01. analisis farmasi anorganik
DESCRIPTION
nisaTRANSCRIPT
-
5/23/2018 01. Analisis Farmasi Anorganik
1/31
Dr.TutusGusdinarPharmacochemistryResearchGroupSchoolofPharmacy
INSTITUTTEKNOLOGI
BANDUNG
-
5/23/2018 01. Analisis Farmasi Anorganik
2/31
Thes llabusGeneralaspectsofpharmaceuticalanalysis:concentrationofelectrolyteand
molecularspeciation,pHandbuffersystem,associationdissociationand
equilibriumconstant;Acidimetryalcalimetry:monoprotic,polyprotic,
amphiprotic
acid
base;
buffer
capacity;
titration
curve,
indicative
reaction,
sam le anal sis Preci itation and reci itatometr : factors that influence
precipitateformationandproperties(nucleation,crystallgrowth,aging),
colloidstabilityandproperties;titrationcurve,indicativereaction,sample
chelatecomplex,
EDTA;
titration
curve,
indicative
reaction,
sample
analysis,
Oxidimetryreductometry:redoxsystem,redoxequilibriumconstant;
cu v , c v c , y ; v c y :
gravimetricanalyticaltechniqueandseparation; Technicalapplicationon
pharmaceuticalsubstances
and
preparation:
titrimetric
typology,
titration
feasibility,calculationandresponsemeasurement,indicativereactions;
Separationandmeasurementtechniquesandanalyticalerrors:separation
techniquesandapplicationofreactionsinpharmaceuticalanalysis;statistics
andanalyticalerrors.
-
5/23/2018 01. Analisis Farmasi Anorganik
3/31
Metodekimiaanalisisuntukmenentukankadar
sen awa
terdiriatas
ravimetri
dan
titrimetri. Keduametodetersebut
dalamsatuan
internasional
(SI
units).
Metodeklasikdigunakanuntukmenentukan
kadardalam
ukuran
besar
(1
100%),
sedangkanuntuk ukurankadaryang
-
5/23/2018 01. Analisis Farmasi Anorganik
4/31
Classical analysishashadalonganddistinguishedhistory.
ecru e
c ass ca
ana yses
o
epas
ave
eenimprovedasbettervaluesforatomicmassesbecame
available,astheprinciplesofphysicalchemistrywereapp ie ,asorganic reagentswereintro uce ,an asinstrumentaltechniquesbecameavailablefortheevaluation
of
the
s stematic
errors
inherent
in
both
gravimetry andtitrimetry.
x s ng
so ope
u on
mass
spec rome ry
an
new
g
performanceinductively
coupled
plasma optical
emission
spectrometry,bothofwhicharemassratiobased,rivalorevenexceedclassicalanalysisinprecision,accuracy,andspeed.
Nevertheless,gravimetry andtitrimetry willendureasaccurate,directlySItraceable,primarymethods,providedt att e r systemat cerrorsareproper yeva uate us ngthe
best
instrumental
techniques
available.
-
5/23/2018 01. Analisis Farmasi Anorganik
5/31
Gravimetri adalah enentuan kadar unsur atau un s esikimiadengancaramengukur berathasilreaksikimia
tidaklarut
yang
diketahui
dengan
pasti.
Hasilreaksiyangtidaklarutbisaberupagasyang
tidakmenguap,
baik
berasal
dari
penguapan
pada
suhurendahmaupundaripemijaranpadasuhutinggi.Padaumumnyayangdimaksudsenyawatidaklarutadalahendapanyangterbentukdidalamsuatu
Gravimetrimeru akanmetode an sudahdikenalse ak
abadke
16.
-
5/23/2018 01. Analisis Farmasi Anorganik
6/31
Titrimetriadalahmetodepenentuankadarunsuratauspesikimiadengancaramengukurjumlahsenyawa
kimia
yang
secara
pasti
diketahui
bereaksi
secara
ditentukantersebut.
Massakimia
tersebut
diukur
dari
sejumlah
volume
larutan
standar(baku)dengancaratitrasi.Ada4metode, ,
kompleksometri,antitrasioksidasireduksi.Titikakhir
titrasi
secara
klasik
ditentukan
dengan
mengamati
,selisihpotensialpadaelektroda,ataumengamatiperubahankonduktivitaslarutan.
-
5/23/2018 01. Analisis Farmasi Anorganik
7/31
T tr metr cmet o s
o
ana ys s
are
capa e
o
rap
an
convenientanalytedeterminationswithhigh accuracyand
.
betweentheanalyteand areagent,thetitrant:
whereAandTrepresenttheanalyteandtitrant,respectively,and
aandtarethestoichiometric coefficients.
