Preparation of Indicator
Solutions
Indicators
In the test and assays of the
Pharmacopoeia, indicators are required to indicate the completion of a chemlcal
reaction in volumetric analysis or to indicate the pH of solutions. Indicators
may be substituted for one another provided the colours change over
approximately the same range of pH but in the event of doubt or dispute as to
the equivalence of indicators for a particular procedure, the indicator specified
in the individual monograph is alone authoritative.
Any solvent required in a
determlnation or test in which an indicator is specified should be previously
neutralized to the indicator unless a blank determlnation is performed or
specified.
Given below are materials
which are to be used as indicators and the manner in which solutions of
indicators are to be prepared.
Table 1 lists the more
commonly used pH indicators in ascending order of the lower limlt of their
range with the corresponding colour changes.
Alizarin Red S; CI 58005; Alizarin S; MordantRedB;
Sodium Alizarine Sulphonate; 9,l0-dihydro- 3,4-dihydroxy-9, l0-dioxo2-
anthrancesulphonic Acid Monosodium salt:
C14H7NaO7S.H20
= 360.27
General laboratory reagent
grade of commerce .
Yellowish brown or orange-yellow
powder.
Alizarin Red S Solution; Alizarin S Solution: A0.1 per cent w/v solution of alizarin red S.
Complies with the following test.
SENSITIVITY TO BARIUM - To 5
ml of 0.05 M sulphuric acid add 5 ml of water, 50 ml of acetate
buffer pH 3.7 and 0.5 ml of the solution under examlnation. Add,
dropwise, 0.05 M barium perchlorate; the colour changes from yellow to
orange-red.
Azo Violet; Magneson; 4-(p-Nitrophenylazo)resorcinol:
C12H9N304=259.22
Red powder; mp, about 1930,
with decomposition.
Brilliant Green; CI 42040; Malachite Green G; Basic
Green 1:
C27H34N2O4S=482.64
Technical Grade of commerce.
Small, glistening golden
crystals.
Brilliant Green Solution: A 0.5 per cent w/v solution of brilliant green in
glacial acetic acid.
Bromocresol Green; Bromocresol Blue; 4,4-(3H-2,1Benzoxathiol-3-ylidene)bis(2,6-dibromo-m-cresol)
S,S-dioxide:
C21HI4Br4O5S=
698.01White or pale buff-coloured
powder.
Bromocresol Green Reagent: Prepare a phosphate buffer solution by dissolving
43.0 g of sodium dihydrogen phosphate and 2.0 g of anhydrous sodium
phosphate in sufficient water to make 1000 ml. Dissolve 0.2 g of bromocresol
green in 30 ml of water and 6.5 ml of 0.1 M sodium hydroxide. Dilute
to 500 ml with the phosphate buffer solution, mlx and adjust the pH to 4.6 with
0.1 M hydrochloric acid.
Bromocresol Green Solution: Dissolve 50 mg of bromocresol green in 0.72 ml
of 0.1 M sodium hydroxide and 20 ml of ethanol (95 per cent). After
solution is effected, add sufficient water to produce 100 ml.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.2 ml of the sol ution and 100 ml of carbon dioxide-free water is blue.
Not more than 0.2 ml of 0.02 M hydrochloric acid is required to change
the colour of the solution to yellow.
Bromocresol Purple; 4,4' -(3H-2, 1-Benzoxathiol-3-ylidene)bis(6-bromo-o-cresol)
S,S-dioxide: C2IH16Br2O5S=
540.23
White to pink, crystalline
powder.
Bromocresol Purple Solution: Dissolve 50 mg of bromocresol purple in 0.92
ml of 0.1 M sodium hydroxide and 20 ml of ethanol (95 per
cent). After solution is effected, add sufficient water to produce
100 ml.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.2 ml of the solution and 100 ml of carbon dioxide-free water to which
0.05 ml of 0.02 M sodium hydroxide has been added is bluish
violet. Not more than 0.2 ml of 0.02 M hydrochloric acid is required to
change the colour to yellow.
