ISO 21741:2020
Stationary source emissions - Sampling and determination of mercury compounds in flue gas using gold amalgamation trap

Standard No.

ISO 21741:2020

Release Date

2020

Published By

International Organization for Standardization (ISO)

Latest

ISO 21741:2020

Scope

This document describes a method for the sampling and measurement of mercury of both vapour and solid phases on stationary source flue gas streams. Mercury generally exists as elemental (Hg0) and oxidized (Hg2+) forms, both in the vapour and solid phases in flue gases. The vapour-phase (gaseous) mercury is captured either isokinetically or non-isokinetically with a gold amalgamation trap after removing solid-phase (particulate) mercury with a filter. Because gold amalgamation trap captures only gaseous elemental mercury, the oxidized mercury (Hg2+) in the vapour phase is converted to elemental mercury (Hg0) prior to the gold amalgamation trap. The concentration of gaseous mercury is determined using atomic absorption spectrometry (AAS) or atomic fluorescence spectrometry (AFS) after releasing mercury by heating the gold amalgamation trap. Separately, particulate mercury is collected isokinetically on a filter and the concentration is determined using cold vapour AAS or cold vapour AFS after dissolving the particulate mercury into solution. The total concentration of mercury in flue gas is expressed as the sum of both gaseous and particulate mercury concentrations. The gold amalgamation method is intended for short-term (periodic) measurements of gaseous mercury ranging from 0,01 μg/m3 to 100 μg/m3 with sampling volumes from 0,005 m3 to 0,1 m3 and sample gas flow rate between 0,2 l/min to 1 l/min. The measurement range of particulate mercury is typically from 0,01 μg/m3 to 100 μg/m3 with sampling volume from 0,05 m3 to 1 m3.

ISO 21741:2020 Referenced Document

• ISO 10396 Stationary source emissions - Sampling for the automated determination of gas emission concentrations for permanently-installed monitoring systems
• ISO 12141 Stationary source emissions - Determination of mass concentration of particulate matter (dust) at low concentrations - Manual gravimetric method
• ISO 12846:2012 Water quality - Determination of mercury - Method using atomic absorption spectrometry (AAS) with and without enrichment
• ISO 16911-1 Stationary source emissions - Manual and automatic determination of velocity and volume flow rate in ducts - Part 1: Manual reference method
• ISO 17852:2006 Water quality - Determination of mercury - Method using atomic fluorescence spectrometry
• ISO 20988 Air quality - Guidelines for estimating measurement uncertainty
• ISO 3696 Water for analytical laboratory use; Specification and test methods
• ISO 9096 Stationary source emissions — Manual determination of mass concentration of particulate matter

ISO 21741:2020 history

• 2020 ISO 21741:2020 Stationary source emissions - Sampling and determination of mercury compounds in flue gas using gold amalgamation trap