A flame test is an analytic procedure used in chemistry to detect the presence of certain elements, primarily metal ions, based on each element's characteristic emission spectrum. The color of flames in general also depends on temperature; see flame color.
The test involves introducing a sample of the element or compound to a hot, non-luminous flame, and observing the color that results. Samples are usually held on a platinum wire cleaned repeatedly with hydrochloric acid to remove traces of previous analytes. Different flames should be tried to avoid wrong data due to "contaminated" flames, or occasionally to verify the accuracy of the color. In high-school chemistry courses, wooden splints are sometimes used, mostly because solutions can be dried onto them, and they are inexpensive. Nichrome wire is also sometimes used. When using a splint, one must be careful to wave the splint through the flame rather than holding it in the flame for extended periods, to avoid setting the splint itself on fire. The use of cotton swab or melamine foam (eraser) as a support have also been suggested. Sodium is a common component or contaminant in many compounds and its spectrum tends to dominate over others. The test flame is often viewed through cobalt blue glass to filter out the yellow of sodium and allow for easier viewing of other metal ions.
The flame test is fast and easy to perform, and does not require any equipment not usually found in a chemistry laboratory. However, the range of detected elements is small, and the test relies on the subjective experience of the experimenter rather than any objective measurements. The test has difficulty detecting small concentrations of some elements, while too strong a result may be produced for certain others, which tends to drown out weaker signals.
Although the flame test only gives qualitative information, not quantitative data about the actual proportion of elements in the sample, quantitative data can be obtained by the related techniques of flame photometry or flame emission spectroscopy. Flame Atomic absorption spectroscopy Instruments, made by e.g. PerkinElmer or Shimadzu, can be operated in emission mode according to the instrument manuals.
Read more about Flame Test: Common Elements
Famous quotes containing the words flame and/or test:
“Do but consider this small dust, here running in the glass,
By atoms moved.
Could you believe that this the body was
Of one that loved?
And in his mistress’ flame playing like a fly,
Turned to cinders by her eye?
Yes, and in death as life unblest,
To have’t expressed,
Even ashes of lovers find no rest.”
—Ben Jonson (1572–1637)
“[17th-century] Puritans were the first modern parents. Like many of us, they looked on their treatment of children as a test of their own self-control. Their goal was not to simply to ensure the child’s duty to the family, but to help him or her make personal, individual commitments. They were the first authors to state that children must obey God rather than parents, in case of a clear conflict.”
—C. John Sommerville (20th century)