All carbohydrates contain carbon,
hydrogen and oxygen in ___ ratio.
1:2:1
6 sided sugars:
-________
5 sided sugars:
-glucose
-galactose
-frucotse
glucose+galactose+fructose= ?
rafinose
POLYSACCHARIDES
• Long-chain polymers of monosaccharides connected
by _______ bonds
glycosidic bonds
general test:
molisch’s test
special test for most of sugars
osazone
test for reducing sugars (6)
nemo: FBB TM P
fehling
benedict
barfoed
trommer
moore
precipitation
test for pentose sugars (2)
nemo: BoAa
bial’s orcinol
aniline acetate
test for hexose
nemo: CAPS
cobalt chloride
ammonium molybdate
phloroglucinol
seliwanoff’s
test for non-reducing
hydrolysis followed by…
test for non-reducing disaccharide
'fehling’s test after hydrolysis
test for non-reducing polysaccharide
iodine
tannic acid
Tests:
_______ -Confirm presence of carbohydrate in a given solution
_______ - Test for reducing sugars; Negative for polysaccharides
_______ - • Monosaccharides vs disaccharides
_______ - Differentiate fructose from glucose and galactose
molisch -Confirm presence of carbohydrate in a given solution
BENEDICT’S TEST - Test for reducing sugars; Negative for polysaccharides
BARFOED’S TEST - • Monosaccharides vs disaccharides
SELIWANOFF’S TEST - Differentiate fructose from glucose and galactose
__________ - sucrose on hydrolysis with HCl os converted to glucose and fructose
used to convert sucrose (non-reducing disaccharide) to glucose + fructose (reducing mono.
__________ - Test for galactose and
lactose
__________ - Confirm presence of carbohydrates
__________ - Pentoses form furfural compounds in the presence of concentrated acid. The furfural compounds formed by pentoses condense with orcinol to form blue colored compounds.
__________ - Test specific for polysaccharides
HYDROLYSIS TEST FOR SUCROSE - sucrose on hydrolysis with HCl os converted to glucose and fructose
PHLOROGLUCINOL TEST - Test for galactose and
OSAZONE’S TEST - Confirm presence of carbohydrates
BIAL’S TEST - Pentoses form furfural compounds in the presence of concentrated acid. The furfural compounds formed by pentoses condense with orcinol to form blue colored compounds.
IODINE REACTION - Test specific for polysaccharides
MOLISCH TEST
reagent:
+result:
reagent: 5% alpha-naphthol solution in ethyl
+result: purple or purplish-red tinted layers
BENEDICT’S TEST
result:
Copper Sulfate
Sodium Carbonate
Sodium Citrate
blue- no
green -trace
yellow - low
orange - moderate
brick red- high
BARFOED’S TEST
Copper Acetate in Glacial Acetic Acid
development of brick red/brown color ppt within 3-5 minutes (in a blue colored solution)
SELIWANOFF’S TEST
50 mg resorcinol
33 ml of concentrated HCL
(+) Test
Ketose monosach (ex:fructose)- Deep cherry red
Ketose disach (ex: sucrose) - cherry red
(-) Test
Aldose -faint pink/red
Yellow - no color change
HYDROLYSIS TEST FOR SUCROSE
HCl, thymol blue, sucrose solution\
-> pink color : acidic
divide into 2
boil one portion (1min), then cool, add 2% Na Carbonate
-> blue color: neutralization
benedict & seliwanof test on boiled
+rxn on benedict: dark red/red
+rxn on seliwanof: orange
-rxn: remained blue
PHLOROGLUCINOL TEST
10 ml concentrated HCl mixed with 8 ml of
0.5% phloroglucinol
red = galactose; lactose
OSAZONE’S TEST
1 part Phenyl Hydrazine
2 parts Sodium acetate
Few drops of glacial
acetic acid
Needle shaped crystals: glucose, fructose, mannose
balls w/ thorny edge shaped crystals: galactose
fine long needle shaped crystals: xylose
sun flower shaped crystals: maltose
powder puff/hedge hog shaped crystals: lactose
BIAL’S TEST
BIAL’S reagent
300 mg of orcinol in 100 ml of concentrated HCL and 0.25 mL ferric chloride solution.
(+) Test:
-blue color indicates the presence of pentose sugar
-ribose: blue green
IODINE REACTION
0.5 ml iodine diluted in 5ml distilled water
If blue color appears, amylase or starch is present in the solution
If reddish-purple color appears, dextrin is present
If reddish-brown color appears, glycogen is present
amylopectin - purple
(-) Test:
Yellow color
summary table of carbohydrate tests rxn
Last changeda year ago