2. What is Analytical Chemistry?
Application of a process or series of processes in
order to indentify and/or quantify a substance,
the components of a solution or mixture, or the
determination of the structure of chemical
compounds
3. Types on basis of analyte size
1. Macro Analysis -0.1g
2. Meso (Semimicro) Analysis -0.01 to 0.1g
3. Micro Analysis -0.001g to 0.01g
4. Submicro Analysis -0.0001g to 0.001g
5. Ultromicro Analysis -0.0001g
4. Classification of Analytical Chemistry
Qualitative Analysis .
It gives information about atomic and molecular
species or the functional group in sample.
Mp,bp,specific gravity, RI,Absorbance,Optical
rotation, Viscosity, particle size,etc.
Quantitative Analysis .
It gives relative amount of one or more of the analyte
in numerical terms.
6. Physico-chemical Methods
Instruments Methods Physical Properties
1.Potentimeter Electrical Potential
2.Conductometer Conductance
3 Polarography Voltametry Current
4 Spectrophotometry, Colorimetry AAS Absorption of radiation
5 Emission Spectroscopy , flame photometry
fluorometry
Emission of radiation
6 Turbidometry Nephalometry Scattering of radiation
7 Refractometry Refraction of radiation
8 Polarimetry, ORD Rotation of Plane polarized light
9 Thermal methods Thermal properties
10 Mass spectrophotometer Mass to charge ratio
7. CATION GROUPS AND REAGENTS
Group Group Reagent Cations (some metals as more
stable oxy anions)
Group I Dil. HCl (2M) Hg+ , Ag+ , Pb+,
Group II Dil. HCl + H2S gas Hg2+, Pb2+, Bi3+, Cu2+, Cd2+ .
As3+, Sb3+, Sn2+, Sn4+, SeO3 2-
, SeO4 2- , TeO3 2- , TeO4 2- ,
MoO4 2-
Group III A NH4Cl + NH4OH solutions (2M) Al3+, Cr3+, Fe2+ , Fe3+, Ce4+,
Th4+, Ti4+, ZrO2+, VO3 2- , UO2
2+
Group III B NH4Cl + NH4OH+ H2S gas Co2+, Ni2+, Mn2+, Zn2+
Group IV NH4Cl + NH4OH + (NH4)2CO3
solutions (2M)
Ca2+, Sr2+, Ba2+
Group V NH4OH + (NH4)2HPO4 or Na2HPO4 Mg2+
Other Radicals No common reagent NH4 + , Na+ ,Li+ , K +
8.
9.
10. Group I
2 cm3 of dilute HCl Boil residue in the
centrifuge tube
Residue: White – Hg2Cl2 or AgCl. Yellow - H2WO4 . Centrifugate
Pb2+or Tl+
Boil the residue with 5 cm 3 of dilute NH3 solution
and centrifuge.
Residue: Centrifugate:
Black precipitate,
Hg(NH2)Cl and Hg.
[Ag(NH3)2] + or H2WO4 .
Dissolve the residue
by heating with 2
cm3 of aqua regia,
cool
dilute HCl,
dilute NH3.
KI,
Residue:
Pale yellow
precipitate
of AgI.
Centrifugate:
Tungstic acid
(H2WO4)
solution.
1 cm3 of conc. H2SO4
Residue:
White – PbSO4 .
Centrifugate
Add dilute NH3 solution
and boil off excess NH3 .
To 1 cm3, acetic acid and K2CrO4
yellow precipitate of Tl2CrO4
11. Hg(I)
Spot test: 1.Place a drop of faintly acid test solution (original) on a drop
reaction paper and add a drop of saturated potassium nitrite (KNO2) solution.
A black spot of Hg is produced.
2.To 1 cm3 of the solution, add K2CrO4 solution and heat. A brown precipitate
changing to red Hg2CrO4 on heating
Spot test
Ag(I)
Spot test: Place a drop of the test solution (original) on a watch glass
and add a drop of ammonium carbonate solution and mix. Withdraw a
drop of clear liquid from the mixture and place it on a drop reaction
paper and add a drop of K2CrO4 solution. A red ring is obtained due to
formation of Ag2CrO4 .
12. Residue: White – PbSO4 . Dissolve in ammonium acetate
solution (or a mixture of NH3 solution and acetic acid) and
the following tests are done:
1) To 1 cm3 of the solution, add acetic acid and K2CrO4
solution. A yellow precipitate of PbCrO4 is formed
2) To 1 cm3 of the solution, add KI solution. Boil and
cool. A yellow precipitate of PbI2 is formed, which
dissolves on heating and re-precipitates as golden
spangles on cooling.
