ANALYTICAL METHODS

ANALYTICAL METHODS BY MR.BHAVESH AMRUTE

1. BY
MR.BHAVESHBHARAT AMRUTE
(M.PHARM, PHARMACEUTICAL CHEMISTRY)
INTRODUCTION TO
ANALYTICAL METHODS

2. Contents
Gravimetricmethods,Titrimetricmethods,Neutralization
titrationsanditsapplications,Complexometricreactionsand
titrations),Advantagesanddisadvantagesofinstrumental
methodsofanalysisandrespectiveproblems,Instrumentsfor
analysis.

3. Organicchemistryisthechemistryofthecompoundsof
carbon.
Analyticalchemistrydealswithmethodsfor
determiningthechemicalcompositionofsamplesof
matter.
CHEMISTRY
ORGANIC
ANALYTICAL

4. Pharmaceuticalanalysisdealswiththesubjectofdetermining
thecompositionofmaterialsintermsoftheelementsor
compound(drug)presentinasystem.
Pharmaceutical Analysis

5. History
During1662-1900ADsignificantanalyticalcontributionsto
chemistryinclude:
1)ThedevelopmentofsystematicelementalanalysisbyJustusvon
Liebigand
2)Systematizedorganicanalysisbasedonthespecificreactionsof
functionalgroups.
Mostofthemajordevelopmentsinanalyticalchemistrytookplace
after1900.
Duringthisperiodinstrumentalanalysisbecameprogressively
dominantinthefield.

6. Analytical
methods
Classical Instrumental

7. Classical Methods
1.Volumetric Analysis:
•Aqueous Acid-Base Titrations
•Non Aqueous Titrations
•Precipitations titrations
•Oxidation-Reduction Titrations
•ComplexometricTitrations
•Diazotization Titrations
•Amino Acid Titrations
2. Gasometry
3. Gravimetric Analysis
4. Karl Fischer Titration
5. Kjeldahl Method

8. Other Techniques
Spectroscopic
Separation
Thermal Analysis
Electrochemistry
Instrumental methods

9. Amperometry
Conductometry
Electrolytic Methods
Polarography
Potentiometry
Electrochemistry
Techniques

10. Chromatography
Electrophoresis Extraction
•Gas chromatography
•High Performance Liquid Chromatography
•Liquid Chromatography
•Thin Layer Chromatography
•Ion Exchange Chromatography
•Paper Chromatography
Column Chromatography
Separation Methods

11. Atomic
Absorption
Spectroscopy
NMR
Spectroscopy
Mass
Spectrometry
Absorption
Spectroscopy
X-ray
Diffraction
Fluorescence
Spectroscopy
Spectroscopic Methods

12. Differential Thermal
Analysis (DTA)
Differential Scanning
Colorimetry (DSC)
Thermogravimetry
Thermal Methods

13. Other
techniques
Flame Photometry
Refractometry
Nephelometry&
Turbidimetry
Polarimetry

14. •Titration
–Analyticalmethodinwhicha
standardsolutionisusedto
determinetheconcentrationof
anunknownsolution.
unknown solution
Titration

15. Titrant
Thesubstanceaddedtotheanalyteinatitration(reagent
solution)
Analyte
Thesubstancebeinganalyzed
Equivalencepoint
Thepointinatitrationatwhichthequantityoftitrantisexactly
sufficientforstoichiometricreactionwiththeanalyte.
Titration Vocabulary

16. Titration Vocabulary
Endpoint
◦Thepointinatitrationatwhichthereisa
suddenchangeinaphysicalproperty,
suchasindicatorcolor,pH,conductivity,
orabsorbance.Usedasameasureofthe
equivalencepoint.
Indicator
◦Acompoundhavingaphysicalproperty
(usuallycolor)thatchangesabruptlynear
theequivalencepointofachemical
reaction.

