Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry
Temperature-programmed desorption mass spectrometry (TPD MS) is discussed with reference to studies of modified pyrogenic oxides. Simple theoretical models are presented in order to allow an approximate analytical treatment of TPD MS data. Rate constants for first- second- and third-order reactions...
Збережено в:
| Дата: | 2001 |
|---|---|
| Автори: | , , |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine
2001
|
| Онлайн доступ: | https://surfacezbir.com.ua/index.php/surface/article/view/71 |
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| Назва журналу: | Surface |
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Репозитарії
Surface| _version_ | 1869291161247547392 |
|---|---|
| author | Pokrovskiy, V. A. Galagan, N. P. Kulik, T. V. |
| author_facet | Pokrovskiy, V. A. Galagan, N. P. Kulik, T. V. |
| author_institution_txt_mv | [
{
"author": "V. A. Pokrovskiy",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "N. P. Galagan",
"institution": "Інститут хімії поверхні НАН України"
},
{
"author": "T. V. Kulik",
"institution": "Інститут хімії поверхні НАН України"
}
] |
| author_sort | Pokrovskiy, V. A. |
| baseUrl_str | |
| collection | OJS |
| datestamp_date | 2018-11-27T09:42:39Z |
| description | Temperature-programmed desorption mass spectrometry (TPD MS) is discussed with reference to studies of modified pyrogenic oxides. Simple theoretical models are presented in order to allow an approximate analytical treatment of TPD MS data. Rate constants for first- second- and third-order reactions have been obtained. Products of thermal decomposition of carbonized surface layer has been observed and identified. The different pathways of uni- and bimolecular desorption were investigated and rate constants of reactions has been derived from TPD MS measurements.
Adsorption and thermal stability of several polyketides has been studied by TPD MS in condensed and adsorbed states. Mass spectrometric analysis allowed observing correlation between chemical structure of morine and venorutone molecules and mechanism of thermolysis. Decomposition of carbon carcass of chromone, the bensanelled y-pyrone in particular, resulted in formation of fragments with mass numbers 91, 95, 108, 111 m/z. Decomposition occurred in three stages with maxima at 200, 280, 380°C for morine and 240, 320, 450°C for venorutone. Presence of carbohydrate residue (ramnose, glucose) in venorutone molecule caused two additional stages of thermolysis in comparison with morine, maxima being located at 220 and 280°C. In this case, different to previous one, the substituted y-pyrone has been produced being characterized by mass numbers 72, 97, 102, 126 m/z. Comparison of adsorption parameters for venorutone and carbohydrates has shown that carbohydrate residue played main role in adsorption of venorutone molecules on ultrafine silica surface. The ring C of venorutone molecule stayed free in adsorption process which attested the fact that hydroxyl group in position 4' responsible for biological activity of flavonoids, did not participate in adsorption. It allows the ring C preserve its antioxidant, membrane- and capillary-stabilizing activity in bound state.
  |
| first_indexed | 2025-07-22T19:30:03Z |
| format | Article |
| fulltext |
NOГ.I.БOTIIЕRN{AL DЕ С oMPosITIoN oF
BIOMOLЕсULЕS STUDIЕD BY МЕAN{s oF
TЕIVIPЕRATURЕ.PRO GRAMIиЕD DЕS ORPTIOI\ MASS
sРЕCTRON{ЕTRY
im
so
V.A. Pokrovskiy, N.P. Gаlagan, and Т.V. Kulik
Ittstitute of Suфсе Сhеnlistrу, Nаtionаl Асаdеmу of Scienсеs
Gеi, Nаuпoу str, ]7, Kуiv-l61,036s0 UKRАINЕ
Abstraсt
Теmpеrature-programmеddesoгptionmassspeсtromеtry(T|DМS)isdisсussеd
with геfегеnсе to studi"es of modifiеd pyrogeniс oхidеs. Simple thеoгеtical modеls arе
pгеsеntеd in оrdег to allow an approхiйtе analрiоal trеatmеnt of ТPD МS data. Ratе
сonstants for first- sеоond- and.ihiгd.oгdеr reaitions havе bееn obtainеd. Pгoduсts of
thегmal dесomposition of сarbonizеd suгfaсе laуer has bееn obseгvеd and idеntifiеd. The
diffеrеnt pathwaуs of uni- and bimolеculaг dеsoгption weге investigated and ratе
сonstants Ьf ,.u.tion* has bеen dегivеd fтom TPD МS mеasurements'
Adsoгption and thегmal stability of seveгal polуketidеs ha,s bееn studiеd by TPD
МS in сondеnsed and adsorbеd statеs. Мass speitromеtгiс analуsis allowеd obseгving
сoггеlation bеtween сhеmiсal structurе of moгinе and vеnorutone moleсulеs and
meсhanism of thегmolysis. Dесomposition of сarbon сarсass of сhromone, thе
ь.n.un.rr.a ^r-pyrone й ia.tiсutar, гesultеd in foгmation of fragments with mass numbеrs
6i, gs, ioв,,tii ы,' DЬсomposition oс.cuпеd in threе stages йth maxima at 200,280,
380"с for morine anoi4o, зio, цso.с foг venorutonе. Pгеsеnсе of сaгbohydгate геsiduе
(ramnosе, gluсosе) in vеnorutonе moleсulе сausеd two additional stagеs of thermolysis in
i".p"'i'Ь",with morinе, maхima bеing loсatе d at 22О and 280oC. In this сase, diffегеnt
;; p;;;"' one, thе suьstitutеd 1.py'on. has bееn produоеd bеing сharaсtегizеd by mass
numbеrs
.72,91' Io2, 126 m/z. Comparison of adsoгption parametеrs for vеnorutonе and
сarbohydгatеs has shown that сaгbohydгate rеsiduе. playJd main- role in adsorption of
vеnorutonе molесules on ultrafinе siliсa suгfaое The гing C of vеnorutonе molесulе
staуed frее in aoso,ption proсеss whiсhзttеstеd thе faсt that hydгoхyl group. in positioл
+',,,.,pon,iьt. ь'. ьiotogi.al aсtivitу- of flavonoids, did not paгtiсipate in adsoгption It
allows the ring C pгesегv"е its antioхidant, membгanе. and сapillary-stabilizing aсtivity in
bound statе.
Introduсtion
Theaгtiсlе.,Deso1ptionmassspeсtгomеtryanditsappliсatioлsin.sцrfaсе
сhеmistry,, Il] has ь..n puьtl,ьеd bу н'A.-Chuiko, V.A Nazarenko and V.A. Pokovskiy
in thе Bullеtinе of д.uс.'y of Sсiеnсеs Ukainе twеlvе yеaгs ago. It is intегеsting to
сompaге some sтaтеm.ni' -а predictions of this reviеw with aсtual progress in rеsearсh
o.u.top'.ntofmassspесtгomеtryappliсationsinsuгfaсесhеmistry.
..Surfacе cь.'i'i'y is suсЁ u.,Ъi.n.. in whiсh traditional appгoасhеs has a'1most
dеplеted thеiг abilitie,. *"* rеsults maу be obtainеd onlу by involving nеw mеthods and
ехpегimеntal idеas ihе.е is no doubi that dеsoгption mass spесtrometry is usеful foг
solving problеms of suгfaсе сhеmistry, but opposiie is also.сoпесt: modеls and mеthods
dеvеiopеd in suгfaсе сhеmistry will givе
'isе
io undeгstanding of unsolvеd pгoblems of
dеsoгption mass Spесtгomеtry'
sP'
frс
rei
dil
in
fol
wl
oс
so
(ltl
nгr'
so
of
сo
wi
rе'
sеr
m(
nr
М
М
pг
hi
Sс
yе
Dr
D
th
(a
(b
o
rF
rF
\
Dispеrse sуstems, usеd in surfeсе сhеmistry aге intеrеsting and pгaсtiсall}
impoпant spесies, but also diffrсult for studiеs bу tгaditional еxpегimеntal mеthods of
solid.statе physiсs
Fгom ouг point of viеw, thе main diffiоultу rvhiсh appеaгs in interprеtation оf mass
spесtгomеtry of thегrnal dеsoгption oгiginаtes nоt from iaсk of еxpегimеntal datа, hut
from inaЬility to dегivе maхimum information abоut meсhanisms and kinеtiсs of sr;rfaсе
rеaсtions. As a rеsult, quantitative intегpгetatiоn оf thегmal desoгption speсtrums is
diffiсult and oftеn еquivoсa['' Тhе most signifiсаnt statеmеnt, whiсh йavе lеad us finailу
in touсh with fundamеntal pгoblеms оf thеrmal analуsis and non-isothеrmal kinetiсs, is as
follows: ..our еxpeгimеntal sсhеmе is almоst similaг to thеrmoanalуtiсal mеasuгеmеnts
whiсh arе widе spгеad in invеstigation of solid statе геaсtions' This similaгity is not
oссasional. It is .оаsеd
on thе similaгity of pгoсеssеs undег invеstigation. In many сasеs
solid statе геaсtions oссuг at intегГaсеs and thus bеlоng tо suгfaсе сhеmistry''.