3) Spot test: Place a drop of the solution on a drop reaction
paper and add a drop of ammonium sulphide solution.
A black spot of PbS is formed.
13. Centrifugate: May contain Tl+ . Add dilute NH3 solution
and boil off excess NH3 . Cool and do the following tests:
1) To 1 cm3 of the solution, add acetic acid and K2CrO4
solution. A yellow precipitate of Tl2CrO4 is formed.
2) Spot test: Place a drop of the solution on a drop reaction
paper and add a drop sodium thiosulphate solution. Add a
drop of KI solution over it. A yellow spot of Tl (I) is
produced.
14. Group II
Wash the Group II residue with 2 cm3 of a solution of ammonium chloride
saturated with H2S and centrifuge. Discard centrifugate. Transfer residue into a
small beaker and add 5 cm3 of yellow ammonium sulphide (amm. polysulphide)
solution. Heat to about 50 to 600C and maintain at this temperature for 5
minutes with stirring. If there is a precipitate, cool and centrifuge.
Residue: Black
HgS, PbS, Bi2S3 or
CuS. Yellow – CdS
Centrifugate: Add conc. HCl dropwise till just
acidic (do not add excess!) and warm while
stirring. A fine white or pale yellow precipitate
is only sulfur. If a flocculant precipitate is
formed, centrifuge.
Residue: Yellow – SnS2, Se or As2S3.
Orange red – Sb2S3. Brown -Te, SnS or
MoS3.
Group IIA
Group IIB
15. Group IIA
residue is washed two times using 2 cm3 of distilled water and centrifuged.
Discard washings. Transfer residue to a small beaker, add 10 cm3 of dilute nitric
acid and boil for 5 minutes. If some solid material remains, cool and centrifuge.
Residue:
Black – HgS.
Centrifugate:
May contain nitrate of Pb, Bi, Cu or Cd.
Add dilute H2SO4 till precipitation
Residue: White – PbSO4
Centrifugate
Bi, Cu or Cd.
Add concentrated NH3
If a residue remains,
centrifuge.
Residue: White – Bi(OH)2 . Centrifugate Cu or Cd
Add dilute acetic acid with shaking till a clear
solution is obtained. Divide into two parts.
16. Group IIB
Residue into a small conical flask and place a funnel in its mouth. Add 5 cm3
of conc. HCl and boil gently for 5 minutes. Dilute with 3 cm3 of distilled
water, cool and centrifuge.
Residue:
Yellow - Se or As2S3 .
Brown –Te or MoS3 .
HCl +potassium chlorate (KClO3 concentrate
by evaporating on a water bath. Cool and add
NH3 solution with stirring till smell of ammonia
persists. Add 2 cm3 of Mg(NO3 )2 solution and
stir for 5 minutes. When precipitation is
complete, centrifuge.
Centrifugate:
May contain Sb or Sn as chloride. Boil to expel
H2S. Cool and carry out the following tests using
small portions of the solution
Residue: White crystalline Mg(NH4 )AsO4 .6H2O Centrifugate: May contain Se, Te or Mo as chlorides
17. Centrifugate: May contain Se, Te or Mo as chlorides. Transfer to a small beaker and
boil off NH3 . Add 2 cm3 of conc. HCl and evaporate to half volume on a water bath.
Add 2 cm3 of a saturated solution of sodium sulphite (Na2SO3 ) solution. If a
precipitate is formed, centrifuge
Residue: Red – Se. Dissolve the residue by heating
with 1 cm3 of conc. HNO3 . Neutralise by adding
amm. carbonate solution dropwise till effervescence
stops
Centrifugate: Dilute with equal volume of water. Add
1 cm3 of KI solution and a drop of sodium sulphite
(Na2SO3 ) solution. If a precipitate is formed,
centrifuge
Residue: Black – Te Dissolve in 2
cm3 of cold dilute HCl. Divide the
solution into three parts.
Centrifugate: Add 1
cm3 of conc. HCl and
boil to remove
dissolved SO2
Mo (VI)
Black – Te
Red – Se
18. Group II B
Centrifugate: May contain Sb or Sn as chloride. Boil to expel H2S. Cool and carry out the
following tests using small portions of the solution.
To 2 cm3 of the solution in a test tube, add a pinch of iron filings and boil to reduce Sn(IV) to
Sn(II). Cool and centrifuge. With draw the clear supernatant carry out the following tests
To 1 cm3 of the solution in a test tube, add just enough NH3 solution to neutralize. (A
slight precipitation may occur ). Add a pinch of solid oxalic acid and boil. Pass H2S
through the solution. An orange precipitate of Sb2S3 is obtained
1) to 1 cm3 of the solution in a test tube, add two drops of mercuric chloride (HgCl2 )
solution. A silky white or grey precipitate of Hg2Cl2 is obtained.
