Reinsch's test for arsenic

it helps in the detection of arsenic heavy metals in the poisoning cases in the forensic toxicology.

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By,
Gopika Babu
1
st
Year MSc. Forensic
science Lovely
Professional University


Reinsch’s test
for Arsenic

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Reinsch’s test is the test which is used to detect one or more
biological samples. It is commonly used in the cases where the toxicologists have a doubt
about the presence of heavy metals in poisoning cases. This test was discovered by Hugo
Reinsch in 1841. It is a presumptive test. In this assignment we are talking about the
reinsch’s test for arsenic.
Arsenic it is a natural compound found on the earth’s crust which can
be seen in air, water and land. It is highly toxic in its inorganic form. Long term exposure
to arsenic can cause cancer and skin leisure. In industries arsenic are used for the processing
of the glass, paper, woods and ammunition. Exposure to arsenic will cause acute and
chronic effects in a body. Arsenic is one of the 10 chemicals which listed by the WHO is a
public concern. It has the atomic number of 33. It is the metalloid and has various
allotropes.
Arsenic poisoning is the amount of arsenic elevated in the body. It is more due to the
over exposure.




Introduction

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Arsenic is the chemical compound otherwise known as heavy metal which
has the atomic number 33. It is a metalloid and has various allotropes. It is a natural
compound found in the earth’s crust and it can widely see in the land, water and air. It is
toxic compound in its inorganic state. Long term exposure can cause cancer like diseases
and skin lesions.
Inorganic arsenic is a carcinogenic type. Arsenic can be in two types: inorganic and
organic.
Organic Arsenic Inorganic Arsenic
 Found mainly in water.  Found mainly in seafoods.
 It is less harmful to the human body.  It is highly toxic and very harmful.




Poison is a type of substance which is harmful for the body. It can be entered to the
body through inhale it, swallow it, inject it or absorb it through skin. There are different
types of poison available. All poisons are not drugs but all drugs are poison.
Poisoning will be of various types like food poisoning. There will be intentional use of
poison as well as accidental use of poison. Poisons are readily available and as well as we
can make anything into a poison. There will be also other types like plant poisoning, house
hold chemicals poisoning like that. Here we mainly focus on arsenic poisoning.


Arsenic poisoning is a type of medical condition in which is occurred due to the
raised level of arsenic in the body. The main reason for the arsenic poison is due to the
drinking of contaminated water. Most of the cases in the arsenic poisoning are the
accidental poisoning. In arsenic poisoning we are testing urine, hair, blood are testing for
the knowing the content of arsenic in the body.


Arsenic poisoning

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As we all know reinsch’s test is used to know the presence of arsenic. In a
poisoning case as a forensic toxicologist it is his duty to identify which poison has been
used in that poison case. For that so many procedures are there:
Before confirming the type of poison used my just intuitions we have to confirm. To
identify the nature preliminary and confirmatory analysis are done. It is because;
Presumptive test is the preliminary examination of a sample. By doing preliminary
examination we don’t be able to confirm and finalize what the sample is. In presumptive
test there may be chance of occurring false positive and false negative results.
False positive result
It means if we add A to B, we will we get C, but in false positive cases if we add A to D
will also get C. So, there is chances to mislead the case.
False negative result
It means if the sample gets decomposed or decayed sometimes will not get negative result.
That does not mean the sample is not that. This will also mislead the case.

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One of the main presumptive tests is the reinsch’s test for arsenic (metallic poison).



As we all know some metallic poison can be used for the homicidal suicide
purposes. It is commonly given with the food or any type of drinks. So, the victim will
consume it easily. Therefore, a number of preliminary tests are done to detect the type of
metal used as poison. Among them one of it is reinsch’s test. In reinsch’s test different
metals will be giving different colors on the copper turnings and then the microscopic
examination is conducted.
Principle
In this test analysis is based on a fact that is metallic arsenic, antimony, bismuth will be
deposited on the copper wire placed within the matrix which is acidified and heated.
Reagents used
 Concentrated Hydrochloric acid
 Concentrated Nitric acid
 Copper wire (approx. 6 inches)
 Mercury stock solution (1000 mg/L)
 Mercury reference solution (10mg/L)
 Distilled water
 Arsenic stock solution (1000mg/L)
 Arsenic reference solution (10mg/L)
 Potassium cyanide (10g/100 ml)

Sample preparation
 Urine- 20 ml
 Blood- 1.0 ml {all the sample diluted to 20 ml of water}
 Tissues- 5.0 ml
 Gastric- 5.0 ml
 Other samples like (vomitus, powder, tablets, residues.)



