see Spectroscopy.

Spectroscopy measures the interaction of the molecules with electromagnetic radiation. Spectroscopy consists of many different applications such as atomic absorption spectroscopy, atomic emission spectroscopy, ultraviolet-visible spectroscopy, x-ray fluorescence spectroscopy, infrared spectroscopy, Raman spectroscopy, dual polarisation interferometry, nuclear magnetic resonance spectroscopy, photoemission spectroscopy, Mössbauer spectroscopy and so on.

Mass spectrometry

For more details on this topic, see Mass spectrometry.

An accelerator mass spectrometer used for radiocarbon dating and other analysis.

Mass spectrometry measures mass-to-charge ratio of molecules using electric and magnetic fields. There are several ionization methods: electron impact, chemical ionization, electrospray, fast atom bombardment, matrix assisted laser desorption ionization, and others. Also, mass spectrometry is categorized by approaches of mass analyzers: magnetic-sector, quadrupole mass analyzer, quadrupole ion trap, time-of-flight, Fourier transform ion cyclotron resonance, and so on.

Electrochemical analysis

For more details on this topic, see Electroanalytical method.

Electroanalytical methods measure the potential (volts) and/or current (amps) in an electrochemical cell containing the analyte.^[7]^[8] These methods can be categorized according to 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).

Thermal analysis

Further information: Calorimetry, thermal analysis

Calorimetry and thermogravimetric analysis measure the interaction of a material and heat.

Separation

Separation of black ink on a thin layer chromatography plate.

Further information: Separation process, Chromatography, electrophoresis

Separation processes are used to decrease the complexity of material mixtures. Chromatography and electrophoresis are representative of this field.

Hybrid techniques

Combinations of the above techniques produce a "hybrid" or "hyphenated" technique.^[9]^[10]^[11]^[12]^[13] Several examples are in popular use today and new hybrid techniques are under development. For example, gas chromatography-mass spectrometry, gas chromatography-infrared spectroscopy, liquid chromatography-mass spectrometry, liquid chromatography-NMR spectroscopy. liquid chromagraphy-infrared spectroscopy and capillary electrophoresis-mass spectrometry.

Hyphenated separation techniques refers to a combination of two (or more) techniques to detect and separate chemicals from solutions. Most often the other technique is some form of chromatography. Hyphenated techniques are widely used in chemistry and biochemistry. A slash is sometimes used instead of hyphen, especially if the name of one of the methods contains a hyphen itself.

Microscopy

Fluorescence microscope image of two mouse cell nuclei in prophase (scale bar is 5 µm).^[14]

For more details on this topic, see Microscopy.

The visualization of single molecules, single cells, biological tissues and nanomaterials is an important and attractive approach in analytical science. Also, hybridization with other traditional analytical tools is revolutionizing analytical science. Microscopy can be categorized into three different fields: optical microscopy, electron microscopy, and scanning probe microscopy. Recently, this field is rapidly progressing because of the rapid development of the computer and camera industries.

Lab-on-a-chip

A glass microreactor

Further information: microfluidics, lab-on-a-chip

Devices that integrate (multiple) laboratory functions on a single chip of only millimeters to a few square centimeters in size and that are capable of handling extremely small fluid volumes down to less than pico liters.

Standards

Standard curve

A calibration curve plot showing limit of detection (LOD), limit of quantification (LOQ), dynamic range, and limit of linearity (LOL).

A general method for analysis of concentration involves the creation of a calibration curve. This allows for determination of the amount of a chemical in a material by comparing the results of unknown sample to those of a series known standards. If the concentration of element or compound in a sample is too high for the detection range of the technique, it can simply be diluted in a pure solvent. If the amount in the sample is below an instrument's range of measurement, the method of addition can be used. In this method a known quantity of the element or compound under study is added, and the difference between the concentration added, and the concentration observed is the amount actually in the sample.

Internal standards

Sometimes an internal standard is added at a known concentration directly to an analytical sample to aid in quantitation. The amount of analyte present is then determined relative to the internal standard as a calibrant.

Standard addition

The method of standard addition is used in instrumental analysis to determine concentration of a substance (analyte) in an unknown sample by comparison to a set of samples of known concentration, similar to using a calibration curve. Standard addition can be applied to most analytical techniques and is used instead of a calibration curve to solve the matrix effect problem.

Signals and noise

One of the most important components of analytical chemistry is maximizing the desired signal while minimizing the associated noise.^[15] The analytical figure of merit is known as the signal-to-noise ratio (S/N or SNR).

Noise can arise from environmental factors as well as from fundamental physical processes.

Thermal noise

Main article: Johnson–Nyquist noise

Thermal noise results from the motion of charge carriers (usually electrons) in an electrical circuit generated by their thermal motion. Thermal noise is white noise meaning that the power spectral density is constant throughout the frequency spectrum.

