PAG (application) Questions and Answers | Latest Update | Graded A+

PAG (application) Questions and Answers | Latest Update | Graded A+ **Qualitative testing - emulsion test** **Why does the emulsion test not show false positives for monosaccharides & disaccharides, starch, nucleic acid, and protein?** The emulsion test relies on the solubility properties of lipids in ethanol. Monosaccharides and disaccharides dissolve in water and do not form a precipitate in ethanol. Starch, although it can form an emulsion in water, remains insoluble in ethanol. Nucleic acids are soluble in water and insoluble in ethanol, thus not precipitating. Proteins, being insoluble in ethanol, are not extracted into the emulsion. **How could the emulsion test be adapted to provide semi-quantitative or fully quantitative data on lipid concentration?** To semi-quantitatively assess lipid concentration, you could measure and correlate the intensity of the emulsion (cloudiness) with known lipid concentrations. For a fully quantitative approach, using a colorimeter to measure light transmission through the emulsion could provide precise quantitative data. --- **Qualitative testing - glucose** **What improvements could be made to enhance the qualitative glucose test method?** Enhancements could include filtering excess liquid after adding NaHCO3 to improve clarity of color changes. Standardizing the volumes of solutions used would also increase consistency in results. **How would you modify this method to obtain semi-quantitative results?** A semi-quantitative approach could involve using a colorimeter to measure the absorbance or % transmission of light through the samples after reacting with Benedict's reagent. Calibration against known glucose standards would allow estimation of glucose concentration. --- **Chromatography** **Why might not all amino acids appear on your chromatogram?**