These four fields are the ones an auditor, a safety officer, or a future you asks about. They are also the ones Labsistant is strictest about, because a wrong value here is worse than no value at all.
This article explains what each field is and how Labsistant handles it. It does not tell you what any particular substance's hazard level or expiry should be. That comes from the manufacturer's documentation and your institution's safety guidance, never from this app.
The one rule behind all of them
Labsistant never invents a compliance value. Not on manual entry, not during an import, not through the AI assistant. If a lot number is not in your file, the field stays empty and you are asked. If a hazard level is not stated, nothing is assumed.
A plausible-looking wrong lot number is far more dangerous than a blank one, because a blank prompts someone to go and check, and a wrong value does not.
Lot number
The lot number, sometimes called the batch number, identifies the specific batch you received from the manufacturer. Copy it from the physical container label or from its certificate of analysis (CoA).
It matters because it is the link between a physical bottle and everything the manufacturer knows about that batch. If a supplier issues a recall, the lot number is what tells you whether it affects you. If an experiment behaves oddly, the lot number is what lets you check whether a different batch was involved.
- Where you enter it: step 2, "Lot Information", of the Add Reagent flow. It is required.
- Do not substitute a placeholder, the date, an order number, or "N/A". If you do not have the real number, use the deferred-lot state described below.
- Reagents have lot numbers. Supplies and samples do not.
Deferring a lot number
Receiving often happens before anyone unpacks the box, so Labsistant has an explicit state for "this arrived, the lot number has not been read off it yet".
Where you can defer
Deferral is available in the guided import and through the AI assistant, not in the manual Add Reagent form.
- In the guided import, each row in the review grid has a No lot yet (add later) switch. Turn it on and the lot number input for that row disappears, since it is no longer being asked for.
- The AI assistant offers the same choice, labelled the same way, on a confirmation card before anything is created.
- The manual Add Reagent form requires a lot number. If you are adding one item by hand and do not have the number, either fetch it from the container, or bring the item in through the import instead.
What "deferred" means
Deferring is recorded as a decision somebody made, not as missing data:
- The item is created with no lot number at all, rather than a filler value. The database physically will not accept a blank lot number unless the deferral marker is set alongside it, so a lot can never be quietly empty.
- Who deferred it and when are both stored.
- The Audit Log entry for the new lot says it was created awaiting its lot number.
- A deferred lot is never merged into an existing lot. Each deferral is treated as its own received batch, because there is no number to match it against.
Finding and finishing deferred items
Deferred items are deliberately hard to lose:
- On the Inventory page they show an amber Awaiting lot badge in the Lot # column, with a pencil button next to it.
- The status filter has an Awaiting lot option that shows only these items.
To complete one:
- Click the pencil next to Awaiting lot, or open the item and use the same action.
- Type the lot number from the physical product or its CoA.
- Click Save.
The Awaiting lot badge clears by itself. The Audit Log records a separate entry naming who entered the number and when, so the trail shows both the deferral and its resolution.
CAS number
A CAS Registry Number is the unique identifier assigned to a chemical substance by the Chemical Abstracts Service. It is the unambiguous way to say which substance you mean, independent of how your lab spells the name.
- Where you enter it: step 1, "Select Reagent", when adding a reagent that is new to your master list.
- Copy it from the container label, the safety data sheet, or the supplier's catalogue entry. Do not reconstruct it from memory.
- The CAS number belongs to the substance, not to the batch, so you enter it once per reagent rather than per lot.
One asymmetry worth knowing: in the manual Add Reagent form the CAS Number is optional, but the guided import requires a CAS number for any reagent that is new to your lab. Rows without one are blocked until you supply it. Supplies are exempt, and so are rows matched to a reagent you already have.
Hazard level
Every reagent carries a hazard level, chosen from five values:
None, Low, Moderate, High, Extreme.
- Where you enter it: step 1, "Select Reagent", and it is required.
- It is set on the reagent, so it applies to every lot and container of that substance.
- It appears as a badge in the Hazard column on the Inventory page, and you can sort by it.
On the Free plan only None and Low are available. Setting anything higher is refused with a message saying higher hazard levels require a paid plan. See Plans and limits.
These five levels are Labsistant's own scale for sorting and filtering your inventory. They are not GHS categories, not NFPA ratings, and not any regulatory classification. Do not treat the level shown here as a compliance determination. Decide which level to assign using the substance's safety data sheet and your institution's guidance, and keep whatever formal classification you are required to hold in the system of record your institution uses for it.
Expiration date
The expiration date belongs to the lot, not the substance, since each batch expires on its own schedule.
- Where you enter it: step 2, "Lot Information", and it is required.
- It must be later than the received date. The form rejects an earlier one.
- If the date you enter is within 30 days, the form warns you that it expires soon.
- Once saved, it drives the Expiring Soon count on the Dashboard, the Expiring Items panel, and the Expiring status filter on the Inventory page.
Take the date from the container or the CoA. If a batch has both a "use by" and a "retest" date, record the one your lab's own policy treats as the expiry, and note the other in the lot's Notes field.
What Labsistant does not do
- It does not tell you whether an expired reagent is still usable.
- It does not assign or validate a hazard level for you.
- It does not check a CAS number against any registry.
- It does not know about recalls, and will not warn you about one.
It records what you tell it, keeps the trail of who told it and when, and makes the gaps visible. The judgment stays with you and your institution's safety procedures.
These fields are filled in as you add a container, so Add a reagent shows where each one appears, and Sterile and RNase-free flags covers the two handling flags that sit beside them. Keeping this record without a second system is part of what the inventory is for.