Rewriting a vague request into a checkable one

"Some Taq and some tips" is a sentence a bench can say in the corridor and still understand. It is not a sentence a quotation can be checked against. The person who receives it has to guess the polymerase class, the activity unit, the storage temperature, whether the tips are filtered, which volume family they belong to, and which water will go into the same tube. This page is a selection guide for those fields. The habit it belongs to is how to write a laboratory sourcing enquiry, and the file goes out through laboratory procurement.

Enzyme classes live among molecular biology records. Tips are a plasticware choice, discussed as classes in when to use plastic tubes, tips, and plates. Water grades are separated in laboratory water types and where they fail. University groups can start from academic research. The finished lines go to the quotation page or the contact page.

Who is rewriting the request

You are the person who will run the reaction, or the person who must order for someone who will. The decision is whether a later reply can be marked line by line. If you are choosing what to specify before an enquiry, commercial intent still means a technical file, not a slogan. A statement of work for a whole study would use the same fields inside a larger scope. Here the job is one reaction's reagents and the plastic that touches them.

Keep the protocol open while you rewrite. Addgene's protocol collection and protocols.io show how methods name enzymes. Copy the class and the unit from the document your laboratory actually follows. Do not invent a catalogue code to make the sentence look precise.

Why the short sentence cannot be checked

Taq DNA polymerase, a hot-start variant, a proofreading blend, and a reverse transcriptase can all be waved at with a single nickname. Tips can be filtered or open, sterile or not, and sized for a 10 microlitre pipette or a 1000 microlitre pipette. Water can be resistivity-grade polish, a wash bottle that has been refilled, or a certificate-backed nuclease-controlled bottle. A quotation that says yes to the nickname has agreed to none of those differences.

The control is simple. Cover the product name and read the line aloud. If a colleague cannot tell which bottle to release, the line is still vague. The branch is to add the missing field from a document you can open, or to write the performance and mark the formulation as unconfirmed. Sending the vague line and hoping the reply will choose well moves the guess into someone else's building.

Polymerase class

Name the class by what the reaction needs. Endpoint PCR of a short amplicon often uses a Taq DNA polymerase. A reaction that must not extend primers before the first denaturation step needs a hot-start enzyme, held inactive by an antibody or by a chemical modification until a heat step. Amplification where fidelity matters, or where the amplicon is long, points toward a proofreading polymerase or a blend. Reverse transcription is a different enzyme class. Calling it Taq because the workflow later uses PCR is how the wrong tube gets ordered.

State whether the enzyme is supplied with its own buffer, and whether that buffer's magnesium is separate or included. Those are class features. A catalogue family, such as the enzyme classes listed by New England Biolabs, shows that formulations differ. It is a map of classes, not a code to paste. How the reaction itself behaves is covered in how polymerase chain reaction works and in PCR controls and contamination control.

The concentration unit

Protocols ask for activity, usually a number of units in a reaction. A unit is defined by the manufacturer's assay. Two bottles with the same common name can carry different activities per microlitre. A checkable line states the activity in that defined unit, the volume of enzyme you need, and whether you are asking for a single tube or a pack. "One tube" is not an activity.

If you do not have the sheet open, do not type an activity from memory. Write "activity as stated on the certificate, in the manufacturer's unit, sufficient for the number of reactions the SOP names" and attach the SOP's reaction count. Mass concentration, such as milligrams per millilitre, is a different unit and does not replace activity for a polymerase. The quotation should repeat the unit it is offering so you can match it to the protocol before anyone thaws the tube.

Storage temperature

Enzyme preparations are usually stored cold, and many polymerase products are stored frozen. A common manufacturer instruction is near −20 °C, and some formulations say otherwise, including storage that must not be at a much colder temperature because of the buffer. The number you write is the number on the document for that formulation, and the laboratory SOP agrees with it. This page cannot assign one temperature to every enzyme.

Separate storage from the condition on arrival. Storage is where the tube lives after you accept it. Arrival is whether it is still inside the range the specification named when it reaches the bench. Ask the quotation to state the arrival condition it will describe, and name the evidence you will accept: a logger, remaining coolant, or an explicit statement that the product travels at ambient. Storing biological samples from fridge to freezer is the page for the storage side of that handoff.

