Questions that stop a wrong reagent being ordered

A wrong reagent often arrives under the right common name. Tris, magnesium chloride, anti-IgG, and water can all be ordered in words that two honest people read differently. The questions below are the terms that stop that. Each term is defined by the ordering mistake it prevents. The place they belong in a file is how to write a laboratory sourcing enquiry. Send the answered lines through laboratory procurement.

Salts and antibodies are browsed as classes in the reagents and chemicals catalogue. Buffer practice that depends on the salt is in preparing a buffer and checking pH. The quotation page, the contact page, and academic research are how a laboratory puts the questions in front of a person who can reply.

The mistake these questions prevent

You are about to turn a shopping sentence into a technical specification. The decision is whether the bottle that arrives can be used in the method you think you ordered. A quotation request that skips a term is how the file stays polite and the assay still fails. Ask the question before the line is sent. If the answer is not on a document you can open, the line stays incomplete.

The control is a second reader. Hand them the line with the common name covered. If they cannot tell two neighbouring products apart, one of the six terms is missing. The branch is to add the term, not to add another adjective.

Salt form

Salt form is the ion that travels with the molecule you named. Tris base and Tris hydrochloride share a buffer family and differ in whether you are adding chloride and in how you will adjust pH. Sodium and potassium salts of a phosphate are both "phosphate" and are not interchangeable when the enzyme or the cell cares which cation is present. EDTA as the free acid and EDTA as a sodium salt dissolve differently and contribute different sodium.

The mistake: ordering "Tris" or "EDTA" and receiving a salt the recipe did not weigh. The question to put on the line is: which salt, and is that the form the SOP tells you to dissolve? A quotation that answers "buffer salt, laboratory grade" has not answered it. Ask again, with the salt name written out.

Hydrate

A hydrate is water built into the crystal. Magnesium chloride hexahydrate and anhydrous magnesium chloride are the same salt family and different masses for the same number of magnesium ions. Weighing the hydrate as if it were anhydrous, or the reverse, moves the concentration by the water you did not account for. Some solids also pick up moisture from humid air after the bottle is opened, so the hydrate on the label and the hydrate in an old bottle are part of the same question.

The mistake: copying a mass from a protocol and buying a different hydrate. The question is: which hydrate does the formula weight assume? Write that hydrate on the order. If the bottle you already have has caked or liquefied, the acceptance check includes whether it is still the form you meant to weigh. Do not "correct" an unknown hydrate by guessing a factor.

Species reactivity

Species reactivity says which organism's molecule the reagent is meant to recognise. A secondary antibody raised against rabbit immunoglobulin will bind a rabbit primary. It will not bind a mouse primary just because both are called anti-IgG. A primary antibody validated on human lysate is not thereby shown to recognise the same protein in a plant extract or in a bacterial lysate. UniProt is a public place to check that the protein you named is the protein the species actually has; it does not replace the antibody's own reactivity statement.

The mistake: ordering "anti-IgG" or "the actin antibody" without the host species, the target species, and the sample you will put it on. The question is: host, target species, and is that pair the one in the method? Add the application (western blot, ELISA, flow) when the supplier states reactivity by application. A line that names only the gene is how a blot stays blank.

Conjugate

A conjugate is the detectable group attached to the antibody or the binding protein. Horseradish peroxidase, alkaline phosphatase, and a fluorophore are different detection chemistries. They need different substrates or different filters. A biotinylated antibody needs a streptavidin step the plain antibody does not. The conjugate is not a minor package option. It decides whether the reader you have can see the result.

The mistake: ordering the primary and assuming the secondary's enzyme, or ordering a fluorescent conjugate for an instrument that does not have that excitation line. The question is: which conjugate, and which substrate or channel will read it? If the method is colorimetric, say so. If it is fluorescent, name the dye class the filter set matches. ELISA formats, controls, and readout shows why the format and the conjugate travel together.

Storage

Storage is the condition that keeps the reagent the thing you ordered. It includes temperature, light, and whether the material is a dry solid, a solution, or a suspension you must mix. A restriction enzyme stored frozen is not in the same state as a lyophilised antibody on the bench, and a stock solution you diluted is not the manufacturer's sealed bottle. Many enzymes are stored near −20 °C, some antibodies are stored near 4 °C and must not be frozen, and the sheet for the product you accepted is the instruction. Write that temperature only after you have read it.

The mistake: one storage sentence for a whole order, so the lyophilised vial and the frozen enzyme share a shelf. The question is: what form is the product, and what temperature does its document name? Arrival condition is the twin question. Storing biological samples from fridge to freezer is the page for placing the accepted item. The order's job is to make that placement obvious before the box is opened.

Nuclease control

Nuclease control is a statement about DNase or RNase, usually on a certificate, for reagents that will touch nucleic acids. It is not the same word as sterile, and it is not the same word as autoclaved. Heat and pressure kill many organisms and do not promise the absence of a stable ribonuclease. Autoclaves and what sterilisation does not do is the page for that limit. Water, tubes, and tips can each carry a nuclease claim or lack one.

The mistake: ordering sterile water, or autoclaving a buffer, and using it for RNA. The question is: which nuclease claim does the certificate state, and does this assay need it? A DNA prep and an RNA prep do not share the answer automatically. Ask for the claim on the goods you will actually pipette, not as a general compliment to the supplier.

When the answer is still incomplete

Sometimes the sheet lists two salts and the protocol names neither. That is a failed control, not a reason to pick the first row. Go back to the person who wrote the method, or write down the form you will standardise on and change the SOP so the next order matches. A quotation cannot repair a protocol that never chose.

A second failure is a certificate that arrives for a different term than the one you asked. You asked for species reactivity and received a purity percentage. Purity can be useful. It does not answer the species question. Quarantine the line until the missing statement is in the file. NIST's metrology pages are a reminder that a measurement claim points at a stated quantity. Species and nuclease claims deserve the same habit even when they are not calibration results.

Biosafety and research limits

These six questions identify a reagent. They do not decide whether the sample you will mix with it may be handled. Infectious material, human specimens, and toxins sit under the institution's biosafety rules. Biosafety basics for research benches keeps that decision institutional. Nothing on this page is medical advice or a diagnostic instruction. Antibodies and salts named here are research reagents. Follow the manufacturer's sheet for storage and handling, and follow the laboratory SOP where it adds a local rule.

Humidity and the hydrate question

In a humid season an opened bottle can gain water, cake, or crust at the cap. The hydrate you ordered and the powder you weigh six months later may not match the formula weight you used on day one. The ordering question still names the hydrate. The acceptance question, later, asks whether the solid still looks and behaves like that form, and whether the SOP tells you to dry it or to discard it. Do not leave either question to the memory of the person who first broke the seal. Write the hydrate on the line, and write the storage condition, including a dry place if the sheet asks for one, so a humid store is a known risk rather than a surprise at the balance.

Putting the questions in an enquiry

Take each reagent in the method and answer the six questions that apply. A simple salt may have no conjugate and no species; write "not applicable" so the blank is deliberate. An antibody may have no hydrate; the species and the conjugate are then the lines that matter. Ask the quotation to repeat the salt, the hydrate, the species pair, the conjugate, the storage temperature, and the nuclease claim it is actually offering.

Send that through the quotation page or the contact page. Keep the protocol beside the lines. A statement of work that contains many reagents uses the same questions on every line that can be confused with its neighbour.