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Flame Analysis

Flame Analysis

Some forensic analytical determinations rely on the separation of the various components in a mixture of compounds. One means of accomplishing this separation is to heat the sample using a flame.

The separated compounds can then be analyzed and identified. For example, when metals are burned, they can produce a characteristic color. The colors produced by the flame test are compared to known standards and the presence of certain elements in the sample can be confirmed. The color of the flame and its spectrum (component colors) is unique for each element.

Flame analysis or atomic emission spectroscopy (AES) is based on the physical and chemical principle that atomsafter being heated by flamereturn to their normal energy state by giving off the excess energy in the form of light. The frequencies of the light given off are characteristic for each element.

Flame analysis is a qualitative test and not a quantitative test. A qualitative chemical analysis is designed to identify the components of a substance or mixture. Quantitative tests measure the amounts or proportions of the components in a reaction or substance.

The unknown to be subjected to flame analysis is either sprayed into the flame or placed on a thin wire that is then put into the flame. Volatile elements (chlorides) produce intense colors. The yellow color of sodium, for example, can be so intense that it overwhelms other colors. To prevent this, the wire to be coated with the unknown sample is usually dipped in hydrochloric acid and subjected to flame to remove the volatile impurities and sodium.

As useful as it is to forensic analysis, the flame test does not work on all elements. Those that produce a measurable spectrum when subjected to flame include, but are not limited to, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, zinc, and cadmium. Other elements may need hotter flames to produce measurable spectra.

Other forensic analytical techniques are required to identify such substances. Typically, if there is enough of a sample, the sample can be divided into portions for testing by various techniques. This increases the likelihood of properly identifying the components of the sample.

Special techniques are required to properly interpret the results of flame analysis. The colors produced by a potassium flame (pale violet) can usually be observed only with the assistance of glass that can filter out interfering colors. Some colors are similar enough that line spectrum must be examined to make a complete and accurate identification of the unknown substance, or the presence of an identifiable substance in the unknown.

Flame analysis can also be used to determine the presence of metal elements in water by measuring the spectrum produced by the metals exposed to flame. The water is vaporized and then the emissions of the vaporized metals can be analyzed.

see also Analytical instrumentation; Chromatography.

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Flame Analysis

Flame Analysis

Flame tests are useful means of determining the composition of substances. The colors produced by the flame test are compared to known standards. And the presence of certain elements in the sample can be confirmed. The color of the flame and its spectrum (component colors) is unique for each element.

Flame analysis or atomic emission spectroscopy (AES) is based on the physical and chemical principle that atomsafter being heated by flamereturn to their normal energy state by giving off the excess energy in the form of light. The frequencies of the light given off are characteristic for each element.

Flame analysis is a qualitative test and not a quantitative test. A qualitative chemical analysis is designed to identify the components of a substance or mixture. Quantitative tests measure the amounts or proportions of the components in a reaction or substance.

The unknown to be subjected to flame analysis is either sprayed into the flame or placed on a thin wire that is then put into the flame. Volatile elements (chlorides) produce intense colors. The yellow color of sodium, for example, can be so intense that it overwhelms other colors. To prevent this the wire to be coated with the unknown sample is usually dipped in hydrochloric acid and subjected to flame to remove the volatile impurities and sodium.

The flame test does not work on all elements. Those that produce a measurable spectrum when subjected to flame include, but are not limited to, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, zinc, and cadmium. Other elements may need hotter flames to produce measurable spectra.

Special techniques are required to properly interpret the results of flame analysis. The colors produced by a potassium flame (pale violet) can usually be observed only with the assistance of glass that can filter out interfering colors. Some colors are similar enough that line spectrum must be examined to make a complete and accurate identification of the unknown substance, or the presence of an identifiable substance in the unknown.

Flame analysis can also be used to determine the presence of metal elements in water by measuring the spectrum produced by the metals exposed to flame. The water is vaporized and then the emissions of the vaporized metals can be analyzed.

FURTHER READING:

BOOKS:

Broekaert, José. C. Analytic Atomic Spectrometry with Flames and Plasmas. New York: Wiley-VCH Publishing, 2001.

