ISO 15192:2021 Soil and waste — Determination of Chromium(VI) in solid material by alkaline digestion and ion chromatography with spectrophotometric detection

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Soil and waste — Determination of Chromium(VI) in solid material by alkaline digestion and ion chromatography with spectrophotometric detection是ISO于2021-06发布的ISO标准，适用于国际范围。

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Soil and waste — Determination of Chromium(VI) in solid material by alkaline digestion and ion chromatography with spectrophotometric detection

1 Scope

This document specifies the determination of Cr(VI) in solid waste material and soil by alkaline digestion and ion chromatography with spectrophotometric detection. This method can be used to determine Cr(VI)-mass fractions in solids higher than 0,1 mg/kg.

NOTE In case of reducing or oxidising waste matrix no valid Cr(VI) content can be reported.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 8466-1, Water quality - Calibration and evaluation of analytical methods and estimation of performance characteristics - Part 1: Statistical evaluation of the linear calibration function

ISO 11464, Soil quality — Pretreatment of samples for physico-chemical analysis

ISO 11465, Soil quality — Determination of dry matter and water content on a mass basis — Gravimetric method

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

EN 15002, Characterization of waste — Preparation of test portions from the laboratory sample

EN 15934, Sludge, treated biowaste, soil and waste — Calculation of dry matter fraction after determination of dry residue or water content

3 Terms a nd definiti ons

No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://w ww. iso .org/ obp

— IEC Electropedia: available at http:// www.e lectropedia. org/ 4 Safety remarks

Anyone dealing with waste and soil analysis shall be aware of the typical risks of the material irrespective of the parameters determined. Waste and soil samples may contain hazardous (e.g. toxic, reactive, flammable, infectious) substances, which can be liable to biological and/or chemical reaction. Consequently, these samples should be handled with special care. The gases which may be produced by microbiological or chemical activity are potentially flammable and can pressurise sealed bottles. Bursting bottles are likely to result in hazardous shrapnel, dust and/or aerosol. It is presupposed that national regulations are followed with respect to all hazards associated with this method.

Avoid any contact with the skin, ingestion or inhalation of Cr(VI) compounds. Cr(VI) compounds are genotoxic and potentially carcinogenic to humans.

5 Principle

5.1 Digestion

This document describes an alkaline digestion procedure for extracting Cr(VI) from soluble, adsorbed and precipitated forms of chromium compounds in solid waste materials and soil. To quantify the content of Cr(VI) in a solid matrix, three criteria shall be satisfied:

a) digestion solution shall solubilize all species of Cr(VI);

b) conditions of the digestion shall not induce reduction of native Cr(VI) to Cr(III);

c) method shall not cause oxidation of native Cr(III) contained in the sample to Cr(VI).

The alkaline digestion described in this document meets these criteria for a wide spectrum of soils and wastes. Under the alkaline conditions of the digestion, negligible reduction of Cr(VI) or oxidation of 2+

native Cr(III) is expected. The additon of Mg in a phosphate buffer to the alkaline solution minimises [1][5][8]

air oxidation of trivalent chromium .

NOTE Background on methods for the determination of Cr(VI) in solid samples is given in Annex C.

5.2 Determination

Quantification of Cr(VI) in the alkaline digestion solution should be performed using a suitable technique with appropriate accuracy. For this purpose ion chromatography is used to separate Cr(VI) from interferences. Following this ion chromatographic separation, Cr(VI) is measured spectrophotometrically either at 365 nm (direct UV detection) or after post-column derivatisation with 1,5-diphenylcarbazide in acid solution at 540 nm. Post-column derivatisation involves reaction of 1,5-diphenylcarbazide with Cr(VI) to produce trivalent chromium and diphenylcarbazone. These then combine to form a trivalent chromium-diphenylcarbazone complex containing the characteristic magenta chromagen ( λ = 540 nm).

max NOTE The choice of detection method is based upon the required sensitivity. Direct UV detection is less sensitive than detection after post-column derivatisation with 1,5-diphenylcarbazide (see Annex C).

Hyphenated methods with ion chromatographic separation and detection techniques, such as inductively coupled plasma mass spectrometry (ICP-MS) or inductively coupled plasma atomic emission spectroscopy (ICP-AES), may be used once validation of the chosen analytical method has been performed.

5.3 Interferences and sources of error

— Use of ion chromatography is necessary for the separation of Cr(VI) from possible interferences in [6]

the alkaline digestion solution from solid material .

— For waste materials or soils, where the Cr(III)/Cr(VI) ratio is expected to be high, Cr(VI) results may be biased due to method induced oxidation. This can be particularly expected in soils high in [3]

Mn content and amended with soluble Cr(III) salts or freshly precipitated Cr(OH) .

3

— Cr(VI) can be reduced to Cr(III) during digestion from the sample due to reaction with reducing agents such as e.g. divalent iron. This problem is minimised in the described procedure using [5]

alkaline digestion solution .

— Cr(III) can be oxidised to Cr(VI) in hot alkaline solutions. This problem is minimised in the described [2][3][5][8]

procedure by adding magnesium to the alkaline digestion solution .

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