Category Archives: Forensic Serology

Leucomalachite Green Test

By @forensicfield

What is Leucomalachite Green?

Malachite is a Triphenyl Methane dye.

It’s an organic compound that is used as a Dyestuff.

Formula of Leucomalachite Green- C23H26N2

It’s Uses In Forensics

It’s a Presumptive test for blood.

Its Sensitivity Is 1:5000 in 20s Time In Dilution.

Basis Of The Test

The basis of the test is that the peroxidase-like activity of hemoglobin in blood catalysis.

Indication for the Presence of Blood

It produces Blue-Green Color if blood is present.

Why Is This Process Is Known as Oxidation Reaction?

In This Process Oxidation Occurs So The Process Is Called Oxidation Reaction.

How To Perform This Test ?

Drawbacks

It Also Give Positive Result In The Case Of Plant Or High Oxygenated Compound.

It is important to use these solutions quickly to prevent premature oxidation.

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Fluorescein Test

By @forensicfield

Introduction

While Luminol is oftenly used for detection of blood around since 1939, another method can also be used to reveal hidden/washed blood stain known as Fluorescein which is also being used around since 1990s.

What is Fluorescein?

Fluorescein is a fluorophore commonly used in microscopy, in a type of dye laser as the gain medium in forensics and serology to detect latent blood stains.

Fluorescein has an absorption max. at 494 nm and emission max. of 512 nm.

It’s Uses In Forensics

It’s a Presumptive test for blood.

It is used in detection of blood remaining after a stain has been cleaned.

It’s sensitivity is 1.105,000 depending upon the dilution rate of the working solution.

Basis Of The Test

Fluorescein is produced BlueGreen fluorescence indicates the possible presence of blood.

Fluorescein react to the iron and proteins found in hemoglobin of blood.

Indication for the Presence of Blood

It will fluoresce when exposed to light at the 420 nm to 485 nm range .

It produces Blue Green  Color if blood is present.

How To Perform This Test ?

Drawbacks

Fluorescein does not give the results with household cleaning items. For examples: Bleach.

This test can only be performed in dark room or at night time.

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Luminol Test

By @forensicfield

What is Luminol?

Luminol is a chemical that exhibits chemiluminescence, with blue glow.

Formula of Luminol – C8H7N3O2

It’s Uses In Forensics

It’s a Presumptive test for blood.

Also known as chemiluminscence test.

It is used in detection of blood remaining after a stain has been cleaned.

Basis Of The Test

Luminol produces chemiluminscence when mixed with appropriate oxidizing agent.

It reacts with Iron atom present in hemoglobin.

Indication for the Presence of Blood

It emits Blue Color if blood is present.

How To Perform This Test ?

Blue Glow is present.

Drawbacks

Luminol test can only be performed in dark room or at night time. Luminol does not give the results with household cleaning items. For examples: Bleach.

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Phenolphtalein Test

By @forensicfield

What is Phenolphthalein (Kastle – Mayer Test) ?

This test is also known as Kastle-Mayer Test.

The kastle- mayer solution is of phenolphthalein indicator solution which have been produce usually by reacting with Zn powder and ZnO.

It’s Uses In Forensics

This Test Is an Inexpensive , Easy and Realiable For Examination of Blood.

It’s Sensitivity Is 1:107 In Dilution.

It is more Sensitive than Benzidine Test.

Basis Of The Test

The basis of the test is that the peroxidase-like activity of hemoglobin in blood catalysis.

Indication for the Presence of Blood

It Produce Pink Color which Indicate Presence Of Blood.

How To Perform This Test ?

If the test is negative, it is reasonable proof that “heme” is absent.

Drawbacks

It Also Give Positive Result In The Case Of Plant Or High Oxygenated Compound.

It Also Give Positive Result for heme molecule of different species so It is hard to differentiate if blood is of human or other species.

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Benzidine Test

By @forensicfield

What is Benzidine Reagent?

Benzidine is a Bladder Carcinogen referred as Aromatic Amines.

Benzidine Reagent is a poisonous, yellow/greyish red/white in color.

Color change into dark when exposed to light & air.

It’s Uses In Forensics

Benzidine Test Is More Acceptable And Reliable Test For Blood.

Its Sensitivity Is 5 Lakh Time In Dilution.

Basis Of The Test

This Test Is Based On Enzyme I.E. Peroxidase Enzyme Found In RBC.

Indication for the Presence of Blood

Produce Bluish Or Intense Green Colour Indicate Presence Of Blood.

Why Is This Process Is Known as Oxidation Reaction?

In This Process Oxidation Of Benzidine Occurs So The Process Is Called Oxidation Reaction.

How To Perform This Test ?

BLOOD+ Benzidine Reagent + H2O2 (30%) (H2O + Nascent) =

Intense GREEN colour

or

BLUISH colour present

Drawbacks

It Also Give Positive Result In The Case Of Plant Or High Oxygenated Compound.

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