Method Statement 2:1 Sulphate
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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.
The analytical procedure described herein outlines the
determination of water soluble sulphate in soils by Inductively
Coupled Plasma – Optical Emission Spectrophotometry (ICP-OES).
Principle
Soil samples are leached at a water:soil ratio of 2:1. The
filtered extracts are aspirated into a plasma torch. Measurement of
the atomic emission of the element is made by an optical
spectroscopic technique. Samples are nebulised and the aerosol
produced is transported to a plasma torch where excitation occurs.
Characteristic atomic-line emission spectra are produced by a
radio-frequency inductively coupled plasma. The spectra are dispersed
by a grating spectrometer and intensities of the lines are monitored
by photomultiplier tubes. The photocurrents from the photomultiplier
tubes are processed and controlled by a computer system.
Performance
Characteristics
Substances Determined
Water soluble Sulphate (2:1 leachate). Note that results are
normally reported in units of g/l upon the 2:1 leachate.
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
A Handbook of Inductively Coupled Plasma Spectrometry. M.
Thompson, J.N.. Walsh. 1983. ISBN 0-412-00371-6)
Standard Methods for the Examination of Waters and Wastewaters.
APHA-AWWA-WEF, 1992 18th Edition
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