The root mean square value of the thermal noise in a resistor is given by^[15]

$v_{{RMS}} = \sqrt { 4 k_B T R \Delta f },$

where k_B is Boltzmann's constant, T is the temperature, R is the resistance, and $Δ f$ is the bandwidth of the frequency $f$ .

Shot noise

Main article: Shot noise

Shot noise is a type of electronic noise that occurs when the finite number of particles (such as electrons in an electronic circuit or photons in an optical device) is small enough to give rise to statistical fluctuations in a signal.

Shot noise is a Poisson process and the charge carriers that make up the current follow a Poisson distribution. The root mean square current fluctuation is given by^[15]

$i_{{RMS}}=\sqrt{2\,e\,I\,\Delta f}$

where e is the elementary charge and I is the average current. Shot noise is white noise.

Flicker noise

Main article: flicker noise

Flicker noise is electronic noise with a 1/ƒ frequency spectrum; as f increases, the noise decreases. Flicker noise arises from a variety of sources, such as impurities in a conductive channel, generation and recombination noise in a transistor due to base current, and so on. This noise can be avoided by modulation of the signal at a higher frequency, for example through the use of a lock-in amplifier.

Environmental noise

Noise in a thermogravimetric analysis; lower noise in the middle of the plot results from less human activity (and environmental noise) at night.

Environmental noise arises from the surroundings of the analytical instrument. Sources of electromagnetic noise are power lines, radio and television stations, wireless devices, Compact fluorescent lamps ^[16] and electric motors. Many of these noise sources are narrow bandwidth and therefore can be avoided. Temperature and vibration isolation may be required for some instruments.

Noise reduction

Noise reduction can be accomplished either in computer hardware or software. Examples of hardware noise reduction are the use of shielded cable, analog filtering, and signal modulation. Examples of software noise reduction are digital filtering, ensemble average, boxcar average, and correlation methods.^[15]

Applications

Analytical chemistry research is largely driven by performance (sensitivity, selectivity, robustness, linear range, accuracy, precision, and speed), and cost (purchase, operation, training, time, and space). Among the main branches of contemporary analytical atomic spectrometry, the most widespread and universal are optical and mass spectrometry.^[17] In the direct elemental analysis of solid samples, the new leaders are laser-induced breakdown and laser ablation mass spectrometry, and the related techniques with transfer of the laser ablation products into inductively coupled plasma. Advances in design of diode lasers and optical parametric oscillators promote developments in fluorescence and ionization spectrometry and also in absorption techniques where uses of optical cavities for increased effective absorption pathlength are expected to expand. Steady progress and growth in applications of plasma- and laser-based methods are noticeable. An interest towards the absolute (standardless) analysis has revived, particularly in the emission spectrometry.

A lot of effort is put in shrinking the analysis techniques to chip size. Although there are few examples of such systems competitive with traditional analysis techniques, potential advantages include size/portability, speed, and cost. (micro Total Analysis System (µTAS) or Lab-on-a-chip). Microscale chemistry reduces the amounts of chemicals used.

Much effort is also put into analyzing biological systems. Examples of rapidly expanding fields in this area are:

Genomics - DNA sequencing and its related research. Genetic fingerprinting and DNA microarray are very popular tools and research fields.
Proteomics - the analysis of protein concentrations and modifications, especially in response to various stressors, at various developmental stages, or in various parts of the body.
Metabolomics - similar to proteomics, but dealing with metabolites.
Transcriptomics - mRNA and its associated field
Lipidomics - lipids and its associated field
Peptidomics - peptides and its associated field
Metalomics - similar to proteomics and metabolomics, but dealing with metal concentrations and especially with their binding to proteins and other molecules.

Analytical chemistry has played critical roles in the understanding of basic science to a variety of practical applications, such as biomedical applications, environmental monitoring, quality control of industrial manufacturing, forensic science and so on.

The recent developments of computer automation and information technologies have innervated analytical chemistry to initiate a number of new biological fields. For example, automated DNA sequencing machines were the basis to complete human genome projects leading to the birth of genomics. Protein identification and peptide sequencing by mass spectrometry opened a new field of proteomics. Furthermore, a number of ~omics based on analytical chemistry have become important areas in modern biology.

Also, analytical chemistry has been an indispensable area in the development of nanotechnology. Surface characterization instruments, electron microscopes and scanning probe microscopes enables scientists to visualize atomic structures with chemical characterizations.

Among active contemporary analytical chemistry research fields, micro total analysis system is considered as a great promise of revolutionary technology. In this approach, integrated and miniaturized analytical systems are being developed to control and analyze single cells and single molecules. This cutting-edge technology has a promising potential of leading a new revolution in science as integrated circuits did in computer developments.

