Tag Archives: Confirmatory test

Spectrophotometry Test

By @forensicfield

What is Spectrophotometry Test?

Spectrophotometry is measuring intensity of light in a part of the spectrum as transmitted by particular substances.

Spectrophotometry Test is based on the identification of hemoglobin and its derivatives (such as; methamoglobin, carboxyhemoglobin, oxyhemoglobin.) through their specific absorption spectra.

It’s Uses In Forensics

It’s a Confirmatory test for blood.

This method was considered one of the most conclusive test for the identification of blood stains.

Basis Of The Test

Hemoglobin and its derivatives exhibit characteristic bands of absorption at specific wavelength , which can be observed by spectrophotometer.

Indication for the Presence of Blood

It produced specific absorption spectra for hemoglobin and its derivative for identification of blood.

How To Perform This Test ?

A complex system of band is present because of heme (part of hemoglobin) in the near UV and Visible region of spectrum.

Sometimes they differs from derivative to derivative of heme portion but they all have common strong absorption band  at 400-425 nm which is also known as Soret Band.

Drawbacks

  • It can not differentiate between Sample and things which produce same wavelength.
  • Low Sensitivity.

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Takayama Test

By @forensicfield

What is Takayama Test?

Takayama test first discovered in 1912 by Takayama for blood detection.

Takayama test is used for the confirmation of blood not species origin.

It’s Uses In Forensics

It is also known as Hemochromogen crystal assay or Immunochromatographic test.

Basis Of The Test

It forms a ferro protoporphyrin ring by a reaction between pyridine and the iron atom of the heme group.

Indication for the Presence of Blood

It produced Salmon pink crystal if blood is present.

How To Perform This Test ?

Drawbacks

The drawback of Takayama test crystallization is difficult to obtained with old blood stains.

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Teichmann Crystal Test

By @forensicfield

What is Teichmann Crystal Test?

Dr. Ludwig Karl Teichman discovered a test for detection of blood in 1853. later the test name as Teichmann Crystal Test.

It’s Uses In Forensics

It’s a Confirmatory test for blood.

It is also known as Haematin crystal acid test or haemin test.

It is used in detection of blood from dried stains.

Basis Of The Test

In Teichmann Test hemoglobin converted to haemin crystals which converted to salt in presence of halogen after then rhombic crystals forms.

Indication for the Presence of Blood

It produced Dark brown Color and rhombic shape if blood is present.

How To Perform This Test ?

Drawbacks

Rust and Exposure or combination of these can interfere with the test.

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