At thе momеnt' all quоtеd сonsideгatiоns sееm tо bе stil1 adеquatе Belоw in this
afticlе somе attеmpts will bе pгеsеntеd of ovегсоmins thеorеtiсal and ехpеrimеnta1
pгoblеms mеntionеd in uppег quotесi tехt.
Almost in thе samе timе whеn thе aпiсlе was publishеd, thе outstanding ехpeп in
solid-statе геaсtions and thеrmal analysis, Pгofеssoг David Dollimorе from thеЪnivеrsity
of Тolеdо, oЦ UsA, staгtеd thinking and rvоrНng on thеrma] analysis оf phaгmaсеutiсil
сompounds and othег bicmolеоulеs His fiгst paper oii thеrmel dесоmpоsition оf aspirrn
was published in 1990, and sегiеs of his publiсations in this aгеa [2.8] was соmplеted bу
rеviеw aгtiсle..Thеrmal Anaiysis'' рublishеd in Anall.tiсalСhеmistгy [8] in 199б.in whiсi
sесtion..Brologiсal' ]Иеdiсai and Phartnaсеuttсal Studiеs'' rvas inсludеd,
Simultanеouslу. we соnduсtеd геsеarсh on suгfaсе сhеmistry of bioiogiсaliу aсtivе
molесulеs in сondеnsеd statе and adsоrbеd оrr ultгafinе oхi,jе suгfaсеs by tеmpегaturе-
progгammеd dеsoгptiоn mass Spесtгomеtry mеthod [9-20]
As a rеsult, ouг sсiеntifiс аnd pеrsоnal сoпtaсts wrth D Dollimоге appеaгеd at |gg7
Мutual interеst tо thе problеms of non-isоthеrmаl kinеtiсs in thегmal analуsis and TPD
МS of biomolесulеs beсamе a basе of ouг fгuitful сооpеraliоn in thе fгamework of STCU
pгojесt ..Мass spесtгomеtry of rndustгiаl aегоsols iл Ukrainе'' rvhiсh was suppoпеd bу
him as Pгofеssог оf Tolеdo Univегsitv and as Нonorary N,fеmbег of Ukгainian Chеmiсal
Soсiеty.
Unfoгtunatеly, wе have lost this outstanding sсiеntist and fasсinating pеrson last
yeaг' Мodels and eхpегimеntal data presеntеd heгe werе moге than оnсе disсussеd with
David' so this papеr is dеdiсatеd to his blеssеd mеn]oгу,
Dеsorption modеls
For thе inteгprеtation of tеmpегature dеpеndеnсiеs оГ mass spесtгa wе assumе that
thе dеsoгption еquation may bе eхрrеssеd as
d@ldt=-|Фn (t)
whеге @ is the suгfaсe сovеragе varying in thе intеrval 0<o<1 , n the геaсtion ordег
(assumed to bе knоwn from ехpегimеntal data) and thе dеsoгption гatе is
k=kceхp(_ЕlKI) (2)
whеге t, is thе aсtivatioп еnегgу of dеsoгрtion and k^ thе рrе-ехpоnеntial faсtoг
(both parametегS assumеd to be known fгom ехpеrimеnts). Аt thе initial сonditiоn
o,=o = 1 wе hаvе thе following solutions of еquation (i)'
MASS
's disсussеd
:а. nodеls aге
t{S data. Ratе
: ?гoduсts of
:::tifiеd. Тhr
r=: and ratе
i: зз by TPD
ъ:: obseгving
п.: .;ulеs and
-- - -.^na the
:]ss nurnbеrs
пд .. 200, 280,
г. ..a:е гesiduе
': =::rolysis in
э... diffеrеnt
в-:.3 by mass
Е.:jtonе and
t i:, :rption of
в.. molесulе
ш :. position
I l"-,::ption, It
!:. rrtivity in
. surfaсe
: : kovskiy
:-ssting to
- геsеarсh
-.s almost
:- 'оds and
- sеful for
. rеthods
:.еms of
o(r) = ехp[-Ф(l)]
@(l1 = 1l [1 + Ф(/)]
@(r) = 1/[1+ 2Ф(r)]r,,
(3)
I
);p
:
lt"t-
I
fоrn=1
for п=2
foгzl=3
3 -ll
whеrе Ф(l) = t rat (4)
In Fig l formulaе (3) arе illustratеd foг rеaсtion ordеrs n:|,2.З'.linеar law T=To*
Bt oftempеratuге upon ii." dеpеndеnсe; anJ paгa.еtеrs of thе modеl F=О1oK.s.',
in=-|o',.:,. t:=zoоkl.molе-| K=8'31 l03kJ'к.'.AsFig. 1illustratеsit,thelеssis
reaсtion ordeг, the steеpег is the tеmpеraturе dеpеndеnсe _lvfgгеtetailеd
information maу
bе dегivеd from thе diffегеntial form of the dеpеndеncе In TPD Мs ехpеriment' due to^
unintеrruptеd pumping of dеsorbеd сompounds, thе ion сurrеnt of chosеn сomponent of
'u,,
,p.it*m is pгopЬпional to dеsoгption гatе of сhosen produсt.
ol
---+-
o2 05
o3
0
550 600 650 750
T
Fig. 1. SuгГaсе сovеragеs 01, @2, 03 as funсtions of tеmprгaturr T foг геaоtion ordeгs
n : |,2,3, сoгrеspondinglу.
Aссoгding to еquations (3), the dеsoгption ratе whiсh is dirесtly pгopoгtional to thе
ion сurгent сan be obtainеd as
d@(t)ldt=-kеxp[_Ф(r)] foг r= 1
d@(t)ldt=_k||iti+о(l)], forn=2 $)
do(t)ldt = -kUlU+2Ф(t))з,2 for n=3
Formulaе (5) aге illustratеd by Fig. 2 in whiсh desoгption ratеs (propoгtional to
dегivatives of surface сovегage) arе pгеsеntеd as a funсtion of thе samе paramеteгs as
were usеd in сalоulations of Fig 1.
Еquations (s) illustгatе йе tуpiсal tеmpегaturе dеpеndеnсiеs of the ion cuгrеnt, thе
seсond-ordеr desoгptiй сu*. ь.ing nearlу sуmmеtгiсal, the fiтst-order сuгvе dесгеasing
fastеr on thе hightemp.''*," 'io.
u,no thе сonvегse bеing tгuе for thе thiгd-oгdег proоess
f
r,
JJЧ
!)
