LIMS vs Excel: the hidden cost of registers in a testing lab

Where does a lab on registers and Excel lose money?

The losses come from copying data between places that do not talk to each other: the analyst's register, the calculation sheet, the report template and the invoice book. Every copy adds work, and every copy is a chance to make a mistake.

How many times is one reading typed in an Excel lab?

In most register-and-Excel labs, a single reading is recorded three times before it reaches the customer. Each copy takes time, and each one has to be checked.

Take a chloride titration. The chemist writes a titre of 18.9 mL in the register. In the afternoon, she types 18.9 into the chloride sheet in Excel, which calculates 186.9 mg/L. The next morning, the report typist opens a Word template and types 186.9 into the report. The same number has now been handled three times by two people.

ISO/IEC 17025:2017 clause 7.11.6 says "Calculations and data transfers shall be checked in an appropriate and systematic manner". In an Excel lab, every one of those transfers needs a checker. In practice, the check is often a glance at the final report, which cannot catch an error made in the register-to-Excel step.

What calculation errors happen in Excel lab sheets?

Spreadsheet errors are rarely dramatic. They are small, silent and repeated until someone notices. These are the ones we see most often:

• A stale input. A chemist copies yesterday's COD sheet to save time. The FAS normality cell still holds yesterday's value, and every result on today's sheet is slightly wrong.
• An overwritten formula. Someone types a result straight into a formula cell to "fix" a row. The sheet looks normal, but that cell no longer calculates.
• A broken reference. A row is inserted, and one sample's formula now points at the wrong blank.
• A missing dilution factor. An effluent was diluted ten times, but the sheet has no column for it, so the analyst multiplies in her head.
• Units. A filter weight is entered in grams where the sheet expects milligrams.
• Rounding. One sheet rounds to one decimal, another to whole numbers, and the report shows a third.

Clause 7.11.2 of ISO/IEC 17025 requires the laboratory information management system to be "validated for functionality" before use. Excel sheets that process and record results are part of that system, and Note 1 to the clause extends it even to paper records. Many labs have never validated their Excel sheets, and that is where findings begin.

How do transcription errors reach the customer?

Most errors in lab reports that come from copying survive because the reviewer checks the wrong copy. If the Technical Manager compares the report with the Excel sheet, a mistake made between register and Excel passes straight through.

A typical case: two drinking water samples sit on adjacent rows. The typist copies the iron result of row 7 into the report for sample 8. Both values are plausible, the report is signed, and the error is found only when the customer's own retest disagrees. Now the lab has to investigate, withdraw the report, issue an amendment and explain to the customer why its results cannot be trusted.

Why are holding times missed in a register-based lab?

A register cannot warn you. Microbiology, BOD and other short-holding-time tests must start within hours of sampling, and a paper system depends on someone remembering.

Picture a Friday evening: six bore well samples arrive for coliforms at 5.30 pm. The front office writes them in the inward register, but the microbiologist has already left. On Monday, nobody can say for certain whether the tests started in time, and the report either hides the problem or the samples have to be collected again. Assessors check holding-time records for exactly this reason.

Why do reports go out with the wrong limits?

Report templates are copied, and old limits travel with them. A Word template built years ago may still carry IS 10500 limits from before the amendments, such as iron 0.3 mg/L or boron 1.0 mg/L. Our IS 10500 guide lists the current values.

Effluent reports have a different trap. Under the E(P) Rules Schedule VI, the COD limit depends on where the effluent is discharged. If the typist picks the wrong template, a result can be reported as passing or failing against a limit that does not apply. Drinking water has its own trap: a chloride of 595 mg/L is above the acceptable limit but within the permissible limit, and a template with a single "Complies" column cannot say that.

How do samples get lost or mixed up?

Samples get lost when the bottle, the register and the report are linked only by handwriting. ISO/IEC 17025 clause 7.4.2 asks for "a system for the unambiguous identification of test or calibration items", so that items "will not be confused physically or when referred to in records".

With marker-pen codes on bottles and a running number in a register, a smudged label or two samples entered in the wrong order is enough. The cost is a lost customer sample, a repeat collection and an awkward phone call.

What does rework really cost?

Rework is the most expensive loss because it is paid for twice. The analysis is repeated, the review is repeated and, if the report has already gone out, an amended report has to be issued and explained.

In an Excel lab, rework also destroys evidence. When a chemist re-analyses a sample, the old figures are usually overwritten in the sheet. If an assessor later asks what the first result was and why it was rejected, the answer depends on memory.

Why do Excel labs deliver reports late?

Reports run late because nobody can see the whole queue. The front office knows what came in, each chemist knows his own register, and the Technical Manager knows what is on her desk. When a customer calls to ask about his report, someone has to walk round the lab to find out.

Late reports cost more than goodwill. Industrial customers with consent deadlines and food businesses waiting to release a batch may move to a lab that tells them when their report will be ready, and then meets that date.

What do NABL assessors find in Excel-based labs?

Findings in spreadsheet-based labs often concern data control: unvalidated calculation sheets, unprotected formula cells, results changed without a record of the earlier value, and no proof of when a test started. Our guide to common NABL nonconformities covers these in detail.

Clause 7.11.3 of ISO/IEC 17025 asks that information management systems be "protected from unauthorized access", "safeguarded against tampering and loss" and that system failures be recorded. An Excel file on a shared desktop meets none of these easily.

What happens to lab data when the power goes or the PC fails?

In many labs, years of results live on one desktop PC. A power cut while a sheet is open can lose an afternoon's entries. A failed hard disk or a ransomware infection can lose everything since the last backup, if there was one.

Imagine the chemist has entered thirty BOD readings when the power goes and the UPS gives out. When the PC restarts, the file has reverted to its last save. She now has to re-enter everything from the register, assuming she wrote it all down first.

How does a LIMS remove each of these losses?

In the LIMS vs Excel comparison, a LIMS removes these losses by keeping every step of a sample in one system: inward, worksheet, calculation, limit check, review and report. Data is entered once and flows forward. A LIMS is not magic, though, and clause 7.11.2 still requires you to validate it before use.