wareami (Hive Bee)
03-01-02 19:39
No 275583
      Rhodium: The Complete SF Extraction Study  Bookmark   

Back in october, I posted Post 227523 (wareami: "Re: Working with red pills...", Newbee Forum) just one chapter concerning a study that involved the extraction of pseudoephedrine from Suphedrine tablets in an effort to get some input and ideas since most of the study was beyond my comprehension. I do have a better understanding and see now that I should include the rest of the study for those that may be interested in the studies results!
In addition, the use of halogenated solvents (E-Gull Method) were found to be useful in the extraction of pseudo from OTC's as a direct result of reading and finally understanding much of what the studies findings concluded!
Links to full study below.

A successful supercritical fluid extraction method includes removal of the analyte from the matrix into the bulk fluid as well as trapping or concentration of the analyte prior
to analysis. In the first phase of this research, the trapping capacities of three solid-phase traps (glass beads, 50/50 (w/w) glass beads/octadecylsilica), 50/50 (w/w) Porapak Q«/glass beads) were determined as a function of trap composition for a mixture of components varying in polarity and volatility. The Porapak Q«/glass beads mixture was found to be the most successful solid-phase investigated exhibiting the highest trapping capacity. The use of the Porapak Q«/glass beads as a solid-phase trap was investigated in later extraction studies in this dissertation.
The extraction of highly polar, multifunctional analytes may not be completely successful with modified carbon dioxide, therefore, a secondary modifier (i.e. additive)
may be added directly to the extraction fluid in hopes of improving the recoveries. In the second phase of this research, the effect of secondary modifiers in the subcritical fluid extraction of lovastatin from in-house prepared tablet powder mixtures and MEVACOR« tablets was investigated. The effect of in-line methanol-modifier percentage, additive type (acidic, basic, neutral) to the in-line methanol, and additive concentration on the extraction efficiency were examined. The extraction recoveries of lovastatin from MEVACOR« tablets were shown to be highly dependent on methanol concentration and additive type.
Isopropylamine was shown to be the most successful additive investigated. An optimized and reproducible extraction method was developed.
The extraction of ionic compounds with carbon dioxide may be difficult due to the high polarity of the compounds. In the third phase of this research, the addition of ionpairing
additives to the matrix in hopes of forming an ion-pair complex of reduced analyte polarity was investigated. Therefore, a screening study consisting of a fractional-factorial design was performed in order to identify the factors which contribute most to the recovery of an anionic species, triphenylphosphinetrisulfonate (TPPTS), from a spikedsand surface employing supercritical fluid extraction with carbon dioxide. The experimental parameters investigated were: type of ion-pairing additive (i.e.
tetralkylammonium hydrogen sulfates) and its concentration, carbon dioxide density, extraction temperature, static extraction time, CO2 mass used, liquid CO2 flow rate, and
the volume of methanol spiked into the matrix prior to extraction. Of the eight factors investigated, four factors were identified as significantly affecting the recovery of the anionic species. They were: 1) ion-pairing reagent added to the spiked sand surface and its concentration; 2) static extraction time; and 3) volume of methanol present in the extraction vessel. The experimental parameters and settings identified as influential by the statistical approach were later shown in concert to yield 100% recovery of TPPTS from the spiked-sand.
In the fourth phase, the extraction of a cationic species, pseudoephedrine hydrochloride, from spiked-sand and Suphedrine tablets, with pure and methanol-modified
CO2 was examined. Once the extraction was shown to feasible, several strategies were compared in terms of their effectiveness in enhancing the analyteĺs extractability. The first strategy involved the addition of ion-pairing additives. Several sodium salts of
alkylsulfonic acids varying in lipophilicity and concentration were investigated. The addition of 1-heptanesulfonic acid, sodium salt, in methanol, in a 5:1 mole ratio of reagent to analyte was shown to be the most useful in recovering the drug from the spiked-sand.
The second strategy considered the influence of acids and bases and other modifier compositions such as a methanol/water mixture with or without 1-heptanesulfonic acid, sodium salt, on the pseudoephedrine recovery. The recoveries obtained from the drug spiked-sand were shown to comparable in the presence of a methanol/water solution, a
tetrabutylammonium hydroxide in methanol solution, and a methanol solution with 1-heptanesulfonic acid, sodium salt. Next the extraction of pseudoephedrine hydrochloride
from Suphedrine tablets was performed with pure and modified CO2. Similar to the sandspike studies, the effect of the addition of the ion-pairing reagent and other in-cell
modifiers were examined. Once again, the recoveries obtained when the matrix was in the presence of a methanol/water mixture and a methanol solution containing 1-
heptanesulfonic acid, sodium salt were similar. Finally, the identity of the extracted analyte was determined via IR analyses, and it was shown that pseudoephedrine  hydrochloride was indeed extractable from the tablets with in-line modified CO2 in the absence of any in-cell modifier.
In the last phase of this research, a supercritical fluid chromatographic separation with evaporative light scattering detection was developed for the separation of five phospholipids varying in polarity and ionic characteristics. Several parameters were investigated and shown to be influential in the separation. They were: 1) stationary phase composition, 2) addition of an acidic additive and its concentration, 2) mobile phase ramp
rate, and 4) column outlet pressure.
Intoduction (http://scholar.lib.vt.edu/theses/available/etd-3898-1435/unrestricted/INTRO.PDF)
ETD (http://scholar.lib.vt.edu/theses/available/etd-3898-1435/unrestricted/ETD.PDF)
CH2 (http://scholar.lib.vt.edu/theses/available/etd-3898-1435/unrestricted/CH2.PDF)
CH3 (http://scholar.lib.vt.edu/theses/available/etd-3898-1435/unrestricted/CH3.PDF)
CH4 (http://scholar.lib.vt.edu/theses/available/etd-3898-1435/unrestricted/CH4.PDF)
CH5 (http://scholar.lib.vt.edu/theses/available/etd-3898-1435/unrestricted/CH5.PDF)
CH6 (http://scholar.lib.vt.edu/theses/available/etd-3898-1435/unrestricted/CH6.PDF)
Conclusion (http://scholar.lib.vt.edu/theses/available/etd-3898-1435/unrestricted/CONCL.PDF)
Peaceof the reaction


