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Blood Chemical Testing Methods

This document discusses several chemical tests that can be used to detect the presence of blood: 1) The Benzidine test uses benzidine reagent and hydrogen peroxide to detect hemoglobin, which produces a blue color complex if blood is present. 2) The Kastle-Meyer test uses phenolphthalein and hydrogen peroxide to detect hemoglobin, turning pink in the presence of blood. 3) The Guaiac test uses a resin called guaiac to detect hidden or occult blood, with the addition of hydrogen peroxide producing a color change if blood is present. These tests can help with chemical analysis of potential blood evidence at a crime scene.

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159 views10 pages

Blood Chemical Testing Methods

This document discusses several chemical tests that can be used to detect the presence of blood: 1) The Benzidine test uses benzidine reagent and hydrogen peroxide to detect hemoglobin, which produces a blue color complex if blood is present. 2) The Kastle-Meyer test uses phenolphthalein and hydrogen peroxide to detect hemoglobin, turning pink in the presence of blood. 3) The Guaiac test uses a resin called guaiac to detect hidden or occult blood, with the addition of hydrogen peroxide producing a color change if blood is present. These tests can help with chemical analysis of potential blood evidence at a crime scene.

Uploaded by

Shane G.
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Chemical Testing of Blood

MLS BIOCHEM LAB


Maria Teresa F. Mateo, RMT,MD,FPCOM,MBA
v Introduction

v Chemical test for blood

Benzidine test
Kastle-Mayer Test

Hemin test

Guaiac test

Confirmatory test
Benzidine Test
Ø a specific test used to detect the presence of
blood (RBCs or hemoglobin) in urine, stool and
other body fluids
Ø Test Principle: H2O2 with the presence of rbc
reduce benzidine solution. Result yields a blue
color complex
Ø Reagents: Benzidine Reagent (Benzidine in
Glacial Acetic Acid), 3% Hydrogen Peroxide,
Distilled Water.
Ø Method: mix 2ml of Benzidine solution with 2ml
H2O2. Take 2ml of specimen and add 2 ml of the
mixture and observe.
Ø Result: Appearance of a blue color solution
The Kastle-Meyer test

Test used to analyze evidence of blood at a crime scene.

PRINCIPLE:
Phenolphthalein reacts with hydrogen peroxide in the presence of
hemoglobin to turn from colorless to pink.

False positive: hemoglobin (meat) and certain vegetables will also


generate a positive response.

An additional benefit of this procedure is that the samples remain


intact and can be used in further testing including DNA analysis.

RESULT: Bright pink color


Hemin Test

ØAlso known as the Teichmann Test

ØPrinciple: When hemoglobin is


heated with glacial acetic acid, it
forms microscopic crystals

ØResult: Rhomboid crystals under


microscope
Method:
Ø Place a drop of blood on a glass slide.
Ø Add a drop of water, stir, and spread
uniformly by using the tip of a cover
glass.
Ø Add a drop of 0.1% NaCl solution.
Ø Dry over a low flame.
Ø Place cover glass in position and add
underneath a drop of concentrated
acetic acid.
Ø Warm as before until bubbles are
formed.
Ø Cool and examine the crystal under
the microscope.
Takayama test

Ø Also known as hemochromogen crystal


assay,
Ø Principle:
Ø Ferrous iron from hemoglobin
interacts with a pyridine solution.
Ø This interaction creates specific
crystals in the form of pyridine
ferroprotoporhyrin.

Ø Result: Red crystals when viewed


under a microscope.
Guaiac Test

Ø Detects hidden or occult blood


Ø Guaic solution (a natural resin from plants)
Ø Principle:
Guiac Test

Method:

Ø To 1 mL diluted blood, add new drops of


Guiac solution, until the resulting
solution becomes turbid.

Ø Add 1% H2O2 dropwise until a color


reaction appears.
THANK YOU.

END

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