law T:To +
= O'1 К.s.l;
':. the lеss is
тation may
:.еnt, due to
:rponent of
эгdеrs
П!: ..:Эthе
Р
do1-*-
dO2
^
A^lv,vv I
ffi
OL'J
).lu
Fig.2. Desoгption rates do1, do2, dФз as funсtions of tempегatuге Т foг геaсtion orders
n : 7,2,З, сoпеspondingly'
Taking into aссount thе diгесt pгopoгtionalitу of d@ l dr to thе ion сuгrеnt, a simplе
proсеdurе of trеating thе ехpеrimеntal data I{t) maу bе pгоposеd. Thе @(r) dependеnсе
on I(t) may be wгittеn as
@(r; = Y(/)/.', or d@ l dt = _I/S' whеге Y(l) = T,o,', =T пt
', "n
Using еquations (5) and (б) we obtain
lnй=ln[Y(l)/1 forrl=1
lnЁ=lnlY2(t)tlsl forn=2 6)
ln& = ln[Y3(t)lIS, ] foг n= 3
Deсonvolution proсeduге pгoposеd by еqns. (6) is illustгatеd by Fig.3. Modеl
dependеnсе foг thiгd ordег геaсtion (sее do3, Fig.2) was сhosen as an ехample of
eхpеrimеntal thегmogram Three сuгvеs of desoгption ratе logarithm aге pгеsеntеd as a
funоtion upon invеrsе tеmpегaturе т = (KT).l сoпеsponding to thгее rеaсtion oгdеrs
n=\,2,3 ' Desoгption ratе paramеtегs aгe thе samе as weге usеd in сalсulations of Fig. l.if all the assumptions arе allowablе and thе геaсtion ordеr is a propегly ".ьo,.n
whole number, n, thеn the funсtion |nk =.f (1/| eхprеssеd aссoгdingio еquations 1оj
is lineaг overthе fulltеmpегaturе гangе (in ouг сasе, lnk3 in Fig. 3). Thе advantagе of thе
pгo-сеdurе involving еquations (6) is thе utilization of all data obtainеd .*p"'iй"ntuпy,
inсluding thosе in thе high.tеmpегatuге paгt of thе thегmogram whiсh is most i'poпuii
in estimating the adеquaсy of the modеl and, in paгtiсular,lhе геaсtion oгdец n вЪsidеs,
as it сan bе sееn from Fig. 3, somе additional simplifiсations are usеful whеn op.iuti"g
with large amounts of ТPD МS data. Thе kеy equation (4) may bе ехprеssed in
б00 650 700 750 80O
.Г
:l
зs
m
р:
i
);-
р
!*
-1J )
lnkl
lnk2
ffi
lnkS
ffi -5
-10
0 15 016 o 17 0.l8 0.l9 О'2 0'21'
Fig. 3. Logarithm of dеsoгption гatе } foг thrее valuеs of rеaсtion oгdег as a funсtion
of invеrsе trmpегaturе т:(KТ).' сaiсtrlatеd from еqns (6),
an appгoхimatе analytiсal form for a slow tеmpеraturе гamp (B<O i oK/s), high valuеs of
thе pге-еxponеntial faсtoг (k>109s.l) and high maхimum.tеmpегaturеs (T>450.K) as
u..,ui1у obЪеrvеd in еxpегiйеnts with сhеmisorbеd oгganiс molесulеs on a dispегsеd
oхidе sцгГaсе.
Assuming a linеar law, T=To - pr anс! ехpanding thе tеmperaturе dеpendеnсе neaг
thе maхimum T,, we obtain an appгoximate еquation
KT: Е
Ф(r; = #ц"*p(fu) (7)
whiсh, in most сases, is valid within ехpегimеntal aссuгaоу.. Aссording to еquations
ts), tье сonсition of maximum vaiuе of dФ ldr (or ion сurтеnt /(l) )' is
Ф(/) = 1 (8)
d@ l dt valuеs сalсulatеd aссoгding to еquation (7) for thе fiгst.ordег гeaсtion with
paгamеteгs P = Оl , T = 45ОK,&o = 1O9s_l providе dеviations from ехaсt solution not
еxсeеding 0.04 throughout thе wholе tеmpегatuгe гangе. This is thе uppeг limit of
possiblе inaссuгaсy of"equation (7) in сompaгison with ехaсt solution. Thе dеviation of
ехaсt valuе T, for a,""ond-o.d"i iеaсion fтom this dеrivеd from еquations (5), (7) is of
order 2{k\ / .Е), , whiсh is lеss than 2 K for uppеr valuеs of pегtinеnt paramеtегs.
If thе speсiai fеaturеs of thе struсturе of thе adsoгрtion сomplех makе nесessary thе
intгoduФion of thе distгibution funсtion foг suгfaсе sites,N(Д), thеn thе total dеsoгption
rate (dФ l dt)" (andthe total ion сurrеnt,1" ) must bе сalсulatеd as an intеgгal
(dФ /dt), =iryNG)dЕ
0
Praсtiсally impoгtant сhеmiсallу modifiеd dispегsеd ultrafinе oxidеs as modеls of
industгial dust miсropaгtiсlеs dеmonstгatе intеrеsting and unеxpесtеd effeсts both in
thеrmal o",o,ption inJ in dесomposition of suгfaсе сomplехеs, inсluding phasе
i.unsition* in adsoгptlon_iaуег. Thе aipliсation of vaгious known multi-paramеtег modеls
io,u,."n.,, of this kind сaггiеs thе impiiсit dangеr that thеу only providе an adjustmеnt to
зз6
: .jnсtion
зiuеs of
K) as
sреrsеd
:е nеaг
- зтlons
the еxpегimеntal data and fostегthe illusion of undеrstаnding, iггеspесtive to adеquaсу of
thе of thе modеl So, thе possibilitiеs of anу mathеmatiйl modеl' prеsеntеd
.hеrе
in
paгticular, aгr not to bе oveгеstimatеd' As was alrеadу emphasizеd in ouг pгеvious wогk
Il5] an independеnt vеrifiсation of thе paгamеtеrs obtained is always nесеssary whiсh is
not an еasy task in thе сasе оf сhеmiсallу modifiеd dispегsеd systеms' Тhе advantagе oГ
ouг simplе appгoaсh is that геsults aге obtainеd in anal1tiсal form, whiсh faсilitatе; thr
сomputeг trеatmеnt of ехpегimеntal thегmogгams.
Tempеraturе-рrogrammеd dеsorption mass spесtrometry
of сarbonized siliсa
oхidе miсropaгtiсles оaгbonized by thе pгoduсts of сombustion aге the main dust
pollutant of thе atmospheге in industгial arеas using сoal as a fuеl Though thе еffесt of
dust miсropaпiсlеs of suсh a kind on thе human oгganism has nоt bееn studiеd in detai!, it
is сleaг that сhеmiсal гeaсtions of biologiсally nеutral оompounds on the suгГaсе of
сarbonizеd oxidе paпiсlеs may гesult in thеir сatalvtiс tгansfoгmations into toхiс
сompounds. Тhosе сompounds may bе dеlivегеd tо thе human organism with thе
respiгablе fraсtion of aегosols oг thгоugh dгinking watеr. It is knоwn that adsomtion of
drugs on еntегosoгbеnts сausе thеir pгolonged aсtion; in thе samе vеin' adsoгption of thе
toxiс сompounds on the suгfaсе of dust miсrоpaгtiсlеs maу lead to pгolongеd Ьxpоsurе of
toxins. Anyway, prеsеnсе of inсomрlеte сombustiоn produсts know.n aS stгoщ. toxins'
сarсinogеns and mutagеns on thе surfaсe оf dispеrsе охidеs may геsu[t in sеrioui hazard
to human hеalth.
Caгbonization appеaгs as сomplеx' multi-stagе ргoс'еss геsulting rn foгmation and
gгowth of сlustеr-likе gегms of сaгЬon phasе. Undеr еffесt of tеmpегatuге and duratiоn оf
сarbonization proсess thе thrее-dimеnsional сarbon lartiсе is foгmеd, thе number оf
hуdrogеn atoms dесгеasеs and thе dесгeasе of thе numbеr of sp2 hуbridizеd atoms in
сondеnsеd polyaгomatiс systеms is obsеrvеd'
Тhе sцгfaсе layеr may also inсludе a largе amount оf сhеmisoгbеd molесulеs
foгmеd on the еarly stagеs of pyrolysis. Thosе surfaсе соmplехеs arе thе main souгсe of
polyсyсliс aгomatiс moleсulеs, potеntial toxins, сaгсinogеns and mutagеns, whiсh may
appear as a геsult of сatalуtic геaсtions in thе suгfaсе layеr of сaгbonizеd dispеrsе oxidе
Hеating of thе сarbon-minегal samples in vaсuum is ехpeсtеd to destгoy еxisiing surfaсe
сomplехеs and to геlеasе сhеmisoгbеd molесulеs. Thе сomposition of produсts and
kinetiсs of thermal deсomposition of suгfacе layег of a сarbon-minегal soгbеnt is a souгсе
of valuablе information about meсhanism of сarbonization of oxidе surfaсе. Тhе
tempегatuге-pгogгammеd desoгption mass spесtromеtry is a геliablе mеthod of
invеstigation thе сhеmisoгbеd сarbon-сontaining сompоunds. Тhе mеthod allows to find
out not only thе сomposition of сhеmisorbеd molесuiеs but also to еstimatе non-
isothегmаl kinеtiс paгamеtеrs of suгfacе rеaсtions, suсh as рre-еxponеntial faсtors and
aсtivation еnегgiеs'
Thе tеmpегature-pгogгammed mass sресtгomеtry was usеd foг analysis of volatilе
pгoduсts of thегmal deсomposition of the сaгbon сoatеd siliсa samplеs papегs. The
сaгbosil samples еaсh of about 1 mg weight weге plaсеd in a quaгtz-molybdеnum tubе
and еvacuatеd at l0.lPa and thеn attaсhй to the inlеt systеm Ъгu мI-tzol (Ukrainе)
mass spесtromеtеr. Тhе геaсtoг-to-mass spесtгomеtеr intегfaсе inсludеd a high-vaсuum
valvе with an oгifiсе of diаmеtег 5 mm and thе inlеt tubе of 20 сm lеngth, rvhiсh was kеpt
at l50 "C' Тhе rеaсtion spaсе was opеn in thе ion-souгсe direоtion, and at the hеating гaiе
usеd (about o t К's.') thе obsеn,еd intеnsity of thе ion сuггеnt was ехpесtеd io bе
pгopoгtional to dеsorption гatе so that diГfi'lsion inlтbition might bе nеglесtеd. Wе
assumеd quasi-stationary сonditions whеn shape and position of dеsoгption pеaks did not
dеpеnd on the tеmpeгature of the spесtгomеtег intегfaсе, thе samрlе dispегsivity and/or its
sizе. Тhе TPD data wеге not сonsidегеd fuпhег if thеsе оonditiоns wеге not fulfillеd.