References

^ Holler, F. James; Skoog, Douglas A.; West, Donald M. (1996). Fundamentals of analytical chemistry. Philadelphia: Saunders College Pub. ISBN 0-03-005938-0.
^ Nieman, Timothy A.; Skoog, Douglas A.; Holler, F. James (1998). Principles of instrumental analysis. Pacific Grove, CA: Brooks/Cole. ISBN 0-03-002078-6.
^ ANALYTICAL SCIENCES 2001, VOL.17 SUPPLEMENT [1], Basic Education in Analytical Chemistry
^ Talanta Volume 51, Issue 5, p921-933 [2], Review of analytical next term measurements facilitated by drop formation technology
^ TrAC Trends in Analytical Chemistry Volume 21, Issues 9-10, Pages 547-557 [3], History of gas chromatography
^ Talanta, Volume 36, Issues 1-2, January–February 1989, Pages 1-9 [4] History of analytical chemistry in the U.S.A.
^ Bard, A.J.; Faulkner, L.R. Electrochemical Methods: Fundamentals and Applications. New York: John Wiley & Sons, 2nd Edition, 2000.
^ Skoog, D.A.; West, D.M.; Holler, F.J. Fundamentals of Analytical Chemistry New York: Saunders College Publishing, 5th Edition, 1988.
^ Wilkins CL (1983). "Hyphenated techniques for analysis of complex organic mixtures". Science 222 (4621): 291–6. doi:10.1126/science.6353577. PMID 6353577.
^ Holt RM, Newman MJ, Pullen FS, Richards DS, Swanson AG (1997). "High-performance liquid chromatography/NMR spectrometry/mass spectrometry: further advances in hyphenated technology". Journal of mass spectrometry : JMS 32 (1): 64–70. doi:10.1002/(SICI)1096-9888(199701)32:1<64::AID-JMS450>3.0.CO;2-7. PMID 9008869.
^ Ellis LA, Roberts DJ (1997). "Chromatographic and hyphenated methods for elemental speciation analysis in environmental media". Journal of Chromatography A 774 (1–2): 3–19. doi:10.1016/S0021-9673(97)00325-7. PMID 9253184.
^ Guetens G, De Boeck G, Wood M, Maes RA, Eggermont AA, Highley MS, van Oosterom AT, de Bruijn EA, Tjaden UR (2002). "Hyphenated techniques in anticancer drug monitoring. I. Capillary gas chromatography-mass spectrometry". Journal of Chromatography A 976 (1–2): 229–38. doi:10.1016/S0021-9673(02)01228-1. PMID 12462614.
^ Guetens G, De Boeck G, Highley MS, Wood M, Maes RA, Eggermont AA, Hanauske A, de Bruijn EA, Tjaden UR (2002). "Hyphenated techniques in anticancer drug monitoring. II. Liquid chromatography-mass spectrometry and capillary electrophoresis-mass spectrometry". Journal of Chromatography A 976 (1–2): 239–47. doi:10.1016/S0021-9673(02)01227-X. PMID 12462615.
^ Schermelleh, L.; Carlton, P. M.; Haase, S.; Shao, L.; Winoto, L.; Kner, P.; Burke, B.; Cardoso, M. C. et al. (2008). "Subdiffraction Multicolor Imaging of the Nuclear Periphery with 3D Structured Illumination Microscopy". Science 320 (5881): 1332. doi:10.1126/science.1156947. PMC 2916659. PMID 18535242. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2916659.
^ ^a ^b ^c ^d Crouch, Stanley; Skoog, Douglas A. (2007). Principles of instrumental analysis. Australia: Thomson Brooks/Cole. ISBN 0-495-01201-7.
^ "Health Concerns associated with Energy Efficient Lighting and their Electromagnetic Emissions". Trent University, Peterborough, ON, Canada. http://www.emrpolicy.org/science/forum/08_havas_cfl_scenihr.pdf. Retrieved 2011-11-12.
^ Bol'shakov, Aleksandr A; Ganeev, Aleksandr A; Nemets, Valerii M (2006). "Prospects in analytical atomic spectrometry". Russian Chemical Reviews 75 (4): 289. arXiv:physics/0607078. doi:10.1070/RC2006v075n04ABEH001174.

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v d e Analytical chemistry

Instrumentation	Atomic absorption spectrometer · Flame emission spectrometer · Gas chromatograph · High performance liquid chromatograph · Infrared Spectrometer · Mass spectrometer · Melting point apparatus · Microscope · Spectrometer · Spectrophotometer

Techniques	Calorimetry · Chemometrics · Chromatography · Electroanalytical methods · Gravimetric analysis · Mass spectrometry · Spectroscopy

Sampling	Coning and quartering · Dilution · Dissolution · Filtration · Masking · Pulverization · Sample preparation · Separation process · Sub-sampling

Prominent publications	The Analyst · Analytica Chimica Acta · Analytical and Bioanalytical Chemistry · Analytical Chemistry · Analytical Biochemistry

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Inorganic chemistry	Cluster chemistry · Inorganic chemistry · Nuclear chemistry

Others	Analytical chemistry · Chemistry education · Click chemistry · Cluster chemistry · Computational chemistry · Environmental chemistry · Green chemistry · Supramolecular chemistry · Theoretical chemistry · Wet chemistry

List of biomolecules · List of inorganic compounds · List of organic compounds · Periodic table

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