GIFSQ Tools · Module 14 — LIMS & Quality · Tool 277 of 500
Manage a working standard: its concentration after dilution, the total amount in the prepared volume, and the days left before it expires.
Try sample values — fills the form with the worked example below.
Saved on this device only.
| Date | Working conc (mg/mL) | Total (mg) | Days left | Expired |
|---|---|---|---|---|
| No saved results yet. | ||||
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Working concentration (mg/mL)
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Total standard (mg)
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Days left
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Expired
Equation: Working concentration (mg/mL) = stock concentration ÷ dilution factor. Total standard (mg) = working concentration × working volume (mL). Days left = prepared day + shelf life − today. The standard is expired when the days left are below zero.
Method: Reference standard handling per ISO 17034:2016 (general requirements for the competence of reference material producers) and ISO/IEC 17025:2017, clause 6.4: working standards are prepared by a recorded dilution from a certified stock, dated, and used only inside their shelf life.
Assumptions: the dilution is made up accurately to the stated factor; the shelf life is the laboratory shelf life for the working standard, not the stock expiry.
Limitations: the amount only covers the prepared volume — it does not track what has already been used from the bottle.
Rounding: concentration to 2 decimal places (4 when under 0.01 mg/mL); total to 2 decimal places; days left is a whole number; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value. Records are kept only in this browser on this device (localStorage); this is a device-only record aid, not a shared multi-user LIMS, and nothing is sent to any server.
Method: Reference standard handling per ISO 17034:2016 (general requirements for the competence of reference material producers) and ISO/IEC 17025:2017, clause 6.4: working standards are prepared by a recorded dilution from a certified stock, dated, and used only inside their shelf life.
Assumptions: the dilution is made up accurately to the stated factor; the shelf life is the laboratory shelf life for the working standard, not the stock expiry.
Limitations: the amount only covers the prepared volume — it does not track what has already been used from the bottle.
Rounding: concentration to 2 decimal places (4 when under 0.01 mg/mL); total to 2 decimal places; days left is a whole number; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value. Records are kept only in this browser on this device (localStorage); this is a device-only record aid, not a shared multi-user LIMS, and nothing is sent to any server.
Worked example: Stock 1,000 mg/mL diluted 100× into 10 mL, prepared day 100 with a 30-day shelf life, today day 110: working concentration 10.00 mg/mL, 100.00 mg in total, 20 days left.
Enter values above to see results.
Saved on this device only — entries stay in this browser and are never sent anywhere. Use the Clear button to remove them. Tool 277 of 500 — GIFSQ