Bromocresol Purple Solution, Phosphate-buffered: Dissolve 43 g of potassium dihydrogen phosphate and
5 g of sodium phosphate in water to make 1000 ml. Adjust
the pH of the solution to 5.3 ± 0.1, if necessary (Solution A). Dissolve 0.4 g
of bromocresol purple in 30 ml of water, add 6.3 ml of 0.1 M
sodium hydroxide and dilute with water to make 500 ml (Solution B).
Shake equal volumes of solution A, solution B and chloroform in a
separator, allow the layers to separate and discard the chloroform. If
appreciable colour is extracted by the chloroform, repeat with additional
quantities of chloroform until no further colour is extracted.
Bromophenol Blue; 4,4' -(3H- 2,1- Benzoxathiol-
3-ylidene)bis(2,6-dibromophenol) S,S-dioxide: C19H10Br4O5S= 669.96
Pinkish crystals.
Bromophenol Blue Solution; Strong Bromophenol Blue
Solution; Ethanolic Bromophenol Blue Solution: Dissovle 0.1 g of bromophenol blue with gentle
heating in 1.5 ml of 0.1 M sodium hydroxide and 20 ml of ethanol (95
per cent) and add sufficient water to produce 100 ml.
Complies with the following
test.
SENSITIVITY- A mlxture of
0.05 ml of the solution and 20 ml of carbon dioxide-free water to which
0.05 ml of 0.1 M hydrochloric acid has been added is yellow. Not
more than 0.1 ml of 0.1 M sodium hydroxide is required to change the
colour to bluish violet.
Bromophenol Blue Reagent: Dissolve 50 mg of bromophenol blue with gentle
heating in 3.73 ml of 0.02 M sodium hydroxide and dilute to 100 ml with water.
Bromothymol Blue; 4,4' -(3H-2, I-Benzoxathiol-3-ylidene)bis(
2-bromothymol) S,S-dioxide: C27H28Br2O5S=624.39.
Crearn-coloured powder.
Bromothymol Blue Solution; Aqueous Bromothymol Blue
Solution: Dissolve 50 mg of bromothymol
blue in 4 ml of 0.02 M
sodium hydroxide and 20 ml of ethanol (95 per cent). After solution is effected, add sufficient water
to produce 100 ml.
Complies with the following
test.
SENSITIVITY - A mlxture of 0.3
ml of the solution and 100 ml of carbon dioxide- free water is yellow.
Not more than 0.1 ml of 0.02 M sodium hydroxide is required to change
the colour to blue.
Calcon; CI 15705; SolochromeDarkBlue; Mordant Black
17; Sodium 2-hydroxy-l-(2-hydroxy-I-naphthylazo )-naphthalene4- sulphonate: C20H13N2NaO5S=416.38
General laboratory reagent
grade of commerce.
Brownish black powder with a
violet sheen. Gives a purplered colour with calcium ions in alkaline solution.
When metal ions are absent, for example, in the presence of an excess of
disodium edetate, the solution is blue.
Calcon Mlxture:
A mlxture of 1 part of calcon with 99 parts of freshly ignited anhydrous
sodium sulphate.
Complies with the following
test.
SENSITIVITY – Dissolve 0.l
gin 2.5 ml of water. To l ml of the solution add 50 ml of water, 10
ml of 1 M sodium hydroxide and 1 ml of a 1 per cent w/v solution of magnesium
sulphate; the solution is blue. Add 0.1 ml of a 0.15 per cent w/v solution
of calcium chloride; the solution becomes violet and on subsequent
addition of 0.1 ml of 0.01 M disodium edentate turns to blue again.
Congo Red; CI 22120; Disodium (4,4' -bipheny Ibis-
2,2-azo) bis(1-amlnonaphthalene-4-sulphonate): C32H22N6Na2O6S2=
696.66
Dark red or reddish brown
powder. Decomposes on exposure to acid fumes.
Congo Red Fibrin: Soak washed and shredded fibrin ovemlght in a 2 per cent w/v
solution of congo red in ethanol (90 per cent), strain,
wash the product with water and store under ether.
Cresol Red; 4,4' -(3H-2, 1-Benzoxathiol-
3-ylidene) di-o-cresol S,S-dioxide: C21HI8O5S=382.44
Red brown powder.
