Overview
ISO 10519:2015 specifies a laboratory spectrometric method for the determination of chlorophyll content in rapeseed (expressed as mg/kg chlorophyll a). The method covers sample preparation, extraction, spectrometric measurement and calculation of results. It is explicitly not applicable to chlorophyll determination in oils. ISO 10519:2015 is intended for routine quality control, research and inter‑laboratory comparability for oilseed/rapeseed material.
Key topics and technical requirements
- Principle: solvent extraction of ground rapeseed followed by absorbance measurement and baseline correction.
- Sample preparation:
- Reduce laboratory sample to test sample per ISO 664.
- If moisture > 10% (m/m), dry for 12 h at 45 °C to protect chlorophyll.
- Grind ~50 g to a uniform sample; use 2 g test portions for extraction.
- Extraction solvent:
- Use anhydrous solvent mix (example given: 100 ml anhydrous ethanol + 300 ml anhydrous iso‑octane or anhydrous n‑heptane or anhydrous petroleum ether).
- Add 30 ml solvent to 2 g test portion.
- Apparatus:
- Mechanical grinder or microgrinder/ball mill (stainless tubes, Ø16 mm balls, 240 min⁻¹ horizontal shake or commercial ball mill).
- Spectrometer capable of absorbance 600–700 nm, spectral bandwidth ~2 nm; optical cell path length ≥ 1 cm.
- Measurement:
- Measure absorbance at 665 nm, 705 nm and 625 nm.
- Corrected absorbance: A_corr = A665 − (A705 + A625)/2.
- Calculation: w (mg/kg) = (k × A_corr × V) / (l × m) with k = 13; V = solvent volume (mL); l = cell path length (cm); m = test portion mass (g).
- Precision:
- Repeatability: difference between two results in same lab should not exceed 10% of mean.
- Reproducibility: difference between labs should not exceed 20% of mean.
- Reporting: include method, sampling reference, test results, any deviations, moisture basis if reporting dry‑product values.
Applications and users
- Quality control laboratories in seed processing, oilseed trading and agronomy.
- Plant breeding and research groups monitoring chlorophyll content for varietal assessment or harvest timing.
- Inspection bodies verifying rapeseed quality for trade specifications.
- R&D teams developing extraction or spectrometric methods for oilseeds (note: method excludes oils).
Related standards
- ISO 664 (reduction of laboratory sample to test sample)
- ISO 665 (moisture determination for oilseeds)
- ISO 648 (pipettes)
- ISO 542 (sampling recommendations)
- ISO 5725 (precision assessment methodology)
Keywords: ISO 10519:2015, rapeseed chlorophyll, chlorophyll determination, spectrometric method, oilseeds, extraction solvent, absorbance 665 nm.