ELECTRONIC:

Helmenstein, Anne Marie. "What You Need To Know About Chemistry-Quantitative Flame Analysis" About, Inc, <http://chemistry.about.com/library/weekly/aa110401a.htm> (March 29, 2003).

SEE ALSO

Air and Water Purification, Security Issues
Chemical and Biological Detection Technologies
Isotopic Analysis
Spectroscopy
Water Supply: Counter-Terrorism

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"Flame Analysis." Encyclopedia of Espionage, Intelligence, and Security. . Encyclopedia.com. 21 Sep. 2018 <http://www.encyclopedia.com>.

"Flame Analysis." Encyclopedia of Espionage, Intelligence, and Security. . Encyclopedia.com. (September 21, 2018). http://www.encyclopedia.com/politics/encyclopedias-almanacs-transcripts-and-maps/flame-analysis

"Flame Analysis." Encyclopedia of Espionage, Intelligence, and Security. . Retrieved September 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/politics/encyclopedias-almanacs-transcripts-and-maps/flame-analysis

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Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

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Notes:
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Flame Analysis

Flame Analysis

Analysis of emission spectra

Qualitative testing

Resources

Allowing analysis of the light (photons) from excited atoms, flame analysis is a form of atomic emissionspectroscopy (AES).

German chemist Robert Bunsens (18111999) invention of the Bunsen burnera tool now commonly used in chemistry laboratoriesalso spurred the development of flame analysis. Working with Gustav Kirchhoff (18241887), Bunsen helped to establish the principles and techniques of spectro-scopy. Bunsens techniques also enabled his discovery of the elements cesium and rubidium.

Bunsens fundamental observation that flamed elements emit light only at specific wavelengths, and that every element produced a characteristic spectra, paved the way for the subsequent development of quantum theory by German physicist Maxwell Planck (18581947), Danish physicist Niels Bohr (1885-1962), and others. Using techniques pioneered by Bunsen, scientists have since been able to determine the chemical composition of a variety of substances ranging from bioorganic debris to the composition of the stars.

Analysis of emission spectra

Bunsen examined the spectra; the colors of light emitted when a substance was subjected to intense flame. When air is admitted at the base of a Bunsen burner it mixes with hydrocarbon gas to produce a very hot flame at approximately 3,272°F (1,800°C). This temperature is sufficient to cause the emission of light from certain elements. Often termed spectral fingerprints, the color of the flame and its spectral distribution of component colors is unique for each element.

To examine the spectra of elements, Bunsen used a simple apparatus that consisted of a prism, slits, and a magnifying glass or photosensitive film. Bunsen determined that the spectral patterns of elements that emitted light when subjected to flame analysis differed because each pattern represented limited portions of the total possible spectrum.

Flame analysis or atomic emission spectroscopy is based on the physical and chemical principle that atomsafter being heated by flamereturn to their normal energy state by giving off the excess energy in the form of photons of light. The mathematically related frequencies and wavelengths of the photons emitted are characteristic for each element and this is the physical basis of the uniqueness of spectral fingerprints.

Qualitative testing

Flame analysis is a qualitative test, not a quantitative test. A qualitative chemical analysis is designed to identify the components of a substance or mixture. Quantitative tests measure the amounts or proportions of the components in a reaction or substance. The unknown sample subjected to flame analysis is either sprayed into the flame or placed on a thin wire that is then introduced into the flame.

Highly volatile elements (chlorides) produce intense colors. The yellow color of sodium, for example, can be so intense that it overwhelms other colors. To prevent this obscuration, the wire to be coated with the unknown sample is usually dipped in hydrochloric acid and subjected to flame to remove the volatile impurities and sodium.

KEY TERMS

Photon The boson or carrier particle of light (electromagnetic waves). Massless, photons because they are lighttravel at the speed of light (c) after emission from an excited atom.

Spectrum A display of the intensity of radiation versus wavelength.

Visible or color spectrum That portion of the electromagnetic spectrum to which the human eye is sensitive. Reception of light (photons) varying in frequency and wavelength is interpreted as color. Longer wavelengths represent red light, shorter wavelengths in the visible spectrum represent blue and violet light.