2) To 0.5 cm3 of the solution in a test tube, add NaOH solution dropwise with shaking. A
white precipitate of Sn(OH)2 soluble in excess NaOH is obtained.
19. Presence of As is confirmed by
Spot test: To the third portion, add two drops of conc. H2O2
solution and warm. Acidify with a few drops of acetic acid. Place
a drop of this mixture on a drop reaction paper followed by a drop
of AgNO3 solution. A red spot is obtained.
Presence of Se (IV) is confirmed.
1)To one part, add BaCl2 solution. A white precipitate
of BaSeO3 is formed.
2)To the second part, add CuSO4 solution. A bluish
green precipitate of CuSeO3 is formed.
20. 1) Neutralise one portion by adding amm. carbonate solution
dropwise till effervescence stops. Add BaCl2 solution. A white
precipitate of BaTeO3 is formed.
2) To the second part, add excess of KI solution. A red colour is
produced due to formation of [TeI6 ] 2- .
Presence of Te (IV) is confirmed.
Presence of Mo (VI) is confirmed.
1) To one part, add pot.ferrocyanide solution. A reddish brown
precipitate of Mo ferrocyanide is formed.
2) To the second part, add two drops of ferroussulphate solution. A
blue colour is produced.
3) Spot test: Place a drop of the third portion on a drop reaction paper
and add a drop of pot. Thiocyanate solution. Then add a drop of
SnCl2 solution. A red spot of [Mo(SCN)6 ] 3- is seen
21. Presence of Sn is confirmed.
1) to 1 cm3 of the solution in a test tube,
add two drops of mercuric chloride
(HgCl2 ) solution. A silky white or
grey precipitate of Hg2Cl2 is
obtained.
2) To 0.5 cm3 of the solution in a test
tube, add NaOH solution dropwise
with shaking. A white precipitate of
Sn(OH)2 soluble in excess NaOH is
obtained.
Presence of Sb is confirmed.
Spot test: Place a drop of the
solution on a spot plate and add
a minute crystal of sodium
nitrite (NaNO2 ) . Then add a
drop of rhodamine- B reagent.
A blue colour is obtained
22. Group-III
A (Iron Group) residue is washed with 2% amm. nitrite (NH4NO2)
solution and dissolved in the minimum quantity of dilute HCl.
Prepare a mixture containing 2 cm3 of 30% H2O2 solution and a
fresh pellet of NaOH dissolved in 2 cm3 of water. Add the weakly
acidic test solution into it and boil for 5 minutes. Centrifuge.
Residue:
White – TiO2.xH2O or
ZrO2.xH2O or ThO2.xH2O
or MnO2.xH2O; Brown –
Fe(OH)3; Yellow –
CeO3.xH2O.Wash the residue
with hot 2% amm. nitrite
(NH4NO2) solution
Dissolve by boiling with 5
cm3 of dilute HCl and do the
following tests as
Centrifugate:
May contain CrO4 2- , [Al(OH)4] -
, VO3 - or U2O7 2- . Transfer to a
small beaker and acidify with 2 cm3
of conc. HNO3 and dilute with
5cm3 of water. Boil and concentrate
to half volume. Add 2 cm3 of lead
nitrate solution and a pinch of solid
amm. acetate. Boil and centrifuge.
23. Residue: White – TiO2.xH2O or ZrO2.xH2O or ThO2.xH2O or MnO2.xH2O;
Brown – Fe(OH)3; Yellow – CeO3.xH2O.Wash the residue with hot 2% amm.
nitrite (NH4NO2) solution). Dissolve by boiling with 5 cm3 of dilute HCl and do
the following tests as appropriate
Spot test: Place a drop of the
solution on a drop reaction
paper. Add a drop of pot.
Ferrocyanide solution. A blue
spot of ferric ferrocyanide
indicates Fe
2) To 1 cm3 of the solution,
add a few drops of H2O2
solution. Orange colour
indicates Ti. White precipitate
indicates Zr.
Spot test: Place a drop of
solution on a drop reaction
paper. Add a drop of
catechol solution. A yellow
or orange spot indicates Ti.