Ibeeware did UTFSE«..Once! All he found were Pro's and Con'scool
(Hive Addict)
03-02-02 09:01
No 275775
      Re: Rhodium: The Complete SF Extraction Study  Bookmark   

their highest yeilds on pseudo were 82% with 7% extra impurities.  not bad for a 30 minute cleaning.

If Pacman had influenced us, we'd run around dark rooms eating pills and listen to repetitive music
(Hive Bee)
03-02-02 11:51
No 275837
      Re: Rhodium: The Complete SF Extraction Study  Bookmark   

Yeah..GJ: The most interesting thing about this study that stuck in my mind was the fact that these are practicing chemists trying to extract a substance that was engineered in such a way as to make it difficult! This really stuck with me and I could not let that fact rest and this further inspired my determination to understand the terminology and comprehend it's meaning! The ionic/cationic pairing is very interesting and seems to be at the root of what makes this so hard to separate and disassemble! I am no chemist and I know absolutely nothing of chemistry except what I've manage to learn here and through reading studies and patents. The red flag went up when I saw this study and knew deep down that there is more to this than what is on the surface. When I found these Documents, I had already scoured the internet in search of anything that was unrestricted to the general public and even remotely associated with OTC engineering. And finding this study was like stumbling onto a piece of the puzzle that was equal to finding a goldmine. In my mind it solved alot of the questions I had to date and set my ambitions in motion toward picking up at the 82% mark and throwing a few curveballs at the approaches they had taken in an effort to surpass that 82% mark. This is where the whole puzzle needed to be taken apart Piece by Piece, inactive by inactive and it became necessary to learn how these inactives were engineered which inturn led to understanding Patents! The wealth of knowledge and learning that this study afforded me is beyond compare and just feeds my eagerness to learn more! It is unfortunate that my level of understanding is not at an academic level where I could just see a problem and find answers among my peers or professors! Careful Experimentation, the use of the Hive and it's knowledgebase and questions to my peers here based on what I read is really the only way.
IMHO, some bees here have performed miracles when you consider the results achieved vs lack of a professional education/setting/equipment/chemicals/literature.
This study is a great example of just how complex the structural engineering is behind these things that even professionals aren't able to achieve 100% recovery without much work!
My methodology may not be conventional or even orthodox whereas chemistry is concerned....and more often than not, my ideas wind up exhausted to find themselves back at square one...but my persistence and determination drives me toward a better understanding and more practical methods of achievment.
I find now that had I not been a newbee at the time I posted that Chapter, I would have posted it in a more appropriate forum than the Newbee Forum where it would have recieved more input and would have saved me from most of the solitary exploration. But all said and done...sometimes there is only one way to know what won't work vs what does  and that is finding out for yourself! Before, I would look at Patents...shake my head and be on my way...Now, I actually enjoy reading them! Imagine That!cool

Peaceof the reaction

Ibeeware did UTFSE«..Once! All he found were Pro's and Con'scool
(Chief Bee)
03-02-02 12:49
No 275876
      Re: Rhodium: The Complete SF Extraction Study  Bookmark   

The compiled PDF file is now uploaded to ../rhodium/archive/pseudo-co2xtract.pdf - Thanks!