Forvolumetrictitrations,theamount,nA,ofanalyteinthe
samp ecan eca cu a e us ng
nA
=
a/t
.
CTVTw ere T s econcen ra ono e ran ,an T s evo umeoftitrantneededtoreachtheendpoint.
-
5/23/2018 01. Analisis Farmasi Anorganik
8/31
Penentuan
a arsuatu
ana t
a am
arutan
memer u an
:
,
tersebutharuscepatdansempurna,dimanahargaadant
diketahui.2) Konsentrasilarutanpenitrasi,CT,harusdiketahuidengan
pasti.Larutanpenitrasiharusdibakukandengansenyawa
a u
pr mer
atau
t tras
engan
arutan
yang
ter uat
ar
senyawabakuprimer.
menggunakanindikatorwarnaataudenganinstrumen.Jika
menggunakaninstrumen
yang
dapat
mengukur
secara
berkelanjutan,makaakandiperolehkurvatitrasi. Caraini
biasadigunakanuntukmenentukankadarcampuranatau
un u men e e s a anya gangguan n er erens .
-
5/23/2018 01. Analisis Farmasi Anorganik
9/31
Syaratkhusus
analisis
titrimetri
:
Gunakanlarutanpenitrasiyangumumdanjenisanalit
yangbereaksi
dengan
penitrasi
tersebut,
metode
pembakuanlarutanpenitrasi,kestabilanlarutan
penitrasi,metodedeteksititikakhir,danhalhallainnya
yangpenting.
GHJeffery,JBassett,JMendham,RCDenney,VogelsTextbook
o uantitative Chemical Anal sis 5th edition.
HALaitinen,WEHarris,ChemicalAnalysis,2ndedition.
-
5/23/2018 01. Analisis Farmasi Anorganik
10/31
AcidBaseTitrations
Reaksitransfer
proton
di
dalam
larutan
air
berlangsungsangatcepat.
suitablefortheanalysisofanyBronstedacid
or ase.Pract ca y,t epKaorpK o t e
analyteshouldbe
less
than
about
10
(i.e.,
pKaorpKb
-
5/23/2018 01. Analisis Farmasi Anorganik
11/31
Inorderforthetitrationreactiontogotocompletion,a
strongacid
or
astrong
base
is
the
usual
choice for
a
titrantinacidbasetitrations.Thelevellingeffectin
aqueoussolutionsshouldbekeptinmind, however :
thestrongest
acid
that
can
exist
at
asubstantial
concentrationisthehydroniumion,H3O+, sinceany
strongacidHAwillreactcompletelywithwater:
HA + H O A + H O+
titratingtheanalytewithhydroniumion. Similarly,the
ion,OH.
-
5/23/2018 01. Analisis Farmasi Anorganik
12/31
Fortheanal sisofbases themostcommona ueoustitrant
is
HCl;
sometimes
H2SO4orHClO4are alsoused.Anyof
thesemaybestandardizedby
tris(hydroxymethyl)aminomethane,(HOCH2)3CNH2, whichis
sometimes
referred
to
simply
as
Tris.
, 2 3,
standard,butitislessdesirablethanTrisduetoitslower
e uivalent wei ht.
Titrationsof
bases
are sometimes
called
alkalimetric
titrations.
Fortheanalysisofacids,NaOHisusuallyused;KOH
orBa(OH)2may
also
be
used.
Any
of
these may
be
standardized
againstpotassiumhydrogenphthalate(KHP).Thehydrogen
phthalateanionis shownbelow.
trat onso ac saresomet mesca e ac metr ct trat ons.
-
5/23/2018 01. Analisis Farmasi Anorganik
13/31
-
5/23/2018 01. Analisis Farmasi Anorganik
14/31
Anyalkalinesolutionwillabsorbsubstantialamountsofcarbon
dioxidefrom
the
atmosphere, resulting
in
the
following
net
reaction : CO +2OH CO 2 +2H O
Exposureof
aqueous
NaOH
or
KOH
titrant
to
the
atmosphere
resu tsincar onateerror.
Solid hydroxidesaltsmayalsocontainsignificantamountsof
2.
NaOHtitrant
solution
is
best
prepared
by
dilution
from
a
concentrated (approximately50w/w%)solution.Sodium
carbonateisinsolubleinthissolution.Thedilutedtitrant
solutions
are
sometimes
boiled
to
drive
dissolved
CO2out
of
the
so ut onan t enprotecte rom exposuretoa r. ea sorpt on
processisfairlyslow,occurringoveraperiodofhoursanddays.
,
preparedand
standardized
solution of
NaOH.