Spot test: Place a drop of solution
on a spot plate. Add a drop of
Alizarin-S solution and a drop of
conc.HCl. A red precipitate
indicates Zr
3) To 1 cm3 of the solution, add a
few drops of saturated oxalic acid
solution. White precipitate
indicates Th or Ce. Centrifuge and
discard supernatant. Boil residue
with 5 cm3 of saturated amm.
oxalate solution. If there is a
residue,centrifuge
Residue: Ce(III)oxalate. Boil
residue with 2 cm3 of NaOH
solution. A yellow precipitate of
Ce(OH)4 is obtained.
Centrifugate: Acidify 1
cm3 of the solution with dilute
HCl. Thoriumoxalate is re-
1) To 0.5 cm3 of the solution,
add a drop of pot. (or amm.)
thiocyanate (KCNS) solution.
Red colour of FeCNS indicates
Fe(III)
24. 4) To 1 cm3 of the solution, add a few drops of conc. H2SO4 and
evaporate till fumes. Cool, dilute and add two drops of conc. HNO3
and a pinch of PbO2. Boil and allow to stand. Purple supernatant
(MnO4 - ) indicates Mn. If Mn is indicated, add excess of NH3
solution into the remaining solution and pass H2S gas. A pink
precipitate of MnS.
Confirm: Mn (II)
Spot test: Place a drop of the aqueous layer on a spot plate
and add a drop of CuSO4 solution. A green
(metavanadate) or yellow (pyrovanadate) precipitate.
Confirm : V (IV)
25. Centrifugate: Group III A
May contain CrO4 2- , [Al(OH)4] - , VO3 - or U2O7 2- . Add 2 cm3
of conc. HNO3 and water. Boil and concentrate ,Add 2 cm3 of lead
nitrate and a pinch of solid amm. acetate. Boil and centrifuge.
Residue: Yellow –
PbCrO4 or Pb(VO3)2
Centrifugate:
May contain Al3+ , UO2 2+
Wash the precipitate with 2 cm3 of water and combine the centrifugates. Boil to expel all the
H2S and concentrate. Neutralise with NH3 solution and add 5 cm3 of amm. carbonate solution.
Boil for 5minutes. Cool and centrifuge
Residue: White – Al(OH)3. Centrifugate:
[UO2(CO3)3] 4- .
26. Spot test: Place a drop of the solution on a drop reaction
paper. Add a drop of pot. Ferrocyanide solution. A blue
spot of ferric ferrocyanide indicates Fe.
Presence of Fe is confirmed.
Spot test: Place a drop of solution on a drop reaction paper. Add a
drop of catechol solution. A yellow or orange spot indicates Ti.
Presence of Ti (IV) is confirmed.
Spot test: Place a drop of solution on a spot plate. Add a drop of
Alizarin-S solution and a drop of conc.HCl. A red precipitate
indicates Zr.
Presence of Zr(IV) is confirmed.
27. Spot test: A yellow precipitate of Ce(OH)4 a little of the above
precipitate and dissolve it in two drops of conc.HNO3. Place a drop
of solution on a spot plate and add a drop of a 5% alcoholic solution
of anthranilic acid. A blackish blue precipitate rapidly changing to a
brown solution.
Presence of Ce(IV) is confirmed.
Spot test: Thoriumoxalate is re-precipitated a little of the above
precipitate and dissolve it in two drops of conc. HNO3. Place a
drop of solution on a spot plate and add a drop of pot.
Ferrocyanide solution. A white precipitate of thorium
ferrocyanide is formed.
Presence of Th (IV) is confirmed.
28. Spot test: Place a drop of the amyl alcohol layer on a spot
reaction paper and evaporate off the alcohol by warming
.Place a drop of diphenyl carbazide reagent on it. A
blueviolet colour is seen.
Presence of Cr(III) is confirmed.
Spot test: Place adrop of the solution on a spot plate and add a
drop of Alizarin-S reagent .Add drops of acetic acid till violet
colourd is appears. A red precipitate.
Presence of Al(III) is confirmed.
29. Group III B
NH3, NH4Cl and H2S
Residue CoS (black), NiS (black), Centrifugate: Mn2+ or Zn2+
Dissolve in 4 cm3 of aqua regia and transfer to a
china dish. Evaporate carefully by heating over a wire
gauze to dryness
Blue residue:
Co2+ .
Yellow residue: Indicates Ni2+ .
Boil down to half volume to remove all
H2S. Add 2 cm3 of NaOH solution and
two drops of conc. H2O2 solution. Boil for
2 minutes and if there is a residue,
centrifuge
Residue: Dark brown MnO2.xH2O Centrifugate: Na2ZnO2.