17. Titrationerror
Thedifferencebetweentheobservedendpointandthetrue
equivalencepointinatitration
BlankTitration
Oneinwhichasolutioncontainingallreagentsexceptanalyte
istitrated.Thevolumeoftitrantneededintheblanktitration
shouldbesubtractedfromthevolumeneededtotitrate
unknown.
Titration Vocabulary

18. PrimaryStandard
Areagentthatispureenoughandstableenoughtobeused
directlyafterweighing.Thenentiremassisconsideredto
bepurereagent.
Standardization
Theprocesswherebytheconcentrationofareagentis
determinedbyreactionwithaknownquantityofasecond
reagent.
Titration Vocabulary

19. StandardSolution
Asolutionwhosecompositionisknownbyvirtueofthe
wayitwasmadefromareagentofknownpurityorby
virtueofitsreactionwithaknownquantityofastandard
reagent.
DirectTitration
Oneinwhichtheanalyteistreatedwithtitrant,andthe
volumeoftitrantrequiredforcompletereactionis
measured.
Titration Vocabulary

20. Titration Vocabulary
BackTitration
Oneinwhichanexcessofstandardreagentisaddedto
reactwithanalyte.Thentheexcessreagentistitrated
withasecondreagentorwithastandardsolutionof
analyte.

21. moles H
3O
+
= moles OH
-
MVn = MVn
M:Molarity
V:volume
n:#ofH
+
ionsintheacid
orOH
-
ionsinthebase
Titration

22. General properties
ACIDS
•Taste sour
•Turn litmus
•React with active metals –Fe, Zn
•React with bases
BASES
Taste bitter
Turn litmus
Feel soapy or slippery (react with
fats to make soap)
React with acids
blue to red red to blue

23. Definitions
Acids –produce H
+
Bases -produce OH
-
Acids –donate H
+
Bases –accept H
+
Acids –accept e
-
pair
Bases –donate e
-
pair
Arrehenius
Bronsted-Lowry
Lewis
only in water
any solvent
used in organic chemistry,
wider range of substances

24. Acid-Base Titration

25. Inacid-basetitrations,aburetteisusedtodelivermeasured
volumesofanacidorbasesolutionofknowntitration(thetitrant)
toaflaskthatcontainsasolutionofabaseoranacid,respectively,
ofunknownconcentration(theunknown).
Iftheconcentrationofthetitrantisknown,thentheconcentration
oftheunknowncanbedetermined.
PlottingthepHchangesthatoccurduringanacid-basetitration
againsttheamountofacidorbaseaddedproducesatitration
curve;theshapeofthecurveprovidesimportantinformationabout
whatisoccurringinsolutionduringthetitration.

26. Beforeadditionofanystrongbase,theinitial[H
3O
+
]equalsthe
concentrationofthestrongacid.
Additionofstrongbasebeforetheequivalencepoint,decreases
the[H
3O
+
]becauseaddedbaseneutralizessomeoftheH
3O
+
present.

27. •Additionofstrongbaseattheequivalencepointneutralizesallthe
acidinitiallypresentandpH=7.00;thesolutioncontainswaterand
asaltderivedfromastrongbaseandastrongacid.
•Additionofastrongbaseaftertheequivalencecausesanexcessof
OH
–
andproducesarapidincreaseinpH.
•ApHtitrationcurveshowsasharpincreaseinpHintheregionnear
theequivalencepointandproducesanS-shapedcurve;theshape
dependsonlyontheconcentrationoftheacidandbase,notontheir
identity.

28. •Forthetitrationofamonoproticstrongacidwithamonobasic
strongbase,thevolumeofbaseneededtoreachtheequivalence
pointcanbecalculatedfromthefollowingrelationship:
molesofbase=molesofacid
(volume)
b(molarity)
b=(volume)
a(molarity)
a
V
bM
b=V
aM
a

29. Titration
Curve

30. indicator changes color
to indicate pH change
e.g. phenolpthalein is colorless in acid
and pink in basic solution
pH
endpoint
equivalence
point
base
7
pink
Titration

32. Applications: Neutralization
Titrations
Elemental Analysis
Nitrogen analysis (Kjeldahlmethods)
Sulfur analysis
Other Elements
Inorganic & Organic Substances
Salts

