Foreword
Introduction
1 Scope
2 Normative references
3 Terms and Definitions
4 Safety remarks
5 Principle
5.1 Digestion
5.2 Determination
5.3 Interferences and sources of error
6 Apparatus
6.1 Digestion equipment
6.2 Filtration equipment,
6.3 Membrane filters,
6.4 Ion chromatographic system,
6.5 Ion chromatographic column,
6.6 Detection system
7 Reagents
7.1 Water
7.2 Sulfuric acid (H[2]SO[4]), concentrated,
rho(H[2]SO[4]) sim 1,84 g/ml, w(H[2]SO[4]) sim 98%
7.3 Sodium carbonate (Na[2]CO[3]), anhydrous,
w(Na[2]CO[3]) > 99,9%
7.4 1,5-Diphenylcarbazide ((C[6]H[5].NH.NH)[2]CO),
w((C[6]H[5].NH.NH)[2]CO) > 98%
7.5 Acetone (C[3]H[6]O)
7.6 Methanol (CH[4]O)
7.7 Potassium dichromate (K[2]C[r2]O[7]),
w(K[2]Cr[2]O[7]) > 99,9%
7.8 Sodium hydroxide (NaOH), w(NaOH) > 99%
7.9 Magnesium chloride hexahydrate (MgCl[2].6H[2]O),
w(MgCl[2].6H[2]O) > 99%
7.10 Dipotassium hydrogenphosphate (K[2]HPO4),
w(K[2]HPO[4]) > 99%
7.11 Potassium dihydrogenphosphate (KH[2]PO[4]),
w(KH[2]PO[4]) > 99%
7.12 Lead chromate (PbCrO[4]), w(PbCrO[4]) > 99%
7.13 Diphenylcarbazide reagent solution
7.14 Eluent solution
7.15 Alkaline digestion solution, 0,5 mol/l sodium
hydroxide (NaOH)/0,28 mol/l sodium carbonate
(Na[2]CO[3])
7.16 Calibration solutions of Cr(VI)
7.17 Phosphate buffer solution,
7.18 Magnesium chloride solution
7.19 Chromium chloride hexahydrate (CrCl[3].6H[2]O),
w(CrCl[3].6H[2]O) > 96%
7.20 Cr(III) spiking solution
8 Sample pretreatment
9 Alkaline digestion procedure
9.1 General
9.2 Preparation of test solutions using a hotplate
or heating block
10 Analytical procedure
10.1 General information
10.2 Instrumental set-up
10.3 Calibration
10.4 Test solution measurement
10.5 Quality Control
11 Calculation
12 Expression of results
13 Test report
Annex A (informative) - Alternative methods for direct
determination of Cr(VI) in the alkaline
digestion solution
Annex B (informative) - Ion chromatographic system
Annex C (informative) - Requirements for test portion preparation
Annex D (informative) - Background on methods for the
determination of Cr(VI) in solid samples
D.1 Summary of literature methods for Cr (VI)
determinations in solids [6]
D.2 Theoretical kinetic background for Cr(III)-Cr(VI)
inter-conversions [6]
D.3 Special needs for Cr(VI) determination in soil
extracts [7]
D.4 Determination of Cr(VI) in glass
D.5 Determination of Cr(VI) in air particulate matter
Annex E (informative) - Validation
Bibliography