ISO 6978-1:2003 PDF

Natural gas — Determination of mercury — Part 1: Sampling of mercury by chemisorption on iodine

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Title (English):

ISO 6978-1:2003

Natural gas — Determination of mercury — Part 1: Sampling of mercury by chemisorption on iodine

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 16
Publication date:: October 24, 2003
Edition:: ISO IS 6978 edition 1 version 1
ICS:: 75.060

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Description (English):

ISO 6978-1:2003 specifies a method for the determination of total mercury content in natural gas using a sampling method at pressures up to 40 MPa by chemisorption on iodine impregnated silica gel. This sampling method is suitable for the determination of mercury contents within the range of 0,1 microgram/m3 to 5 000 micrograms/m3 in natural gas. This method is applicable to sampled gas volumes containing less than 20 mg hydrogen sulfide and less than a total liquid hydrocarbon condensate of 10 g/m3 under the sampling conditions. The collected mercury is determined by measuring the absorbance or fluorescence of mercury vapour at 253,7 nm.

Technical details

Technical committee: ISO/TC 193/SC 1 - Analysis of natural gas
SKU: ISO 6978-1:2003

Abstract

Overview - ISO 6978-1:2003 (Natural gas - Determination of mercury)

ISO 6978-1:2003 specifies a high-pressure sampling method for total mercury in natural gas by chemisorption on iodine-impregnated silica gel. The standard covers sampling at pressures up to 40 MPa and is intended for mercury concentrations from 0.1 µg/m3 to 5 000 µg/m3. After chemisorption, collected mercury is recovered and measured as mercury vapour by cold-vapour atomic absorption spectrometry (AAS) or atomic fluorescence spectrometry (AFS) at 253.7 nm. The procedure is designed for pipeline-quality natural gas provided sampled volumes contain < 20 mg hydrogen sulfide (absolute) and < 10 g/m3 liquid hydrocarbon condensate under sampling conditions.

Key topics and technical requirements

Sampling principle: Mercury (elemental or organomercury) reacts with iodine on silica gel forming mercury iodide (e.g., Hg + I2 → HgI2), which is later dissolved and reduced to elemental Hg for cold-vapour analysis.
Pressure capability: Apparatus options and special components cover sampling up to 10 MPa (electrically heated pressure relief) and 40 MPa (pressure relief + heat exchanger).
Sampling media: Use iodine-impregnated silica gel (grain size 0.2–0.5 mm), prepared by loading iodine onto silica in n‑pentane; the loaded sorbent has a shelf life > 6 months when protected from light.
Analytical measurement: Mercury vapour transferred to AAS/AFS; calibration must be matrix-matched to the sample. Detection capability down to ~1 ng Hg in the analytical system is expected.
Traceability & uncertainty: Volume, temperature and pressure measurements must be traceable; volume measurement uncertainty should be minimized (

Related standards

Other ISO standards

Overview - ISO 6978-1:2003 (Natural gas - Determination of mercury)

Key topics and technical requirements

Sampling principle: Mercury (elemental or organomercury) reacts with iodine on silica gel forming mercury iodide (e.g., Hg + I2 → HgI2), which is later dissolved and reduced to elemental Hg for cold-vapour analysis.
Pressure capability: Apparatus options and special components cover sampling up to 10 MPa (electrically heated pressure relief) and 40 MPa (pressure relief + heat exchanger).
Sampling media: Use iodine-impregnated silica gel (grain size 0.2–0.5 mm), prepared by loading iodine onto silica in n‑pentane; the loaded sorbent has a shelf life > 6 months when protected from light.
Analytical measurement: Mercury vapour transferred to AAS/AFS; calibration must be matrix-matched to the sample. Detection capability down to ~1 ng Hg in the analytical system is expected.
Traceability & uncertainty: Volume, temperature and pressure measurements must be traceable; volume measurement uncertainty should be minimized (

ISO 6978-1:2003 PDF

Technical details

Abstract

Overview - ISO 6978-1:2003 (Natural gas - Determination of mercury)

Key topics and technical requirements

Related standards

Abstract

Overview - ISO 6978-1:2003 (Natural gas - Determination of mercury)

Key topics and technical requirements

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