refined Analytical_chemistry Information, explanation, recent texts, monographs, and related patents.
Information & explanations, latest texts & monographs on Analytical_chemistry (including recent related patents.)


Analytical chemistry

Analytical chemistry is simply the analysis of material samples to gain an understanding of their chemical composition and structure. There are two major types of analysis:
  • Qualitative analysis, which seeks to establish the existence of a given element or compound.
  • Quantitative analysis, which seeks to establish the amount of a given element or compound.
Most modern analytical chemistry is quantitative, however quantitative measurement can be further split into different areas of study. A simple example of quantitative analysis is the measurement of a sample's percentage of a given element. However, this gives no indication of the molecules that this element may be contained in (also referred to as species). More detailed analysis methods investigate what species a given element might be contained within. This is of particular interest in biological systems; the molecules of life contain carbon, hydrogen, oxygen, nitrogen, and others, in complex structures. The analyst may perform studies that indicate the presence and abundance of any of thousands of known compounds. Techniques There are a bewildering array of techniques available to separate, detect and measure chemical compounds. The oldest methods required painstaking separation of substances in order to measure the weight or volume of a final product. Many modern, sensitive and accurate devices rely on the principles of spectroscopy. Measuring the absorption of light by a solution or gas, we can calculate the amounts of several species, often without separation. Newer methods include atomic absorption spectroscopy (AAS), Nuclear Magnetic Resonance (NMR) and neutron activation analysis (NAA). Many techniques combine two or more analytical methods. Examples of this include ICP-MS(Inductively-Coupled Plasma - Mass Spectrometry), where volatilisation of a sample occurs in the first step, and measuring of the concentration occurs in the second. The first step may also involve a separation technique, such as chromatography, and the second a detection / measuring device. Techniques that involve volatilisation aim to produce free atoms of the elements making up the sample, which can then be measured in concentration by the degree to which they absorb or emit at a characteristic spectral frequency. These methods have the disadvantage of completely destroying the sample, and any species contained within it. These techniques include [(atomic absorption spectroscopy)] and [(ICP-MS / ICP-AES)]. These techniques can still be used to study speciation, however by the incorporation of a separation stage before volatilisation. Methods Analytical methods rely on scrupulous attention to cleanliness, sample preparation, accuracy and precision. Many practitioners will keep all their glassware in acid to prevent contamination, samples will be re-run many times over, and equipment will be washed in specially pure solvents. A standard method for analysis of concentration involves the creation of a calibration curve. The experimenter will create a series of standards across the range of concentrations that are of interest. They must take care that these concentrations are in the detection range of the technique (instrumentation) they are using. These standards will have a precisely known concentration of the element or compound under study. Running each of these standards several times using the chosen technique will produce a series of readings, each set indicative of one of the known concentrations. By plotting these points (reading vs concentration) on a graph, it is possible to plot a line of reading vs concentration across the detection range of that technique. Thus, when the sample is run and a reading obtained, the experimenter can simply refer to the graph to read off the concentration. If the concentration of element or compound in the 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.
This article is adapted from from Wikipedia All Wikipedia article text is available under the terms of the GNU Free Documentation License


Recent Analytical_chemistry related patents

From USPTO:
6717668: Simultaneous imaging and spectroscopy apparatus
6717137: Systems and methods for inducing infrared multiphoton dissociation with a hollow fiber waveguide
6717136: Microfludic system (EDI)
6716637: Chemiluminescent gas analyzer
6716636: Methods for sequencing proteins
6716620: Biosensor and related method
6716584: Polynucleotide separation method and apparatus therefor
6716394: DNA sequencing using multiple fluorescent labels being distinguishable by their decay times
6714815: Method for the iontophoretic non-invasive determination of the in vivo concentration level of an inorganic or organic substance
6713573: Catalyst modifiers and their use in the polymerization of olefin(s)
6713452: Mixtures of calcitonin drug-oligomer conjugates comprising polyalkylene glycol, uses thereof, and methods of making same
6713308: System for electrochemical quantitative analysis of analytes within a solid phase
6713298: Method and apparatus for the delivery of samples to a chemical sensor array
6713279: Non-stochastic generation of genetic vaccines and enzymes
6713272: Attachment of biomolecules to hydrophobic surfaces
6713255: DNA chip, PNA chip, and their preparation methods
6713021: Dispensing method and assembly for liquid droplets
6712587: Hydraulic amplifier pump for use in ultrahigh pressure liquid chromatography
6711516: Method for calibrating spectrophotometric apparatus
6711503: Hybrid least squares multivariate spectral analysis methods
6711423: Optical-based sensing devices
6710872: System for spectrometry
6710334: Quadrupol ion trap mass spectrometer with cryogenic particle detector
6710200: Cyanohydrin ethers and esters as high-sensitivity enzyme substrates
6710084: Inhibition of TNF.alpha.-initiated neutrophil response
6709746: Reducing concentration of organic materials with substituted cyclodextrin compound in polyester packaging materials
6709559: Microfabricated structures for facilitating fluid introduction into microfluidic devices
6707548: Systems and methods for filter based spectrographic analysis
6707539: Portable product authentication device
6706952: Arabidopsis gene encoding a protein involved in the regulation of SAR gene expression in plants
6706729: Thiolesters and uses thereof
6706539: Enzyme substrate delivery and product registration in one step enzyme immunoassays
6706535: Pulsed carrier gas flow modulation for selectivity enhancements with gas chromatography using series-coupled column ensembles
6706534: Pulsed carrier gas flow modulation for selectivity enhancements with gas chroma tography using series-coupled ensembles
6706530: IR-MALDI mass spectrometry of nucleic acids using liquid matrices
6706529: Methods for sequencing proteins
6706489: Motor proteins and methods for their use
6706287: Prebiotic and probiotic compositions and methods for their use in gut-based therapies
6706263: Composition for alleviating symptoms of uremia in patients
6706254: Receptor-avid exogenous optical contrast and therapeutic agents
6706187: Packing material for chromatography having novel characteristic and method for isolation of substance using the same
6706164: Method for controlling sample introduction in microcolumn separation techniques and sampling device
6706162: High speed, high resolution compositions, methods, and kits for capillary electrophoresis
6706161: Methods and compositions for modifying the surface of a polymeric substrate
6705357: Method and apparatus for gradient generation
6703611: Electrospray ionization device
6703539: Method and compositions for modifying levels of secondary metabolic compounds in plants
6703513: Production and use of derivatized homoserine lactones
6703423: Inhibition of TNF.alpha.-initiated neutrophil response

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