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International Standard ISO 13959-15: Determination of Plant Treatment Agents and Biocide Products in Water by SPME-GC-MS
Analytical Methods for Water Quality Monitoring: Scope, Technical Requirements, and Compliance
ISO 13959-15 (CAN/CSA-ISO 13959-15) is an international standard that specifies a method for the determination of selected plant treatment agents (herbicides, insecticides, fungicides) and biocide products in drinking water, surface water, and groundwater. The method uses solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS). This article reviews its scope, technical requirements, implementation considerations, and compliance aspects.
1. Scope and Application
ISO 13959-15 applies to water matrices including drinking water, natural waters (surface and ground), and treated industrial effluents. It covers a defined list of organic analytes such as triazine herbicides (e.g., atrazine, simazine), phenylurea herbicides (e.g., diuron, linuron), and several biocides used in antifouling paints and wood preservatives. The method is suitable for quantification at concentration levels typically required by environmental regulations (sub-µg/L down to 0.1 µg/L).
The standard is intended for use by water testing laboratories, environmental monitoring agencies, and industrial compliance teams. It provides a reliable and cost-effective approach compared to liquid-liquid extraction methods, as SPME reduces solvent consumption and sample handling.
Note: ISO 13959-15 does not cover all possible plant treatment agents or biocides. Laboratories should verify that their target analytes are included in the scope or validate the method for additional compounds.
2. Technical Requirements
The method consists of three main stages: sample preparation, SPME extraction, and GC-MS analysis. Key technical parameters are specified in the standard.
2.1 Solid-Phase Microextraction (SPME) Conditions
A suitable SPME fiber must be selected based on the polarity of target compounds. The standard recommends a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber for optimal extraction of a broad range of semi-volatile and polar compounds. Extraction is performed by direct immersion or headspace depending on analyte volatility; for the targeted compounds, direct immersion SPME is typically used for 30–60 minutes at ambient temperature with stirring. Desorption is carried out in the GC injector at 250–270 °C for 2–5 minutes.
Tip: To minimize carryover, a fiber bake-out step (e.g., 270 °C for 10 min) should be performed between samples, especially when analyzing complex matrices.
2.2 GC-MS Parameters
The standard specifies the use of a capillary column with a non‑polar or medium‑polar stationary phase (e.g., 5% phenyl‑95% dimethylpolysiloxane). Typical dimensions: 30 m × 0.25 mm I.D. × 0.25 µm film thickness. The oven temperature program begins at 40 °C for 1–2 min, increases at 8–12 °C/min to 280 °C, and holds for 5 min. Helium is used as carrier gas at a constant flow of 1.0–1.5 mL/min.
Mass spectrometric detection is performed in selected‑ion monitoring (SIM) mode for improved sensitivity. The standard lists specific quantification and confirmation ions for each analyte. Electron ionization (EI) at 70 eV is required.
Warning: Mass spectrometer tuning per manufacturer specifications is critical. The standard requires daily tuning with perfluorotributylamine (PFTBA) to ensure mass accuracy and sensitivity.
2.3 Calibration and Quantification
Calibration must be performed using at least five calibration standards prepared in reagent water free of target compounds. The concentration range should bracket expected sample concentrations (e.g., 0.1–10 µg/L). Internal standard addition (e.g., triphenylmethane or deuterated analogs) is required to compensate for fiber variability and matrix effects. The linearity of calibration curves must be checked, with a correlation coefficient (r²) ≥ 0.990.
Quantification is based on the ratio of analyte response to internal standard response. The standard specifies acceptance criteria for retention time windows (within ±0.1 s) and ion ratios (within ±20% of the reference standard).
