ISO 10540-2:2003

Overview - ISO 10540-2:2003 (Phosphorus in fats and oils)

ISO 10540-2:2003 specifies a rapid, trace-level method for the determination of phosphorus in crude or refined animal and vegetable fats and oils using graphite furnace atomic absorption spectrometry (GFAAS). The method is applicable for phosphorus contents up to 40 mg/kg, with a stated limit of determination of 1.0 mg/kg. It is part of the ISO 10540 series on phosphorus determination in fats and oils.

Key topics and technical requirements

• Scope: Trace phosphorus (≤ 40 mg/kg) in animal and vegetable fats and oils; limit of determination 1.0 mg/kg.
• Analytical principle: Sample mixed with a matrix modifier and vaporized in a graphite furnace; phosphorus measured by atomic absorption at 213.5 nm.
• Reagents & standards:
  • Cyclohexane as solvent.
  • Lanthanum organometallic matrix modifier (lanthanum essential to measure total phosphorus reliably).
  • Soya lecithin used to prepare stock and working standards (typical working concentrations: 10, 20 and 40 mg/kg; stock ~400 mg/kg).
  • Blank oil (refined edible oil <1 mg/kg P).
  • Argon purge gas (purity 99.98%); nitrogen may be used with reduced sensitivity (warning about HCN formation above 2 300 °C).
• Instrumentation:
  • Atomic absorption spectrometer with graphite furnace atomizer and deuterium background corrector.
  • Electrode-less discharge/hollow cathode lamp for phosphorus.
  • Graphite tubes (with or without platform), micropipettor (20 µl) and optional autosampler.
• Procedure highlights:
  • Precondition samples and standards (oven 60 °C).
  • Inject 20 µl aliquots; use the calibration curve from soya lecithin standards corrected for blank oil.
  • Each new graphite tube requires conditioning with standards until stable response is achieved.
• Precision (examples from the standard): repeatability (r) and reproducibility (R) limits:
  • At 10 mg/kg: r = 2.5 mg/kg, R = 3.5 mg/kg
  • At 20 mg/kg: r = 4.7 mg/kg, R = 6.6 mg/kg
  • At 30 mg/kg: r = 6.5 mg/kg, R = 9.8 mg/kg

Applications and who uses it

• Routine quality control and trace analysis in edible oil/refinery laboratories.
• Analytical service laboratories performing compliance testing and product specification verification.
• Research and development groups studying lipid composition and minor components.
• Regulatory and standards bodies needing a validated method for phosphorus determination in fats and oils.

Related standards and references

• ISO 10540 series:
  • Part 1 - colorimetric method (ISO 10540-1)
  • Part 3 - ICP optical emission spectroscopy (ISO 10540-3)
• Normative references: ISO 661 (sample preparation), ISO 5555 (sampling guidance), and ISO precision guidance (ISO 5725 series).

Keywords: ISO 10540-2, phosphorus determination, graphite furnace atomic absorption spectrometry, GFAAS, fats and oils, trace phosphorus, soya lecithin standards, matrix modifier.