Method Statement Chromium 6
@(#) Uncontrolled Document chromium6.html Version 1.1 Last
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 chromium 6 in soils and waters by colorimetric
methods.
Principle
Soil samples are leached at a water:soil ratio of 2:1. The aqueous
extracts or water samples are then analysed after addition of nitric
acid and 1,5-diphenylcarbazide by determination of absorbance at 540
nm spectrophotometrically.
Performance
Characteristics
Substances Determined
Hexavalent Chromium (Chrome 6).
Range of Application
Limit of Detection
Soil samples 1 mg / kg
Water sample 0.01 mg/l
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
Methods for the Examination of Waters and Associated Materials,
"Chromium in Raw and Potable Waters and Sewage Effluents 1980".
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