Method Statement Sulphide
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Revised on 12/09/02
Contents
Introduction
Principle
Performance
Characteristics
Range
of Application
Limit of
Detection
Analytical
Quality Control
References
Introduction
The performance of this method is validated in accordance with
internationally recognised procedures.
This procedure describes the determination of sulphide in soils
and waters by distillation using appropriate reagents followed by a
colorimetric measurement at 665nm.
Principle
Sulphides are decomposed by steam distillation using sodium
hydroxide. The sulphide liberated is trapped in a solution of dilute
sodium hydroxide and measured colorimetrically at a wavelength of 665
nm after addition of sulphuric acid, N,N-Diethyl-p-phenylenediamine
sulphate and potassium dichromate to an aliquot of the distillate.
Performance
Characteristics
Substances Determined
Sulphide in soils and waters.
Range of Application
Limit of Detection
Analytical Quality
Control
Analytical quality control is maintained by a number of measures:
Multi-point calibration with
authentic standards (with defined minimum performance
characteristics)
Analysis of control samples within
each analytical batch, such as independent standards, matrix spikes
or reference materials
Analysis of reagent/method blanks
within each analytical batch
Ongoing quality assured by the use
of control charts in conjunction with warning and action limits for
the QC sample data
Participation in external
proficiency testing and interlaboratory schemes such as LGC CONTEST,
HSE WASP, CSL FAPAS
References
Standard Methods for the
Examination of Waters and Wastewaters. 18th Edition 1992.
APHA-AWWA-WEF.
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