34. Table 16-1, p.438

38. Nonaqueoustitrationisthetitrationofsubstancesdissolvedin
nonaqueoussolvents.Itisthemostcommontitrimetricprocedure
usedinpharmacopoeialassaysandservesadoublepurpose:itis
suitableforthetitrationofveryweakacidsandveryweakbases,
anditprovidesasolventinwhichorganiccompoundsaresoluble.
Themostcommonlyusedprocedureisthetitrationoforganic
baseswithperchloricacidinanhydrousaceticacid.These
assayssometimestakesomeperfectingintermsofbeingableto
judgetheendpointprecisely.
Non Aqueous titration

39. Thetypesofcompoundsthatmaybetitratedasacidsincludeacid
halides,acidanhydrides,carboxylicacids,aminoacids,enolssuchas
barbituratesandxanthines,imides,phenols,pyrroles,andsulfonamides.
Thetypesofcompoundsthatmaybetitratedasbasesincludeamines,
nitrogen-containingheterocycliccompounds,quarternaryammonium
compounds,alkalisaltsoforganicacids,alkalisaltsofinorganicacids,
andsomesaltsofamines.Manysaltsofhalogenacidsmaybetitratedin
aceticacidoraceticanhydrideaftertheadditionofmercuricacetate,
whichremoveshalideionastheunionizedmercurichalidecomplex.

40. Inthetitrationofabasiccompound,avolumetricsolutionof
perchloricacidinglacialaceticacidisusuallyused,Inthetitrationof
anacidiccompound,avolumetricsolutionoflithiummethoxideina
methanol-toluenesolventisoftenused.Formanyapplicationsitis
convenienttouseasolutionoftetrabutylammoniumhydroxidein
toluene;sodiummethoxide,formerlyinwideuse,mayoftengiverise
totroublesomegelatinousprecipitates.

41. Precipitation titrations are volumetric methods based on the formation of a
slightly soluble precipitate.
Becauseoftheprecipitatingtitrationbaseduponutilizingsilvernitrate
(AgNO3)asaprecipitatingagent,itiscalled"argentimetricprocesses".
Thefactorgoverningthecompletenessofapptn.,reactionisthesolubilityofthe
ppt
•Themoreinsolubletheppt.,themorecompleteisthereactionatthe
equivalencepoint.
Precipitationtitrationisaveryimportant,becauseitisaperfectmethod
fordeterminehalogensandsomemetalions.
Precipitation Titrations

42. What is oxidation?
Old definition:
Combination of substance with oxygen
C (s) + O
2(g) CO
2(g)
Current definition:
Loss of Electrons is Oxidation (LEO)
Na Na
+
+ e
-
Positive charge represents electron deficiency
ONE POSITIVE CHARGE MEANS DEFICIENT BY ONE ELECTRON

43. What is reduction?
Old definition:
Removal of oxygen from a compound
WO
3(s) + 3H
2(g) W(s) + 3H
2O(g)
Current definition:
Gainof Electrons is Reduction (GER)
Cl + e
-
Cl
-
Negative charge represents electron richness
ONE NEGATIVE CHARGE MEANS RICH BY ONE ELECTRON

44. Oxidationandreductiongohandinhand.Inareaction,ifthereis
anatomundergoingoxidation,thereisprobablyanotheratom
undergoingreduction.
Whenthereisanatomthatdonateselectrons,thereisalwaysan
atomthatacceptselectrons.
Electrontransferhappensfromoneatomtoanother.
Oxidation-reduction

45. Atitrationwhichdealswithareactioninvolvingoxidation
andreductionofcertainchemicalSpecies.
Redox Titration

46. Thetechniqueinvolvestitratingmetalionswithacomplexing
agentorchelatingagent(Ligand)andiscommonlyreferredtoas
complexometrictitration.
Thismethodrepresentstheanalyticalapplicationofa
complexationreaction.
Complexometric
Titration

47. Inthismethod,asimpleionistransformedintoacomplexion
andtheequivalencepointisdeterminedbyusingmetalindicators
orelectrometrically.
.Variousothernamessuchaschilometrictitrations,
chilometry,chilatometrictitrationsandEDTAtitrationshave
beenusedtodescribethismethod.

48. Thechargedorneutralspecieswithlonepairofelectronsthatform
thecoordinatebondwiththemetal(atomorion)toformthecomplex
arecalledligands.ThesemaybesimpleionssuchasCl
–
,small
moleculessuchasH
2OorNH
3,largermoleculessuchas
H
2NCH
2CH
2NH
2(ethylenediamine)orevenverylarge
macromolecules,likeproteinsetc.
Thenumberofbondsformedbytheligandsiscalledastheir
denticity.

