Preparation of Ninhydrin reagent in alcoholic 5% aloe vera barbadensis gel used as hair colourant

Ninhydrin Reaction

The reaction of ninhydrin with primary amino groups to form the purple dye now called Ruhemann's purple (RP) was discovered by Siegfried Ruhemann in 1910. In addition, imines such as pipecolic acid and proline, the guanidino group of arginine, the amide groups of asparagine, the indole ring of tryptophan, the sulfhydryl group of cysteine, amino groups of cytosine and guanine, and cyanide ions also react with ninhydrin to form various chromophores of analytical interest. Since its discovery, extensive efforts have been made to apply manual and automated ninhydrin reactions as well as ninhydrin spray reagents to the detection, isolation, and analysis of numerous compounds of interest across a broad spectrum of disciplines. These include agricultural, biochemical, clinical, environmental, food, forensic, histochemical, microbiological, medical, nutritional, plant, and protein sciences. This reaction is unique among chromogenic reactions in that at pH 5.5 it results in the formation of the same soluble chromophore by all primary amines which react, be they amines, amino acids, peptides, proteins, and even ammonia.

NINHYDRIN TEST PRINCIPLE

The amino group belonging to a free amino acid undergoes a chemical reaction with ninhydrin, which behaves as an oxidizing agent. When exposed to ninhydrin, the amino acid undergoes oxidative deamination, resulting in the liberation of CO2, NH3, and an aldehyde along with hydrindantin (which is a reduced form of ninhydrin).

Now, the ammonia goes on to react with another ninhydrin molecule to form diketohydrin (which is also known as Ruhemann’s complex). This complex is responsible for the deep blue colour. When the analyte contains Imino-acids like proline, a yellow coloured complex is formed. When asparagine is used, the colour of the resulting complex is brown.

How to Make Aloe Vera Gel

The aloe vera plant is a succulent that stores water in its leaves in the form of a gel.

This gel is highly moisturizing and great for sunburns, bug bites, minor cuts or wounds, and other skin problems.

However, many store-bought aloe vera products contain potentially harmful additives like dyes.

This article explains how to easily make aloe vera gel yourself using fresh aloe vera leaves.

Here’s what you need

Aloe vera gel is easy to make using either the leaves of an aloe plant you have at home, or ones you’ve purchased at a grocery store or farmer’s market.

To make aloe vera gel, you need:

an  aloe vera leaf

a knife or vegetable peeler

a small spoon

a blender

an airtight container for storage

powdered vitamin C and/or vitamin E (optional)

It’s best to only use one or two leaves at a time, as the gel only lasts about 1 week without additional preservatives.

If you plan to keep it longer, you need to freeze it or add a preservative in the form of powdered vitamin C or E.

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Directions

Once you have gathered all of the materials you need, it only takes about 30 minutes to make your aloe vera gel.

1. Prepare the aloe leaves

To use a fresh aloe leaf from a plant, first cut off one of the outer leaves from the base of the plant.

You can also use a store-bought leaf.

Wash it well, removing any dirt, and then stand it upright in a cup or bowl for 10–15 minutes. This allows the yellow-tinted resin to drain out of the leaf.

The resin contains latex, which can irritate your skin, so completing this step is important.

After the resin has drained completely, wash off any remains on the leaf and peel off the thick skin using a small knife or vegetable peeler.

2. Make the gel

Once the leaf has been peeled, you will see the natural aloe vera gel.

Using a small spoon, scoop it into your blender. Be careful not to include any pieces of the aloe vera skin.

Blend the gel until it’s frothy and liquefied, which should only take a few seconds. And can be used

 However, if you plan on keeping it for more than 1 week, you should add preservatives.

3. Add preservatives (optional)

Vitamins C and E are excellent preservatives that can greatly extend the shelf life of your aloe vera gel.

Though the gel naturally contains some of these vitamins, it’s not enough to preserve the gel for longer than 1 week.

Still, you can add more of one or both of these vitamins to extend your gel’s shelf life.

Plus, both contain antioxidant and anti-aging properties, so these additions can help boost the skin-protecting power of your aloe vera gel

For every 1/4 cup (60 ml) of aloe vera gel you make, add 500 mg of powdered vitamin C or 400 International Units (IU) of powdered  vit E — or both.

Simply add the powdered vitamins directly to the blender and mix the gel once more until the additives are fully incorporated.