в:- :. rvith
*- not
.'. t of
::nof
]S oт
.-.' ih€
-:::on
Е
E:
lт
:Е.
р.F
r
I -l -l r'
Thedеsoгptionmassspесtrawеrеrесordеdinthе1o-22oDaltonrangеandthе
,.'p.i"iu,. ,t.p *u, about io .i(. Мass spесtra of deсomposition produсts ше presеntеd
in Fis. 4 foг four tеmpеratuгеs.
l,As 'л
lo0 l
I
l,lDt'л,
lф0.
9
r ot'c
h
t.r с
I,flв'tл.
lш.]
I
тп]
lu
Аu
ооо.с
5Dl
ll"
'n]ll"r*
oliliilil'll ,,, , ,,.,
nlz . 10 1ш 2l0 do
Fig.4.TPDmass.spесtraobtaineduч::dесomposition-rеaсtionsofphеnуlethanol
bound to siriсa gеr surfaсе at: iоз (a), 300 (b),495 (с), and 606 "с (d).
Thеfirstmass-spесtrum(Fig4a)соrrеspondingtolo.3oС.inсludеsthemJzlinеsat
43 and 58 as thе main сomponеnts еxсеpt watег (m/i at 18 and 17). Thеir oгigin сan bе
.u,ily .*prыnеd fтom tье йitaьititу of adsoгbеd aсеtonе usеd upon samplе prеtrеatmеnt.
Its TРD maхimum tiеs at сa. 100 t It should bе notеd that thе linеs сoггesponding to
ij-,йi.".hylformamidе usеd in parallеl with aсеtonе upon samplе prеparation wеrе not
obsеrvеd in any spесtrum.
Тhеnехt.u,,-,p..'.m(Fig.4b)obtainedatз00oCinvolvеsthem/zlinesat9l,
92, and 122 сausеd ьy J.,o,ption"of phеnуlеthonol (this tеmpеratuIе сorтеsponds to its
maximal dеsoгption). тйе 'ain
lines jп/z at 51,78, 92,91', and 104) in thе speоtrum
obtainеd at 495 .C (Fig.;i;;st that phеnуlethylеnе and toluеne dеsorb Thе formation
of phenylеthуlenе is а," to unimoleсuiar dесomiosition of bound phеnуlethanol with H
tгansfегfromthеСH2$roup(nearesttoаromatiсring)toofrom:sioRgгoup.
;;i;;;;-;есhanism oi d.Ьo*po,ition of butanol bound to the siliсa suгfaсе was
studiеdlnourpreviouswoгk,Howеvеr,kinеtiсsofsuсhproоеssеsforbound
pьеnуtеtьanol andbutanol еssеntiallу diffеrеd.
The last 'u,,-.,рй' Gie 4d) obtainеd at 606.C inсludеs thе linеs
сoпеsponding to ь.*J* 1i, it iв) unс biphеnyl (mlz at l54). Inasmuсh as thе
338
],qts'ш.
d thе
еntеd
еХistеnсe of thеse molесulеs in thе suгГaсе layег at suсh tеmpеratuге is impгobablе' thеу
сan bе foгmеd duе to migгation of phеnуl radiсals alоng thе suгfaсе and thеiг intегaсtion
with FГ oг bound Fl (bеnzеnе foгmation) oг bound CoHs or frее CoHэ. (biphеnyl
foгmation). At thе tеmрeгatuгеs abovе 600 oС, thе thегmal tгansformations of bоund
oгganiсs havе сomе to an еnd and only baсkground linеs arе obsеrvеd,
Thе tеmpегatuге dеpеndеnсiеs of thе main сomponеnts of thе mass-spесtгa
obsегvеd aгe shown in Fig 5
Phenylethanol desогption oссuгS in thе 200 - 450 oс гangе and it is maхimal at сa.
300 "с. For phеnylеthylеnе, thе tеmpегаtuге intегval width of dеsorption is thе samе but it
shifts to highег tеmperatuгеs (300 - 550 "C) with a maхimum at 450 "С. Тhе thегmogram
of phеnylеthylеnе (miz at 104) dеsorption has asymmеtгiсal shape, whiсh is typiсal fог
fiгst огder гeactions, Thе thегmogram af n/z at 91 has two maхima at 300 and 470 .C
that
сan bе еxplainеd fгom thе oгigin оf thе fragmеnt CьHsCHz- (rеsponsiblе foг m/z at 9l)
obsегvеd in thе еlесtгon imрaсt mass sрeсtra foг phеnylеthanоl (rrJz at 122),
phenylеthуlеne (m/z at l04), and toluеnе (rn|z at 92); thеrеwith, thе fiгst maхimum of rn/z
at 9l сoггеsрonds to phеnylеthanol dеsoгption. A bеnzеne sресtrum (rrlz at 78) is
obsегvеd in thе 300 - 700 "с rangе and its shapе indiсates that CоlIс* ion is foгmеd
thгoush to two meсhanisms.
],AЬs,uп
а00П
el I
0 .1I)0 2(0 3l)0 400 50c 600 i00 8с0
lmршаt;с ,ti
Fig' 5. Thеrmograms of dеsoгption of phеnylеthanol (m/z a| 122 and 91), phеnуl-
еthylеnе (mlz at l04 and 91), toluеnе Qnlz at92,91' and 39) and bеnzеne
(m/z at 78 and 39)
At low tеmpегatuгes (300-500 "С)' this ion is gеnегatеd as a Гragmепt оf
phenуlеthylenе or phenуlеthanol and, at high tempегatuгеs (500-700'с), it is obtainеd via
ionization of bеnzеnе еliminatеd (sее Fig. 5) Thе deсonvolution of thе bеnzеnе TPD
speсtrum aссoгding the oгigin of Cс}L- shоws that its width aftеr subtraсtion of thе
сontгibution by the deоomposition of dеsorbеd рhеnуlеthуlеnе is сlosе to that fог
phеnylethanоl and рhеnylеthy1еnе (about 250 "с). СonsеquеntIy, broadеning of
spесtrums foг those dеsorbеd сompounds is сlosеlу rеlatеd. thегеby implying that it is
339
lеlhanol
: -inеs at
: сan be
rsiment.
rг-3ing to
.; еrе not
..:.е linеs
::. as thе
сausеd bу similar fеatuгеs of thе dесomposition оf gгoups bоund to thе sцlfaсе of paгtially
сarbonizЬd siliсa. It should bе notеd that thе maхima of dеsoгption of bеnzеnе and
ьipь.nyr сoinсidе' Тhis faсt points at сommon огigin оГ both сompounds duе to
гесombination oг сaptulе rеaсtions at thе surfaсе i,l'ith thе paгticipation of mobilе phеnyl
гadiсals' Biphеnyl Jеsorbs in moге narгow high-tеmpегaturе rangе than othеr pгoduсts
that givе thе highеr valuеs of lь and t'' . "Сo*putйon of kinеtiс paramеtегs fтоm this thеrmogram, aссording to the
tесhniquе desсгibed in prеvious Ъeсtion, gll'еs the valuеs dеpеnding on a сurvеf)ortions
usеd foг thе сalсulations of a prе.еxponеntial Гaсtоr Ь and aсtivation еnеrgy t dце to
broadening ofthе spесtra. The ialсulitions ofthеsе pa'amеtrгs Гrom thе сuгvе shapе neaг
thе maхiйm givеihе }ъ and.Е valuеs (4.4.lO5s.t and 85 kJ/molе' respесtivеly) сlosе for
obtained fог thЪ total сuгvе. Undеrestimatеd value of thе pге-eхрonеntiai faсtor (сausеd
bу spесtrum bгoadеning) attеsts that thе obsеrved rvidth of the spесtrurn is dеtегminеd not
onrf ьу thе meсhani'*"uгtь" bоund group dесomposition but also bу thе depеndеnсе of
thе aсtivation еnегgy on thе сonсеntration Ьfthе'е groups and thе suгfaсе hеtеrogenеity.