30. Separation of co2+ andNi2+
Cobalt and nickel sulphides are soluble in aqua regia .cobalt and Nickel
chloride are form soluble complexes with a KCN
3CoS+6HCl +2HNO3 3CoCl2 +2NO+3S+ 4H2O
3NiS +6HCl +2HNO3 3NiCl2 +2NO+3S+ 4H2O
CoCl2 +2KCN Co(CN)2 +2KCL
Co(CN)2 +4KCN k4 [Co(CN)6+ NaOH+Br2 k3 [Co(CN)6
NiCl2 +2KCN NI(CN)2 +2KCL
Ni(CN)2 +4KCN k4 [Ni(CN)6 Ni2O3 +4NaCN+4KCN+2H2O
CoCl2 +2KNO2 Co(NO2)2 +2KCL
KNO2+CH3COOH CH3OOK +HNO2
Co(NO2)2 +3KNO2 + 2HNO2 K3Co(CN)6] +NO +H2O
31. Spot test: Place a drop of the solution on a spot plate
and two drops of amm. (or pot.) thiocyanate solution. A
blue colour appears due to the formation of
[Co(SCN)4] 2- . Presence of Co2+ is confirmed
Spot test: Place a drop of the solution on a spot plate. Add one
drop each of dimethylglyoxime reagent and NH3 solution. A
red colour or precipitate of nickel dimethyl glyoxime complex is
formed.
Presence of Ni(II) is confirmed.
32. Spot test: Place a drop of the solution on a spot plate. Add one
drop of conc. HNO3 and a small crystal of solid sodium
bismuthate. A purple colour is produced due to formation of
permanganate ions.
Presence of Mn(II) is confirmed.
Spot test: Place a drop of the above solution on a spot plate. Add
one drop each of CuSO4 solution and amm. Mercurothiocyanate
reagent. A violet precipitate consisting of the mixed
mercurothiocyanates of Cu and Zn is formed.
Presence of Zn(II) is confirmed
33. Group IV
NH4Cl + NH4OH + (NH4)2CO3 solutions (2M)
PPT of of Ca Sr, Ba Carbonates
5 cm3 of dilute acetic acid +Potassium Chromate and Boil.
Residue: Yellow - BaCrO4. Centrifugate
Sr, Ca.
saturated amm.
Sulphate + 0.5M
sodium thiosulphate
Residue: White – SrSO4. Centrifugate
Ca
34. Spot test: Place a drop of the second part on a drop reaction paper
and add a drop of sodium rhodizonate reagent. A red stain is
produced due to the formation of barium rhodizonate.
Presence of Ba(II) is confirmed.
Spot test: Place a drop of the second part on a drop reaction
paper and add a drop of sodium rhodizonate reagent. A reddish
brown stain is produced due to the formation of strontium
rhodizonate. Presence of Sr(II) is confirmed.
Spot test: Extract the remaining residue with 1 cm3 of dilute
acetic acid. Place a drop of it on a spot plate and add two drops of
picrolinic acid reagent. A white precipitate of calcium picrolinate
is produced. Presence of Ca(II) is confirmed.
35. Group V Mg2+
NH4OH + (NH4)2HPO4 or Na2HPO4
Dissolve the Ppt in 2 cm3 of dilute HCl.
The Solution is used as follows
For magnesium 1) Two drops of the solution in a test tube + 4N NH4OH,
and then NH3 solution drop wise till smell persists. Add 1 cm3 3% Oxine
reagent in CHCl3.Shake well and centrifuge – Yellowish Green layer
2) Two drops of solution in a test tube + 0.5cm3 of 10% NaOH + 2-3 drops
of 0.1% Titan Yellow Reagent ,Centrifuge it – Red Ppt or Colour.
3) Two drops of solution in a test tube + 2 drops of 1N NaOH Solution + 2
drops of 0.001 % p-nitrobenzene azo resorcinol (Magneson-I) reagent – A
blue colour or precipitate is obtained (which is different from the violet
colour of the reagent). This is due to adsorption of the dye on the
precipitated Mg(OH)2.
4) 2 drops of solution + 3-4 drops of freshly prepared hypo iodide reagent –
reddish brown Ppt. Presence of Mg(II) is confirmed.
