Foreword

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This document was prepared by Technical Committee ISO/TC 201, Surface Chemical Analysis, Subcommittee SC 10, X-ray Reflectometry (XRR) and X-ray Fluorescence (XRF) Analysis.

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Introduction

Air pollution originates from both natural sources (volcanoes, dust winds) and anthropogenic activities (industry, transportation, agricultural, household). It represents a major health, environmental, societal, and economic burden. Particulate matter (PM) is one of the six primary pollutants in the air and its danger varies depending on the size, concentration, and composition of the particles. Various sampling approaches and analytical requirements have been applied to the study of PMs according to the specific frameworks for and under which samples are collected, for instance for monitoring ambient air quality, workplace air, or stationary source emissions. Air filtering membrane (PM filter) remains the preferred sampling substrate. PM concentration in the volume of sampled air is determined gravimetrically by weighing filters collected from air monitoring stations, which can also perform size fraction selection. PM chemical composition, physical properties, and biological content are determined by analysing the whole or part of the PM filter.

The most widely used analytical techniques for determining the elemental composition, mainly for metals and metalloids in PM filters are atomic absorption and inductively coupled plasma-based spectroscopies (AAS and ICP). These methods are destructive as they require the complete solubilization of the solid samples in a liquid mixture. Energy dispersive X-ray fluorescence (EDXRF) is an alternative technique to the above mentioned for elemental analysis, which is non-destructive, with lower environmental impact, and which does not require sample solubilization or the use of gasses for operation. Several International Standards exist and describe methods for elemental analysis based on AAS and ICP, while only a few non International Standards describe methods based on XRF techniques.

This document is developed in response to a worldwide demand to use green and environmentally sustainable analytical methods according to the 2030 Agenda for Sustainable Development. This document supports the use of energy dispersive XRF based techniques for elemental analysis of PM filters, targeting the Sustainable Development Goals (SDGs) 11, 12, 14, 15.

1 Scope

This document gives guidance on sample preparation, and on qualitative and quantitative determination of elements in particulate matter collected on filtering membranes (PM filter) by energy dispersive X-ray Fluorescence (EDXRF) in different geometrical configurations. This document does not apply to PM filter sampling. This document only applies to the analysis of X-ray emission from filters that are probed using an X-ray beam as the exciting source. X-ray emissions generated by electron microscope are excluded^[ 1 ^].

This document is applicable under a range of contexts including, but not limited to, those highlighted in the introduction. The described method is generally applicable for the determination of elements with atomic number higher than 11 (Na) and having a deposited mass on the filter greater than 10 ng. The elements that can be identified and the detection limits depend on the specific instrumental configuration employed.

Various types of filtering membranes (filter) materials can be used, such as glass fibre, quartz fibre, cellulose, nylon, polycarbonate (PC) and polytetrafluoroethylene (PTFE). The entire filter, or portions of various sizes thereof, can be submitted for analysis.

NOTE Reference free analysis, based on fundamental parameters is excluded, as the nature of the PM filter samples means that the parameters are not sufficiently well defined.

2 Normative references

3 Terms and definitions

4 Symbols and abbreviated terms

5 Safety

6 Preliminary remarks

7 Measurements

8 Filter materials and interferences

9 Sample preparation and handling

10 Qualitative Analysis

10.1 Identification of analytes

10.2 Determination of the analyte net intensities

10.3 Determination of LOD

11 Quantitative analysis

11.1 Certified reference material, reference material and calibration sample

11.2 Calibration curve

11.3 Uncertainty budget

11.4 Precision and accuracy

12 Quality check

13 Test analysis report

Bibliography