Standard or Bunsen burner based flame tests do not work on all elements. Those that produce a measurable spectrum when subjected to flame include, but are not limited to: lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, zinc, and cadmium. Other elements may need hotter flames to produce measurable spectra.

Analysts use special techniques to properly interpret the results of flame analysis. The colors produced by a potassium flame (pale violet) can usually be observed only with the assistance of glass that can filter out interfering colors. Some colors are similar enough that a line spectrum must be examined to make a complete and accurate identification of the unknown substance, or the presence of an identifiable substance in the unknown.

Flame analysis can also be used to determine the presence of metal elements in water by measuring the spectrum produced by the metals exposed to flame. The water is first vaporized to allow observation of the emissions of the subsequently vaporized residual metals.

Flame tests are useful means of determining the composition of substances. The colors produced by flame tests are compared to known standards to identify or confirm the presence of certain elements in the sample.

See also Atomic spectroscopy; Electromagnetic field; Electromagnetism; Forensic science; Geochemical analysis; Spectral classification of stars; Spectral lines; Spectroscope; Spectroscopy.

Resources

BOOKS

American Water Works Association. Water Quality and Treatment. 5th ed. Denver: American Water Works Association, 1999.

Daintith, John, and D. Gjertsen, eds. A Dictionary of Scientists. New York: Oxford University Press, 1999.

Hancock, P. L., and B. J. Skinner, eds. The Oxford Companion to the Earth. New York: Oxford University Press, 2000.

Keller, E. A. Introduction to Environmental Geology. 2nd ed. Upper Saddle River: Prentice Hall, 2002.

Klaassen, Curtis D. Casarett and Doulls Toxicology. 6th ed. Columbus: McGraw-Hill, Inc., 2001.

Klein, C. The Manual of Mineral Science. 22nd ed. New York: John Wiley & Sons, Inc., 2002.

Lide, D. R., ed. CRC Handbook of Chemistry and Physics. Boca Raton: CRC Press, 2001.

OTHER

Helmenstine, A. M. Qualitative analysisFlame Tests. About.com. <http://chemistry.about.com/library/weekly/aa110401a.htm> (accessed October 20, 2002).

eNotes. Chmical Elements <http://science.enotes.com/earth-science/chemical-elements> (accessed November 24, 2006).

K. Lee Lerner

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"Flame Analysis." The Gale Encyclopedia of Science. . Encyclopedia.com. 21 Sep. 2018 <http://www.encyclopedia.com>.

"Flame Analysis." The Gale Encyclopedia of Science. . Encyclopedia.com. (September 21, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/flame-analysis

"Flame Analysis." The Gale Encyclopedia of Science. . Retrieved September 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/flame-analysis

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Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Flame Analysis

Flame analysis

Allowing analysis of the light (photons) from excited atoms , flame analysis is a form of atomic emission spectroscopy (AES).

German chemist Robert Bunsen's (1811–1999) invention of the Bunsen burner—a tool now commonly used in modern chemistry laboratories—also spurred the development of flame analysis. Working with Gustav Kirchhoff (1824–1887), Bunsen helped to establish the principles and techniques of spectroscopy. Bunsen's techniques also enabled his discovery of the elements cesium and rubidium.

Bunsen's fundamental observation that flamed elements emit light only at specific wavelengths, and that every element produced a characteristic spectra, paved the way for the subsequent development of quantum theory by German physicist Maxwell Planck (1858–1947), Danish physicist Niels Bohr (1885–1962), and others. Using techniques pioneered by Bunsen, scientists have since been able to determine the chemical composition of a variety of substances ranging from bioorganic debris to the composition of the stars.


Analysis of emission spectra

Bunsen examined the spectra; the colors of light emitted when a substance was subjected to intense flame. When air is admitted at the base of a Bunsen burner it mixes with hydrocarbon gas to produce a very hot flame at approximately 3,272°F (1,800°C). This temperature is sufficient to cause the emission of light from certain elements. Often termed "spectral fingerprints," the color of the flame and its spectral distribution of component colors is unique for each element.

To examine the spectra of elements, Bunsen used a simple apparatus that consisted of a prism , slits, and a magnifying glass or photosensitive film. Bunsen determined that the spectral patterns of elements that emitted light when subjected to flame analysis differed because each pattern represented limited portions of the total possible spectrum .

