Overview
ISO/TS 18507:2015 - Surface chemical analysis - Use of Total Reflection X‑ray Fluorescence spectroscopy in biological and environmental analysis - provides guidance on using Total Reflection X‑ray Fluorescence (TXRF) spectroscopy for qualitative and quantitative elemental analysis of biological and environmental samples. The Technical Specification describes relevant terms, sample preparation, instrumentation options (from laboratory instruments to synchrotron beamlines and automated industrial systems), experimental procedures, data analysis and interpretation, uncertainty assessment, and illustrative case studies.
Key SEO keywords: ISO/TS 18507:2015, TXRF spectroscopy, Total Reflection X‑ray Fluorescence, surface chemical analysis, elemental analysis, biological analysis, environmental analysis.
Key topics and technical requirements
- Instrumentation and quality control
- Requirements for X‑ray sources, monochromators, detectors, and sample stations.
- Performance checks: beam stability, spectroscopic resolution, energy calibration, and sensitivity testing.
- Sample carriers and specimen preparation
- Guidance on choice and cleaning of flat sample carriers (reflective substrates) and handling residues.
- Treatment procedures for liquid and solid samples, and preparation of internal standard solutions.
- Measurement geometry and principles
- TXRF geometry uses a glancing incident angle below the critical angle (total reflection) to enhance fluorescence yield and reduce background.
- Benefits include double excitation (primary + reflected beam) and reduced matrix effects.
- Data collection, analysis and reporting
- Procedures for data acquisition, background correction, determination of X‑ray intensities, derivation of relative sensitivities, internal‑standard quantification, and statistical treatment.
- Detailed list of experimental and procedural information required when reporting TXRF results.
- Uncertainty and validation
- Discussion of uncertainty sources and examples via case studies (environmental and biological).
- Comparative performance
- Annexes compare TXRF detection limits with techniques such as AAS and ICP‑MS and include case studies for practical contexts.
Applications and practical users
ISO/TS 18507:2015 is practical for:
- Technicians, analytical chemists, and laboratory staff
- Biologists and medical researchers (blood, serum, urine, tissue analysis)
- Environmental scientists and engineers (water, soil, aerosols, plant deposits)
- Food, pharma and forensic analysts
- Semiconductor industry for wafer contamination control
Practical advantages: multi‑element trace and ultra‑trace analysis, analysis of very small sample amounts, detection of halides, relatively short measurement times, and potentially low detection limits depending on sample and instrumentation.
Related standards
- The Technical Specification cites no normative references but includes comparisons to techniques such as AAS, GF‑AAS, ICP‑MS and discusses applicability versus conventional XRF methods.
This document is essential for labs and facilities implementing TXRF for environmental monitoring, biomedical assays, food safety, and industrial quality control, offering standardized best practices for reliable elemental analysis.