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Determination of amphetamine purity at home conditions

G.Patton

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Introduction

The determination method of the real amount of amphetamine in a sample at home conditions without expensive or rare equipment is shown in this article. Moreover, the step by step manual of the titrimetric method are minutely represented with full explanation.

You need:
  • Sodium nitrite (NaNO2);
  • 10% Hydrochloric acid (HCl);
  • Distilled water;
  • Indicators: tropaeolin OO and methylene blue.
Equipment:
  • Vial or flask 10 ml;
  • Bakers 200 ml x2;
  • Measuring graduated pipette 0.001 ml;
  • Scales.
If you have not got opportunities to buy analytical scales, you can replace it by pharmacy scales with a set of weights. It is cheaper than the analytical one and gives quite accurate results. At the opposite side, you cannot replace the graduated pipette by syringe. Cheap, inaccurate equipment would not let you get precise results. Glassware should be perfectly clean, so you need to rinse it 3-4 times by acetone and keep it under lint-free napkin.

Titrant preparation (0,1M sodium nitrite solution).
Put 0.73 g (94.51% purity) of sodium nitrite into a measuring glass and add distilled water up to 100 ml (the accuracy is very important). You will get 100 ml of 0.1M solution of sodium nitrite.

Sample preparation.
Put the accurate weights of 10 mg of the sample into the vial, add 1 ml of distilled water and 1 ml of 10% of hydrochloric acid. Add distilled water to get the total volume of solution of 5 ml. Then add 2 drops of tropaeolin OO and 2 drops of methylene blue.
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Fill the pipette with solution of sodium nitrite. Drop in sodium nitrite solution into sample solution, one by one, until the sample solution change the color (the blue color would be occurred). After that, mention the volume of sodium solution, that was used for titration.
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For example, we add 0.2 ml for titration. We know that 100 ml of solution contain 0.69 g of pure sodium nitrite. Hence, 0.2 ml of solution contain 0,00146 g (94.51% purity) of sodium nitrite or 0.0013798 g (100% pure). The molar mass of sodium nitrite equivalent is 68.995 g/eq, the molar mass of amphetamine sulfate is 184.25 g/eq. It is possible to calculate the mass of amphetamine sulphate in investigated sample: (0.0013798/68.995)*184.25=0,00368 g or 3.68 mg. The sample weight was 10 mg; hence, the sample contain 36.8% of pure amphetamine.

This method could be applied to analysis of any other amines (all amphetamines and cathinones). This method has one disadvantage. If the sample contain any other amine, its amount would be included in the result. It means that you cannot calculate the amount of amine you are interested in. That is why it is recommended to carry out the qualitative reactions preliminary.
 
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GinaCollada

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Thank you very much!!

I got one question, does this work for the liquid amphetamine base, too?

Thank you
 

G.Patton

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I got one question, does this work for the liquid amphetamine base, too?
Hello, no, it won't. Amph base doesn't solve in water in the first step.
 
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Forgotten

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Can you use 1g amphetamine instead of 10g? And what do i Need to change ?
 

G.Patton

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Can you use 1g amphetamine instead of 10g? And what do i Need to change ?
Sorry. It's mistake. You need to take sample 10 mg. I fixed it.
 

diogenes

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Hi, can in theory other indicators be used? E.g tropaeolin OO is not too available in my country, but maybe I have just been looking in the wrong places.
 

ACAB

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That is why it is recommended to carry out the quantitative reactions preliminary.
Could you please explain to me what a quantitative reaction is and how to do it?
 

ACAB

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Ok, thank you, I am familiar with this, I am also familiar with the TLC analysis, but you need a reference sample to make quantitative statements. A titration with mass fraction determination would of course be best suited to determine a percentage.

After some searching I found the two indicators we need here, but it seems that this is present as a solid, or powder and here is the talk of drops. Can I make the indicator solutions myself, if so which solvent should I use, if not, what do I have to pay attention to what the solutions consist of?
 

G.Patton

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Ok, thank you, I am familiar with this, I am also familiar with the TLC analysis, but you need a reference sample to make quantitative statements. A titration with mass fraction determination would of course be best suited to determine a percentage.

After some searching I found the two indicators we need here, but it seems that this is present as a solid, or powder and here is the talk of drops. Can I make the indicator solutions myself, if so which solvent should I use, if not, what do I have to pay attention to what the solutions consist of?
Sorry, i mean qualitative analysis. Fixed it.
 

G.Patton

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Sorry, misunderstanding, I meant the indicators: tropaeolin OO and methylene blue, found them only as solids :D

The other indicator solutions I have so far there.
100 mg of indicators were taken in two glasses and pour to 100 ml with distilled water.
Rj4BfV0KbI
40pfq7asJC
Ip6y8bYO2W
 

ACAB

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perfect, thank you. Sometimes the simplest solutions are also the best ones :D
 
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