Static and Dynamic: Why a Printed Chromatogram Is Not the Raw Data

There is a natural assumption that paper is the safest place to keep a result. Print it, sign it, file it, and nothing can happen to it. For some instruments that is exactly right. For others it is the one thing you are told not to do, and the reason is worth understanding, because it also explains what a PDF certificate can and cannot tell you.

Quick answer

What is the difference between a static and a dynamic record? The UK MHRA defines a static record format as one that is fixed and allows little or no interaction between the user and the record content, and a dynamic record as one that allows an interactive relationship between the user and the record content. The US FDA uses the same split: static indicates a fixed-data record such as a paper record or an electronic image, while dynamic means the record format allows interaction between the user and the record content.

The consequence is a rule about what counts as raw data. The MHRA states that information originally captured in a dynamic state should remain available in that state, and that where data has been captured in a dynamic state and generated electronically, paper copies cannot be considered as raw data.

The chromatogram, both ways

Both agencies reach for chromatography to illustrate the point, and their examples are almost interchangeable.

The MHRA: once printed or converted to static electronic format, chromatography records lose the capability of being reprocessed or enabling more detailed viewing of baselines. Whereas chromatography records maintained as electronic records allow the user or reviewer, with appropriate access permissions, to reprocess the data and expand the baseline to view the integration more clearly.

The FDA: a dynamic chromatographic record may allow the user to change the baseline and reprocess chromatographic data so that the resulting peaks may appear smaller or larger.

Notice that the agencies describe the same capability from two directions. The MHRA frames reprocessing as what a reviewer needs — the ability to go back and look at how the baseline was drawn. The FDA frames it as what an analyst could do — make peaks appear smaller or larger. Both are true of the same file, and that is precisely why it has to be kept in the form that permits either.

A printed chromatogram cannot be checked. You can see where the integration lines were placed; you cannot see whether placing them elsewhere was defensible. What that review involves is the subject of reprocessing and manual integration.

Where the printout is the original

The rule is not an instruction to distrust paper. It is a rule about matching the record to the instrument.

The MHRA is explicit: in the case of basic electronic equipment that does not store electronic data, or provides only a printed data output — it names balances and pH meters — then the printout constitutes the raw data. The FDA agrees: during data acquisition, pH meters and balances may create a paper printout or static record as the original record, and in that case the paper printout, or a true copy, must be retained.

PIC/S adds the practical handling. Simple electronic systems such as balances, pH meters or simple processing equipment which do not store data generate directly-printed paper records, and these records provide limited opportunity to influence the presentation of data by reprocessing or by changing electronic date and time stamps. In those circumstances the original record should be signed and dated by the person generating it, and information to ensure traceability — sample ID, batch number — should be recorded on the record itself, which should then be attached to the batch processing or testing record.

So the slip from the balance, initialled and stapled into the notebook, is a complete and compliant original. The printed HPLC trace, filed the same way, is a picture of one.

The test is the instrument, not the format

The MHRA puts the general principle in a single line: where the capability of the electronic system permits dynamic storage, it is not appropriate for static printed or manual data to be retained in preference to dynamic electronic data.

What a printout silently leaves out

The FDA makes one observation about printed spectra that is easy to miss and hard to forget once read. Discussing stand-alone laboratory instruments, it notes that a static record or printout is fixed and would not satisfy the requirement to retain original records — and then adds: also, if the full spectrum is not displayed in the printout, contaminants may be excluded.

The printout is not merely less useful than the file. It can be less complete in a way that removes evidence of the thing you were testing for. A spectrum cropped to the region of interest is a perfectly honest-looking document that cannot show you what was outside the window.

The same structural problem appears whenever a result is reported as a figure rather than a trace, which is why not detected is not zero and why reading the chromatogram tells you more than reading the purity line.

When paper is allowed to stand in: the true copy

A true copy is the recognised route to replacing an original, and the definition is demanding. The MHRA defines it as a copy, irrespective of the media used, of the original record that has been verified — by a dated signature or by generation through a validated process — to have the same information, including the data that describe the context, content and structure, as the original. A true copy may be stored in a different file format from the original if required, but must retain the metadata and audit trail needed to ensure the full meaning of the data is kept and its history can be reconstructed.

The FDA frames the same requirement in terms of what must survive the copy: electronic copies can be used as true copies provided they preserve the content and meaning of the original record, which includes all metadata required to reconstruct the activity and the static or dynamic nature of the original records.

That final clause is the crux. A true copy of a dynamic record has to stay dynamic. Printing it does not copy it; it converts it.