49. Werner(1891)firstnoticedthatforeachatomtherewereanobserved
maximumnumberofsmallgroupswhichcanbeaccommodatedaroundit.
Thisnumber,whichiscalledWerner’sco-ordinationnumber
1.UnidentateLigands:Ligandsthatareboundtometaliononlyat
oneplacearecalledunidentateligands(onetoothed).NH
3,for
example,isaunidentateligandcapableofcomplexingwithcupric
ions.Halideions,cyanideionsandNH
3arecommonexamplesof
unidentateligands.
Classification of Ligands

50. 2.BidentateandMultidentateLigands:Manyligandsareknown
thatcontainmorethanonegroup,capableofbindingwithmetal
ions.Suchligandsareknownasmultidentateligandsorchelating
agents.Theyincludebidentateligands(2donaratoms),tridentate
ligands(3donaratoms),quadridentateligands,etc.
Thus,ethylenediamineisanexampleofbidentateligand.
H
2NCH
2CH
2NH
2

51. Sometimes,theligandiscapableofformingthebondthroughtwo
differentatoms.Suchligandsarecalledambidentateligands.For
example,NO
2cancoordinateeitherthroughnitrogenorthrough
oxygenatomtoacentralmetalatom/ion.Similarly,thethiocyanate
ioncanformbondsthroughSorNatoms.

52. Whenapolydentateligandsimultaneouslyformsmorethanonebond
withthesamemetalatom/ion,itformsaringtypestructurecalled
chelate.Thecomplexingagentiscalledachelatingagent.EDTAis
agoodexampleofachelatingagent.InEDTAapairofunshared
electronscapableofcomplexingwithametalionislocatedoneach
ofthetwonitrogenatomsandeachofthefourionisedcarboxyl
groups.
Chelates

53. Sequesteringagentsarethosechelatingagentsthatformwater-
solublecomplexeswithbi-orpoly-valentmetalions.Thus,
althoughthemetalsremaininsolution,theyfailtogivenormal
ionicreactions.
Ethylenediaminetetra-aceticacidisatypicalsequesteringagent,
whereas,dimethylglyoximeandsalicylaldoximearechelating
agents,forminginsolublecomplexes.

55. Principle
Indicator
Sample
(metal)
MIn
-
Themetal-indicatorhasalowstability
constantthanthechelate-metal
complex.
Therefore,inthecourseofthetitration
thecolourofthesolutionremainsthat
ofthemetal-indicatorcomplexuntil
theendpoint,whenanequivalent
amountofthetitranthasbeenadded.
Attheequivalencepointthetitrant
decomposesmetal-dyecomplexto
producefreedyewhichismanifested
byachangeinthecolour.

56. Indicators

57. Types of Complexometric Titrations
Direct Titration
Itisthesimplestandthemost
convenientmethodusedin
chelometry.Inthismethod,
thestandardchelonsolutionis
addedtothemetalion
solutionuntiltheendpointis
detected.Thismethodis
analogoustosimpleacid-base
titrations.E.g.-calcium
gluconateinjection,calcium
lactatetablets.
Back Titration
Inthismethod,excessofastandardEDTA
solutionisaddedtothemetalsolution,
whichistobeanalyzed,andtheexcessis
Backtitratedwithastandardsolutionof
Asecondmetalion.E.g.Determinationof
Mn.Thismetalcannotbedirectlytitrated
WithEDTAbecauseofprecipitationof
Mn(OH)
2.Anexcessofknownvolumeof
EDTAisaddedtoanacidicsolutionofMn
saltandthenammoniabufferisusedto
adjustthepHto10andtheexcessEDTA
remainingafterchelation,isbacktitrated
withaZnsolutionkeptinburetteusing
EriochromeblackTasindicator.