-
5/23/2018 01. Analisis Farmasi Anorganik
15/31
additionofacidorbaseistermed thebufferingcapabilityofthe
solution.The
ability
of
anatural
water
body
to
resist
adecrease
in
Hisveryimportantduetotheubiquitouspresenceofacidrain.
Thealkalinityofawaterbodyisdefinedasthenumberofmolesof
nee e o r nga samp e op = . .
moreacidmustbeaddedtothe1 LsampletobringthepHto4.5.
Acidimetrictitration
to
pH = 4.5
(rather
than
to
an
endpoint)
is
thus
widelyusedtocharacterizethe abilityofawaterbodytoresist
acidification.Ifpotentiometricdetectionisnotused,bromcresol
indicator;the
color
change
signifies
the
end
of the
titration.
-
5/23/2018 01. Analisis Farmasi Anorganik
16/31
KJELDAHL apparatus
-
5/23/2018 01. Analisis Farmasi Anorganik
17/31
Kjeldahl Analysis of Organic Nitrogen
organic nitrogen in the 3 oxidation state. The sample is
di ested with sulfuric acid to convert the or anic nitro en
to ammonium, NH4+. The digested sample is then basified
and ammonia is then disti lled into acid. The ammonia maybe disti lled into excess standard HCl; the amount of HCl
remaining after the distillation is determined by alkali-
. ,
excess boric acid, H3BO3; the dihydrogen borate, H2BO3,
formed b reaction with ammonia is determined b
acidimetric titration. The total Kjeldahl nitrogen (TKN)
content of a water sample is a measure of the totalconcentration of nitrogen in the 3 oxidation state in the
sample: ammonia/ammonium plus organic nitrogen.
protein content of food samples.
-
5/23/2018 01. Analisis Farmasi Anorganik
18/31
Titrimetr Methods
PrecipitationTitrations
Precipitationreactions
in
aqueous
solution
range
from
rapi tos ow, epen ingont ei entityo t e
precipitant.
Manyprecipitationsaresufficientlyrapidandcomplete
to ormt e as so quant tat on yt trat on.
rec p tat ont tr metry assevera a vantagesover
precipitationgravimetry,including speed,sensitivity,and
conven ence.
-
5/23/2018 01. Analisis Farmasi Anorganik
19/31
ArgentometricTitrations+
, .
precipitationsarerapidand quantitative,andsilvernitrate,AgNO3,isusedforthedirecttitrationofanumberofanionsthat
precipitatesilver :allthehalidesexceptF;SCN,CNO,AsO43,
PO43
,CN
,C2O4
2
,CO3
2
,S
2
,CrO4
2
.ee a e onpage n arr s ormore e a .
Titrationsusin A NO astitrantare termedar entometric
titrations.Sodium
chloride
is
suitable
as
aprimary
standard,
and
is
mostoftenusedforstandardizationofthe titrantinargentometric
titrations.Solidsilvernitrateisalsoavailableinhighenoughpurity
toserve asaprimarystandard,butitismoreexpensive.
,
areusedforstorage.Exposuretolight cancausephotoreductionof
thesilvercations, articularinthe resenceoftraceim urities
that
may catalyze
the
reaction.
-
5/23/2018 01. Analisis Farmasi Anorganik
20/31
u a e
na ys sThesulfatecontentofanaqueoussolutionmaybe
,
BaCl2.Thetitrantisusuallystandardizedusingsodium
.
Fluoridecannotbeanalyzedbyargentometrictitration,
withlanthanumnitrate,La(NO3)3,orleadnitrate,
3 2, 3 . PbF2(pKsp=7.57)areinsoluble.Sodiumfluorideisa
.
-
5/23/2018 01. Analisis Farmasi Anorganik
21/31
EndpointDetection
Avarietyofchemicalindicatorsareusedtoindicatethe
, ,
somedetailinthelaboratory handoutTitrimetric
,
chapter7).
Asilverwireorringisasufficientindicatorelectrodefor
3, ISEissuitableforpotentiometricendpointdetectionfor
.
-
5/23/2018 01. Analisis Farmasi Anorganik
22/31
Example:AnalysisofChlorideinSurfaceWaters
Chlorideisfrequentlyamajoranioninsurfaceand
seawater.Althoughchlorideinfreshwaterisusuallyof
,
wintermaysignificantlyincreasethechloridecontentof
, .
concentrationmay
impart
anoticeably
salty
taste
to
,
growingplants.
methodforchloridedetermination; concentrationsin
potentiometrictitration.
-
5/23/2018 01. Analisis Farmasi Anorganik
23/31
TitrimetricMethods:
RedoxTitrations
Redoxreactionsarethemostdiverseofthefourmain
precipitation,complexationandredox).
analyze forany
oxidizing
or
reducing
agent.