Тhеrеfo,", й thе dеtегmination of thе гeal ko and .Е valuеs, additional infoгmation
is nееdеd' Hоwеvег, wе сan usе an initial slope of thе TPD Spесtгa, whеrе thе influеnсе of
broaoeпing faсtогs is small, for thе сalоulations of kinеtiс paгamеtегs. Thе valuеs obtainеd
foг this pu,п oгthе TPD сuгvе foг mJz at 104 and 103 aге сlosеlу rеlatеd and wе сan^
assumе that thеу arе сlosе tо thе rеal valuеs of kinеtiс paramеtеrs foг dеsoгption of
phеnуlеthу1еnе'
Tеmpеraturе.programmеd desоrption
of polyketidеs from siliсa surfaсе
Polykеtidеs гeprеsеnt a widе сlass of natuгal bioiogiоa1lу aсtivе сompounds, whiсh
have similar biosуnthеtiс oгigin. Thеy plaу important rо]е in 1iving oгganisms
|a.ticipating, in paiiсulaг, in o=хidation-геduсtion pгoсеssеs, Tурiсal геprеsеntativеs of
polyк"iiJ.'Ъrе bioflauЬnoids, whiсh arе joined in tЬе gгoup of vitamin P. Theу arе usеd
in mеdiсal tгеatmеnt of pathologiс statеs сausеd bу peroxidе-oхidation of mеmbrane
iipid,. t'.obilization of suсh сБmpounds on thе suгГaсе of ultгafinе minеral matгiсеs
allows dеsigning nеw mеdiсal formJ with nеъ, usеful рropеrtiеs. Studiеs on adsoгption of
poryкеtio.JunJ in paгtiсulaг on flavonoids on ultrafinе oхidе suгfaсеs may, to some
ехtent, оlarifу pгoсеsses, whiсh ocсuг with those biomolесulеs on thе се1l mеmbгanе
surfaсе. Thе most intегеiting and promising is investigation of polуkеtidе adsoгption on
high surfaое aгеa siliсa bесiusе its isoеlесtгic point is сlosе to pH 2 whеreas isoеleсtгiс
p"]"'
"г
majoritу of сеlls lies bеtwееn pH 2 ind ptl 4. Thus, studiеs of adsoгption on
ultгafinе siliсa surfaсе may bе useful in mоdеling such pгoсеssеs in living systеms.
ouг prеvious sшdiеs of vitamins and сarbЪhydratеs in сondеnsеd and adsorbеd on
thе siliсa surfaсе states by TPD МS mеthod IlO,1з-14] has shown that this mеthod is a
prornising tool in invеstijation of adsогрtion Ъn high-suгfaсе.aIеa oхidеs. Thе reason is
that usе оf this mеthod allоw to сompaге thегmal transfоrmatiоn of biologiсally aсtive
moleсulеs in сondеnsеd statе with that in adsorbеd statе and to find out pесuliaritiеs in
thегmal dеcomposition of molесulеs сausеd bу' adsoгption.
Rеlativelу high tеmpеraturе usеd in tempеratuге-рrogrammеd mass spесtгomеtry
makеs possiblе foгЪiomolесulеs to ovегcomе aсtivation baггiеrs of suсh rеaсtions whiсh
do not takе plaсе at loiv tеmpегaturе, but сan oссuг in living systеms цndеr еffесt of
еI|zymеs. StaЪlе produсts of thЪгmolуsis idеntifiеd in mass speсtгomеtriс еxpегimеnt may
bе Ёоrnpaгеd wiй biologiсallу aсtirnе molесulеs kncwn in еvolutionary alliеd oг.rеmotе
biologiсal systеms' гЬ.in'tu*., it was fоund prеviouslу that-охуgеn fгee thеrmоlysis of
,ugu,i (gluсоsе, galaсtosе, laсtosе, saссharosе, rafТinosе) геsults in solid statе biomimetiс
rеaсtion with еlimination of rvatег molесulе and foгmation in molесulaг form thе
substitutеd ^y-рy.on", *,ьiсh is onе of polуkеtidеs. it is knоwn thet biоs1,nthеsis of
з.l0
i paпially
rzеnе and
is duе to
:1е phеnyl
: ргoduсts
is to thе
е portions
5 due to
shapе nеaг
. с1оsе for
'.: (сausеd
=linеd not
з:.cеnсе of
-
-:!llwl0,.
:-iгmation
-.i uеnсe оГ
зs obtainеd
:: we сan
i.- ."-.tion of
::s. whiсh
l:sanisms
::..tlvеs of
е.' зге usеd
::-зmbranе
:* тatгiсes
s.:ttion of
г. :c somе
--зmbranе
*ч.- тt1on on
s .:еlесtriс
s: т:lon on
t-:
ш..:bеd on
т.::.od is a
t -.asоn is
Е. aсtivе
tr- .::tiеs in
polykеtidеs is prоvidеd bу aсеtyl.Kola whrсh is fоrnrеd in thе proсеss of sugaг
mеtabolism. Thus, somе analogiеs aге possiblе bеiц'ееn сhеmiсal transfогmation of
moleсulеs and mеtabolism of molесulеs in living systеms.
Еxpеrimеntаl Adsогption оf vеnorutonе half sуnthеtiс falсonoid vеnorutonе, the
mixturе оf thгее isomегs (3',4'and 7(B-oxy-еthуl)-3.ramnоglukosidе-5-oхуflavоn) on
ultгafinе oxide suгfaсе was donе as follоws' Adsorbеnt was pгеliminary tгеatеd at 400 oс
foг 2 houгs in atmosрhеге. It was еnough to геmovе thе геsiduе oгganiс substanсes
adsoгbеd on thе suгfaсе Aquеоus solution of vеnorutonе of 10 m1 volumе was mixеd
with O.l g of ultгafinе sili'сa (Aегosol A-300, spесifiс surfaсе aгеa 300 m2lg) and kеpt аt
гoom tempеratuге for twо hours. Thеn suspеnsions trеatеd in сеntrifugе, washеd and driеd
at гoom tеmpегatuге' Adsorption was studiеd in thе соnсеntration inteгval 10-35Omg/l"
SuгГaсе conсеntгation was mеasuгеd bу spесtгоphotometеr (r,vavеlеngth }.=з40 fli.') as
сonсеntration diffегеnсе bеfoгe and after adsогption. Мass spесtromеtry studies weге
сonduсtеd fог vеnorutonе surfaсе сonсеntгation 2. l0-3 !e Samplеs fог mass
spесtгomеtгiс studiеs оf quеrсеtinum (3',4',3,5.7-pеntaoхуflal'on). morinе, the struсtural
isomег of querсеtinum (2'.J,.3,5.7.pеntaoхyflar,оn), 1.2-dioхiantгa.quinonе-З-sulfoасid
(alizaгinе rеd S) in adsoгbеd' statе v'.'еге obtainеd bу thеir adsогption frоm rvаtег-alсohol
mixtuге (50 96) Si.rгtЪсе сonсепtratiс)n оn thе siliсa surfaсе fоr mеntionеd thгее
сomрounds ц'аs ab()]'rt l0..;irоlе s,
Rеsults апd disсtissioil' Adsoгption and ih,.-rmal stability of a гоw оf polykеtides:
bioflavоnoid qrlеrсеtinum. half.s1.nthеtrс flаr'onоid vеnoгutonе, alizarine геd S -
antгaquinonе and struсtuгal isоmег оf quегсеtinum - moгinе (sее Fig 6) has.0ееn studiеd.