Cresol Red Solution: Warm 0.1 g of cresol red in a mlxture of 2.65 ml of 0.1 M
sodium hydroxide and 20 ml of ethanol (95 per cent). After
solution is effected, add sufficient water to produce 100 ml.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.1 ml of the solution and 100 ml of carbon dioxide-free water to which
0.15 ml of 0.02 M sodium hydroxide has been added is purplish
red. Not more than 0.1 5 ml of 0.02 M hydrochloric acid is required to
change the colour to yellow.
Crystal Violet; CI 42555; Basic Violet 3;
Hexamethylp-rosaniline Chloride: C25H30CIN3=
407.98
When used for titrations in
non-aqueous media, changes from violet (basic) through blue-green (neutral) to
yellowish green (acidic).
Crystal Violet Solution: A 0.5 per cent w/v solution of crystal violet in
anhydrous glacial acetic acid.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.1 ml of the solution and 50 ml of anhydrous glacial acetic acid is
bluish purple. Add 0.1 ml of 0.1 M perchloric acid; the solution turns
blue-green.
Dimethyl Yellow; CI 11020;
4-Dimethylamlnoazobenzene: CI4HI5N3=
225.29
Yellow crystalline leaflets;
mp, about I16°.
Complies with the following
test.
HOMOGENEITY - Carry out the
method for thin-layer chromatorgraphy, using silica gel G as the
coating susbtance and dichloromethane as the mobile phase. Apply
to the plate 10 µl of a 0.01 per cent w/v solution in dichloromethane.
The chromatogram shows only
one spot.
Dimethyl Yellow Solution: A 0.2 per cent w/v solution of dimethyl yellow in
ethanol (90 per cent).
Complies with the following
test.
SENSITIVITY - A solution
containing 2 g of ammonium chloride in 25 ml of carbon dioxide-free
water, to which is added 0.1 ml of the dimethyl yellow solution, is
yellow. Not more than 0.1 ml of 0.1 M hydrochloric acid is
required to change the colour to red.
Dimethyl Yellow-Oracet Blue B Solution; Dimethyl
YellowSolvent Blue 19 Solution:
Dissolve 15 mg of dimethyl yellow
and 15 mg of oracet blue B in chloroform and dilute to 500 ml with chloroform.
Eosin; CI 45380; Acid red 87:
C20H6Br4Na2O5= 691.86
General laboratory reagent
grade of commerce.
Red powder.
Eosin Solution:
A 0.5 per cent w/v solution of eosin in water.
Eriochrome Black T; CI 14645; Mordant Black
11;SolochromeBlack; Sodium 1-(l-hydroxy-2-naphthylazo
)-5-nitro-2naphthol-4-sulphonate: C20HI2N3NaO7S=
461.38
General laboratory reagent
grade of commerce.
Brownish black powder having
a faint, metallic sheen. Gives a red colour with calcium, magnesium, zinc and
certain other metals in alkaline solutions. When metal ions are absent, for
example in the presence of an excess of disodium edetate, the solution is blue.
Store protected from light
and moisture.
Complies with the following
test.
SENSITIVITY - To 10 ml of a 1
in 200,000 solution in a mlxture of equal parts of methanol and water
add a 1 per cent w/v solution of sodium hydroxide until the pH is
10; the solution is pure blue in colour and free from cloudiness. Add 0.01 ml
of 0.05 M magnesium sulphate; the colour of the solution changes to
red-violet, and on adding more 0.05 M magnesium sulphate, the
solution becomes wine-red in colour.
Eriochrome Black T Mlxture; Eriochrome Black T
Triturate; Mordant Black 11 Mlxture:
A mlxture of 1 part of eriochrome
black T and 99 parts of sodium chloride.
Store protected from light
and moisture.
Complies with the following
test.
SENSITIVITY - Dissolve 50 mg
in ] 00 ml of water, a brownish violet colour is produced. Add 0.3 ml of
6 M ammonia; the colour changes to blue. Add 0.1 ml of a 1 per cent w/v
solution of magnesium sulphate; the colour changes to violet.
Eriochrome Black T Solution; Mordant Black 11 Soluton:
Dissolve 0.2 g of eriochrome
black T and 2 g of hydroxylamlne hydrochloride in sufficient methanol
to produce 50 m\.
