Overview
ISO 5985:2002 - Animal feeding stuffs - Determination of ash insoluble in hydrochloric acid specifies laboratory procedures to measure the fraction of feed ash that is insoluble in dilute hydrochloric acid. The standard defines two procedures (A and B) depending on the sample matrix and sets out the principle, reagents, apparatus, test steps, precision data and reporting requirements for routine quality control and regulatory testing of animal feeding stuffs.
Key topics and technical requirements
- Scope and applicability
- Procedure A: for simple organic feeding stuffs and most compound feeds.
- Procedure B: for minerals, mineral mixtures and compound feeds where Procedure A shows >1% (mass fraction) ash insoluble in HCl.
- Analytical principle
- Incinerate the test portion to obtain ash, treat ash with 3 mol/L hydrochloric acid, filter, dry, incinerate residue and weigh the HCl‑insoluble ash; Procedure B treats the sample with HCl before incineration.
- Reagents and solvents
- Dilute hydrochloric acid (3 mol/L); trichloroacetic acid solutions (200 g/L and 10 g/L) for difficult-to-filter samples.
- Apparatus
- Analytical balance (0.001 g), muffle furnace controlled at 550 °C (±20 °C uniformity), drying oven (103 ± 2 °C), incineration dishes (platinum or Pt‑Au alloy recommended).
- Precision
- Repeatability and reproducibility are defined (examples from interlaboratory trials): fishmeal mean 8.2 g/kg with repeatability limit r = 0.8 g/kg and reproducibility limit R = 2.3 g/kg. Two determinations are required and results reported to 0.1% (mass fraction).
- Reporting
- Identify sample, sampling method, procedure used (A or B), operating details, any incidents, and final result (mean of two determinations if repeatability satisfied).
Applications and users
- Quality control laboratories in feed mills and ingredient suppliers
- Regulatory and accreditation laboratories enforcing feed safety and labelling
- Research labs studying mineral contamination, grit, soil or inert matter in feeds
- Use cases: verifying mineral content, detecting excessive soil/grit in raw materials, batch release testing, and compliance with feed composition specifications
Related standards
- ISO 5984 - Animal feeding stuffs - Determination of crude ash
- ISO 6498 - Animal feeding stuffs - Preparation of test samples (normative reference)
- ISO 6497 - Animal feeding stuffs - Sampling (recommended)
- ISO 5725 series - Accuracy (trueness and precision) of measurement methods (precision assessment)
Keywords: ISO 5985:2002, ash insoluble in hydrochloric acid, animal feeding stuffs, Procedure A, Procedure B, muffle furnace, analytical method, feed quality control, repeatability, reproducibility.