Qualitative Test on Lipids PDF

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Summary

Prof. Glaidel Cruz - QUALITATIVE TEST ON LIPIDS...

Description

Enabling Assessment

Qualitative Tests of Lipids

Aaron Albert Domenden; Angelika Bedua, Hannah Nicole Bawar; Keith Louise Bacarro; and Krisha Mae Dalumpines

Name

Teacher Points

30 points

Ms. Glaidel Key Cruz Time Allotment 180 minutes

Date

01/20/2022

CYS

BSY23

Score

A. Experimental Results (15pts) Table 1. Results of the Qualitative Tests of Unknown Lipid Samples Sample No. 1 2 3 4 5

Copper acetate Test Greenish-blue color Colorless Colorless Greenish-blue color Colorless

Acrolein Test

Hubl’s Test

No distinct odor Pungent odor No distinct odor No distinct odor Pungent odor

Brown solution Light pink color Brown solution Light pink color Light pink color

Ammonium Molybdate Test No precipitates No precipitates No precipitates No precipitates Yellow precipitates

LiebermannBurchard Test No color change No color change Bluish-green color No color change No color change

Table 2. Sample Identity of Unknown Lipid Samples Sample No.

1

2

3

Sample Identity

Oleic acid

Rationale

Oleic acid appears as a colorless oily liquid with a lard-like strong odor. Its chemical structure contains an acid end group including one double bond (from C9 to C10) which is why it tested positive with the Copper acetate and Hubl’s tests.

Canola oil

Canola oil remained colorless in the copper acetate test nor formed precipitates in the Ammonium Molybdate test. When the LiebermanBurchard Test was utilized, there were no visible color shifts. Thus, all these are proven negative. Meanwhile, it tested positive on the Acrolein Test, which created a pungent odor, indicating the presence of fat or oil. Finally, Hubl’s test also exhibited a positive result, confirming its unsaturated fat.

Pork lard

Lard, extracted from pig's fat, is commonly used as a shortening or cooking fat. The Liebermann-Burchard test detects cholesterol, and since the animal sterol of lard is cholesterol, the sample reacted positively with the test. Due to the cholesterol found in lard, it will react negatively with the Acrolein test. It will also react negatively to the Copper Acetate test because of the fat contents. It reacted positively to Hubl's because of the detection of unsaturation. Lastly, it reacted negatively with the Ammonium Molybdate because lard does not have phosphorus.

Lauric acid

4

Lauric acid is exclusively found in vegetable fats, most notably coconut milk and oil, laurel oil, and palm kernel oil. The sample tested negative in both the Acrolein and Ammonium Molybdate tests and did not change color when the Liebermann-Burchard test was used, remaining in its same state. As a result of all of the reactions in the sample, it is clear that it is a saturated fatty acid.

Lecithin is a mixture of fats that are essential to cells in the human body. It can be found in many foods, including soybeans and egg yolks. Lecithin occurs colorless in the copper acetate test and remained to its color during Liebermann-Burchard Test, but it tested positive in the acrolein 5 Lecithin test, which produced a pungent odor indicating the presence of glycerol, and because it is composed of phosphoric acid, the sample positively reacted in the ammonium molybdate test, resulting in a yellow precipitate. B. Follow-up Questions (15 pts) Illustrate the general chemical reaction involved for each qualitative test for lipids. (3 pts each) A. Copper acetate Test

R-OH + (CH3COO]2Cu  No reaction B. Acrolein Test Glycerol + KHSO4  Acrolein + Fatty acid

H2 C

OH OH

KHSO4

OH Acrolein

Glycerol C. Hubl’s Test Alcoholic I2 HgCl2

R OH

R

R

R O

O

R

O

R

R

R

O

OH

Saturated molecules

Unsaturated lipid D. Ammonium molybdate Test O O

R O O

R O

OH O

P O

OH

CH3 O

NCH3

CH3

OH

O

O R

HO OH

P

CH3 HO

-

O

HO

NCH3

CH3

E. Liebermann-Burchard Test H3C

H2C

CH3

CH3

CH2

OH3 CH3

H2C

CH2

H2SO4 CH3COOH H

H2C

O S

HO O

Cholesterol

Cholestahexane sulphonic acid...