Download stomach contents analysis

STOMACH CONTENTS ANALYSIS
What do you look for?
• Drugs
• Type of food that was
ingested: can test for the
presence of fats, sugars,
proteins, etc.; this will give an
indication of the type of food
that was ingested
• Degree of breakdown: food
takes anywhere from 2 to 6
hours to pass through the
stomach
Carbohydrates
• Includes sugars, starches, and cellulose
• Function to store energy and to provide
shape to organisms
• Composed of carbon, hydrogen, and
oxygen
Carbohydrates (cont.)
• Can be divided into 3 groups
based on their size:
– Monosaccharides: simple
sugars like glucose (blood
sugar) and fructose
– Disaccharides: double
sugars like sucrose (table
sugar) and lactose (milk
sugar)
– Polysaccharides: chains of
sugars like starch,
glycogen, cellulose and
chitin
Carbohydrates (cont.)
• Simple sugars are also called reducing sugars
and can be identified using the Benedict’s test
• Benedict’s solution is a light blue color
(contains copper II)
• In the presence of a reducing sugar, the
Benedict’s solution will change color ranging
from green to yellow to red, depending on the
amount of reducing sugar present
BENEDICT'S TEST
A positive test
results in a color
change from light
blue to orange,
green, yellow, or
red.
A negative test results in
NO color change. The
solution will remain light
blue.
• To perform the test, place about 30 drops of
your sample into a test tube. Add about 30
drops of Benedict's. Place the test tube into a
hot water bath for 5 minutes and observe any
changes.
Carbohydrates (cont.)
• Starch can be tested for using the iodine test
• Iodine is a yellow/orange color
• In the presence of starch, the iodine changes
color ranging from royal blue to purple to
black
IODINE TEST
A negative test results
in no color change.
A positive test results in a
color change from
yellow/brown to
blackish/purple.
• To perform the test, add about 30 drops of
your sample to a test tube. Add 2-3 drops of
iodine. Observe any color changes.
Proteins
• Make up ½ of the dry body weight
• Structure is a complex molecule composed of
20 different, smaller molecules called amino
acids
• The presence of protein in foods can be
identified using the biuret test
• Biuret solution (blue in color) contains copper
sulfate dissolved in a strong base
• Protein causes the solution to change color
ranging from lavender to purple depending on
the nature and amount of protein present
BIURET'S TEST
A negative test is
seen here. The
color stays blue.
A positive result is
seen here. The color
changes to purple.
• To perform the test, put about 30 drops of
your sample into a test tube. Add 2-3 drops of
Biuret's. Observe any color changes.
Lipids
• Include fats, phospholipids and steroids
• Insoluble in water
• Functions include:
– Provide long-term energy storage
– Act as insulators
– Important in cell membranes
– Act as hormones
Lipids (cont.)
• Structure:
– Fats: a glycerol and 3
fatty acids
– Phospholipids: a
glycerol, a phosphate
group and 2 fatty acids
– Steroids: four fused
rings with various side
groups
Lipids
• Lipids are insoluble in water
• The presence of lipids can be identified using
the Sudan III test
• Sudan III is a pink dye that is attracted to and
dissolves in non-polar compounds
• Sudan III does not dissolve in water or other
polar solvents
• In the presence of lipids, Sudan III changes
color from pink to yellow/white
SUDAN III TEST
This is a
positive test
result.
• This is the test for lipids.
You can also do the brown paper test.
Vitamin C
• Ascorbic acid, commonly called Vitamin C, is
important in the body for collagen
production (an important component of
bone, cartilage, and other connective
tissues)
• Vitamin C deficiency results in the disease
scurvy which causes bleeding gums and a
tendency to bruise easily
Vitamin C (cont.)
• High concentrations of Vitamin C can be
found in citrus fruits (oranges, limes,
grapefruits, etc.), tomatoes, potatoes, and
leafy green vegetables
• Vitamin C is water soluble and a reducing
agent (gives up electrons)
• 2,6-dichloroindophenol is a blue color
indicator that turns colorless in the presence
of Vitamin C