Notre Dame of Dadiangas University
College of Health Sciences
Bachelor of Science in Medical Technology
NAME: FELEO, LOUISE JEM G. YR &SEC: 2nd year BSMT 2C
PROFESSOR: Ms. Aiyn Boclaras DATE: 10/06/2020
STUDY GUIDE NO. 4
LIPIDS (PART 1)
INTRODUCTION
The term “lipid” refers to both true fats and fat-like substances. There are biomolecules that are
insoluble in water but are soluble in organic solvents. The water insolubility is due to the fact
that the polar portion of the molecule is much smaller than the non-polar portion. This property
is important for the cell in the separation of components containing aqueous solutions from each
other. Another important function of lipids is the storage of energy in the form of body fat. Some
lipids are important constituents of protoplasm. The brain and nervous tissues are rich in certain
lipids, a fact that indicates the importance of these compounds in the maintenance of life.
Lipids can be divided into five groups: (1) fats and oils; (2) waxes; (3) compound lipids; (4)
sterols and steroids; and (5) derived lipids. Fatty acids, one of the building blocks of lipids, is just
one of the examples of the hydrolysis products of fats and oils as well as of the compound
lipids.
STUDY QUESTIONS:
BROMINE WATER TEST
1. What is the principle involved in the bromine water test? What is its purpose?
The bromine water test is a qualitative test which is used to classify the functional
groups of alkene or alkane present in the compound. In the dark state, alkene groups
react with bromine water and undergo an additional reaction to provide a decolorized
solution. On the other hand, with bromine water, alkane does not react and the color of
the bromine water remains the same. The most common compounds to undergo
bromine water testing are enol, alkenes, aniline, glucose, phenols, and acetyl groups.
The test also identifies in the compound the presence of an aldehyde group. The color of
the bromine water changes from yellow to colorless during the process.
Source: Bromine water test - Preparation of bromine water solution and
application of bromine water solutions. (2020, March 5). BYJUS.
ACROLEIN TEST
1. What is the principle involved in the acrolein test? What is its purpose?
The presence of glycerol or fat is detected using the Acrolein test. The glycerol
part of the molecule is dehydrated to form an unsaturated aldehyde, acrolein with a
Reference: Piedad C. Pena (et al.) Biochemistry laboratory manual – 1 st ed. – Quezon City: C&E
Publishing, Inc., 2015.
potent irritating odor, when fat is heavily handled in the presence of a dehydrating agent
such as potassium bisulphate (KHSO4).
Source: Qualitative analysis of oils and fats (Theory) : Class 12 : Chemistry :
Amrita online lab. (n.d.). Amrita Online Lab.
2. what group of lipids were identified in the test?
It is possible to use this test to differentiate between triglycerides and fatty acids.
Due to their free carboxylic community, triglycerides are chemically neutral whereas fatty
acids are acidic and may decolorize the alkaline red color of phenolphthalein. This test is
used to detect saturated and unsaturated fatty acids; cupricacetate reacts with fatty
acids to form cupric fatty acid salts.
Source: Identifying lipids using chemical tests. (n.d.). Academia.edu - Share
research.
MOLISCH TEST
1. What is the principle involved in the test? What is its purpose?
In Molisch 's test, after the application of concentrated hydrochloric or sulphuric
acid, the carbohydrate (if present) undergoes dehydration, resulting in the formation of
an aldehyde. This aldehyde, along with two phenol-type molecules, undergoes
condensation, resulting in the formation of a complex of purple or reddish-purple colors.
Source: Identifying lipids using chemical tests. (n.d.). Academia.edu - Share
research.
2. What is the purpose of the reagent used?
The examination of Molisch includes the addition to the analyte of Molisch's
reagen, a solution of al-naphthol in ethanol and the subsequent addition to the mixture of
a few drops of concentrated sulphuric aci. The test by Molisch is a chemical test used to
verify the presence of carbohydrates in a given analyte.
Source: Identifying lipids using chemical tests. (n.d.). Academia.edu - Share
research
3. What group of lipids was identified by this test? How?
For the Molisch test, all carbohydrates and lipids, such as phospholipids, produce
a positive reaction. First of all, this test for the presence of carbohydrates is the Molisch
test. Because of the carbohydrate dehydration that is present. The sulfuric acid does
this and produces an aldehyde. This aldehyde then condenses with Molisch 's reagent,
phenol and 1-napthol.
Source: Test for carbohydrates,lipids and proteins. (2013, April 6).
mandysbiochemistrylair.
Reference: Piedad C. Pena (et al.) Biochemistry laboratory manual – 1 st ed. – Quezon City: C&E
Publishing, Inc., 2015.
NINHYDRIN TEST
1. What is the principle involved in the Ninhydrin test? What is its purpose?
A chemical reaction with ninhydrin that acts as an oxidizing agent is experienced
by the amino group belonging to a free amino acid. The amino acid is subjected to
oxidative deamination when exposed to ninhydrin, resulting in the release of CO2, NH3,
and an aldehyde along with hydrindantin, a reduced form of ninhydrin.
Source: Ninhydrin test. (2019, December 10). BYJUS.
2. What is the purpose of the reagents used?
The ninhydrin test is a chemical test used to verify if amines or alpha-amino acids
are present in a given analyte. In this test, a chemical compound containing the formula
C9H6O4 with an IUPAC name of 2,2-dihydroxyindane-1,3-dione is added to the test
solution of the analyte ninhydrin. The appearance of ammonia, primary / secondary
amines, or amino acids in the analyte suggests the formation of a deep blue hue.
Source: Ninhydrin test. (2019, December 10). BYJUS.
3. What group of lipids was identified by this test? How?
Ninhydrin Identification of a lipid-containing amino group of PAO1 cells after
incubation in water. To visualize the amino group-containing lipids, complete lipids were
removed, separated by thin layer chromatography, and sprayed with ninhydrin.
Source: Fig 7. Ninhydrin detection of amino group containing lipids of PAO1...
(2020, April 15). ResearchGate.
4. What are the precautions to account with the ninhydrin test?
Perform in a well-ventilated environment or fume hood. Ninhydrin is an irritant,
biologically active, normally dissolved in an alcohol solvent. Flammable liquids are
alcohol solvents. Keep away from fires or other sources of ignition. Ninhydrin can stain
your skin. Wear chemical splash goggles, gloves that are chemical resistant, and an
apron that is chemical resistant. For additional safety, handling, and disposal
information, please review the current Material Safety Data Sheets.
Source: Amino Acid Fingerprints. (n.d.). Flinn Scientific.
Reference: Piedad C. Pena (et al.) Biochemistry laboratory manual – 1 st ed. – Quezon City: C&E
Publishing, Inc., 2015.
