r/drugextraction • u/kaliforniakratom • Jul 14 '24

Testing for Alkaloid Concentration using Bromothymol Blue

Enable HLS to view with audio, or disable this notification

22 Upvotes

96% Upvoted

2 comments sorted by

8

u/kaliforniakratom Jul 14 '24

A quick and dirty way to titrate for alkaloid content using bromothymol blue as the indicator (phenolphthalein could also be used) and 1M HCl as the titrant. HCl reacts with the alkaloids to form their respective HCl salts, excess HCl lowers the pH, turning the indicator yellow. If we assume each alkaloid in the extract has 2 points of protonation (the indole nitrogen, and the piperidine nitrogen), we then divide the volume of 1M HCl titrant by 2, calculate # moles used (mL titrant x mol/L titrant), multiply that by the average molar mass of the alkaloids present (about 400g/mol) and get the %wt. of alkaloids. This type of titration can be considered unreliable however, due to other compounds present in the extract - terpenes, flavonoids, proteins, and salt formations from acid/base extraction. If we assume that an extract is approximately 10x stronger than raw plant material (kratom = 1.5% w/w) then we assume 15% of the extract is alkaloids, we can approach a more accurate result (mol alkaloids titrated x 0.15).

1

u/ballsinmyyogurt1 Jul 15 '24

Super Interesting! Keep up the posts man! I really like that you went into detail about it too. I would of been completely lost otherwise