Standard for the testing of chromatographic plates

Standard for the testing of chromatographic plates

1. Coating thickness:

The analysis plate shall not be less than 0.2mm, and the preparation plate shall not be less than 0.4mm or 0.9mm

2, bonding fastness:

With n-butanol: glacial acetic acid: water = 4:1:1 as the developing agent, the coating was repeated for three times, and no obvious peeling phenomenon. Bake at 110℃ for 10 minutes, plate surface without cracking.

3, anti-detection interference:

Concentrated sulfuric acid: ethanol = 1:1 solution evenly spray until the surface is moist, bake at 110℃ for 10 minutes, the surface remains black. Take 2% potassium permanganate solution for color development and leave it for 30 minutes without fading.

4, coating uniformity:

(1) Randomly select 5 thin laminates, each with 2 positions, a total of 10 positions, and the thickness of each point should meet the labeling requirements.

(2) Developing agent: n-hexane: isopropyl alcohol = 9:1

Sample: A mixture of o-nitroaniline and p-nitroaniline (ethyl acetate solution) at a concentration of 1.5mg/ml.

a. After sampling, first look at whether the sample moves with the development agent, and then look at whether the sample is separated, and do not move or do not separate as unqualified products. Finally, see whether the sample has the trailing phenomenon, the unqualified plate has the trailing phenomenon.

b. In the appearance detection, it can not be seen whether the TLC surface is uniform. After running the plate, it can be seen whether the TLC surface is uniform by the distribution of the liquid front and sample points. The leading edge and sample points should be distributed in a straight line, if there is an obvious jagged phenomenon, that is, uneven paving, unqualified.

5. PH value

Scrape off the coated silica gel powder 2g and add 50ml distilled water. Stir thoroughly for 5 minutes. The pH meter should be 6.5±0.3.

6. Separation effect

Azobenzene 25mg, p-methyl azobenzene 5mg, Sudan yellow 5mg, Sudan red 5mg, p-amino-azobenzene 5mg, dissolved in 5ml benzene, as substances to be separated, with benzene as the development agent, after the five colors separated, no obvious tail for qualified products.

7. Salicylic acid experiment

Sample: 1) Salicylic acid, concentration: 20mg/ml (methanol as solvent)

2), salicylic acid and methyl p-nitrobenzoate mixed solution, the concentration is 1mg/ml

Developing agent: n-hexane: ethyl acetate =1:1

Sample 1) salicylic acid ratio shift value is between 0.2 and 0.35, the error shall not exceed 10%

In sample 2), the salicylic acid ratio was transplanted between 0.1 and 0.25, and the ratio of methyl p-nitrobenzoate was transplanted between 0.75 and 0.9, with an error of no more than 10%

8. Immersion experiment

(1) Vanillin: 25 g vanillin +2.5 mL concentrated sulfuric acid + 250 mL ethanol, soaked for 5 minutes, and then put in the oven to dry at 110℃ for 60 minutes.

After drying, there is no surface bubbling off powder phenomenon, that is qualified.

(2) Anisaldehyde soaking solution: 15 g (anisaldehyde, p-anisaldehyde) +2.5 mL concentrated sulfuric acid + 250 mL ethanol, soaked for 5 minutes, and then put in the oven at 110℃ for 60 minutes.

After drying, there is no surface bubbling off powder phenomenon, that is qualified