REAZIONI DI IDENTIFICAZIONE DI ANIONI DI
INTERESSE FARMACEUTICO E
TOSSICOLOGICO
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Cloruri
Bromuri
Ioduri
Solfati
Borati
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Nitrati
Fosfati
Ossalati
Carbonati e bicarbonati
Acetati
1
CLORURI
CHLORIDES (Eu Ph)
a) Dissolve in 2 ml of water R a quantity of the substance to be examined equivalent to
about 2 mg of chloride (Cl–) or use 2 ml of the prescribed solution. Acidify with dilute nitric
acid R and add 0.4 ml of silver nitrate solution R1. Shake and allow to stand. A curdled,
white precipitate is formed. Centrifuge and wash the precipitate with three quantities, each
of 1 ml, of water R. Carry out this operation rapidly in subdued light, disregarding the fact
that the supernatant solution may not become perfectly clear. Suspend the precipitate in
2 ml of water R and add 1.5 ml of ammonia R. The precipitate dissolves easily with the
possible exception of a few large particles which dissolve slowly.
Cl- + Ag+  AgCl
AgCl + 2NH3  [Ag(NH3)2]+ + Cl[Ag(NH3)2]+ + Cl- + 2H+ AgCl + 2NH4+
Composti di interesse farmaceutico
HCl, NaCl, KCl, CaCl2, MgCl2, NH4Cl
Attività farmacologica e tossicologica
Elemento essenziale.
2
BROMURI
BROMIDES (Eu Ph)
a) Dissolve in 2 ml of water R a quantity of the substance to be examined equivalent to
about 3 mg of bromide (Br–) or use 2 ml of the prescribed solution. Acidify with dilute
nitric acid R and add 0.4 ml of silver nitrate solution R1. Shake and allow to stand. A
curdled, pale yellow precipitate is formed. Centrifuge and wash the precipitate with
three quantities, each of 1 ml, of water R. Carry out this operation rapidly in subdued
light disregarding the fact that the supernatant solution may not become perfectly clear.
Suspend the precipitate obtained in 2 ml of water R and add 1.5 ml of ammonia R. The
precipitate dissolves with difficulty.
Br - + Ag+  AgBr
AgBr + 2NH3  [Ag(NH3)2]+ + Br Acqua di cloro
2Br - + Cl2  Br2 + 2Cl -
(colora di giallo CHCl3)
Acido solforico conc.
2Br - + SO42- + 4H+  Br2 + SO2 + 2H2O
Composti di interesse farmaceutico
KBr, NaBr, NH4Br
Attività farmacologica e tossicologica
Elemento microessenziale.
3
IODURI
IODIDES (Eu Ph)
a) Dissolve a quantity of the substance to be examined equivalent to about 4 mg of
iodide (I–) in 2 ml of water R or use 2 ml of the prescribed solution. Acidify with
dilute nitric acid R and add 0.4 ml of silver nitrate solution R1. Shake and allow to
stand. A curdled, pale-yellow precipitate is formed. Centrifuge and wash with
three quantities, each of 1 ml, of water R. Carry out this operation rapidly in
subdued light disregarding the fact that the supernatant solution may not become
perfectly clear. Suspend the precipitate in 2 ml of water R and add 1.5 ml of
ammonia R. The precipitate does not dissolve.
I- + Ag+  AgI
b)
To 0.2 ml of a solution of the substance to be examined containing about 5 mg of
iodide (I–) per millilitre, or to 0.2 ml of the prescribed solution, add 0.5 ml of dilute
sulphuric acid R, 0.1 ml of potassium dichromate solution R, 2 ml of water R and
2 ml of chloroform R. Shake for a few seconds and allow to stand. The chloroform
layer is coloured violet or violet-red.
6I + Cr2O72 + 14H+  2Cr3+ + 3I2 + 7H2O
Acqua di cloro
2I - + Cl2  2Cl - + I2 (colora di viola CHCl3)
4
2I - + Cl2  2Cl - + I2
I2 + 5 Cl2 + 6 H2O  2 IO3- + 10 Cl- + 12 H+
Acido solforico conc.
2 I- + SO42- + 4H+  I2 + SO2 + 2H2O
Composti di interesse farmaceutico
KI, NaI, I2
Attività farmacologica e tossicologica
Elemento oligoessenziale.
5
IO3- / I2 = 1,19
BrO3- / Br2 = 1,52
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SOLFATI
SULPHATES (Eu Ph)
a) Dissolve about 45 mg of the substance to be examined in 5 ml of water R or use
5 ml of the prescribed solution. Add 1 ml of dilute hydrochloric acid R and 1 ml of
barium chloride solution R1. A white precipitate is formed.