Those соmpounds wеrе studird iп соndелsеd Statе and adsoгbеd rln thе surfaсе оf
ultгafinе siliсa by mеans с.rf tегnpегatuге-рrograi-nПlеd desоrрtion with mass spесtгomеtry
rеgistгatiоn оf dесоmроsitiоn prоducts
It was fоund that quегсеtinum and a1izaгinе bеing hеatеd in оxуgеn-frее сonditions
aге sublimed at thе tеmреraturе оl аbout 30О "с. Duгing tеmрегatuге'pгоgгаmmed
expегimеnt molесulеs of quегсеtinum and alizaгinе aге соndеnsеd on thе сool dеtails of
apparatus. No thегmogгams сould bе obtainеd fог thosе соmpounds,
P' at
/,-..'., \-1лн
I rl at: )
\-''o ^ - soH
oHo
^p
b R =R,.=R =R :a,=il, R =OH,
,v ",. \ "' с, R =R =R =R'=H' R,=oH
Г д ] в , R, d] 1)' R =R,=R.=oН, R,=lGiu-Rha], R'= -oCН,CH,oН,
. ^\-t \ /^ - >\ R 2) R =R,=.]'R'=[Glu-Rhа], R'=oH' R'= .сH,сН,oH'
к v U -,- У,' 3) ; =.эn 6ц'9l' д:{G|u-Rhа], R'=R'=гl R =oH
tс
хt-хo-.'^\o
R.
Fig. 6. Structuгеs of рolуkеtidеs: a: 1,2.dioхiantraquinonе-3-sulfoaсid; b: quегсetinum;
с: moгinе; d: vеnorutone (miхtuге of l' 2, З isоmегs).
Мolесulе of moгinе is lеss stablе in сorrrparison with quегсеtintim and alizarine
molесulеs. Bioflavonoids havе thе similaг сaгbоn сaгсass and сharaсtегistiс loсаtion of
oxidе substitutients whiсh has its biоsynthеtiс sicnifiсanсе: гing A is usually hydгoxillatеd
ovег nеighboгing positions (5,,7') whегеas in thе гing С nеighboгing positions arе
hydгoxillatеd (at fiгst 4,, thеn positions 3,and 5') N{оrine, though having thе samе сarbon
сarсass as quеrсеtinum' has гing C hуdroхillarеd in position 2' and 4, whiсh is not
сhaгaсteгistiс Гor bioflavonoids. Мav be this is thе fundamеntal diffегеnсе оf
lpr .
!n,
E
F
I
ts-
l:
h
Ь
::lmetry
. whiсh
.:Ъсt of
':]t mAy
- :еmote
- .r sis of
' .limеtiс
:m thе
:sis of
-141
bioflavonoids ftom morinе - absenсе of intгamoleсular hydrogеn bond in. ring
.
C.
Alizarinе is not a bioflavonoid but its molесulе has two hуdгoхyl groups in ortho.
po'ition' whiсh also сan providе'intramolесulaг hуdгogеn bond.
Мass spесtromеtгiс analуsis allowеd to find сorrelation bеtwеen сhеmiсal struсture
of morinе and venorutonе moiесulеs, on onе side, and mесhanisms of thеiг thеrmolуsis,
on thе othег' In Ftg 7 ih. ,ugg.,*d sсhemе oГ moгinе dесomposition is pгеsеntеd.
Thегmal dесompоsition of сaгbon caгсass of сhromonе oссuгs bу ruptuгe of сhеmiсal
bonds by mесhanisms A, B, с
In thегmal dесomposition mass speсtгa оГ moгinе (sее Fig. 8) and vеnorutonе the
f,ugmеш of thеrmal JеЪomposition of b.n,ulrеllеd .y.pyrone was obsеrvеd whiсh was
-"i],u",",i,."d
bу following йu,, numbеrs' typе A.- lз.7,.1з6,'108, 91 mJz,tуpе A - 141,
I23, |12,11l, 9б, 95 m\Z; and also fгagments of substituted aryl гadiсal: typе с . l09,
1 10. 1 l 1 m]z.Itis to be noiеd that simllaг сomрonеnts of mass spесtrum wеrе obsегvеd in
mass speсtrum of quегсеtinum.
туpe A
туpe в:
rype e
OH
)_
/,/ -:т,
rlL
Нo,\:>-1
136 m/2.
у"
юH: \
141 ,12з,112,111 ,96 95 m/z
1 09, 11 0, 1',l',1 , 95 m/z
Fig.7.Sсhеmеofthегmaldеstruсtionandfгagnl9ntationofmoгinеmolесulе.
Thеrmolysis of 2-aгyi.сhromonе oссuг's irl thгее main stagеs (22o,280,
'з!0.".с).|or
morinе and in iour ,tug; (zso' з60, 420,480 "с) Гог venorutonе-(sее Fig 9 and Tablе l).
.
Analysis of mass spесtгomеtriс infoгmatiЬn shows that diffеrencе in struсturе of
moгinе and vеnoгutonе molесulеs' in paгticular, difГегеnt positions of hydroхillation of C-
гing and pгеsenсe of еthoху-gгoup in u.no.to,.'. do not еffесt еssеntially the pathwaуs of
dесomposition oг ьеnzan.itй т.pу,onе. Ргеsеrlсс oГ еthoxу-gгoup eхplains intense linеs
at mJz 26,28, and 43' in venorutonе mass spесtгa. Pгesеncе of caгbohуdгatе rеsiduе
i'"'й*,,eь"ose; in vеnоrutonе molесulе rеsults in nеw spесifiс fеaturеs of thегmal
dесomposition. In this
"u,.
n.* stagеs of dесoпlposition appеaг at thе tеmpегaturеs 250,
360 "с сharaсtегized ьy е'юlution oisubstitutес] ,-pyronе (12, g'7 , 1o2, 726 m/z). As it
in ring C.
s in oгtho.
al struсturе
hегmolysis,
i pгеsеntеd.
эf сhеmiсal
:orutonе thе
whiсh was
ре A - 141,
pе C . 109,
оЬsегved in
r. l.
з
a
'1
0
|Аlz
Fig. 8. Еlесtron impaсt п]ass sресtrum of mоrinе thегmolysis at 330 oс.
was found out in ouгpгеviol.ts woгk [19] thегnlolysis of сarbohydгatеs inсluding pyranosе
гings (gluсosе, galaсtosе' laсtosе, saссhaгosе, raffrnosе) rеsults in foгmation this set of
linеs; thегmolуsis of disaссhaгidеs laсtose and гaflnosе also oссuгs in two stases . 260
and 330 oС
l, aф'u
4.4
70 140 210 280 350 420 490 560 630 700 т, с
Fig.9. Thегmogгams of fгagmеnts mlz 1З1 - 1з6, 172, l11, l 10, 108, 96, 95,91;
thегmal dесomposition of 2.arylсhiolllone _ typе A' D, C foг vеnorutonе in
adsoгbеd statе
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Flavonoids in living organisms ехist in thе Гoгm оГglусosidеs' onthе last stagеs of
biоsynthеsis in thе form ofl mеthoху- and mеthylеn.dioхy- dегivativеs; that is why
vеnorutonе (miхturе oГ 3 , 4 and 7-(p-oхyеthyl)rut sidеs. whiсh is simultanеouslу
glyсosidе and еthoхy-dеrivativе of querсеtinum, is most similar to physiologiсally aсtivе
сompounds among thе invеstigatеd samplеs. Its adsorption from watеr solutions on thе
ultrafinе siliсa surfaсе has bееn studiеd. Thе adsoгption isothеrm has bееn obtainеd, thе
сonstant of adsoгption еqurlibrium Е:2.013 t 0'106.l0з Vmole, and adsогption сhange of
Gibbs еnегgy AG=l8,8_ 1.2 kJimole (R2 =0,9882)' Thе valuе of adsoгption limit for
vеnorutonе was A:о:6.9 рmolе/g and moгe than two oгdеr of magnitudе laгgег than
adsorption limit of alizarin геd S and of quегсetinЦm.
Vеnorutonе in adsoгbеd statе on thе ultrafinе siliсa surfaсе was investigatеd by
TPD МS' It was found out thаt main pathways of venorutonе dесomposition dо not
сhangе aftеr adsoгption on thе ultгafinе siliсa suгfaсе' Nеvегthеlеss, additional maxima
appеaг for l09, 110, l|1 rnlz in thе viсinity of 220"С (typе C dесomposition) and
maхimurn for \26, 91' .72 rrl/z a| l80.с (dесomposition of сaгbohydratе гesiduе).