39. Quantitative Chemical Analysis
Aluminum (Al) :
Gravimetric Estimation :Aluminum as Oxinate 8-hydroxyquinoline
Redox Titration:
Complexometric titration
Colorimetric method
40. CHEMICALS AND
APPARATUS
1. Water sample, dominion
2. Standard 0.01M
Ethylenediamminetetraacetic
acid( EDTA)
3. Standard 0.01M zinc sulphate
solution
4. 0.5% (wt/vol.) Erichrome
Black T
5. Dilute ammonia solution
6. Distilled water
7. 25ml pipette
8. Burette
9. Funnel
10. Heating plate
PROCEDURE 1. 25ml of the unknown
sample was pipetted into a 250ml conical
flask. 2. 30ml 0.01M EDTA was then
added. 3. To ensure complete
complexation of the aluminum, the
resultant solution was boiled for a few
minutes. 4. The solution then cooled to
room temperature. 5. To ensure a suitable
pH range, 1ml NH3 was added. 6. About 5
drops of Erichrome black T (EBT)
indicator was then added. 7. 0.01M ZnSO4
in the burette was titrated against the
excess EDTA solution until the end point
is reached and the volume of ZnSO4 that
reacted is recorded. 8. Step 7 was repeated
twice more to obtain two other titre value
and the average titre calculated.
Total Moles EDTA = No moles Zn2+ [EDTA] + No moles Al3+ [EDTA]
41. Gravimetric Determination of Aluminum as Oxinate
(1) Aluminum forms an oxine complex that can be quantitatively
precipitated from aqueous solution between pH 4.2-9.8; it can
thus be precipitated from an acetic acid - acetate buffer solution
or from an ammonia cal solution.
(2) The precipitate is crystalline, easily filtered and can be readily
dried between 102 - 120°C.
(3) Precipitation from an acetic acid - acetate buffer solution
serves to separate aluminum from beryllium, barium, calcium,
strontium, and magnesium which are often associated with
aluminum.
Disadvantages
(1) Oxine is not a highly selective reagent and if aluminum is to be precipitated
from an acetic acid - acetate buffer solution, all metals except the alkalis,
alkaline earths and magnesium must be absent.
(2) The precipitate tends to retain the reagent leading to high results. However
the method is sufficiently satisfactory for almost all practical purposes.
(3) It is carcinogenic.
42. Gravimetric estimation : Weigh accurately about 0.3 g of potassium alum in a
400-ml beaker, dissolve it in 150 ml of DW containing 1.0 ml of 0.1 N HCl and
warm the contents of the beaker to about 60°C. Add the requisite quantity of
the oxine reagent and then add a 2 N solution of ammonium acetate gradually
from a pipette till precipitation just commences. Add a further portion (50 ml)
of ammonium acetate solution with vigorous stirring. Allow the contents of the
beaker to stand for 60 minutes with frequent stirring. Filter the precipitate
through No : 3 or 4 sintered glass crucible that has been previously dried to a
constant weight at 130—150°C. Wash the precipitate throughly with cold DW
and dry at 130 to 150°C to constant weight.
Each gram of aluminium oxinate is equivalent to 0.05873 g of Al.
43. Determination of Aluminium by
colorimetric Method
Principle : Oxine
It is a chelating agent with Al at pH 4-5 which is sparingly soluble in water but readily
dissolves in chloroform
The yellow complex of aluminium Oxine is determine by spectrophotometrically at
400 nm
Reagent : 1% Oxine
Standard Al solution 1mg/ml ( 17.59g Potash alum per litre .
Procedure: To a solution containing a 60 micro gram of Al +2ml 5%EDTA + 1ml 3%
Hydrogen peroxide adjust the pH 9 with ammonia add sodium thiosulphate and KCN
Heat the solution at 70 to 80 0C
Transfer the solution in to a Separating funnel and extract with two portion of
Chloroform , wash with water and to make the volume with chloroform . Measure the
absorbance at 400nm.
44. Al as potassium trioxalatoaluminate trihydrate.
Theory : The purity of the complex can be determined in terms
of the oxalate ions. When the complex is dissolved in dilute
sulphuric acid, oxalic acid is produced which can be titrated
with standard potassium permanganate solution
Dissolution of the complex :
Weigh accurately about 0.3 g of the complex on a watch glass.
Transfer it in a 100 ml. beaker. Add to it 20 ml 2N H2SO4 (table reagent).
Heat it till the complex dissolves completely. Cool it and dilute it to exactly
100 ml. in volumetric flask with distilled water
Procedure :
Weigh accurately about 0.3 g of the complex on a watch glass.
Transfer it in a 100 ml. beaker. Add to it 20 ml 2N H2SO4 (table
reagent). Heat it till the complex dissolves completely. Cool it and
dilute it to exactly 100 ml. in volumetric flask with distilled water.
