Keep trustworthy lab records, query LIMS data, run QC with Westgard rules, build calibration curves, estimate uncertainty, and work within SOPs, CAPA and accreditation.

Lab Data & Quality

Choose a measurement: for example, checking whether your kitchen measuring cup really holds 250 mL by weighing the water it holds on a kitchen scale (water is close to 1.00 g per mL).

Start a new page. Write the date, a title, the objective and a page number.

Write a short procedure in numbered steps before you begin, as if it were an SOP (give it a made-up number and version, such as SOP-HOME-001 v1).

List your materials and equipment with identifiers: for example, "scale: brand and model, readability 1 g" and "cup: marked 250 mL".

Do the measurement three times. Record every reading in ink as you take it, with units.

Deliberately make one recording error, then correct it properly: a single line through the wrong value, the right value, your initials, the date and a reason.

Show your calculation of the mean and of the difference from 250 g.

Write a one-line result and conclusion, and note any deviation from your written procedure (or write "Deviation: none").

Sign and date the entry, then cross out any unused space on the page.

Swap with a friend or classmate if you can: can they repeat your measurement from your entry alone?

## 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 |
|---|---|---|
| **A**ttributable | You can tell who recorded it and who did the work | Initials or signature, user login in an ELN |
| **L**egible | Anyone can read it, now and later | Permanent ink, clear handwriting |
| **C**ontemporaneous | Recorded at the time it happened | Write as you go, not at the end of the day |
| **O**riginal | The first record, or a certified true copy | Raw instrument printouts kept, not retyped |
| **A**ccurate | 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

```text
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

1. **Date, title and objective.** What are you trying to do?
2. **Reference to the method.** SOP number and version, or a full procedure if it is new.
3. **Materials.** Reagents with **lot numbers and expiry dates**, sample IDs, standards with certificate numbers.
4. **Equipment.** Instrument IDs, and confirmation that calibration was current.
5. **Procedure as performed.** Especially any change from the written method.
6. **Raw data and observations.** Every reading with units, colours, times, anything unexpected.
7. **Calculations.** Show the formula and the numbers, not just the answer.
8. **Results and conclusion.** What the data show, and whether acceptance criteria were met.
9. **Deviations.** Anything that did not go to plan, and the deviation number if one was raised.
10. **Signature** (and reviewer or witness, if required).

### Worked example (short)

```text
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.


Write a complete, ALCOA+-compliant notebook entry and know what an electronic lab notebook adds.

Lab notebooks and ELNs

Ten Tips For Keeping a Better Lab Notebook

Chemistry Lab Skills: Maintaining a Lab Notebook

## Why it matters

A busy lab handles thousands of samples a day. Each one must be matched to the right patient or batch, tested by the right method on a calibrated instrument, reviewed, reported to the right person and stored or discarded on time. Paper cannot keep up. Laboratory information systems do this work, and almost every lab job involves using one. Understanding how they track a sample makes you faster, and it helps you spot when something has gone wrong.

## LIMS, LIS and ELN

| System | Typical setting | Centred on |
|---|---|---|
| **LIMS** (laboratory information management system) | Research, pharmaceutical QC, environmental, food, contract testing labs | Samples, batches, tests, specifications, instruments |
| **LIS** (laboratory information system) | Hospital and clinical labs | Patients, orders from clinicians, results reported to the medical record |
| **ELN** (electronic lab notebook) | Research and development | Experiments and the scientist's narrative |

The lines blur: many products combine features. The key difference is focus. A LIS lives inside the healthcare system and exchanges orders and results with the electronic health record, often using the **HL7** messaging standard. A LIMS is built around samples, specifications and batch release.

## The life of a sample

Whatever the system, a sample follows the same broad path.