Pгеsеnсе of thosе maxima being сonnесtеd gеnеtiсallу with adsoгption on thе siliсa
surfaсе may bе сausеd bу thе faсt that сaгbohydгate rеsiduе takеs paгt in adsorption
mесhanism. At higheг tеmpегaturеs numbеr of dесomposition stagеs, thеir loсation on
temperatuгe sсale and sеquеnое arе similaг to thosе in сondеnsеd statе (Sее Tablе 1).
Thus, as it is сlеar frоm Тablе l theгmal dесomposition of morinе takеs plaсе in thrее
main stagеs, Pгеsеnсе of сarbohуdratе substitution in оhromonе Stгuсturе (vеnorutone)
геsults in an additiоnal stagе of thегmal dесompositiоn; thе dесomposition of sugar
геsiduе and сhгomonе tyре B and С takеs plaсе simultanеouslу. Тhis may bе ехplainеd
taking into acсount that гamnogluсosil is loсatеd in thе point 3 of сhromonе, i.е.
paгtiсiрatеs in thе struсtuге whiсh fragmеnts Wе obsегvе in thегmolysis of B+уpе.
Adsorption on siliсa surfaсе dеmonstгatе itsеlf by appеarancе of maхima at high
tеmpеraturеs Thе first stagе (I) of thегmo1уsrs of сaгbohуdгatе rеsiduе thе thегmolysis of
сhromonе of B-typе is shiftеd to low tеmpегatuге appгoхimаtеly to 40 oC in сomparison
with sugaг, whегеas duгing two nеxt stages (II and IIГ) thегmolysis of сhromonе and
сarbohydratе геsiduе oссuг simultanеously.
Pгaсtiсallу impoгtant сhеmiсallу modifiеd dispегsеd ultгafinе oxidеs dеmonstratе
intеrеsting and uneхpесtеd еffесts both in thегmal dеsoгption and in dесomposition of
suгfaсе сomp1еxеs, inсluding phasе tгansitions in thе adsorption laуег. The application of
vaгious known multi-paгameteг models to systеms of this kind сaггiеs thе impliсit dangег
that thеу only pгovidе an adjustmеnt to the ехpегimеntal data and foster thе illusion of
undегstanding, геgaгdless of thе adеquaсy of thе modеl' Тhегеfore, thе meсhanistiс
impliсation of any mathеmatiсal model, and in paгtiсulaг of thе one prеsеnted here, arе
not to bе ovеrеstimatеd. Ал indеpendеnt vегifiсation of thе paгamеtегs obtainеd is always
nесеssary but pгoduоing it is not an easу task in thе сasе of оhemiсally modifiеd
dispeгsеd systеms. Thе advantage of our simple approaсh is that thе геsults aге obtainеd
in an analуtiсal foгm, whiсh faсilitatеs thе сomputег tгеatment of еxpегimеntal
thегmogгams'
Fuгtheг aсcumulation of ехpегimеntal data сonсeгning TPD Мs of dispегsеd oxidеs
is nесеssary Гoг a dеtailеd undеrstanding of thе сhеmisoгption meсhanism, thе stгuсturе
of сhеmisorbеd biоlogiсаllу aсtir,е moiесulеs and thе non-isothегmal kinеtiсs of thеiг
dесomposition.
AсknowIedgеmеnts
Authoгs aсknowlеdgе Prof. D Dollimorе Гoг peгmanent hеlpful disсussions and foг
his suppoп of SТСU Pгojесt N 1068..Мass spесtromеtry of industгial aеrosols in
I
ьF
Г
Ь
!
I
:i
ti
iii
З45
Ukrainе''. Finanсial suppoгt of Sсienсе and Tесhnology Cеntеr in Ukгainе is also gгеatly
apprесiatеd.
Refеrеnсes
l. Chuiko A.A., Nazaгеnko VA., Pokrovskiy V.A. Dеsoгption mass spесtгomеtry and
its appliсations in suгfaсe сhemistrу i/ Visnyk As UssR - 1989. . N. 10. - P. 31 .41.
2' Тhе solid statе thermal dеgгadation of aspirin / GV Guсhup, K'S. Alехandег,
D. Dollimore еt al. ll Proc. 19th Noпh Amег. Thегmal Analysis Soсiеty Conf' (Еd
I R. Harгison) (Тolеdo, Мaу 20 - 25, |990)' - P. 549.555.
3. Guсhup G.V., Aleхandеr K S., Dollimoге D. Thе Usе of Thегmal Analysis and Мass
Speсtгomеtry to Study thе Solid Statе Bеhavioг in Pharmaсеutiсal Tablеt Мiхtuгеs //
Тhегmoоhimiсa Aсta. - 1992. - v. 196. -P.267-2.78'
4 Thе Dеtеrmination of Cholesteгol, Calсium Caгbonatе and Calсium oхalatе in
Gallstonеs by Thегmogгavimetry i K.S. Alехandеr, D' Dollimoге, J.G. Dunn et al. l
Thеrmoсhimiсa Aсta' . 199з. _ У, 2|5. - P. 17l-l8l.
5. Thе Influеnсе of Pесtin and Bi1е Saltlleсithin/Сholеstегoi systеm on thе Paгtiсlе Sizе
of Calсium Caгbonatе Suspеnsions / J D. Skеlton' K.S. Alехandеr, D. Dollimorе еt al.
// s.T P. Phaгma' Sсiеnсеs' - 1993. - V 3 - P' 153-162.
6. Dollimoге D., Мaпin A., Pinkепon A.A. A Study of thе Thегmal Deсompositioп of
Biguadinium Dipегсhiorate Using Thегmogravimеtry and Мass Speсtгosсopу //
Thегmoсhimiсa Aсta' - 1996' * V' 285 - P. 109-l17.
7. Dollimorе D., Lегdkanсhanaрoгn S., Alеxandeг K S Thе Usе of thе Haгсouгt and
Еsson rеlationships in Intеrpгеting thе Kinеtiсs оf Rising Tеmpегaturе Solid Statе
Dесompositions and Its Appliоation to Phaгmaсеutiсal Foгmulations //
Thеrmoсhimiсa Aсta. - 1996. -У 290' -P, |з9.141,
8' Dollimoге D. Тhеrmal analysis ll tna|уtical сhеmistгy' _ 1996'- V. 68, N 12. -
P 6зR-71R.
9. Pokrovskiy V.A.,Ustуuzhanin P F. Мodеl of aсtivatеd statе in сyanсobalamine
dесomposition // Tеoгеt. i Еkspегim. Khimia. . i988.- v. 24, N 6. - P.75l,-,75з'
10. Pokrovskiy v.A, Galagan N.P., Dеmbnovеtskaya L.I. Мass spесtromеtry of
суanoсobalaminе, gluсosе and гafftnosе in thе so1id statе and on a dispегsе oxide
suгfaсe // Rapid Communiсations in Мass Spесtгomrtry. - 1995. - v' 9. - P. 585-587'
11. Pokovskiy V' A. Tempеratuге-pгogгammеd mass spесtгomеtry of biomolесulеs in
surfacе сhеmistry studiеs// Rapid Communiоations in Мass Spесtromеtry' . 1995. -
v. 9. - P. 588-591
l2. Тhегmal dеstruсtion of amino pгopyl-siliсa suгfaсе layег / Е.М. Pakhlov,
Е.F. Voronin' V A. Pokгovskiу, A A. Chuiko ll Zhuгna| pгikladnoy khimii. - 1996. -
v. 69' N з.-P.42З.426
l3. organosiloхanе and monoеthanolaminе tгansfoгmations on fumеd siliсa and siliсa-
alumina suгfaсеs / A'A. Сhuiko, G Ya Guba, V A Pokrovskiy, М.I. Tегеz // Colloids
and suгfaсеs. - 1996' - N 106.. P 89. 95.
14. Kulik Т.V', Galagan N'P., Pokrovskiy V.A. Мass spесtromеtгiс invеstigation of
thегmolysis of sugaгs // FaгmatseЙyсhny zhuгna|' - 1997. - N 2. - P' 16 - 79'
15' Мass spесtromеtгiс studiеs on сyanсobalaminе on dispеrsе oxidе suгfaсе l
V.A. Pokrovskiy, T V. Kulik, N P Galagan, A.A Chцiko // Faгmatsеvtyсhny
zhuгnal. -199'7. -N5 -P.52.57
16. Pokrovskiy V.A. Теmpеraturе-programmеd desoгption mass spесtгomеtry (TPD МS)
of dispегsеd oхidеs// Adsoгption Sсiеnсе & Tесhnologу' . i997 ' - V' 14, N 5. - P. з0l-
317.
