Anabolicm inds Archive
BEGI N N ERS GU I D E T O SO X H LET EX T RACT I O N S
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BEGI N N ER | I n t er m ed iat e | Adv an ced A N A BO LI CM I N D S. CO M CH EM O
Adm inist r at or
Subm it t ed: Apr il, 2003
SUM M ARY
The ex t r act ion m et hods pr esent for m ost solid sam ples usually inv olv e a subst ant ial am ou n t of w et chem ist r y . I f one w er e not v er sed in t he chem ical ar t s it is har d t o be confident and pr oact iv e in heading off exper im ent failur e due t o lack of educat ion, ex per ience, or under st anding. A v iable alt er nat iv e t o t he t r adit ional w et m et hods of solv ent ex t r act ion is a Sox hlet t y pe of appar at us w hich allow s for near 100% act iv e m ateria l recovery and user fr iendliness. Th e gen er al
I n t his m ini- ar t icle w e w ill ex plor e efficient solid- liquid ex t r act ions using a Sox hlet t y pe appar at us and applicat ion of t h eor y t o u t ilit y set ups.
GEN ERAL BACKGRO U N D
The sim plest for m of solid- liquid ex t r act ion is t he t r eat m ent of a solid w it h a solvent . An ex am ple of t his w ould be in separ at ing a sand/ salt m ix t ur e by using w at er . Sw ir l for a few m om ent s and decant , or pour off, t he salt ( now in t he w at er lay er ) . The sand r em ains since it is I N SOLU BLE. I n all solv ent ex t r act ions an at t em pt is m ade t o t ak e adv ant age of differ ences in solubilit y bet w een t h e species being separ at ed.
1. Soxhlet
Th e appar at us, fir st descr ibed in 1879, is a v er sat ile t ool t hat can be used t o separ at e a single gr am t o hundr eds of gr am s w it h near 100% r ecov er y .
The basic pr ocedur e calls for a solid sam ple t o be placed in a por ous cont ainer and allow ing condensed solv ent t o ex t r act cont inuously . The figur e on t he r ight show s t h e basic com pone nt s of a Sox hlet appar at us:
• Con d e n se r
Fu n ct ion is t o cool t he solv ent v apor and cause it t o c ondense ( t ur n back int o a liquid) . Figur e 1. 1 show s a r ing t y pe of condenser w hich funct ions by incr easing t he sur face ar ea t hat can be used t o t r an sfer h eat . This is ver y sim ilar t o a h eat ex ch an g er or aut om ot iv e r adiat or t hat is used t o du m p ex cess h eat .
• P o r o u s Co n t a in e r
Funct ion is t o hold t he solid sam ple and allow for t he condensed solv ent t o sat ur at e and pass t hr ough t her eby ex t r act ing act iv e m at er ial. This can be lik ened t o a filt er in t hat it r et ains t he insoluble com ponent s and allow s w hat ev er is dissolv ed t o pass.
• D ist illin g Pot
Funct ion is t o hold t he solv ent pool and ser v e as a r eser v oir for t he concent r at ed m at er ial.
Anabolicm inds Archive
BEGI N N ERS GU I D E T O SO X H LET EX T RACT I O N S
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BEGI N N ER | I n t er m ed iat e | Adv an ced A N A BO LI CM I N D S. CO M 2. Basic Oper at ion
The solv ent v apor , gener at ed by gent ly heat ing t he r eser v oir, condenses and is allow ed t o dr ip back ont o t he porous sam ple cu p.
The liquid condensat e t hat dr ips ont o t he sam ple per for m s t he ex t r act ion w hich t hen passes t hr ough t he cont ainer and back int o t he r eser v oir . The cy cle is r epeat ed
cont inuously and can be sust ained as long as needed. As it pr ogr esses t h e species of int er est is concent r at ed in t he r eser v oir .