Prepare immediately before
use.
Fast Blue B Salt; CI 37235: CI4Hl2Cl2N4O2=
339.18
General laboratory reagent
grade of commerce.
Dark green powder, stabilised
by the addition of zinc chloride.
Store protected from moisture
in a cold place.
Ferroin Solution; Ferroin Sulphate Solution; Tris-(l,
10phenanthroline) ferrous Sulphate Complex: Dissolve 0.7 g of ferrous sulphate and 1.5 g of 1,1 O-phenanthroline
hydrochloride in 70 ml of water and add sufficient water to
produce 100 ml.
Complies with the following
test.
SENSITIVITY - Add 0.1 ml of
the solution and 0.15 ml of osmlc acid solution to 50 ml of 1 M
sulphuric acid. Add 0.1 ml of 0.1 M eerie ammonium nitrate; the
colour changes from red to light blue.
Indophenol Blue; CI49700: CI8H26N2O=276.34
General laboratory reagent
grade of commerce.
Dark purple powder.
Complies with the following
test.
HOMOGENEITY - Carry out the
method for thin-layer chromatography (2.4.17), using silica gel G
as the coating substance and dichloromethane as the mobile phase.
Apply to the plate 10 /11 of a 0.0 I per cent w/v solution in
dichloromethane. After removal of the plate, allow it to dry in air.
The chromatogram shows only one spot, but a stain may remain at the
point of origin.
Litmus:
Fragments of blue pigment prepared from various species of Rocella, Lecanora
or other lichens. It has a characteristic odour. Partly soluble in water
and in ethanol.
NOTE - Litmus is unsuitable for determlning the pH of
alkaloids, carbonates and bicarbonates.
Litmus Solution: Boil 25 g of coarsely powdered litmus with 100 ml of ethanol
(90 per cent) under a reflux condenser for 1 hour and discard the clear
liquid. Repeat this operation with two quantities, each of 75 ml of ethanol
(90 per cent). Digest the extracted litmus with 250 ml of water and
filter.
Metacresol Purple; 4,4' -(3H-2, I-Benzoxanthiol-3-ylidene)-dim-
cresol S,S-dioxide: C21H16O5S=
380.40
General laboratory reagent
grade of commerce.
Metalphthalein; Phthalein Purple: C32H32N2O12+aq
Creamy white brown powder.
Complies with the following
test.
SENSITIVITY - Dissolve 10 mg
in 1 ml of strong ammonia solution and dilute to lOaml with water. To
5 ml of the solution add 95 ml of water, 4 ml of strong
ammonia solution, 50 ml of ethanol (95 per cent) and 0.2 ml
of 0.1 M barium chloride; the solution is bluish violet. Add 0.24 ml of 0.05
M disodium edetate; the solution becomes colourless.
Metanil Yellow; CI 13065; Sodium
4-anilinoazobenzene-3sulphonate:
C18H14N3NaO3S
= 375.40
Brownish yellow powder;
soluble in water and in ethanol; slightly soluble in acetone and
in ether.
Metanil Yellow Solution: A 0.1 per cent w/v solution of metanil yellow in
methanol.
Complies with the following
test.
SENSITIVITY - Add 0.1 ml of
the solution to 50 ml of anhydrous glacial acetic acid; the mlxture is
pinkish red.
Add 0.05 ml of 0.1 M
perchloric acid; the colour changes to violet.
Methyl Orange;
CI 13025; Sodium 4-dimethylamlnoazobenzene- 4-sulphonate: C14H14N3NaO3S
= 327.34
Orange-yellow powder or
crystalline scales; Sparingly soluble in hot water; slightly soluble in water;
practically insoluble in ethanol.
Methyl Orange
Solution: Dissolve 0.1 g of methyl
orange in 80 ml of water and add sufficient ethanol (95 per
cent) to produce l00 ml.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.1 m] of the solution and 100 ml of carbon dioxide-free water is
yellow. Not more than 0.1 ml of 0.1 M hydrochloric acid is required to
change the colour to red.
Methyl Red; CI 13020; 2-(4-Dimethylarninophenylazo
)-benzoic Acid: C15H15N3O2=269.30
Dark red powder or violet
crystals; mp, about 182°; soluble in ethanol; practically insoluble in water.