58. Replacement Titration
In this method the metal, which is to be
analyzed, displaces quantitatively the metal
from the complex. When direct or back
titrations do not give sharp end points, the
metal may be determined by the
displacement of an equivalent amount of Mg
or Zn from a less stable EDTA complex.
In this method, excess quantity of Mg EDTA
chelate is added to Mnsolution. Mn
quantitatively displaces Mg from Mg EDTA
chelate. This displacement takes place because
Mnforms a more stable complex with EDTA. By
this method Ca, Pb, Hg may be determined
using EriochromeblackTindicator.
Indirect Titration
Certain anions that form precipitate with
metal cations and do not react with EDTA
can be analyzed indirectly. The anion is
first precipitated with a metal cation and
the precipitate is washed and boiled with
an excess of disodium EDTA solution to
form the metal complex.
The protons from disodium EDTA are
displaced by a heavy metal and titrated
with sodium alkali. Therefore, this method
is also called alkalimetric titration.
For example, barbiturates can be
determined by this method.

59. Masking and Demasking

60. Complexometrictitrationshavebeenemployedwithsuccessfor
determinationofvariousmetalslikeCa,Mg,Pb,Zn,Al,Fe,Mn,
Cretc.indifferentformulationsthatareofficialinI.P.,andalsofor
thedeterminationofHardnessofwater.
DeterminationofCalciumindifferentformulations:Calciumcanbe
determinedinalmosteveryformulationbyEDTA-titrations.e.g.-
FivememberedheterocyclicringsareformedwithEDTA,which
arestain-free,andthushighlystable.
Applications of Complexometric Titrations

61. Determination of Magnesium
DeterminationofHardnessofWater:WaterhardnessduetoCaand
MgisexpressedastheamountofCaandMgionsinppm.Actually,
thehardnessisduetobothCaandMgsaltsbuthetwoare
determinedtogetherinthetitration.ThetotalCaandMgistitrated
withstandardEDTAsolutionusingeriochromeblackTasindicator.

62. Gravimetric Analysis
GRAVI–METRIC
(WEIGHING -MEASURE)
Gravimetric methods arequantitative methods
that are basedupon determining themass of a
pure compound to which the analyte is related

63. The Process
Separate -by phases
volatilization methods
precipitation methods
selective ppt'n
account for interferences
assure completeness (solubility
equilibrium)

64. •What steps are needed?
1.Sample dried
2.Preparation of the solution
3.Precipitation
4.Digestion
5.Filtration
6.Washing
7.Drying or igniting
8.Weighing
9.Calculation

65. Species
analyzed
Precipitated form Form
weighed
Some interfering
species
K
+
KB(C
6H
5)
4 NH
4
+
, Ag
+
, Hg
2+
, Tl
+
,
Rb
+
, Cs
+
Mg
2+
Mg(NH
4)PO
4.6H
2O Mg
2P
2O
7 Many metals except Na
+
and K
+
Ca
2+
CaC
2O
4.H
2O CaCO
3or CaOMany metals except
Mg
2+
, Na
+
, or K
+
Ba
2+
BaSO
4 BaSO
4 Na
+
, K
+
, Li
+
, Ca2+,
Al3+, Cr
3+
, Fe
3+
, Sr
2+
,
Pb
2+
, NO
3
-
Ti
4+
TiO(5,7-dibromo-8-
hydroxyquinoline)
2
same Fe
3+
, Zr
4+
, Cu
2+
, C
2O
4
2-
,
citrate, HF
VO
4
3-
Hg
3VO
4 V
2O
5 Cl
-
, Br
-
, I
-
, SO
4
2-
, CrO
4
2-
,
AsO
4
3-
, PO
4
3-
Cr
3+
PbCrO
4 Ag
+
, NH
4
+
Mn
2+
Mn(NH
4)PO
4.H
2O Mn
2P
2O
7 Many metals
Fe
3+
Fe(HCO
2)
3 Fe
2O
3 Many metals
Ni
2+
Ni(dimethylglyoximate)
2 same Pd
2+
, Pt
2+
, Bi
3+
, Au
3+

66. Small samples can be used
High sensitivity
Reliable
Fast
Complex samples can be handled
Advantages of instrumental methods

67. Calibration required
Sensitivity and accuracy depends on instrument
Cost is high
Concentration range is limited
Specialized training
Sizable space required
Skilled persons
Cost of analysis is high
Disadvantages of instrumental methods

68. THANK YOU…!