Method
A presumed blood sample is first collected with a swab. A drop of phenolphthalin reagent is added to the sample, and after a few seconds, a drop of hydrogen peroxide is applied to the swab. If the swab turns pink rapidly, it is said to test presumptive positive for blood. Waiting for periods over 30 seconds will result in most swabs turning pink naturally as they oxidize on their own in the air.
Optionally, the swab can first be treated with a drop of ethanol in order to lyse the cells present and gain increased sensitivity and specificity. This test is nondestructive to the sample, which can be kept and used in further tests at the lab; however, few labs would use the swab used for the Kastle-Meyer test in any further testing, opting instead to use a fresh swab of the original stain.
Read more about this topic: Kastle-Meyer Test
Famous quotes containing the word method:
“The most passionate, consistent, extreme and implacable enemy of the Enlightenment and ... all forms of rationalism ... was Johann Georg Hamann. His influence, direct and indirect, upon the romantic revolt against universalism and scientific method ... was considerable and perhaps crucial.”
—Isaiah Berlin (b. 1909)
“One of the grotesqueries of present-day American life is the amount of reasoning that goes into displaying the wisdom secreted in bad movies while proving that modern art is meaningless.... They have put into practise the notion that a bad art work cleverly interpreted according to some obscure Method is more rewarding than a masterpiece wrapped in silence.”
—Harold Rosenberg (1906–1978)
“You know, I have a method all my own. If you’ll notice, the coat came first, then the tie, then the shirt. Now, according to Hoyle, after that the pants should be next. There’s where I’m different. I go for the shoes next. First the right, then the left. After that, it’s every man for himself.”
—Robert Riskin (1897–1955)