1000 ml 1N KMnO4 = 27g. Al
45. DETERMINATION OF ALUMINIUM BY ICP-MS
PRINCIPLE OF THE METHOD
Solutions with aluminium compounds are nebulised into an argon
plasma, where all components are vaporised. The ions produced are
entrained in the plasma gas and introduced into a mass
spectrometer, sorted according to their mass-to-charge ratios, and
quantified with a channel electron multiplier. Aluminium is
determined at mass 27 amu.
This determination may be carried out on digest 2.3 (microwave
digestion HNO3 - H2O2 - HF), digest 2.4 (digestion with HNO3 -
H2O2 - HF) and digest 2.7 (digestion by dry-ashing followed by
treatment with HF)
46. APPARATUS
Inductively coupled plasma mass spectrometer.
REAGENTS
Stock Solution, Al concentration 1000 mg/L - Merck nr 1.19770.
Stock Solution, Al concentration 1000 mg/L - Dissolve 17.5760 g
potassium aluminium sulphate dodecahydrate, KAl(SO4)2.12H2O,
in a volumetric flask of 1000 mL. Make up to 1000 mL with ultra
pure water.
Standard Solution, Al concentration 20 mg/L - Pipette 1 mL
concentrated nitric acid (65 % s.p.) in a 100-mL polythene
volumetric flask which already contains about 50 mL ultra pure
water. Add 2.00 mL stock solution (and make up to volume with
ultra pure water.
KAl(SO4).12H2O may lose crystal water on standing. The reagent
should be standardised by adding an excess of EDTA with ZnSO4
and back-titration with Eriochrome Black T as an indicator
47. CALIBRATION AND STANDARDS
Standard Series - pipette 0 – 1.00 – 2.00 – 5.00 mL of the standard
solution (6.2) in a 100-mL polythene volumetric flasks which
already contain 40 mL ultra pure water. Add either 1.0 mL
concentrated nitric acid (65 %) (digestion 2.3), 0.3 mL concentrated
nitric acid (65 %) (digestion 2.4) or 0.1 mL concentrated
hydrochloric acid (36 %) (digestion 2.7). Let cool down and make
up to the mark with ultra pure water. This standard series has Al
concentrations of 0 – 200 – 400 – 1000 µg/L. 7.2 Calibration Curve -
The counts per second are plot versus Pg/L aluminium in the
standard series.
48. PROCEDURE
Measurement – Dilute the blanks and the sample digests 1 + 9
(v/v) with ultra pure water and mix. Measure in the standard series,
the blanks and the sample digests the Al concentration with the
ICP-MS at a mass of 27 amu. Make use of corrections if necessary.
Remarks:
A data management system and system controller are used. In this
way the measurements are checked continuously and the data
output is in concentration units in the digests.
. Due to the linearity of the ICP-MS it is possible to calibrate the
ICP-MS only with the highest and zero standard of the standard
series. As a check all standards can be measured as samples.
49. Methods for Iron (Fe)
Gravimetric Estimation : iron is estimated by ammonium chloride and
Ammonium hydroxide as precipitating reagents.
Redox Titration: titration with known concentration of Potassium dichromate
by using internal or external indicatiors in presence of stanous chloride and
mercuric chloride
Potentiometric titration : Ferric ion titrated with known concentration of
Potassium dichromate , by using a saturated calomel electrode and platinum
electrode in presene of quinehydrone electrode
Colorimetric method : iron estimated by using ammonium thiocyanate and
sulphosalicylic acid at at wavelength.
51. Volumetric Titration of Iron (Redox Titration )
10 mL pipet, transfer
exactly 10.00 mL of an
unknown solution into
an Erlenmeyer flask
Using a graduated
cylinder, add 10 mL
of 1 M H2SO4 to the
flask.
Fill your buret with
the KMnO4 solution
Titrate the iron solution in the flask. The
pinkish color produced by the first drop of
excess KMnO4 signals the end point for
the titration.
Obtain the final volume
reading from the calibration
scale on the buret.
52. Potentiometric titration
• Theory: This experiment involves the determination
of the percentage of ferrous iron in an unknown
samplemixture by redox titration with potassium
dichromate solution as the standard using: (i) ferroin
indicator (ii) potentiometric titration.
53. PROCEDURE
Using 100 cm3 volumetric flasks prepare of 0.02 M potassium dichromate
solution and 0.10 M ammonium iron (II) sulphate solution.
to add sufficient amount of dilute acid to prepare ammonium iron (II) sulphate
solution. 2. Take 25 cm3 of given Fe2+ solution and add 25 cm3 dilute H2SO4
acid and 50 cm3 of distilled water in a 250 cm3 beaker.
3. SCE is used as the Reference electrode. Platinum metal foil, dipped in Fe2+
solution is used as the indicator electrode.