3. Implementation Highlights
Adoption of ISO 13959-15 requires careful planning regarding equipment, consumables, and personnel training. Below is a summary of typical target analytes and their expected retention times and detection limits (illustrative values based on common practice).
| Analyte | Compound Class | Retention Time (min) | Detection Limit (µg/L) |
|---|---|---|---|
| Atrazine | Triazine herbicide | 10.2 | 0.05 |
| Simazine | Triazine herbicide | 9.8 | 0.05 |
| Diuron | Phenylurea herbicide | 11.5 | 0.10 |
| Irgarol | Biocide (antifouling) | 12.8 | 0.03 |
| Permethrin | Pyrethroid insecticide | 15.4 | 0.20 |
Note: The above values are examples. Exact parameters must be validated according to the laboratory’s procedures and the standard’s requirements.
Implementation tip: Laboratories should establish a robust maintenance schedule for SPME fibers. Fiber performance degrades over time; periodic checks with a control standard (e.g., atrazine at 1 µg/L) help identify when replacement is needed.
4. Compliance and Quality Assurance
Compliance with ISO 13959-15 is assessed through method validation and ongoing quality control. Key requirements include:
- Method detection limit (MDL): Determined using spiked reagent water (7–8 replicates at low concentration). MDL must be ≤ 0.1 µg/L for most compounds.
- Accuracy and precision: Recovery of spiked samples (fortified at mid‑range concentration) should be between 70% and 120%, with relative standard deviation ≤ 20%.
- Blank analysis: Method blanks must be free of target compounds (response less than MDL).
- Field duplicates: Relative percent difference (RPD) ≤ 30% for sample concentrations above 1 µg/L.
- Laboratory accreditation: Testing facilities should be accredited to ISO/IEC 17025 and include the SPME‑GC‑MS method in their scope.
Important: Non‑compliance with the calibration acceptance criteria or QC limits invalidates the analytical batch. Re‑analysis of all affected samples is mandatory unless corrective measures are documented and justified.
The standard also recommends participation in proficiency testing programs to verify inter‑laboratory comparability.
Frequently Asked Questions
Q: What types of water are covered by ISO 13959-15?
A: The standard applies to drinking water, surface water, groundwater, and treated industrial effluents. It is not validated for wastewaters with high turbidity or high organic content without prior dilution or filtration.
A: The standard applies to drinking water, surface water, groundwater, and treated industrial effluents. It is not validated for wastewaters with high turbidity or high organic content without prior dilution or filtration.
Q: Can I use a different SPME fiber than specified?
A: The standard recommends the use of DVB/CAR/PDMS fibers. A different fiber may be used if it can be demonstrated to provide equivalent or superior extraction efficiency and reproducibility for all target analytes. Validation studies must be performed to justify the change.
A: The standard recommends the use of DVB/CAR/PDMS fibers. A different fiber may be used if it can be demonstrated to provide equivalent or superior extraction efficiency and reproducibility for all target analytes. Validation studies must be performed to justify the change.
Q: How often should the GC‑MS system be calibrated?
A: A full calibration curve (5+ levels) must be established before sample analysis and verified every 12 hours by a continuing calibration check standard. The check standard concentration should be at the midpoint of the calibration range; if the drift exceeds ±20%, re‑calibration is required.
A: A full calibration curve (5+ levels) must be established before sample analysis and verified every 12 hours by a continuing calibration check standard. The check standard concentration should be at the midpoint of the calibration range; if the drift exceeds ±20%, re‑calibration is required.
Q: Is ISO 13959-15 recognized by regulatory agencies?
A: Yes, ISO 13959-15 has been adopted by several national standards bodies, including CSA in Canada (CAN/CSA-ISO 13959-15). It meets the requirements of many environmental monitoring programs and can be used for compliance with water quality regulations.
A: Yes, ISO 13959-15 has been adopted by several national standards bodies, including CSA in Canada (CAN/CSA-ISO 13959-15). It meets the requirements of many environmental monitoring programs and can be used for compliance with water quality regulations.
This article was prepared in 2026 and is provided for informational purposes. Always refer to the latest edition of the standard for official requirements.