Write a complete, ALCOA+-compliant notebook entry and know what an electronic lab notebook adds.
Why it matters
In a lab, if it was not written down, it did not happen. Your notebook is the legal and scientific record of what you did, when, with what, and what you saw. Patent disputes have been decided on notebook entries. Regulators reject results that cannot be reconstructed from records. And on a practical level, six months from now you, or a colleague, will need to repeat or troubleshoot your work from what you wrote today.
ALCOA+: the data integrity standard
Regulators and quality systems describe good records with the acronym ALCOA, extended to ALCOA+:
| Letter | Meaning | In practice |
|---|---|---|
| Attributable | You can tell who recorded it and who did the work | Initials or signature, user login in an ELN |
| Legible | Anyone can read it, now and later | Permanent ink, clear handwriting |
| Contemporaneous | Recorded at the time it happened | Write as you go, not at the end of the day |
| Original | The first record, or a certified true copy | Raw instrument printouts kept, not retyped |
| Accurate | Correct and complete, with no undocumented edits | Real values, every digit, errors corrected properly |
| + Complete, Consistent, Enduring, Available | Nothing missing, in order, lasting, retrievable | Numbered pages, dated entries, backed up |
The US FDA's data integrity guidance for drug manufacturing uses these principles: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/data-integrity-and-compliance-drug-cgmp-questions-and-answers (Checked on 2026-10-23.)
Rules for a paper notebook
- Use a bound notebook with numbered pages. Do not tear out pages.
- Write in permanent ink, never pencil.
- Date every entry and sign or initial it. Many regulated labs also require a witness or reviewer signature.
- Never erase, use correction fluid or overwrite. Correct an error with a single line through it, so the original is still readable, then write the correct value with your initials, the date and a short reason.
- Do not leave blank spaces that someone could fill in later. Cross out unused space on a page.
- Attach printouts permanently and sign across the edge of the attachment and the page.
- Record what actually happened, including mistakes and failed runs.
A correction done right
Mass of standard: 0.2514 g 0.2541 g AB 2026-10-23 transcription error, value re-read from balance printout
(In a notebook, the first value has a single line through it.)
What a complete entry contains
- Date, title and objective. What are you trying to do?
- Reference to the method. SOP number and version, or a full procedure if it is new.
- Materials. Reagents with lot numbers and expiry dates, sample IDs, standards with certificate numbers.
- Equipment. Instrument IDs, and confirmation that calibration was current.
- Procedure as performed. Especially any change from the written method.
- Raw data and observations. Every reading with units, colours, times, anything unexpected.
- Calculations. Show the formula and the numbers, not just the answer.
- Results and conclusion. What the data show, and whether acceptance criteria were met.
- Deviations. Anything that did not go to plan, and the deviation number if one was raised.
- Signature (and reviewer or witness, if required).
Worked example (short)
2026-10-23 Prep of 0.10 M phosphate buffer, pH 7.40, 1 L p. 47
Objective: buffer for enzyme assay EA-12 (SOP-BUF-004 v3)
Materials: Na2HPO4 anhydrous, lot K2291, exp 2028-02; NaH2PO4 anhydrous, lot J1170, exp 2027-11
Equipment: balance BAL-02 (daily check pass 08:05), pH meter PH-03 (cal 08:12, slope 96.1 percent)
Weighed: Na2HPO4 8.6283 g; NaH2PO4 4.7069 g
Dissolved in ~800 mL DI water, 22.4 C. pH read 7.36; adjusted with 0.5 mL 1 M NaOH to 7.40.
Made up to 1000 mL in flask VF-1000-03. Labelled BUF-1023-01, exp 2026-11-23, stored 4 C.
Deviation: none. AB 2026-10-23
Electronic lab notebooks (ELNs)
Many labs now use an ELN. It brings templates, search, links to instrument files and sample records, and automatic time stamps. In regulated work, US rules for electronic records and signatures are in 21 CFR Part 11 (https://www.ecfr.gov/current/title-21/chapter-I/subchapter-A/part-11, checked on 2026-10-23). Key features you should expect:
- Unique user logins, never shared accounts.
- An audit trail that records who changed what, when, and why, and cannot be switched off by users.
- Electronic signatures linked to the person.
- Backups and controlled access.
The ALCOA+ principles apply exactly the same way. An ELN that lets anyone edit an entry without a trace is not meeting them.
Common mistakes
- Writing results on a glove, paper towel or sticky note and copying them later. That breaks "original" and "contemporaneous".
- Recording only the final answer, not the raw readings.
- Omitting lot numbers, so a bad reagent lot cannot be traced.
- Scribbling out an error until it is unreadable.
- Sharing an ELN login with a colleague.
Quick recap
- Follow ALCOA+: attributable, legible, contemporaneous, original, accurate, plus complete, consistent, enduring, available.
- Bound notebook, permanent ink, dated and signed, single-line corrections with initials, date and reason.
- A complete entry lets someone else repeat your work: method, lots, instrument IDs, raw data, calculations, deviations.
- ELNs add audit trails and e-signatures; in regulated labs they fall under 21 CFR Part 11.
Try it
Open the Do tab to write a complete notebook entry for a simple kitchen measurement.