Appendix A

Levels of Impurities

 

A.1      potassium chloride, KCl

 

 

Impurity/Item

 

Concentration (%)

 

minimum assay

 

99.8

 

insoluble matter

 

0.003

 

free acid, HCl

0.0018

 

Bromide, Br, & iodide, I

0.005

 

nitrate, NO3

 

0.001

 

phosphate, PO4

 

0.001

 

sulphate, SO4

 

0.001

 

ammonium, NH4

 

0.001

 

arsenic, As

 

0.00004

 

barium, Ba

 

0.001

 

calcium, Ca, group
& magnesium, Mg

 

0.004

 

iron, Fe

 

0.0003

 

heavy metals, such as lead, Pb

 

0.0005

 

sodium, Na

 

0.05

 

Table A.1 – stated maximum levels of impurities in analytical reagent (AnalaR) potassium chloride (KCl) powder (BDH)

 

A.2      potassium hydroxide, KOH

 

 

Impurity

 

Concentration (%)

 

carbonate, K2CO3

 

2

 

chloride, Cl

 

0.005

 

sulphate, SO4

 

0.01

 

heavy metals, such as lead, Pb

 

0.001

 

sodium, Na

 

1

 

Table A.2 – stated maximum levels of impurities in general purpose reagent (GPR) potassium hydroxide (KOH) pellets (BDH)

 

 

A.3      sodium chloride, NaCl

 

 

Impurity

 

Concentration (%)

 

iron, Fe

 

0.0002

 

potassium, K

 

0.02

 

heavy metals, such as lead, Pb

 

0.0005

 

sulphate, SO4

 

0.01

 

ammonium, NH4

 

0.002

 

Table A.3 – stated maximum levels of impurities in general purpose reagent (GPR) sodium chloride (NaCl) powder (Scientific & Chemical Supplies Limited)

 

A.4      ferrous sulphate heptahydrate, FeSO4.7H2O

            (iron (II) sulphate heptahydrate)

 

 

 

Impurity/Item

 

Concentration (%)

 

minimum assay

 

98

 

copper, Cu

 

0.005

 

lead, Pb

 

0.005

 

potassium, K

 

0.05

 

sodium, Na

 

0.05

 

Table A.4 – stated maximum levels of impurities in

the hydrated ferrous sulphate (FeSO4.7H2O) powder

 

 

A.5      ferric sulphate pentahydrate, Fe(SO4)3.5H2O
(iron (III) sulphate pentahydrate)

 

 

Impurity/Item

 

Concentration (%)

 

minimum assay

 

97

 

Table A.5 – stated maximum levels of impurities in

the hydrated ferric sulphate (Fe(SO4)3.5H2O) powder (Aldrich)

 

 

A.6      ferric nitrate nonahydrate, Fe(NO3)3.9H2O
            (iron (III) nitrate nonahydrate)

 

 

 

Impurity/Item

 

Concentration (%)

 

minimum assay

 

98.0

 

insoluble matter

 

0.003

 

“acidity”, HNO3

 

0.4

 

chloride, Cl

 

0.0005

 

phosphate, PO4

 

0.004

 

sulphate, SO4

 

0.005

 

calcium, Ca

 

0.005

 

copper, Cu

 

0.005

 

ferrous iron, Fe

 

0.008

 

sulphate, SO4

 

0.005

 

lead, Pb

 

0.003

 

magnesium, Mg

 

0.005

 

manganese, Mn

 

0.02

 

potassium, K

 

0.01

 

sodium, Na

 

0.01

 

zinc, Zn

 

0.003

 

Table A.6 – stated maximum levels of impurities in

the hydrated ferric nitrate (Fe(NO3)3.9H2O) powder