Reinsch’s Test for arsenic (metallic poison)

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Procedure
1) Firstly, take about 40ml of distilled water in a china dish and then add a few drops of
dil. HCL to it.
2) Then add 4-5 drops of cu turnings to it and boil it for 8-10 minutes. This is done to
check whether the acid and cu turnings are free of other metals. If any other impurities
are found do start the test again with the new fresh materials.
3) Then the next step is to the suspected sample to the china dish and boil it for 8-10
minutes, while boiling add appropriate amount of water and acid to makeup the loss
during evaporation.
4) If a steel grey stain is present in the cu turning that may indicate the presence of arsenic.
5) After that the next step is to remove the cu turnings and place it in a test tube and heat
the test tube and heat the bottom of the test tube in a low flame.
6) Then remove cu turning from the test tube and observe the test tube under microscope
in a low power.
7) If the arsenic is present octahedral crystals of arsenious oxide can be observed.
Note: - 1. Note inhale any chemicals.
2. Always dry cu turnings otherwise water drops will interfere with the results.

 This can be confirmed by using a confirmatory test:
Arsenic will be in the form of arsenic (III) ion in the samples. Therefore, when hydrogen
sulfide gas is passed through the sample a yellow precipitate is formed, it shows the
presence of arsenic (III) in that suspected sample. This yellow precipitate will get dissolved
when the concentric nitric acid is added to it. Then yellow precipitate will again form when
ammonium molybdate is added to it.
By this the presence of arsenic in the sample can be confirmed.


As2S3Yellow+10conc.HNO3→2H3AsO4+2H2O+10NO2+3S

H3AsO4+12(NH4)2MoO4+21conc.HNO3→(NH4)3AsO4⋅12MoO3Yellow+21NH4NO3+12H2O

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In 1849, Richard Geering, his son George, Benjamin was killed by Mary
Geering. Mary was born in 1800 and she is lived in Guestling, East Sussex, UK, in
1846 when her husband Richard Geering was inherited £20. That was a lot of money
back, but not enough to induce murder plans in most of the people. Two years later,
Richard, husband of Mary died after a painful illness of five days. His death was due
to heart disease. Four months later, and Geering’s 21-year-old son George was also
died. Then after a few weeks later in 1849, 26-year-old son James was also died from
a painful illness of just a few days. Then her third son, 18-year-old Benjamin, fell ill
shortly afterward on a Sunday. This time, doctors shifted Benjamin from the home,
and Benjamin recovered.
Due to doubts, His doctors raised an alarm, and police take against the series of death
because in benjamin’s body presence of arsenic were found. Mary Ann Geering’s
husband and her two dead sons was digged out and examined. Then in laboratory
tests were conducted and found that the bodies were full of arsenic. Geering was
confessed, arrested and her three younger children were taken to a poorhouse. During
the trial, she was confessed and then was hanged in 1849.

Case Study
Famous cases of arsenic poisoning
1. MARY ANN GEERING

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Jennings Barfield was killed in 1971 by Mary Velma Barfield.
When the first killing happens, Velma Barfield was not in home when her house fire killed
her first husband Thomas Burke in 1969 in North Carolina. Another fire was soon
afterwards that destroyed what was left of the home. Then She married to Jennings Barfield
in 1970, but he also died in 1971. After that Barfield moved with her parents, but her father
died of cancer after few months and her mother also died in 1974 of a mysterious illness.
After that her boyfriend also died in a car accident.
Then Barfield moved from that place with Dollie and Montgomery Edwards in
1976, and then she worked as a nurse for the elderly couple. But they both died in 1977.
Then the next elderly man in her care, John Henry Lee, also died in 1977. Barfield then
moved with her boyfriend Stuart Taylor, but as the mysterious death he soon died of a
mysterious illness. But this time Taylor’s autopsy showing the presence of arsenic, and
witness oath from Barfield's sister led to her arrest. Jennings Barfield's body was also then
exhumed and also found to contain arsenic. The widow finally confessed to several
murders. In 1978, Velma Barfield was convicted of murder of Stuart Taylor and then in
1984 became the first woman in the US who was executed by lethal injection.


2. Margie Velma Bullard Barfield

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 From all these we understand that how arsenic poisoning is dangerous like the other
types of the poisoning cases. Through these assignments I explained about the arsenic
and what is poisoning, what is arsenic poisoning, preliminary and the confirmatory tests
done to detect the arsenic in the body. What is the reinsch’s test and the famous cases
related to it.



 https://study.com/academy/answer/what-happens-in-the-confirmatory-test-for-
arsenic.html
 https://www.mentalfloss.com/article/72351/12-female-poisoners-who-killed-arsenic
 http://www.healthofchildren.com/P/Poisoning.html