GIFSQ Tools · Module 1 — Food Composition & Proximate Analysis · Tool 19 of 500
Plan how much sample to weigh out for a run: replicates plus spares, each at the same aliquot weight. Enter the sample you have and the aliquot size.
Try sample values — fills the form with the worked example below.
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Sample needed (g)
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Sample left (g)
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Aliquots planned
Equation: Aliquots planned = replicates + spares
Sample needed = aliquot weight × aliquots planned
Sample left = sample available − sample needed.
Method: Laboratory sample preparation planning, AOAC / ISO 17025 practice — weigh enough for the planned repeats plus spares for a retest, and record the balance.
Assumptions: each aliquot weighs the same; the sample is uniform, so any portion stands for the whole; spares are weighed at the same time as the tests.
Limitations: the plan does not cover subsampling error — a non-uniform sample needs mixing and quartering first; it does not allow for spillage or reweighs.
Rounding: results to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Sample needed = aliquot weight × aliquots planned
Sample left = sample available − sample needed.
Method: Laboratory sample preparation planning, AOAC / ISO 17025 practice — weigh enough for the planned repeats plus spares for a retest, and record the balance.
Assumptions: each aliquot weighs the same; the sample is uniform, so any portion stands for the whole; spares are weighed at the same time as the tests.
Limitations: the plan does not cover subsampling error — a non-uniform sample needs mixing and quartering first; it does not allow for spillage or reweighs.
Rounding: results to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Sample available 50.00 g, aliquot 2.00 g, 3 replicates plus 1 spare. Aliquots planned = 3 + 1 = 4. Sample needed = 2.00 × 4 = 8.00 g. Sample left = 50.00 − 8.00 = 42.00 g — enough, with 42.00 g to spare.
Enter values above to see results.
Always plan at least one spare aliquot for a retest. If the sample left is negative, weigh a smaller aliquot, cut the spares, or get more sample. Tool 19 of 500 — GIFSQ
