Seliwanoff s Test

7/25/2019 Seliwanoff s Test

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SELIWANOFFS TEST

GROUP 4


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A.)WHAT IS THE PRINCIPLE

INVOLVED IN THE SELIWANOFF'S

TEST?

When heated, ketoses are more rapidlydehydrated than aldoses.

When Seliwanoff's reagent is added to a solutionontaining ketoses, a red olor is formed rapidlyindiating a positi!e result. When added to asolution ontaining aldoses, a slower forming light

pink or faint red is o"ser!ed instead.


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B. WHAT IS THE PURPOSE OF

THE TEST?

#o distinguish if the ar"ohydrate present in the

solution is an aldose or ketose sugar.


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PROCEDURE:TEST TUBE 1 TEST TUBE 2

$ ml %$& drops G(U)OS* $ ml %$& drops SU)ROS*

%$& drops S*(+W-O/SR*G*-#

%$& drops S*(+W-O/SR*G*-#

0i1 thoroughly for $ minute. -ote any hanges. When no hanges is o"ser!ed, plae

the tu"e in a warm water %23 degrees ).

Remo!e all tu"es one a hange is o"ser!ed in some ofthe samples. -ote any hanges and reord your o"ser!ations.


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RESULTS AND DISCUSSION:

RU)#OS* POS+#+5* G(U)OS* 6 yellowish %SU)ROS* faint pink %7

#*R & 0+-U#*S

G(U)OS* 6 yellowish %SU)ROS* red %7

#*R $3 0+-U#*S


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The reagent dehydrates et!he"!ses t! #!r$ %&

hydr!"y$ethy'#(r#(ra'


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%&hydr!"y$ethy'#(r#(ra' #(rther )!ndenses

*+th res!r)+n!' -resent +n the test reagent t!

-r!d()e a )herry red -r!d()t *+th+n t*! t! #+,e$+n(tes.


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D. PRO5IDE A POSSIBLE E6PLANATION FOR T/E

POSITI5E AND NEATI5E RESULTS OBTAINED WIT/

3OUR SA0PLE.

FRUCTOSE SUCROSE LUCOSE

:*#OS* :*#OS*, (;OS* (;OS*

Red Pale red


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rutose and surose are two ommon sugars

whih gi!e a positi!e test.

Surose gi!es a positi!e test as it is a

disaharide onsisting of frutose and gluose.


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Negat+,e Res('ts

no red olor appearing in the solution ll other sugars e1ept frutose and surose gi!es

negati!e result with seliwanoff/s reagent.

ldose sugars ha!e an aldehyde group, while ketose

ha!e a ketone group. So if heated, ketose is faster

dehydrated than aldose.


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E. CO0PARE T/E TEST WIT/ T/E

0OLISC/ TEST

=oth tests are used to identify presene ofar"ohydrates using ondensation reagents whihreats with the ar"ohydrates to produe highly

olored produts. Often, the ar"ohydrate is initiallydehydrated into smaller saharide units. 0olish test is a sensiti!e "ut nonspeifi hemial

test for the presene of all ar"ohydrates while

Seliwanoff/s #est is a speifi test on detetingketose sugars.

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Seliwanoff s Test