1. **Order or request.** A clinician orders tests (LIS), or a production step triggers QC testing (LIMS).
2. **Collection and labelling.** The sample gets a unique ID, usually a **barcode**. Clinical labs require at least **two patient identifiers** (such as full name and date of birth) on the tube.
3. **Receipt and accessioning (login).** The lab checks the sample against the request: right container, right volume, labelled correctly, received in time and at the right temperature. Samples that fail are **rejected** with a reason, and the requester is told.
4. **Chain of custody.** Every handover is recorded. For forensic, drug testing and some environmental work, the chain of custody is a legal requirement.
5. **Test assignment and worklists.** The system assigns tests and builds worklists or instrument run lists.
6. **Analysis.** Instruments receive the run list and send results back through an **instrument interface**, avoiding retyping.
7. **Review and approval.** QC must pass for the run. Results are checked against specifications or reference ranges. Many clinical labs use **autoverification**: rules that release normal results automatically and hold unusual ones for a person to review.
8. **Reporting.** Results go to the clinician, the medical record, or a certificate of analysis for a batch. **Critical values** (results that suggest immediate danger to a patient) are phoned to a responsible person and the call is documented.
9. **Storage and disposal.** The sample is kept for its retention period, then discarded, and the system records where it is and when it went.

## What the system remembers

A LIMS or LIS keeps far more than results:

- **Specifications and reference ranges**, so out-of-range values are flagged.
- **QC results** for each run, linked to the patient or sample results they cover.
- **Instrument status**, including calibration and maintenance due dates. Many systems block a run on an instrument that is overdue.
- **Reagent lots** used in each run.
- **Analyst training records**, so only qualified people can enter or approve certain tests.
- **An audit trail** of every change.

Because all of this is linked, the lab can answer questions like "which results used reagent lot K2291?" or "which samples ran on HPLC-02 after its last good calibration?" in seconds. In the next lesson you will write those queries yourself in SQL.

## Worked example: tracing a sample

A QC sample from tablet batch B-102 has ID S-2051.

- Logged in at 09:14 by AB; condition acceptable; stored at room temperature, shelf R3.
- Assigned: assay (HPLC) and dissolution.
- Assay run on HPLC-02, run R-778, system suitability passed, result 99.1 percent of label claim (specification 95.0 to 105.0).
- Reviewed by CD at 15:02; approved.
- Certificate of analysis generated for batch B-102 after all tests passed.

If an auditor asks how 99.1 percent was obtained, every link (sample, run, instrument, analyst, reviewer) is in the system.

## Common mistakes

- Relabelling a tube by hand instead of reprinting through the system.
- Accepting a sample that does not match its request "to save time".
- Entering results by hand when an instrument interface exists, which introduces transcription errors.
- Sharing logins, which destroys attribution.
- Ignoring a system warning about an overdue calibration.

## Quick recap

- LIMS focuses on samples and batches; LIS on patients and clinical orders; ELN on experiments.
- A sample moves through request, labelling, accessioning, testing, review, reporting and storage, with each step recorded.
- Specifications, QC, instruments, reagents, training and audit trails are linked, which makes tracing possible.

## Try it

This lesson is quiz-only. Open the **Do** tab to check your understanding.


Trace a sample through a LIMS or LIS, from request and accessioning to review, reporting and storage.

LIMS and LIS

Introduction to Laboratory Informatics: Life of a Specimen – What is a LIMS?

What is the difference between an LIS and a LIMS?

## Why it matters

A LIMS stores its records in a relational database, and the questions a lab asks every day are database queries. Which samples from this batch are still untested? What did HPLC-02 measure after its last good calibration? Which results used reagent lot K2291? Most LIMS screens are built on queries like these, and many labs let analysts and QC reviewers run read-only reports in **SQL** (Structured Query Language). You do not need to be a programmer to read and adapt a simple query. This lesson shows the handful of SQL pieces that cover most lab questions.

## Tables and keys

A lab database splits information into tables so each fact is stored once:

- `samples`: one row per sample, with `sample_id`, `batch_id`, `sample_type` and `received_date`.
- `results`: one row per result, with `result_id`, `sample_id`, `analyte`, `value`, `units`, `run_date` and `instrument_id`.

`sample_id` is the **primary key** of `samples` (unique for each sample) and appears in `results` as a **foreign key**, linking each result to its sample. One sample can have many results: an assay, a water content, a dissolution test.

