32. Which among the following is the easiest method to estimate the concentration of
glycerol in an aqueous solution of glycerol?
A. UV absorption spectroscopy
B. Gas chromatography
C. pH measurement
D. Viscosity measurement
Viscosity measurement is the easiest method to estimate glycerol concentration in an aqueous solution due to its direct correlation with concentration, simplicity, and minimal sample preparation.
Option Analysis
Glycerol solutions exhibit a strong, predictable increase in viscosity with higher concentrations, allowing calibration curves for quick estimation using basic viscometers. This approach requires no derivatization or complex instrumentation, making it accessible for routine analysis.
-
A. UV absorption spectroscopy: Glycerol lacks strong UV absorption above 200 nm, requiring chemical derivatization for detection, which adds steps and reduces simplicity. Not ideal for direct, easy estimation in aqueous solutions.
-
B. Gas chromatography: Effective for precise quantification but involves sample volatilization challenges, column contamination risks, and lengthy preparation for non-volatile glycerol. Far from the easiest due to equipment needs and expertise required.
-
C. pH measurement: Glycerol is neutral and does not significantly alter pH in aqueous solutions, offering no reliable correlation for concentration estimation. Impractical and inaccurate for this purpose.
-
D. Viscosity measurement: Correct choice; viscosity rises sharply (e.g., from ~1 cP at 0% to ~1500 cP at 50% glycerol at 20°C), enabling straightforward calibration and measurement.
Why Viscosity Excels
Standard tables and empirical formulas link glycerol-water viscosity to concentration across temperatures, supporting rapid quality control without advanced tools. This method suits educational and industrial settings, aligning with CSIR NET Life Sciences focus on practical analytical techniques.
