Aloe is the dried latex of the leaves of Aloe barbadensis Mill. (Aloe vera L.), known in commerce as Curaçao Aloe, or of Aloe ferox Mill. and hybrids of this species with Aloe africana Mill. and Aloe spicata Baker, known in commerce as Cape Aloe (Fam. Liliaceae). Aloe yields NLT 50.0% of water-soluble extractive.
• A. Powdered Aloe dissolves in nitric acid with effervescence, forming a reddish-brown to brown or green solution.
• B. Procedure
Sample: 1 g, finely powdered
Analysis: Mix the Sample with 25 mL of cold water. Shake the mixture occasionally during 2 h, filter, and wash the filter and residue with sufficient cold water to make the filtrate measure 100 mL.
Acceptance criteria: The color of the filtrate, viewed in the bulb of a 100-mL volumetric flask, is dark orange with Curaçao Aloe, and greenish yellow with Cape Aloe. The filtrate darkens on standing. [NoteReserve the filtrate for Identification tests C and D. ]
• C. Procedure
Sample: 5 mL of the filtrate obtained in Identification test B
Analysis: Add 2 mL of nitric acid to the Sample.
Acceptance criteria: The mixture exhibits a reddish-orange color with Curaçao Aloe, and a reddish-brown color that changes rapidly to green with Cape Aloe.
• D. Procedure
Sample: 10 mL of the filtrate obtained in Identification test B
Analysis: Mix the Sample with 2 mL of ammonium hydroxide.
Acceptance criteria: The mixture exhibits an amber color with Cape Aloe, and a dark amber color with Curaçao Aloe.
• Water-Soluble Extractive
Sample: 2 g of powdered Aloe
Analysis: Macerate the Sample in 70 mL of water in a suitable flask. Shake the mixture during 8 h at 30-min intervals, and allow it to stand for 16 h without shaking. Filter, and wash the flask and residue with small portions of water, passing the washings through the filter, until the filtrate measures 100.0 mL. Evaporate a 50-mL aliquot of the filtrate in a tared dish on a steam bath to dryness, and dry at 110 to constant weight.
Acceptance criteria: The weight of water-soluble extractive so obtained is NLT 50% of the weight of Aloe taken.
• Water Determination, Method III 921
Sample: Use a powdered sample. If the Aloe is not powdered, crush it in a mortar until it passes through a no. 40 sieve, and mix the ground material before weighing the sample.
Analysis: Dry at 105 for 5 h
Acceptance criteria: NMT 12.0%
• Articles of Botanical Origin, Total Ash 561
Acceptance criteria: NMT 4.0%
• Alcohol-Insoluble Substances
Sample: 1 g of powdered Aloe
Analysis: Add the Sample to 50 mL of alcohol in a flask. Heat the mixture to boiling, and maintain at incipient boiling for 15 min, replacing any loss due to evaporation. Remove from the heat, and shake the mixture at intervals during 1 h. Pass through a small dried and tared filter paper or a dried and tared filtering crucible, and wash the residue on the filter with alcohol until the last washing is colorless. Dry the residue at 105 to constant weight.
Acceptance criteria: The weight of the residue does not exceed 10.0% of the weight of Aloe taken.
• Botanic Characteristics
Curaçao aloe: Brownish black, opaque masses. Its fractured surface is uneven, waxy, and somewhat resinous.
Cape aloe: Dusky to dark brown irregular masses, the surfaces of which are often covered with a yellowish powder. Its fracture is smooth and glassy.
Powdered aloe: Yellow, yellowish brown to olive-brown in color. When mounted in a bland expressed oil, it appears as greenish-yellow to reddish-brown angular or irregular fragments, the hues of which depend to some extent upon the thickness of the fragments.