Tip filter and volume

A filter tip has a barrier meant to stop aerosols reaching the pipette barrel. Ask for it when the reaction is sensitive to carry-over, which includes PCR set-up and RNA work. Say "non-filtered" only when the SOP has a reason and you record that reason. Sterile is a separate claim from filtered. Low binding, or low retention, is a third claim, useful when you are moving small amounts of nucleic acid and the SOP cares about recovery.

Volume is an interface with the pipette, not a brand. Name the family the pipette uses. Typical families are the small tips used with pipettes up to about 10 microlitres, the mid-range tips used up to about 200 microlitres, and the large tips used up to about 1000 microlitres. Match the family to the pipette you will actually use, and say whether the tips are racked or loose. A 1000 microlitre tip on a 20 microlitre pipette is a failed interface even if both items are sterile. Technique for that match is in accurate micropipetting technique.

Grade of water

The water line is part of the same request. For PCR and for RNA, ask for water that the certificate describes as nuclease-controlled, in a pack size you can finish before the SOP's expiry rule. Resistivity, or a Type I polish, is a different specification. A carboy of high-resistivity water that has been open on the bench is not the bottle the certificate described. Laboratory water types and where they fail sets out that distinction.

Write the grade, the certificate claim, and the pack. If the reaction uses the enzyme's supplied buffer and no added water, say that, so nobody orders a grade you will not use. Leaving the water implicit is how "some Taq and tips" still fails when the enzyme was right.

The branch when a field is still blank

Lay the five fields in a row: class, activity unit, storage temperature, tip filter and volume, water grade. Any blank is a failed control. Return to the SOP or to a sheet you can open. If the SOP itself is vague, write the performance you can defend and mark the formulation "to be confirmed in the quotation". Do not invent a code, a unit, or a temperature to fill the blank. A wrong precise line is harder to catch than an honest gap.

If two people need two classes, split the request. A teaching practical and a genotyping assay can share a tip family and still need different enzymes. One blended line called "Taq for the lab" will satisfy neither when the boxes arrive.

Failure modes of a half-rewritten request

The first failure fills three fields and leaves two blank. A perfect class and unit, with "tips" and "water" still bare, will quote an enzyme you can check and plastic you cannot. The reaction fails for the blank, and the file looks as if the enzyme was the problem.

The second failure invents precision. A remembered activity, a temperature from a different enzyme, or a code nobody can open will pass a visual check and fail in the cold room. If the figure is not on a document the laboratory can open today, write "unconfirmed" and stop.

The third failure mixes classes in one quantity. "Six tubes of Taq" for three different assays produces one formulation and two disappointed protocols. Split the lines. Each line keeps its own class, unit, and storage figure.

Research use and the limits of a reagent line

A rewritten enzyme request is still a research specification. It does not choose a diagnostic claim, and it does not approve the biological material you will amplify. If the template is infectious, human, or otherwise restricted, the institution's biosafety and ethics arrangements decide whether the work may proceed. Biosafety basics for research benches keeps that decision with the institution. This page is not that approval, and it is not medical advice.

Follow the manufacturer's protocol for the formulation you finally accept, and follow the laboratory SOP where it is stricter. The fields above tell a seller what to quote. They do not replace the reaction sheet on the day you pipette.

A warm laboratory and the cold line

In a hot, humid season the storage line and the arrival line do different work. An enzyme specified at a frozen storage temperature can still warm up on a dock, in a courier bag, or during a power cut between the dock and the freezer. The request should say what evidence of temperature you will file, and who may accept the tube if that evidence is missing. Tips and water are often ambient goods. Do not let their ambient line erase the enzyme's cold line when all three sit in one message. Write them as separate rows so a warm dock is a recorded fact for the enzyme and an ordinary condition for the plastic.

The enquiry you can send

Send five rows, not a nickname. Row one is the polymerase class and whether buffer and magnesium come with it. Row two is the activity unit and the quantity. Row three is the storage temperature from the document you opened, and the arrival condition. Row four is the tip filter, the volume family, the sterile claim, and racked or loose. Row five is the water grade and the certificate claim.

Ask the reply to answer each row. Put the file through the quotation page or the contact page. Academic research is available when the work sits in a university laboratory. Keep the protocol citation next to the rows so the unit you asked for is the unit the method uses.