17' Tеmpегatuге-pгoglammed dеsoгption mass spectгometry of сarbonizеd siliсa surfaсe /
V. A. Pokгovskiy, R. Lеboda, V. V. Tuгov etal. ll 1998.- Carbon.- N 17. - P. 1039-
\04'7 .
з46
o grеatlу
rеtry and
-1 I - +1.
'ехandеr,
::f (Еd'
:l Мass
.'.l':гes //
r. зtе in
т :.. a|. l
::,е Sizе
-::: еt al.
:. . ..п of
l.*..:у //
;.: -.- and
;r.. Statе
L--s ll
of
- хidе
-: t7
..:S ln
-;5 -
-:...:.lov,
- --6. -
1ся-
oids
шз' :r of
g*-'.:е l
в - ':hnу
\1S)
_r0l-
i39-
l8 Gunko v.V., LеЬоdа R., Pokovskiy v.A. Pathwaуs fоr dесomposition ofphеnуlеthanolbоund to siliсa sцrfaсе. Polish J Сhеm l99Ъ - v.7з.-P. 1345-l356.
19 Kulik TV', Galagan NP, Pogorеliy V.K, Pokovskiу V.A. TPD Мs studiеs of
sеvегal polyketidеs in solid statе and adsorbеd on siliоi suгfaсе zz rs* йt.йuiio""iМass Spесtгomеtry Confегеnсе, Baгсеlona' Aug. 28.Sеpt. l, 2000; Book Abstг.P 105.
20 Pokrovskiy V. A Теmp-егatuгe-pгogгammеd dеsoгption mass spесtro metry l/ Joumal ofТhеmalAnalysis and Сaloгimеtry -2ООО..У' 62.-P' 4o7-415. '
э+I
|
| id | oai:ojs.pkp.sfu.ca:article-71 |
| institution | Surface |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2025-07-22T19:30:03Z |
| publishDate | 2001 |
| publisher | Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | surfacezbircomua/c3/72ebf9d9bea734a6ea0de2410c989ec3.pdf |
| spelling | oai:ojs.pkp.sfu.ca:article-712018-11-27T09:42:39Z Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry Pokrovskiy, V. A. Galagan, N. P. Kulik, T. V. Temperature-programmed desorption mass spectrometry (TPD MS) is discussed with reference to studies of modified pyrogenic oxides. Simple theoretical models are presented in order to allow an approximate analytical treatment of TPD MS data. Rate constants for first- second- and third-order reactions have been obtained. Products of thermal decomposition of carbonized surface layer has been observed and identified. The different pathways of uni- and bimolecular desorption were investigated and rate constants of reactions has been derived from TPD MS measurements. Adsorption and thermal stability of several polyketides has been studied by TPD MS in condensed and adsorbed states. Mass spectrometric analysis allowed observing correlation between chemical structure of morine and venorutone molecules and mechanism of thermolysis. Decomposition of carbon carcass of chromone, the bensanelled y-pyrone in particular, resulted in formation of fragments with mass numbers 91, 95, 108, 111 m/z. Decomposition occurred in three stages with maxima at 200, 280, 380°C for morine and 240, 320, 450°C for venorutone. Presence of carbohydrate residue (ramnose, glucose) in venorutone molecule caused two additional stages of thermolysis in comparison with morine, maxima being located at 220 and 280°C. In this case, different to previous one, the substituted y-pyrone has been produced being characterized by mass numbers 72, 97, 102, 126 m/z. Comparison of adsorption parameters for venorutone and carbohydrates has shown that carbohydrate residue played main role in adsorption of venorutone molecules on ultrafine silica surface. The ring C of venorutone molecule stayed free in adsorption process which attested the fact that hydroxyl group in position 4' responsible for biological activity of flavonoids, did not participate in adsorption. It allows the ring C preserve its antioxidant, membrane- and capillary-stabilizing activity in bound state. &nbsp; Temperature-programmed desorption mass spectrometry (TPD MS) is discussed with reference to studies of modified pyrogenic oxides. Simple theoretical models are presented in order to allow an approximate analytical treatment of TPD MS data. Rate constants for first- second- and third-order reactions have been obtained. Products of thermal decomposition of carbonized surface layer has been observed and identified. The different pathways of uni- and bimolecular desorption were investigated and rate constants of reactions has been derived from TPD MS measurements. Adsorption and thermal stability of several polyketides has been studied by TPD MS in condensed and adsorbed states. Mass spectrometric analysis allowed observing correlation between chemical structure of morine and venorutone molecules and mechanism of thermolysis. Decomposition of carbon carcass of chromone, the bensanelled y-pyrone in particular, resulted in formation of fragments with mass numbers 91, 95, 108, 111 m/z. Decomposition occurred in three stages with maxima at 200, 280, 380°C for morine and 240, 320, 450°C for venorutone. Presence of carbohydrate residue (ramnose, glucose) in venorutone molecule caused two additional stages of thermolysis in comparison with morine, maxima being located at 220 and 280°C. In this case, different to previous one, the substituted y-pyrone has been produced being characterized by mass numbers 72, 97, 102, 126 m/z. Comparison of adsorption parameters for venorutone and carbohydrates has shown that carbohydrate residue played main role in adsorption of venorutone molecules on ultrafine silica surface. The ring C of venorutone molecule stayed free in adsorption process which attested the fact that hydroxyl group in position 4' responsible for biological activity of flavonoids, did not participate in adsorption. It allows the ring C preserve its antioxidant, membrane- and capillary-stabilizing activity in bound state. &nbsp; Temperature-programmed desorption mass spectrometry (TPD MS) is discussed with reference to studies of modified pyrogenic oxides. Simple theoretical models are presented in order to allow an approximate analytical treatment of TPD MS data. Rate constants for first- second- and third-order reactions have been obtained. Products of thermal decomposition of carbonized surface layer has been observed and identified. The different pathways of uni- and bimolecular desorption were investigated and rate constants of reactions has been derived from TPD MS measurements. Adsorption and thermal stability of several polyketides has been studied by TPD MS in condensed and adsorbed states. Mass spectrometric analysis allowed observing correlation between chemical structure of morine and venorutone molecules and mechanism of thermolysis. Decomposition of carbon carcass of chromone, the bensanelled y-pyrone in particular, resulted in formation of fragments with mass numbers 91, 95, 108, 111 m/z. Decomposition occurred in three stages with maxima at 200, 280, 380°C for morine and 240, 320, 450°C for venorutone. Presence of carbohydrate residue (ramnose, glucose) in venorutone molecule caused two additional stages of thermolysis in comparison with morine, maxima being located at 220 and 280°C. In this case, different to previous one, the substituted y-pyrone has been produced being characterized by mass numbers 72, 97, 102, 126 m/z. Comparison of adsorption parameters for venorutone and carbohydrates has shown that carbohydrate residue played main role in adsorption of venorutone molecules on ultrafine silica surface. The ring C of venorutone molecule stayed free in adsorption process which attested the fact that hydroxyl group in position 4' responsible for biological activity of flavonoids, did not participate in adsorption. It allows the ring C preserve its antioxidant, membrane- and capillary-stabilizing activity in bound state. &nbsp; Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine 2001-06-10 Article Article application/pdf https://surfacezbir.com.ua/index.php/surface/article/view/71 Surface; No. 4-6 (2001): Chemistry, Physics and Technology of Surface; 332-347 Поверхность; № 4-6 (2001): Химия, физика и технология поверхности; 332-347 Поверхня; № 4-6 (2001): Хімія, фізика та технологія поверхні; 332-347 3154-8091 3154-8083 en https://surfacezbir.com.ua/index.php/surface/article/view/71/70 Авторське право (c) 2001 V.A. Pokrovskiy, N.P. Galagan, T.V. Kulik |
| spellingShingle | Pokrovskiy, V. A. Galagan, N. P. Kulik, T. V. Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry |
| title | Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry |
| title_alt | Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry |
| title_full | Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry |
| title_fullStr | Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry |
| title_full_unstemmed | Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry |
| title_short | Non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry |
| title_sort | non-isothermal decomposition of biomolecules studied by means of temperature-programmed desorption mass spectrometry |
| url | https://surfacezbir.com.ua/index.php/surface/article/view/71 |
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