4. Standardise the potentiometer using a standard cell before replacing it with the
working cell.
6. Add 2 cm3 of 0.02 M K2Cr2O7 solution from burette, operate the magnetic
stirrer for 2 minutes, stop it, wait it for 1 minute and measure the E.M.F.
7. Repeat the above step, each time adding two more cm3 of K2Cr2O7 at a time
and go on noting the E.M.F. after each addition.
8. When the volume reached near about 1 cm3 of the expected equivalence point
(approximate), add the solution from burette in 0.5 cm3 instalments and note the
potential each time.
54. Colorimetric Analysis of Fe
1.Thiocyanate method
2. 1 10-phenanthroline
3.Sulhosylicylic Acid
1,10-phenanthroline (C12H8N2, ortho-phenanthroline or o-
Phen) is a tricyclic nitrogen heterocyclic compound that
reacts with metals such as iron, nickel, ruthenium, and silver
to form strongly colored complexes. This property provides
an excellent and sensitive method for determining these
metal ions in aqueous solution. For example, o-Phen reacts
with ferrous ion to produce a deeply colored red complex:
at 508nm
55. Methods for Copper (Cu)
• 1. Redox Titration : Reactions:
• 1) 2 CuSO4 + 4 KI Cu2I2 + I2 + 2 K2SO4
• 2) I2 + 2 Na2S2O3 2 Nal + Na2S4O6
Given : Na2S2O3 Solution
To find : Amount of copper
Burette1 : Na2S2O3 solution
Burette2 : Diluted ore solution
Indicator : Starch solution
End point : Blue to white
Calculations
1ml 0.025 N Na2S2O3 = 0.001589 g Cu
Procedure
Neutralise the solution by adding dilute
ammonia , add acetic acid
10% KI and two to three mal of Starch
solution thenTitrate the liberated 12 with
Na2S2O3 solution till a pale yellow colour
appears to the solution. Then add 1 to 2 ml.
starch solution. The solution becomes blue.
Continue the titration
58. 2.Colorimetric methods
Procedure : aliquot 10 mLsolution of lead in a 250 ml
separating funnel ,add ammona –sulphide –cyanide
solution then addition of dilute hydrogen chloride
solution to adjust the pH 9.5 and add Dithiozone
reagent in chloroform in to separating funnel shake
well few minutes and allow to separating organic layer
in to separate beaker .measure the absorbance against
the blank solution at 510nm.
60. Determination of sodium by Flame photometry
Procedure
1. Operate Flame Photometer according to the instructions provided for the equipment.
2. Run a series of suitable Na standards, and draw a calibration curve.
3. Measure Na in the samples (soil extracts) by taking the emission readings on the Flame
Photometer at 589-nm wavelength.
4. Calculate Na concentrations by inferring to the calibration curve.
Calculation
61. DETERMINATION OF POTASSIUM
PRINCIPLE OF THE METHOD
The sample is vaporised in an air-propane flame and the
potassium compounds
are atomised. The potassium atoms thus formed emit radiation
of which the
intensity is measured at a wavelength of 766.5 nm
. RANGE AND DETECTION LIMIT
This procedure yields a standard curve that is linear up to
approximately 50 mg/L
K.
INTERFERENCES
To prevent ionisation interferences, cesium is added to act as an
ionisation buffer.
62. PRECISION AND ACCURACY
The reproducibility of determinations by this procedure should give,
at reasonable
control and thorough sample preparation, a coefficient of variation
within 5 % + 5
mmol/kg.
APPARATUS Flame atomic emission spectrometer.
REAGENTS
A Stock Solution, K concentration 1000 mg/L
Stock Solution, K concentration 1000 mg/L - Dissolve 1.9068 g
potassium chloride,
KCl in some water in a 1000-mL volumetric flask and make up to
the mark with water.
63. The potassium chloride has to be dried at 200 C for at least 24 hours just before
weighing. Just before drying, any lumps should be cut down so that only fine
crystals remain.
Standard Series - Pipette 0 – 1.00 – 2.00 mL of the stock solution
into 100-mL volumetric flasks which already contain 40 mL water.
Add either 4.5 mL concentrated sulphuric acid (96 %) 10 mL
concentrated nitric acid (65 %) (digestion 2.3), 3.0 mL concentrated
nitric acid (65 %) 1.0 mL concentrated hydrochloric acid (36 %)
Let cool down and make up to the mark with water. This standard
series has K concentrations of 0 – 10 – 20 mg/L.
Calibration Curve - The emission counts are plot versus mg/L
potassium in the standard series.