Methyl Red- Methylene Blue Solution; Methyl Red Mlxed
Solution: Dissolve 0.1 g of methyl
red and 50 mg of methylene blue
in 100 ml of ethanol (95 per cent). Colour changes from reddish violet to green (pH range, 5.2
to 5.6).
Methyl Red Solution: Dissolve 50 mg of methyl red in a mlxture of 1.86 ml of 0.1
M sodium hydroxide and 50 ml of ethanol (95 per cent). After
solution is effected, add sufficient water to produce 100 ml.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.1 ml of the solution, 100 ml of carbon dioxide-free water and 0.05 ml
of 0.02 M hydrochloric acid is red. Not more than 0.1 ml of 0.02
M sodium hydroxide is required to change the colour to yellow.
Methylenebisacrylamlde: C7H10N2O2
= 154.2
A fine, white or almost white
powder, slightly soluble in water, soluble in alcohol.
mp. it melts with
decomposition at a temperature above 300°.
Methylene Blue; CI 52015; Basic Blue 9;
3,7-Bis-(dimethylamlno)phenothiazin- 5-ium chloride:
C16H18CIN3S.xH20
= 319.86 (anhydrous)
Redox indicator grade
suitable for biological work.
Dark green or brown crystals
with bronze lustre or crystalline powder; hygroscopic; soluble in water and
in chloroform; sparingly soluble in ethanol; insoluble in ether.
Methylene Blue Solution: Dissolve 150 mg of methylene blue in 100 ml of
ethanol (95 per cent) and dilute with ethanol (95 per cent) to
produce 250 ml.
Methyl Orange-Xylene Cyanol FF Solution: Dissolve 0.1 g of methyl orange and 0.26 g of xylene
cyanol FF in 50 ml of ethanol (95 per cent) and add
sufficient water to produce l00ml.
Methyl Thymol Blue;
[3H-2,1-Benzoxathiol-3-ylidenebis(6-hydroxy- 5-isopropyl- 2-methyl-m-pheny
lene) methy lenenitrilo]tetraacetic acid S, S-dioxide Tetrasodium salt:
C37H40N2Na4O13S
= 844.75
General laboratory reagent
grade of commerce.
Produces a blue colour with
calcium ions in alkaline solution. When metal ions are absent, for example, in
the presence of an excess of disodium edetate, the solution is grey.
1-Naphtholbenzein; a-Naphtholphthalein;
Phenylbis-(4hydroxynaphthyl)methenol:C27H20O3
= 392.50
Brownish red powder or shiny brownish black crystals.
1-Naphtholbenzein Solution; a-Naphtholbenzein Solution: A 0.2 per cent w/v solution of 1-naphtholbenzein in anhydrous glacial acetic acid.
Complies with the following
test.
SENSITIVITY - Add 0.25 ml to
50 ml of anhydrous glacial acetic acid. Not more than 0.05 ml of 0.1 M
perchloric acid is required to change the colour of the solution
from brownish yellow to green.
Neutral Red; CI 50040; Basic Red 5;
3-Amlno-7-dimethylamlno2-methylphenazine Monohydrochloride: C15Hl6N4.HCI =
288.78
Reddish to olive green coarse
powder; sparingly soluble in ethanol and in water.
Neutral Red Solution: A 0.1 per cent w/v solution of neutral red in ethanol
(50 per cent).
Nile Blue A; CI 51180; 5-Amlno-9-diethylamlnobenzo[
a]phenoxazinylium Hydrogen Sulphate:
C20H21N3O5S=415.47
Green,crystalline powder with
a bronze lustre.
Complies with the following
test.
LIGHT ABSORBTION - A 0.0005
per cent w/v solution in ethanol (50 per cent) exhibits a maximum
at about 640 nm.
Nile Blue A Solution: A 1 per cent w/v solution of nile blue A in anhydrous
glacial acetic acid.
Complies with the following
test.
SENSITIVITY - A solution
containing 0.25 ml in 50 ml of anhydrous glacial acetic acid is blue.
Not more than 0.1 ml of 0.1 M perchloric acid is required to change the
colour of the solution to bluish green.
Colour changes from blue to
red (pH range, 9.0 to 13.0).
