Specifications that describe performance not a rumour

A specification is a list of observations the laboratory can repeat. The decision it supports is whether a quotation, and later a delivery, matches the job on the bench. Rumour is a different kind of sentence: which brand a neighbouring group prefers, which column "everyone" uses, which enzyme appeared in a paper whose methods line you have not actually checked. Those sentences can start a conversation. They cannot be scored. The working method for turning a job into numbered lines is how to write a laboratory sourcing enquiry. A written specification can be sent through laboratory procurement, and a university group can also start from academic research. The file goes out through the quotation request or contact. A scope can be discussed there. Nothing on this page is a claim that a shelf already holds the item.

The decision you are writing down

You are deciding what you will accept before a seller answers. If the acceptance test is missing, two quotations cannot be compared, and a wrong bottle cannot be distinguished from a right one on the day it arrives. Write the note so that a refusal is informative. "Cannot state nuclease testing on the certificate" tells you something. "We will send the usual one" tells you that the usual one has not been defined.

This guide covers reagents and instruments the laboratory can hold and check. An outsourced sequencing or proteomics study is a statement of work with sample numbers and file types. Keep that scope in its own note, and do not hide it inside a reagent line.

What a checkable line actually is

Performance, here, means a property a competent person can test or can read off a document that names the test. Four families cover most laboratory goods.

Purity class is the grade the method needs. For a salt, that may be identity, hydrate, and an analytical grade. For an enzyme, it may be activity in the unit the supplier defines, plus a statement about a named contaminant such as a nuclease or an endotoxin when the downstream step cares. The class is not a slogan such as "high quality". It is the phrase the certificate of analysis is willing to repeat, lot by lot.

Temperature class is the storage band the product is qualified for. Write the band the manufacturer states, for example a refrigerated class or a frozen class, and name it as a range rather than "keep cold". The laboratory SOP and the product instructions decide the number. A specification that says only "cold chain" has not said whether a gel-pack shipment and a dry-ice shipment are the same offer.

The document set is the paper that makes the class checkable. Typical members are a certificate of analysis carrying the lot, a safety data sheet, and, for an instrument, a calibration or verification record against a named check. A brochure adjective is not a member of the set. ISO 9001 is a public reminder that a quality requirement is something an organisation can trace. It does not pick your assay. It does support the habit of writing the requirement down.

The acceptance test is what you will do when the box arrives, before the item enters use. At minimum it compares the label with the numbered line, checks that the certificate fields you named are present for that lot, and records the storage condition on arrival if you specified one. An instrument acceptance test is a verification the laboratory can run: a mass, a speed, a volume, or a temperature, against the limit you wrote. NIST laboratory metrology is a useful public frame for the idea that a measurement needs a procedure, not a reputation.

Classes of goods, without copying an insert

Write the reagent as a class. Identity includes the chemical name and, where it changes the mass or the counter-ion, the salt form and hydrate. Activity or concentration includes the unit and the basis (weight, volume, or enzyme unit as defined by the supplier). Container class matters when the method loses sample to the tube: a low-binding plastic, a glass bottle, or an amber vessel is a performance line if light or adsorption is part of the science. It is decoration if you only prefer the colour of the cap.

Write the instrument as a class. Range, readability or resolution, the tube or vessel it must accept, the environment it must tolerate, and the document that shows it was checked. A centrifuge line that says "suitable for microtubes" is weaker than a line that names the tube volume, the relative centrifugal force the protocol needs, and a lid interlock. A balance line that says "analytical" is weaker than a line that names the readability and the verification weight you will use on receipt.

Do not paste a vendor's microlitre table into the specification. If your assay needs a volume, your SOP already has it. The sourcing note asks for the reagent class that SOP consumes.

A worked pair: polymerase and a small centrifuge

Take a routine PCR polymerase first. A rumour says "the Taq the cloning paper used". A specification says something closer to this. The enzyme is a Taq DNA polymerase, hot-start if your primer dimers require it, supplied at a stated concentration in the supplier's unit definition. Storage is the frozen class the manufacturer states for that product. The certificate names the lot, the activity assay, and a nuclease statement if the amplicon will be cloned. The acceptance test is: label matches the line, certificate lot matches the vial, the vial arrived inside the storage class you named, and a small control PCR with a known template produces the expected band before the enzyme is released to the project. If that control fails, the vial stays quarantined. You do not "use it up on the real samples and see".

Now a benchtop centrifuge for the same bench. The rumour says "the same model as building two". The specification says: relative centrifugal force at least the highest speed your protocol names, a rotor that accepts the tube you already use, a timer, a lid lock that prevents opening while the rotor is moving, and a verification on receipt against a tachometer or the laboratory's chosen speed check, with the limit written down. The brand may appear as an example after those lines. Equivalence is meeting the lines, including the verification, not sharing a colour.

Number the lines. A quotation can then meet a line, take exception to a line, or leave a line blank. Blank is not a quiet yes.

When the acceptance test fails

Stop. The branch is quarantine, not improvisation.

If the certificate lacks a field you numbered, ask for that field in writing against the lot in your hand. Do not start the assay to generate a substitute certificate. A successful gel does not invent a nuclease statement you required and did not receive.

If you specified an arrival-temperature check and the shipment is outside the class, do not thaw and refreeze "to be sure" and then release the lot. Follow the excursion rule you wrote: who is told, whether the lot is discarded, and whether a replacement is a new quotation line. If you never wrote that rule, you do not have one, and the honest next step is to write it before the next shipment.

If an instrument meets the brochure range and fails your verification, the acceptance test has failed. Record the reading. Do not average it with a second, kinder reading and call the mean a pass. Fix the instrument or reject the line.

Failure modes that look like agreement

The common failures are quiet. A quotation repeats your product name and drops the purity class. A certificate arrives for a different lot than the vial. An instrument quotation meets the range and omits the verification you named, so you have bought a device you cannot accept. A specification becomes so narrow that it copies a catalogue sentence, including adjectives nobody can test. Narrow the science. Leave the decoration out.

Another failure is mixing two jobs. You needed a polymerase, and you also needed someone to run the PCR. The second job is a service scope: sample number, what is included, and the file you expect back. Putting "and analyse it" on a reagent line makes both the reagent and the study impossible to score.

Safety, research use, and the institution

Ask for the safety data sheet as part of the document set so the chemical hygiene plan has something to file. Containment, disinfection, and waste are institutional decisions. The WHO laboratory biosafety manual is a public reference for that responsibility. It is not a permit for your building. Research use of a specified enzyme or instrument is not a diagnostic claim, and a passing acceptance test is not a clinical validation.

Heat, humidity, and the evening shift

In a warm, humid building the temperature class is an operational line, not a courtesy. A box that sits on a receiving dock through the hot part of the day can leave the storage class before anyone opens the certificate. Write who may receive, what they record, and where the item goes next. Paper specifications stored in a damp office also need a durable copy: the numbered file, not a marginal note that fades. Where a public laboratory buys against a form, the procurement office owns the form. The scientific lines on that form still have to be performance the laboratory can check.

What the enquiry should carry

Send the numbered lines, the document set, the acceptance test, the quantity in scientific units, and the storage class. Say which lines are mandatory. If a brand appears, label it as an example and point at the lines that define equivalence. Use laboratory procurement when you want a structured specification read against a quotation. University groups can begin from academic research. Reach a person through contact or place the file with a quotation request. Ask the answer to meet, exception, or decline each number. Then file the answer next to the specification. The next person who covers your leave should be able to accept or quarantine the lot without reconstructing a rumour.