Virtual Labs

HPTLC-Densitometric Assay of Lactose and Sucrose in Milk

1. Why is a derivatization step, such as using an aniline-diphenylamine-phosphoric acid reagent, necessary when analyzing sugars like lactose and sucrose by HPTLC?

a: To make the sugars soluble in the mobile phase. Explanation

Explanation

b: To separate the sugars from milk proteins. Explanation

Explanation

c: Because the sugars are not naturally visible under UV or white light. Explanation

Explanation

d: To convert sucrose into glucose and fructose for easier detection. Explanation

Explanation

2. A key advantage of using High-Performance Thin-Layer Chromatography (HPTLC) for analyzing sugars in dairy products, as compared to other methods, is-

a: Its ability to analyze samples with complex matrices like milk with minimal preparation. Explanation

Explanation

b: Its significantly lower cost than all other analytical techniques. Explanation

Explanation

c: Its ability to analyze samples in real-time without any sample preparation. Explanation

Explanation

d: Its superior sensitivity and ability to detect single molecules of sugar. Explanation

Explanation

3. A validated HPTLC method for honey analysis achieved excellent sensitivity. What was the reported Limit of Detection (LOD) for glucose?

a: 100.00 ng Explanation

Explanation

b: 33.00 ng Explanation

Explanation

c: 66.62 ng Explanation

Explanation

d: 21.17 ng Explanation

Explanation

4. In quantitative HPTLC, how is the amount of a specific sugar (e.g., lactose) in a sample typically determined after the plate has been developed and derivatized?

a: By weighing the scraped-off silica gel containing the sugar spot. Explanation

Explanation

b: By visually comparing the size and color intensity of the sample spot against standard spots. Explanation

Explanation

c: By using a densitometer to scan the plate and measure the absorbance of the colored spots. Explanation

Explanation

d: By measuring the distance the sugar spot traveled on the plate. Explanation

Explanation

5. According to official Chinese standards (GB 5413.5-2010), what is a common method for determining lactose and sucrose in milk products besides HPTLC?

a: Refractometry Explanation

Explanation

b: High-Performance Liquid Chromatography (HPLC) Explanation

Explanation

c: Mass Spectrometry (MS) Explanation

Explanation

d: Polari Explanation

Explanation