Oracet Blue B; Solvent Blue 19: A mlxture of 1-methylamlno4-anilinoanthraquinone, C21H16N2O2,
and l-amlno-4anilinoanthraq uinone, C20H14N2O2.
When used for titration in
non-aqueous media, it changes from blue (basic) through purple (neutral) to
pink (acidic).
Oracet Blue B Solution: A 0.5 per cent w/v solution of oracet blue B in
anhydrous glacial acetic acid.
Phenol Red; Phenolsulphonphthalein; 4,4' -(3H-2,1Benzoxathiol-3-ylidene
)diphenol S,S-dioxide:
C19HI4O5S=
354.39
Bright to dark red
crystalline powder; freely soluble in solutions of alkali carbonates and
hydroxides; slightly soluble in ethanol (95 per cent); very
slightly soluble in water.
Phenol Red Solution: Dissolve 0.1 g of phenol red in 2.82 ml of 0.1 M sodium
hydroxide and 20 ml of ethanol (95 per cent). After
solution is effected, add sufficient water to produce l00 ml.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.1 ml of the solution and 100 ml of carbon dioxide-free water is
yellow. Not more than 0.1 ml of 0.02 M sodium hydroxide is required to
change the colour of the solution to reddish violet.
Phenol Red Reagent:
SOLUTION I - Dissolve 33 mg
of phenol red in 1.5 ml of 2 M sodium hydroxide and dilute to 100
ml with water.
SOLUTION n - Dissolve 25 mg
of ammonium sulphate in 235 ml of water, add 105 ml of 2 M
sodium hydroxide and 135 ml of 2 M acetic acid.
Add 25 ml of solution I to
solution II. If necessary, adjust the pH of the mixture to 4.7.
Phenolphthalein: Of the Indian Pharmacopoeia.
Phenolphthalein Solution: A 1.0 per cent w/v solution of phenolphthalein in
ethanol (95 per cent).
Phenolphthalein Solution, Dilute: Dissolve 0.1 g of phenolphthalein in 80 ml of ethanol
(95 per cent) and add sufficient water to produce 100 m!.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.1 ml of the solution and 100 ml of carbon dioxide-free water is
colourless. Not more than 0.2 ml of 0.02 M sodium hydroxide is required
to change the colour to pink.
Phenolphthalein-Thymol Blue Solution: Dissolve 0.1 g of thymol blue in a mixture of
2.2 ml of 0.1 M sodium hydroxide and 50 ml of ethanol (95 per
cent) and dilute to 100 ml with water. Mix 3 volumes of this
solution with 2 volumes of phenolphthalein solution.
Pyridylazonaphthol; PAN; 1-(2-Pyridylazo )-2-naphthol:
C15H11N3O=
249.27
General laboratory reagent
grade of commerce.
Brick red or orange-red
powder; mp, about 1400.
Pyridylazonaphthol Solution: A 0.1 per cent w/v solution in ethanol.
Complies with the following
test.
SENSITIVITY - To 50 ml of water
add 10 ml of acetate buffer pH 4.4,0.1 ml of 0.02 M disodium
edetate and 0.25 ml of the reagent under examlnation; a yellow
colour is produced. Add 0.15 ml of a 0.5 per cent w/v solution of cupric
sulphate; the colour changes to violet.
Quinaldine Red; 2-(4-Dimethylamlnostyryl) quinoline
Ethiodide: C21H23IN2=
430.33
When used for the non-aqueous
titration in anhydrous glacial acetic acid, the colour changes from
magenta (basic) to almost colourless (acidic).
Quinaldine Red Solution: A 0.1 per cent w/v solution of quinaldine red in
methanol.
Ruthenium Red; Ammoniated Ruthenium Oxychloride: H12Cl2N1402Ru3,4H20 = 858.42
Mlcroscopical staining grade
of commerce.
Brownish red powder.
Ruthenium Red Solution: Dissolve 8 mg of ruthenium red in
10 ml of lead acetate
solution.
Sudan Red G; CI
12150; Sudan
Red I; 1-(2'-Methoxyphenylazo)-2-naphthol; C17HI4N4O=290.32
Complies with the following
test.
