ISO 22855:2008

Overview

ISO 22855:2008 specifies a validated analytical method for the determination of benzoic acid and sorbic acid concentrations in fruit and vegetable juices using high-performance liquid chromatography (HPLC). Based on IFU method 63, the standard defines sample preparation, extraction, chromatographic conditions and calculation procedures to obtain reliable quantitative results for preservative residues in fruit and vegetable products.

Key topics and technical requirements

• Scope and principle: Extraction of benzoic and sorbic acids from juices with an ammonium acetate/acetic acid buffer–methanol mixture under acidic conditions, followed by quantification by reverse‑phase HPLC with UV detection.
• Reagents & solutions: HPLC‑grade methanol; ammonium acetate buffer (0.01 mol/l); extraction solution (60:40 buffer:methanol); eluent (≈50:40 ammonium acetate:methanol adjusted to pH 4.5).
• Standards and calibration: External calibration using stock standards diluted to 10, 25 and 50 mg/l; injection volume 10 µl; calibration by plotting peak area versus concentration.
• Chromatographic conditions: Reverse‑phase column (example: C8, 250 × 4.6 mm, 5 µm); flow rate ≈1.2 ml/min; UV detection at 235 nm (0.08 AUFS). Membrane filtration (0.45 µm) of extracts is required.
• Sample cleanup: Ultrasonic extraction for clear and cloudy samples; Carrez clarification (potassium hexacyanoferrate II and zinc sulfate) for turbid juices; paper filtration followed by membrane filtration.
• Calculation & reporting: External standard method for concentration calculation; results reported in mg/l to one decimal place. Test report must document sample ID, sampling method, method reference (ISO 22855), operating details and results.
• Precision: Precision was established in an IFU interlaboratory study (orange and grape juices). Reported repeatability and reproducibility limits demonstrate the method’s suitability for routine analysis (e.g., benzoic acid r ≈ 3.5 mg/l; R up to ≈13.9 mg/l in tested matrices).

Applications and users

• Food testing laboratories performing regulatory or quality control analysis of preservatives in fruit and vegetable juices.
• Producers and brand owners verifying compliance with national and international limits for benzoic and sorbic acids.
• Regulatory agencies and inspection bodies requiring a standardized HPLC method for enforcement and surveillance.
• Research groups studying preservative occurrence, migration or stability in fruit and vegetable products.

Related standards

• ISO 5725‑2 (precision - statistical treatment) referenced for expression of precision data.
• IFU method 63 (method basis) - informative reference cited in the standard.

Keywords: ISO 22855:2008, benzoic acid, sorbic acid, HPLC method, fruit and vegetable juices, preservative determination, high‑performance liquid chromatography.