Carbohydrate Lab Report
Carbohydrate Lab Report
Introduction
Qualitative identification of a substance is of significant importance in chemistry. Physical constants such as melting points have traditionally been used by organic chemistry for identification of unknown compounds. As for inorganic substances, the precipitation of a solid, results of a flame test, or the formation of a colored substance could all be keys to identifying a sample. Chromatography and spectra are amongst the newer techniques practiced today. A problem that arises in biochemistry when attempting to identify a particular compound is that the tests that are utilized to identify these compounds rely on the reaction of a functional group and therefore will yield positive reactions with more than just one compound. This means that more than one test has to be performed in order to deduce which compound is present by process of elimination. Carbohydrate chemistry allows us a great opportunity to better understand qualitative testing. The tests run within this experiment are usually carried out to identify simple carbohydrates. It is possible that by running these tests with a variety of different carbohydrates we determine the identity of an unknown sample.
Tests
Benedict’s Test
Tests for: Reducing Sugar (+), Nonreducing Sugar (–)
Positive result: Red precipitate Negative result: No precipitate
Bial’s Test
Tests for: Pentoses (+), Other (–)
Positive result: Change in color to cloudy dark blue Negative result: Not cloudy dark blue
Barfoerd’s Test
Tests for: Monosaccharides (+), Disaccharides (–)
Positive result: Red precipitate Negative result: No precipitate
Seliwanoff’s Test
Tests for: Fructose (+), Other (–)
Positive result: Change in color to orange Negative result: Not orange
Glucose Oxidase Test
Tests for: Glucose (+), Other (–)
Positive
Introduction
Qualitative identification of a substance is of significant importance in chemistry. Physical constants such as melting points have traditionally been used by organic chemistry for identification of unknown compounds. As for inorganic substances, the precipitation of a solid, results of a flame test, or the formation of a colored substance could all be keys to identifying a sample. Chromatography and spectra are amongst the newer techniques practiced today. A problem that arises in biochemistry when attempting to identify a particular compound is that the tests that are utilized to identify these compounds rely on the reaction of a functional group and therefore will yield positive reactions with more than just one compound. This means that more than one test has to be performed in order to deduce which compound is present by process of elimination. Carbohydrate chemistry allows us a great opportunity to better understand qualitative testing. The tests run within this experiment are usually carried out to identify simple carbohydrates. It is possible that by running these tests with a variety of different carbohydrates we determine the identity of an unknown sample.
Tests
Benedict’s Test
Tests for: Reducing Sugar (+), Nonreducing Sugar (–)
Positive result: Red precipitate Negative result: No precipitate
Bial’s Test
Tests for: Pentoses (+), Other (–)
Positive result: Change in color to cloudy dark blue Negative result: Not cloudy dark blue
Barfoerd’s Test
Tests for: Monosaccharides (+), Disaccharides (–)
Positive result: Red precipitate Negative result: No precipitate
Seliwanoff’s Test
Tests for: Fructose (+), Other (–)
Positive result: Change in color to orange Negative result: Not orange
Glucose Oxidase Test
Tests for: Glucose (+), Other (–)
Positive