HOMOGENEITY - Carry out the
method for thin-layer chromatography, using silica gel G as the
coating substance and dichloromethane as the mobile phase but allowing
the solvent front to ascend 10 cm above the line of application. Apply
to the plate 10 fll of a 0.1 per cent w/v solution in dichloromethane.
After removal of the plate, allow it to dry in air. The chromatogram
shows only one spot.
Thymol Blue; Thymolsulphonphthalein; 4,4' -(3H)-2,
1Benzoxathiol-3-ylidene) dithymol S,S-dioxide: C27H30O5S
=466.60
Brownish green, crystalline
powder; soluble in ethanol (95 per cent) and in dilute alkali solutions;
slightly soluble in water.
Thymol Blue Solution: Dissolve 0.1 g of thymol blue in 2.15 ml of 0.1
M sodium hydroxide and 20 ml of ethanol (95 per cent). After
solution is effected, add sufficient water to produce 100 ml.
Complies with the following
test.
SENSITIVITY - A mlxture of
0.1 ml ofthe solution and 100 ml of carbon dioxidejree water to which
0.2 ml of 0.02 M sodium hydroxide has been added is blue. Not
more than 0.1 ml of 0.02 M hydrochloric acid is required to change the
colour to yellow.
Thymol Blue Solution, Ethanolic: Dissolve 0.1 g of thymol blue in 100 ml of ethanol
(95 per cent) and filter, if necessary.
Thymolphthalein; 3,3-Bis( 4-hydroxy-5-isopropyl-
2mehtylphenyl)phthalide: C28H30O4=430.55
White to slightly yellow
crystalline powder; soluble in ethanol (95 per cent) and in solutions of
alkali hydroxides; insoluble in water.
Thymolphthalein Solution: A 0.1 per cent w/v solution of thymolphthalein in
ethanol (95 per cent).
Complies with the following
test.
SENSITIVITY - A mlxture of
0.05 ml and 100 ml of carbon dioxide-free water is colourless. Not more
than 0.05 ml of
0.1 M sodium hydroxide is required to change the colour to blue.
Titan Yellow; CI 19540; Thiazol Yellow; Sodium
2,2[(diazoamlno )di-p-phenylene] bis(6-methylbenzothiazole-7sulphonate): C28HI9N5Na2O6S4=
695.71
Yellowish brown powder.
Titan Yellow Solution: A 0.05 per cent w/v solution of titan yellow.
Complies with the following
test.
SENSITIVITY - Add 0.1 ml to a
mlxture of 10ml of water, 0.2 ml of a 0.0101 per cent w/v solution of magnesium
sulphate and 1.0 ml of 1 M sodium hydroxide; a pink colour is
produced.
Xylene Cyanol FF: C142135
Blue, ethanol-soluble dye
used as a screening agent in methyl orange-xylene cyanol FF solution.
Xylenol Orange;
[3H-2,1-Benzoxathiol-3-ylidenebis-(6hydroxy- 5-methyl-m-pheny lene )methylenenitrilo
]tetra acetic acid S,S-dioxide Tetrasodium Salt: C3IH28N2NH2OI3S=760.60
General laboratory reagent
grade of commerce.
Reddish brown, crystalline
powder; gives a violet colour with mercury, lead, zinc and certain other metal
ions, in alkaline solutions. When metal ions are absent, for example in the
presence of an excess of disodium edetate, the solution is yellow.
XylenolOrange Mlxture; Xylenol Orange Triturate: Triturate
1 part of xylenol orange with
99 parts of potassium nitrate.
Complies with the following
test.
SENSITIVITY - Add 50 mg to a
mlxture of 50 ml of water, 1 ml of 2 M acetic acid and 0.05 ml of
lead nitrate solution. Add sufficient hexamlne to change the
colour from yellow to violet red. Add 0.1 ml of 0.1 M disodium edetate; the
colour changes to yellow.
Xylenol Orange Solution: Mlx 0.1 g of xylenol orange with 100 ml of water
and filter, if necessary.
The chemical compound is prepared by dissolving Barium Oxide in water
ReplyDeleteBarium Hydroxide Manufacturers India This results in a Barium Octahydrate that can be converted to Monohydrate upon heating in air.