## SELECT, FROM, WHERE, ORDER BY

```sql
SELECT sample_id, value, run_date
FROM results
WHERE analyte = 'assay'
ORDER BY run_date;
```

- `SELECT` lists the columns you want.
- `FROM` names the table.
- `WHERE` keeps only rows that meet a condition. Text values go in single quotes.
- `ORDER BY` sorts the output (add `DESC` for newest first).

Combine conditions with `AND` and `OR`, and use parentheses when you mix them:

```sql
WHERE analyte = 'assay' AND (instrument_id = 'HPLC-01' OR instrument_id = 'HPLC-02')
```

### Dates

Many systems store dates as `YYYY-MM-DD` text, which sorts correctly. A date range uses `BETWEEN`, which includes both ends:

```sql
WHERE run_date BETWEEN '2026-10-01' AND '2026-10-07'
```

If a column stores a full timestamp (`2026-10-07 14:30`), `BETWEEN '2026-10-01' AND '2026-10-07'` misses results from later on the 7th. Use `run_date < '2026-10-08'` for the upper end in that case.

## Joining tables

The batch is stored on the sample, not on the result. To see results by batch, **join** the tables on the shared key:

```sql
SELECT r.sample_id, s.batch_id, r.analyte, r.value
FROM results AS r
JOIN samples AS s ON s.sample_id = r.sample_id
WHERE s.batch_id = 'B-102';
```

`AS r` and `AS s` are short aliases, so `r.value` means the `value` column of `results`. `JOIN ... ON` pairs each result with its sample row.

## Counting and summarising

```sql
SELECT s.batch_id, COUNT(*) AS n_results, ROUND(AVG(r.value), 2) AS mean_assay
FROM results AS r
JOIN samples AS s ON s.sample_id = r.sample_id
WHERE r.analyte = 'assay'
GROUP BY s.batch_id;
```

`GROUP BY` makes one output row per batch, and `COUNT`, `AVG`, `MIN` and `MAX` summarise each group.

## Worked example: an instrument question

HPLC-02 failed its calibration check on 2026-10-09. The last good calibration was 2026-10-04. Which results need review?

```sql
SELECT sample_id, analyte, value, run_date
FROM results
WHERE instrument_id = 'HPLC-02'
  AND run_date >= '2026-10-04'
ORDER BY run_date, sample_id;
```

This is the kind of query a QC reviewer runs during an investigation. The output is the list of results to assess.

## Good habits

- **Read-only.** Reporting queries use `SELECT` only. Changing records (`UPDATE`, `DELETE`) in a regulated system happens only through the application, with an audit trail, never by hand in the database.
- **Check the row count.** If you expected 3 rows and got 300, a condition is missing.
- **Be exact with text.** `'B-102'` and `'b-102'` may not match, and stray spaces matter.
- **Name your columns** in `SELECT` instead of using `SELECT *`, so reports stay stable when the table changes.

## Common mistakes

- Forgetting the join condition, which pairs every result with every sample.
- Using double quotes for text values (in many databases double quotes mean a column name).
- Mixing `AND` and `OR` without parentheses.
- Forgetting that `BETWEEN` includes both ends.

## Quick recap

- `SELECT` columns, `FROM` a table, `WHERE` conditions, `ORDER BY` for sorting.
- `JOIN ... ON` links results to samples through `sample_id`.
- `GROUP BY` with `COUNT` and `AVG` summarises by batch or instrument.
- Reporting queries are read-only; changes go through the application and its audit trail.

## Try it

Open the **Do** tab. The query already joins the tables and sorts the rows: you add one `WHERE` clause to pull one batch's assay results for one week.


Query lab results by sample, batch and date with SELECT, WHERE, JOIN and GROUP BY.

Querying sample data

Learn Basic SQL in 15 Minutes | Business Intelligence For Beginners | SQL Tutorial For Beginners 1/3

Write ALCOA+ notebook entries, trace samples through a LIMS or LIS, and query sample results in SQL.