Ba 2+ + SO4 2-  BaSO4
Composti di interesse farmaceutico
Na2SO4.10H2O, MgSO4.7 H2O, CuSO4, BaSO4, ZnSO4
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BORATI
Borax
Borax
Na2B4O7,10H2O
Mr 381.4[1303-96-4]
DEFINITION
Disodium tetraborate decahydrate.
Content: 99.0 per cent to 103.0 per cent of Na2B4O7,10H2O.
CHARACTERS
Appearance: white ►or almost white◄, crystalline powder, colourless crystals or
crystalline masses, efflorescent.
Solubility: soluble in water, very soluble in boiling water, freely soluble in glycerol.
IDENTIFICATION
A. To 1 ml of solution S (see Tests) add 0.1 ml of sulphuric acid R and 5 ml of
methanol R and ignite. The flame has a green border.
3CH3OH + H3BO3  3 H2O + B(OCH3)3
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HO
Curcumina
O
R
R=
O
O
R
CH=CH
R
OH
B
OH
O
R
O
H3BO3
R
R
+ H2O
OH
OCH3
Composti di interesse farmaceutico
H3BO3, Na2B4O7.10H2O, NaBO3
Attività farmacologica e tossicologica
Elemento traccia-essenziale.
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NITRATI
a) Via umida
Solfato ferroso soluzione satura
NO3- + 3Fe2+ + 4H+  3Fe 3+ + NO + 2H2O
Fe 2+ + NO + SO42-  [Fe(NO)]SO4
b) Via secca
Lega di Devarda (45% Al, 5% Zn, 50% Cu)
NO3- + 4Zn + 7OH - + 6H2O
 NH3 + 4[Zn(OH)4]2-
3NO3- + 8Al + 5OH - + 18H2O  3NH3 + 8[Al(OH)4]Composti di interesse farmaceutico
KNO3
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FOSFATI
PHOSPHATES (ORTHOPHOSPHATES) (Eu Ph)
a) To 5 ml of the prescribed solution, neutralised if necessary, add 5 ml of silver
nitrate solution R1. A yellow precipitate is formed whose colour is not changed
by boiling and which dissolves on addition of ammonia R.
3 Ag+ + PO43-  Ag3PO4
b)
Mix 1 ml of the prescribed solution with 2 ml of molybdovanadic reagent R. A
yellow colour develops.
Reattivo molibdico
3NH4+ + 12MoO42- + PO43- + 24H+  (NH4)3PO4.12MoO3 + 12H2O
Composti di interesse farmaceutico
NaH2PO4.2H2O, CaHPO4, KH2PO4
Attività farmacologica e tossicologica
Elemento essenziale.
11
OSSALATI
Argento nitrato
2 Ag+ + C2O4 2- Ag2C2O4
Calcio cloruro
C2O4 2- + Ca2+  CaC2O4
2 MnO4- + 5 H2C2O4
+ 6 H+  2 Mn 2+ + 10 CO2 + 8 H2O
Attività farmacologica e tossicologica
Sequestra ioni calcio.
12
CARBONATI e BICARBONATI
CARBONATES AND BICARBONATES (Eu Ph)
Introduce into a test-tube 0.1 g of the substance to be examined and suspend in 2 ml
of water R or use 2 ml of the prescribed solution. Add 3 ml of dilute acetic acid R.
Close the tube immediately using a stopper fitted with a glass tube bent twice at right
angles. The solution or the suspension becomes effervescent and gives off a
colourless and odourless gas. Heat gently and collect the gas in 5 ml of barium
hydroxide solution R. A white precipitate is formed that dissolves on addition of an
excess of hydrochloric acid R1.
CO32- + 2H+  CO2 + H2O
CO2 + Ba2+ + 2OH-  BaCO3 + H2O
Composti di interesse farmaceutico
CO2, Na2CO3, NaHCO3, CaCO3, MgCO3, K2CO3, KHCO3
Attività farmacologica e tossicologica
Antiacido gastrico
HCO3- /H2CO3: sistema tampone dell’organismo
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ACETATI
ACETATES (Eu Ph)
a) Heat the substance to be examined with an equal quantity of oxalic acid R. Acid
vapours with the characteristic odour of acetic acid are liberated, showing an acid
reaction (2.2.4).
2CH3COOK + H2C2O4  2CH3COOH + K2C2O4
Composti di interesse farmaceutico
Acido acetico, Mg-acetato, Na-acetato, K-acetato, Ca-acetato
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