However,
man redox reactions are eithertoo slowor have
inconsistentstoichiometry.Thestabilityoftitrantand
anal te solutions can also be a roblem.
Nevertheless a wide variet of anal tes can be
convenientlydetermined
by
redox
titrations.
-
5/23/2018 01. Analisis Farmasi Anorganik
24/31
Consideragenericredoxhalfreaction(chargesomitted
forclarity) : ox
+n
e
reAchemical(i.e.,oxinthisequation)thatpullselectrons
fromanothersubstanceisanoxidizing agent,whilea
chemical(red)
that
forces
another
substance
to
accept
electronsisareducingagent.
Together,ox/redformaredoxcouple;redoxcouplesare
analogousto
acid/base
conjugate
pairs.
And just
like
acidbasereactions,theconjugateofastrongoxidizing
agentisaweakreducingagent.
The
strength
of
oxidizing/reducing
agents
can
bededucedbythestandardreductionpotential:avery
positivestandardpotentialindicatesastrongoxidizing
agent,
while
a
low
positive
or
a
negative potential
is
characteristicofastrongreducingagent.
-
5/23/2018 01. Analisis Farmasi Anorganik
25/31
Thestrengthofanoxidizingorreducingagentisvery
.
acidicconditionstendtomakeoxidizingagentsmore.
fewredoxreagentsarerelativelyinsensitivetopH,which
.
MostredoxreagentsarestableonlywithinacertainpH
.
Sampletreatment
is
often
necessary
to
adjust
the
.
reducedorpreoxidized.Forprereductionoftheanalyte,
canbeused.Itiscommontouseareductor,whichisa
solutionis
poured.
-
5/23/2018 01. Analisis Farmasi Anorganik
26/31
Twocommon
reductors
are :
the
Jones
Reductor,
which
usesamal amatedzinc(ZnH ) ranules,andtheWalden
Reductor,whichusessilvergranules (chlorideisadded
tothe
sample,
usually
as
HCl).
The
Walden
Reductor
is
moreselective(i.e.,aless powerfulreducingagent)than
theJonesReductor.
Preoxidationisnotascommonasprereduction,since
theanalyteisusuallydesiredinareduced formfor
titrationwith
an
oxidizing
agent.
However,
when
pre
oxidationisnecessary,sodium bismuthate,NaBiO3,
ammoniumperoxydisulfate,(NH ) S O ,orhydrogen
peroxide
may
be
used.
-
5/23/2018 01. Analisis Farmasi Anorganik
27/31
TitrimetricMethods:
ComplexometricEDTA
Titrations
Complexometrictitrationsarebasedonthereaction
betweenLewis
acids
(usuall
metal
cations)
and
Lewisbases. M+:L M:L .
donatestwo
electrons
to
form
abond
withthe
acid.
Since
+ , , ,
BronstedbasewillbeaLewis base.Lewisbaseswill
donatetotheLewis acid.Lewisbasesarealsosometimes
,
theligandbinding
site.
-
5/23/2018 01. Analisis Farmasi Anorganik
28/31
-
5/23/2018 01. Analisis Farmasi Anorganik
29/31
Aspecialsubsetofligandsarethosethatcontainmore
an
one
n ng
s e
on
e
mo ecu e;
ese are
ca e
chelatingagents.Chelatingagentsformparticularly
.
Byfarthemostcommoncomplexometrictitrantis
, .hexadentatechelatingligand,meaningthattherearesix
.
EDTAtitrations
are
very
versatile:
they
can
be
used
for
metals,andcanevenbeused(throughbacktitration
.
EDTAtitrationsarealsofairlysensitive,capableof
approximately10
ppm
(i.e.,
10
mg/L).
-
5/23/2018 01. Analisis Farmasi Anorganik
30/31
AdvantagesofEDTAasaComplexingTitrant
Complexationofmetalcationswithunidentateligandsisnot
wehaveasolutionofCu2+ tobeanalyzedbycomplexometric
titration.Wecanuseatitrantsuchasaqueousammonia,aunidentate
ligand.Thefollowingequationsshowthe stepwiseformationof
comp exes e ween eme a an e gan :
2++ 2+ =
CuNH32+ +NH3 Cu(NH3)2
2+ logK=3.34
Cu(NH3)22+
+
NH3 Cu(NH3)32+
logK
=
2.73Cu(NH3)3
2++NH3 Cu(NH3)42+ logK=1.97
nce ecoor na onnum ero u , ea ywewou o serve
fourdistinct
endpoints
during
the titration
with
NH3.
-
5/23/2018 01. Analisis Farmasi Anorganik
31/31