Overview
EN ISO 22892:2011 (ISO 22892:2006) provides guidelines for identifying target compounds in soil by gas chromatography–mass spectrometry (GC‑MS). It sets out objective identification criteria based on relative retention times and electron ionization mass spectra, and describes when to apply additional mass spectrometric techniques or supporting information. The standard is intended to be used together with specific analytical methods for particular target compounds and is applicable to other environmental matrices as well.
Key topics and technical requirements
- Identification principle: Compare relative retention time to a retention time standard, then interpret MS spectra (full scan and/or selected ion monitoring, SIM). The outcome classification is identified, indicated, or absent.
- Retention time: Use a retention time standard or internal standard to calculate relative retention time (ratio of target RT to retention time standard). Relative RT values should be < 2.
- Diagnostic ions: Where possible select three diagnostic ions per target compound and measure their relative intensities in calibration standards. If three are not available (e.g., PAHs), use the available ions.
- Ion selection guidance:
- Prefer high m/z values and even mass fragments.
- Include the molecular ion when possible.
- Diagnostic ion intensity preferably > 15% of base peak.
- Use isotopic clusters (e.g., chlorine-containing compounds) for increased specificity.
- Avoid common column artefact masses (e.g., m/z 73, 207, 281).
- Instrument minima:
- Ionization mode: Electron ionization (commonly 70 eV).
- Mass range: from m/z 35 to (highest target mass + 10 u) in full scan.
- Scan rate: ≈10× peak frequency, minimum 7 scans/peak.
- Mass resolution: tuned to nominal (peak width at half-height ≤ 0.7 u).
- Sensitivity and detection: Lowest concentration for identification depends on instrument/method; the least-intense diagnostic ion must have signal‑to‑noise > 3:1.
- Qualification & reporting: Includes requirements for method qualification and standardized reporting of identification results.
Applications and users
EN ISO 22892 is practical for:
- Environmental and soil testing laboratories performing GC‑MS analysis of pesticides, PAHs, PCBs, organics, and other target analytes in soil.
- Regulatory agencies and consultants needing robust, reproducible identification criteria for compliance monitoring.
- Method developers and instrument vendors who design or validate GC‑MS protocols for environmental matrices.
- Research groups working on contaminant fate, remediation monitoring, and forensic soil analysis.
Keywords: soil quality, GC‑MS identification, gas chromatography mass spectrometry, diagnostic ions, retention time, electron ionization, environmental analysis, target compounds.
Related standards
- ISO/IEC 17025 (laboratory quality and competence) - referenced for quality assurance.
- Specific analytical standards for individual target compounds (used in conjunction with ISO 22892).
