2
Introduction
determination of copper, mercury, chromium, manganese, nickel, zinc, lead, iron,
cobalt, cadmium, silver and cobalt. Mixtures of nitric and hydrofluoric acids have also
been employed to ensure more a complete breakdown of siliceous matrices in sediments preparatory to the determination of, for example, selenium and chromium.
Other binary acid digestion mixtures used in sediments, fish and crustacea digestions
include nitric-sulphuric acid and nitric-perchloric acid (mercury, chromium, copper,
zinc, cadmium, nickel, lead, cobalt, manganese, iron and aluminium) using, as an
analytical finish, atomic absorption spectrometry, neutron activation analysis and
anodic scanning voltammetry. Mixtures of hydrochloric and hydrobromic acids have
been used to digest crustacea samples prior to the determination of tin by anodic
scanning voltammetry. Mixtures of nitric and hydrochloric acids have been used to
digest sediments prior to the determination of arsenic by hydride generation atomic
absorption spectrometry.
Tertiary acid digestion mixtures that have been investigated include (i) nitricsulphuric-perchloric acid mixtures used to digest fish and crustacea samples prior to
the determination of arsenic, selenium and mercury by hydride generation atomic
absorption spectrometry, (ii) nitric-sulphuric-perchloric acid mixtures used to digest
fish and crustacea samples prior to the determination of zinc, cadmium, nickel, lead
and mercury by inductivly coupled plasma atomic emission spectrometry and (iii)
nitric-hydrochloric-sulphuric acid mixtures used to digest fish samples prior to the
determination of mercury by cold vapour atomic absorption spectrometry.
In the case of sediments, where the opening up of a siliceous lattice is required,
mixtures of nitric-perchloric-hydrofluoric acids or nitric-hydrochloric-hydrofluoric
acids have been used to break down samples in open tube or PTFE-lined bomb
digestions preparatory to the determination of cadmium, lead, tin, zirconium, selenium, aluminium, iron, copper, sodium, magnesium, mercury, nickel, cobalt and zinc
by appropriate techniques, including atomic absorption spectrometry, hydride generation atomic absorption spectrometry and inductivly coupled plasma atomic emission spectrometry.
Other digestion reagents that have been employed include sodium hydroxide (arsenic and selenium in sediments and fish), nitric acid - magnesium nitrate (selenium,
copper, lead and cadmium in fish), Lumatom (tin in sediments), ammonium or
potassium persulphate (mercury and cadmium in sediments and fish), and fusion
with lithium metaborate at 900°C (chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium and lead in sediments).
It is thus seen that a wide variety of sample digestion techniques and final analytical
finishes have been employed in the analysis of solid materials taken from the aqueous
environment. Generally speaking, very careful analytical studies are required to ensure that correct results are obtained for each type of sample, and one of the objectives
of this book is to present the most reliable techniques now available.
An essential part of any method development is to check the method against
authenticated standards of similar materials which, in many cases, are available from
the National Bureau of Standards (USA) or other sources.
A decision has to be made, especially in the case of sediments, as to whether it is
required to determine the concentration of relatively loosely adsorbed elements in the
sample or whether it is required to determine the total concentration of elements
Introduction
determination of copper, mercury, chromium, manganese, nickel, zinc, lead, iron,
cobalt, cadmium, silver and cobalt. Mixtures of nitric and hydrofluoric acids have also
been employed to ensure more a complete breakdown of siliceous matrices in sediments preparatory to the determination of, for example, selenium and chromium.
Other binary acid digestion mixtures used in sediments, fish and crustacea digestions
include nitric-sulphuric acid and nitric-perchloric acid (mercury, chromium, copper,
zinc, cadmium, nickel, lead, cobalt, manganese, iron and aluminium) using, as an
analytical finish, atomic absorption spectrometry, neutron activation analysis and
anodic scanning voltammetry. Mixtures of hydrochloric and hydrobromic acids have
been used to digest crustacea samples prior to the determination of tin by anodic
scanning voltammetry. Mixtures of nitric and hydrochloric acids have been used to
digest sediments prior to the determination of arsenic by hydride generation atomic
absorption spectrometry.
Tertiary acid digestion mixtures that have been investigated include (i) nitricsulphuric-perchloric acid mixtures used to digest fish and crustacea samples prior to
the determination of arsenic, selenium and mercury by hydride generation atomic
absorption spectrometry, (ii) nitric-sulphuric-perchloric acid mixtures used to digest
fish and crustacea samples prior to the determination of zinc, cadmium, nickel, lead
and mercury by inductivly coupled plasma atomic emission spectrometry and (iii)
nitric-hydrochloric-sulphuric acid mixtures used to digest fish samples prior to the
determination of mercury by cold vapour atomic absorption spectrometry.
In the case of sediments, where the opening up of a siliceous lattice is required,
mixtures of nitric-perchloric-hydrofluoric acids or nitric-hydrochloric-hydrofluoric
acids have been used to break down samples in open tube or PTFE-lined bomb
digestions preparatory to the determination of cadmium, lead, tin, zirconium, selenium, aluminium, iron, copper, sodium, magnesium, mercury, nickel, cobalt and zinc
by appropriate techniques, including atomic absorption spectrometry, hydride generation atomic absorption spectrometry and inductivly coupled plasma atomic emission spectrometry.
Other digestion reagents that have been employed include sodium hydroxide (arsenic and selenium in sediments and fish), nitric acid - magnesium nitrate (selenium,
copper, lead and cadmium in fish), Lumatom (tin in sediments), ammonium or
potassium persulphate (mercury and cadmium in sediments and fish), and fusion
with lithium metaborate at 900°C (chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium and lead in sediments).
It is thus seen that a wide variety of sample digestion techniques and final analytical
finishes have been employed in the analysis of solid materials taken from the aqueous
environment. Generally speaking, very careful analytical studies are required to ensure that correct results are obtained for each type of sample, and one of the objectives
of this book is to present the most reliable techniques now available.
An essential part of any method development is to check the method against
authenticated standards of similar materials which, in many cases, are available from
the National Bureau of Standards (USA) or other sources.
A decision has to be made, especially in the case of sediments, as to whether it is
required to determine the concentration of relatively loosely adsorbed elements in the
sample or whether it is required to determine the total concentration of elements