Flame analysis or atomic emission spectroscopy is based on the physical and chemical principle that atoms—after being heated by flame—return to their normal energy state by giving off the excess energy in the form of photons of light. The mathematically related frequencies and wavelengths of the photons emitted are characteristic for each element and this is the physical basis of the uniqueness of spectral fingerprints.

Qualitative testing

Flame analysis is a qualitative test, not a quantitative test. A qualitative chemical analysis is designed to identify the components of a substance or mixture. Quantitative tests measure the amounts or proportions of the components in a reaction or substance. The unknown sample subjected to flame analysis is either sprayed into the flame or placed on a thin wire that is then introduced into the flame.

Highly volatile elements (chlorides) produce intense colors. The yellow color of sodium , for example, can be so intense that it overwhelms other colors. To prevent this obscuration, the wire to be coated with the unknown sample is usually dipped in hydrochloric acid and subjected to flame to remove the volatile impurities and sodium.

Standard or Bunsen burner based flame tests do not work on all elements. Those that produce a measurable spectrum when subjected to flame include, but are not limited to: lithium , sodium, potassium, rubidium, cesium, magnesium , calcium , strontium, barium , zinc, and cadmium. Other elements may need hotter flames to produce measurable spectra.

Analysts use special techniques to properly interpret the results of flame analysis. The colors produced by a potassium flame (pale violet) can usually be observed only with the assistance of glass that can filter out interfering colors. Some colors are similar enough that a line spectrum must be examined to make a complete and accurate identification of the unknown substance, or the presence of an identifiable substance in the unknown.

Flame analysis can also be used to determine the presence of metal elements in water by measuring the spectrum produced by the metals exposed to flame. The water is first vaporized to allow observation of the emissions of the subsequently vaporized residual metals.

Flame tests are useful means of determining the composition of substances. The colors produced by flame tests are compared to known standards to identify or confirm the presence of certain elements in the sample.

See also Atomic spectroscopy; Electromagnetic field; Electromagnetism; Forensic science; Geochemical analysis; Spectral classification of stars; Spectral lines; Spectroscope; Spectroscopy.


Resources

books

American Water Works Association. Water Quality and Treatment. 5th ed. Denver: American Water Works Association, 1999.

Daintith, John, and D. Gjertsen, eds. A Dictionary of Scientists. New York: Oxford University Press, 1999.

Hancock, P. L., and B. J. Skinner, eds. The Oxford Companion to the Earth. New York: Oxford University Press, 2000.

Keller, E. A. Introduction to Environmental Geology. 2nd ed. Upper Saddle River: Prentice Hall, 2002.

Klaassen, Curtis D. Casarett and Doull's Toxicology. 6th ed. Columbus: McGraw-Hill, Inc., 2001.

Klein, C. The Manual of Mineral Science. 22nd ed. New York: John Wiley & Sons, Inc., 2002.

Lide, D. R., ed. CRC Handbook of Chemistry and Physics. Boca Raton: CRC Press, 2001.

other

Helmenstine, A. M. "Qualitative analysis—Flame Tests." About.com. <http://chemistry.about.com/library/weekly/aa110401a.htm> [cited October 20, 2002].


K. Lee Lerner

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Photon

—The boson or carrier particle of light (electromagnetic waves). Massless, photons—because they are light—travel at the speed of light (c) after emission from an excited atom.

Spectrum

—A display of the intensity of radiation versus wavelength.

Visible or color spectrum

—That portion of the electromagnetic spectrum to which the human eye is sensitive. Reception of light (photons) varying in frequency and wavelength is interpreted as color. Longer wavelengths represent red light, shorter wavelengths in the visible spectrum represent blue and violet light.

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"Flame Analysis." The Gale Encyclopedia of Science. . Encyclopedia.com. 21 Sep. 2018 <http://www.encyclopedia.com>.

"Flame Analysis." The Gale Encyclopedia of Science. . Encyclopedia.com. (September 21, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/flame-analysis-1

"Flame Analysis." The Gale Encyclopedia of Science. . Retrieved September 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/flame-analysis-1

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Citation styles

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Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

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http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
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  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.