LimsPulse
Fibre analyser · Calibration procedure

Recovery check with a reference material

Runs a reference material with a known crude fibre value through the full procedure and compares the result with the assigned value.

Illustration of Fibre analyser
PURPOSE

Why this is checked

Crude fibre is defined by the method, so the only meaningful check of the analyser is to show it reproduces the accepted value for a known material. This tests reagent strength, boiling time, filtration, drying and ashing together.

Frequency

Typically monthly, after maintenance and when new reagent batches are prepared, as defined in your SOP.

Learn how the Fibre analyser works
YOU WILL NEED

Standards & tools

  • Feed or cereal reference material with an assigned crude fibre value (certified or from a proficiency test)
  • Sulphuric acid and sodium hydroxide reagents checked for strength
  • Empty crucible reagent blank
BEFORE YOU START

Prerequisites

  • Analytical balance, drying oven and muffle furnace calibrated
  • Crucibles clean, ignited and free from cracks
  • Reagents prepared to the method strengths
PROCEDURE

Step by step

  1. 1Weigh duplicate portions of the reference material into prepared crucibles.
  2. 2Defat, then carry out the acid and alkali boils exactly as in the routine method.
  3. 3Dry, weigh, ash and weigh again.
  4. 4Run a blank crucible through the same steps.
  5. 5Calculate crude fibre %, the mean and the recovery against the assigned value.
RECORD

Example observation table

ReplicateCrude fibre found (%)Assigned value (%)Recovery (%)
17.717.8598.2
27.797.8599.2
Mean7.757.8598.7
CALCULATION

How to calculate the result

Formula
Recovery (%) = mean crude fibre found ÷ assigned value × 100
Worked example
  1. 1
    Mean = (7.71 + 7.79) ÷ 2 = 7.75%
  2. 2
    Recovery = 7.75 ÷ 7.85 × 100 = 98.7%
ACCEPTANCE CRITERIA

Pass if

  • Mean within the certified range (value ± uncertainty) or the proficiency test acceptance range (for example |z| ≤ 2)
  • Duplicates within the repeatability limit of the method
  • Blank change in crucible mass negligible
IF IT FAILS

What to do

  • Do not report crude fibre results from the batch.
  • Check reagent strength, boiling time, crucible frits and the ashing temperature.
  • Repeat the check after correction.
In LimsPulse · Calibration Management

LimsPulse schedules this calibration, records the result against limits, and blocks the instrument everywhere if it fails or goes overdue.

See how