ISO 22104:2021

Overview

ISO 22104:2021 specifies a validated, performance‑based analytical method for the determination and quantification of microcystins in drinking water and freshwater using liquid chromatography coupled to tandem mass spectrometry (LC‑MS/MS). The standard covers 12 specified microcystin variants (microcystin‑LR, ‑LA, ‑YR, ‑RR, ‑LY, ‑WR, ‑HtyR, ‑HilR, ‑LW, ‑LF, [Dha7]‑microcystin‑LR and [Dha7]‑microcystin‑RR) over a working range of 0.05 µg/L to 1.6 µg/L. It is performance‑based, allowing laboratories to adapt sample‑handling or injection volumes provided all method performance criteria are met.

Key technical topics and requirements

• Analytical technique: Direct flow injection LC‑MS/MS with electrospray ionization and multiple reaction monitoring (MRM); internal standard calibration (nodularin commonly used).
• Target analytes: Twelve microcystin congeners listed above; method may be extended to additional congeners after validation of chromatographic and MS conditions for each.
• Sample preparation: Homogenization, freeze/thaw cell lysis, centrifugation and filtration prior to injection. Annexes describe alternatives:
  • Annex A - High‑resolution mass spectrometry (HRMS) as an alternative detector.
  • Annex B - On‑line solid‑phase extraction (automated on‑line SPE) coupled to LC for higher throughput.
  • Annex C - Manual SPE clean‑up/concentration when instrument sensitivity is insufficient.
• Calibration & quantification: Multi‑point calibration with internal standard; non‑linear (quadratic) curve fitting is expected due to response variability across concentration ranges.
• Quality & interference considerations: Use inert labware (unscratched borosilicate or polyethylene) to avoid adsorption losses; check blanks for nodularin in brackish samples; high organic matrices (e.g., humic‑rich waters) may require extra clean‑up or HRMS for selectivity.
• Scope limitations: Method validated for water samples (drinking and freshwater). Applicability to very high organic content matrices is not established.

Practical applications and users

• Who uses it: Water quality laboratories, public health agencies, environmental monitoring organizations, drinking water utilities, and contract testing labs responsible for cyanotoxin monitoring and regulatory compliance.
• Practical value: Provides a standardized LC‑MS/MS procedure for reliable microcystin screening and quantification, guidance on method extensions (additional congeners), and options to improve sensitivity (on‑line or manual SPE, HRMS).
• Use cases: Routine monitoring of drinking water sources, bloom event investigations, compliance testing, and method development/validation for added microcystin congeners.

Related standards and references

• ISO 3696 - Water for analytical laboratory use (recommended water quality for reagents and solvents).
• ISO 20179 - HPLC‑UV methods for confirmation/purity checks of toxin standards.
• Prepared by ISO/TC 147 (Water quality).

Keywords: ISO 22104:2021, microcystins, LC‑MS/MS, water quality, drinking water, freshwater, on‑line SPE, HRMS, internal standard calibration, MRM, solid‑phase extraction.