I n a r ev er se ex t r act ion t he species being elim inat ed m ay be con cen t r at ed in t he reserv oir inst ead. An ex am ple of t his m ay be t o use w at er as t h e solv ent w it h a m et hylc ellulose based m at r ix t o be ex t r act ed. I n t his scenar io t he
m et hy lcellulose w ould be collect ed in t he r eser v oir and t he act iv e species r et ained in t he porous sam ple cu p. As elim inat ion of solv ent m ay be a concer n for som e t his met hod only uses w at er t o per for m t he ext ra ct ion and is easily pushed off dur ing co m m on dr y ing pr ocedur es.
Rat e of r eflux is especially im por t ant her e as low v apor pr essu r e solv en t s su ch as acet on e or m et hanol m ay condense fast er t han t he pass- t hr ough r at e. This w ill c ause t he lev el of solv ent in t he por ous sam p le cu p t o accum ulat e and ev ent ually spill ov er t he side possibly t ak ing m at er ial w it h it .
FI GURE 1. 2 – Ut ilit y Set up
3. Ut ilit y Applicat ion
• Th e c ondenser can sim ply be an inv er t ed lid t hat is fille d w it h a sufficient am ount of ice. This w ill efficient ly c ondense t he solv ent v apor and also allow for a cent r al dr ip point . • The sam ple cup can be m ost any cont ainer t hat is por ous, or m ade t o be so, and has
sufficient v olum e t o hold t h e desir ed am ount of m at er ial.
• The sam ple cup filt er can be r egular filt er paper t hat has sufficient por e size and can w it hst and t he solv ent being used. As an alt er nat iv e, a com m on t ea bag t hat is pr oper ly r insed is v er y r obust for applic at ions r equir ing less t han 5 g ram s of st ar t ing m at er ial. I n t his m anner one could em ploy a “ Sox t ec ” pr ocedur e and decr ease ex t r act ion t im e and allev iat e spill over.
• The r eser v oir can be a r egular pot .
Anabolicm inds Archive
BEGI N N ERS GU I D E T O SO X H LET EX T RACT I O N S
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BEGI N N ER | I n t er m ed iat e | Adv an ced A N A BO LI CM I N D S. CO M CH OI CE OF SOLV EN TS
This m ust be w it h consider at io n of m at er ials being separ at ed and t he degr ee t o w hich each w ill or will not dissolv e. As an ex am ple for discussion, let ’s ex am ine t he binar y sy st em of an or ganic non-polar m olecule such as cholest er ol in a m et hy lcellulose m at r ix.
Cholest er ol or ot her est er fied m olecule w it h a st er oidal back bone
• Gener ally NON- POLAR • Wat er I NSOLUBLE
FI GURE 1. 3 – St er oidal m olecule
Met hy lcellulose
• WATER SOLUBLE
• Slight non- polar qualit ies
FI GURE 1 . 4 – Met hy lcellulose
The m at er ials in our ex am inat io n lend t hem selv es t o solv ent ex t r act ion as t her e is sufficient char act er differ ence t o at t ain ex c ellent separ at ion w it h com m on solv ent s. One could use w at er t o ex t r act t he m et hy lcellulose fr om t he st er oidal m at er ial.
As an alt er nat iv e one could use acet one but t he car bony l w it h heat m ay lend t o r eact ion w it h t h e specie of in t er est .
SUM M ARY
Alt h ou gh w et ch em ist ry m et hods w ill pr ov ide decent ex t r act ion efficiencies t her e ar e fact or s t hat m ay decr ease consist ency and pr oduct pur it y t hat is r elat ed t o bot h m an and m et hod. By using a Sox hlet appar at us t o per for m t he ex t r act ions t he am ount of solv ent w ill be significant ly r educed, consist ency im pr ov ed, and ov er all pr oduct qualit y r anging fro m 97 % t o 99% + pu r it y . The basic set up is sim ple and can be r eused as oft en as needed. The m at er ials can be con v en ien t ly locat ed if not alr eady in possession and solv ent s com m o n.