The paper route, costed out

The MHRA does not forbid keeping electronic data in paper form outright. It says it is conceivable for some data generated by electronic means to be retained in an acceptable paper or electronic format, where it can be justified that a static record maintains the integrity of the original data — and then lists what that would actually require. The retention process must be shown to include verified copies of all raw data, all metadata, the relevant audit trail and result files, any variable software or system configuration settings specific to each record, and all data processing runs including methods and audit trails necessary for reconstruction of a given raw data set. It would also require a documented means of verifying that the printed records were an accurate representation.

Its own conclusion: to enable a compliant record, this approach is likely to be demanding in its administration.

Which is a measured way of saying that printing everything is more work than keeping the file, not less.

Enduring is the attribute that fails quietly

Keeping the dynamic file solves one problem and creates another, because software outlives nothing. The MHRA addresses it directly: archive arrangements must be designed to permit recovery and readability of the data and metadata throughout the required retention period, and when legacy systems can no longer be supported, consideration should be given to maintaining the software for data accessibility purposes — which, it suggests, may be achieved by maintaining software in a virtual environment.

Where that is not possible, migration involves a real trade-off, and the guidance names it. The migration file format should be selected considering the balance of risk between long-term accessibility versus the possibility of reduced dynamic data functionality, such as data interrogation, trending and reprocessing. It is recognised, the document says, that the need to maintain accessibility may require migration to a format that loses some attributes.

So the honest position is not that dynamic data must be preserved forever in full fidelity. It is that losing fidelity should be a decision with a rationale, not an accident.

What to ask, and what to conclude

• Ask which instrument produced a figure before judging the paperwork. A balance result and a chromatographic result have different original records, and the same filing practice is correct for one and wrong for the other.
• Treat a PDF certificate as a static record, because it is one. It cannot be reprocessed, which also means it cannot be re-examined.
• Check whether a reported spectrum shows the full range. A cropped window is where an unexpected peak would not be.
• Do not read signed-and-filed as equivalent to retained. For a dynamic record, the signature is on the picture.
• Where a result matters, ask what method produced it rather than asking for the file. A dynamic file you cannot open is worth less than knowing the measurement principle — see HPLC versus mass spectrometry.

Key takeaways

• Static records are fixed; dynamic records allow interaction between the user and the record content. Both the MHRA and the FDA use this distinction.
• The MHRA states that paper copies cannot be considered raw data where the data was captured in a dynamic state and generated electronically.
• For basic equipment that stores no data — balances, pH meters — the printout is the raw data, per both the MHRA and the FDA.
• PIC/S asks for such printouts to be signed, dated and annotated with traceability information, then attached to the testing record.
• The FDA notes that if a printout does not display the full spectrum, contaminants may be excluded.
• A true copy must preserve context, content, structure, metadata, audit trail — and, per the FDA, the static or dynamic nature of the original.
• The MHRA allows paper retention of electronic data in principle but describes the required scope as likely to be demanding in its administration.
• Long-term archiving may force a trade-off between accessibility and dynamic functionality; the guidance asks for that choice to be justified.

Frequently asked questions

Is a signed printout worthless then?

No — it is a useful static summary, and for some instruments it is the original record. What it cannot do is stand in for a dynamic file that still exists, because it removes the ability to verify how the result was derived.

Can a system print its own audit trail?

It should be able to. PIC/S states it should be possible to print out a legible and meaningful record of all the data generated by a computerised system, including metadata, and that if a change has been made it should be possible to print the change too, showing when and how the original data was changed.

Why does the baseline matter so much in these examples?

Because where the baseline is drawn sets the peak area, and peak area sets the number. Two defensible-looking baselines on the same trace can give different purity figures — the mechanism behind what 99% purity actually means.

Does this apply to a photograph of a gel or a plate?

The MHRA treats photography and imagery as a record format in its own right, and says the requirements for storage throughout its lifecycle should follow the same considerations as other formats, with any additional controls that format needs.

What should a research buyer take from this?

That the certificate is a static record by design and nobody is hiding anything by issuing one. The useful questions are about provenance — which lot, which method, which date — rather than about the file format, as set out in the nine words that decide whether a record counts.

Sources

• Medicines and Healthcare products Regulatory Agency. GXP Data Integrity Guidance and Definitions. Revision 1, March 2018. MHRA guidance
• US Food and Drug Administration. Data Integrity and Compliance With Drug CGMP: Questions and Answers — Guidance for Industry. December 2018. FDA guidance
• Pharmaceutical Inspection Co-operation Scheme. PI 041-1: Good Practices for Data Management and Integrity in Regulated GMP/GDP Environments. Adopted 1 June 2021; entry into force 1 July 2021. PIC/S guidance

All quoted text is taken from the published guidance documents linked above.

This article describes record-keeping and documentation practice only. It contains no usage instructions, no dosing information and no protocols of any kind.

For laboratory and in-vitro research use only. Not for human or veterinary use.