Quick facts
- A cuvette is the optical cell that holds the sample in a spectrophotometer, and in the United States the instrument it feeds is a Class I device at 21 CFR 862.2300, with the cell itself handled as a general-purpose laboratory article under 21 CFR 862.2050.
- In Canada a cell that does not enter the body and is not wired to another device is a non-invasive device classified as Class I under Rule 7(1) of the Medical Devices Regulations.
- The properties that decide whether a reading can be trusted — path length, material, matching and cleanliness — are fixed by laboratory practice under ISO 15189 rather than by the cell supplier alone.
- A cuvette is only as good as the instrument it is matched to: a cell that is not matched to its pair introduces a blank error that no calibration can remove.
- The entries and rule text below were checked against the current eCFR text and the Regulations on 2026-10-07.
A spectrophotometer cuvette is the small optical cell that carries a sample through a light beam so a clinical chemistry analyser can read its absorbance. In the United States the instrument is a named device and the cell is an accessory to it; in Canada the cell is a non-invasive device filed by rule. This article compares the two rulebooks, sets out the properties a cell has to hold, and explains why a mismatched pair of cuvettes can move a result without any change to the patient sample.
What is a spectrophotometer cuvette?
It is a precisely made container with two or four polished optical faces, a defined path length, and a material chosen so that it does not absorb in the wavelength range the test uses. A clinical laboratory will hold glass cells for the visible range, quartz or UV-transparent cells for ultraviolet methods, and disposable plastic cells for high-throughput assays where cross-contamination is a risk.
None of these enters the body and none is implanted. Their clinical role is to carry the sample at a known optical depth so the instrument can turn absorbance into a concentration. That role is what makes the cell a device accessory rather than a piece of glassware.
Why does a cell inherit the class of the instrument it feeds?
A device is defined by the function it performs in a clinical decision. A cell on its own measures nothing. It becomes part of a measuring system the moment it is placed in a clinical photometer, and the reading it produces is used to report a patient result. The regulator reads the cell as part of that system, and the instrument entries carry the class.
The practical consequence for a laboratory is that the cell specification is part of the assay's control, not a purchasing detail. A cell with the wrong path length or the wrong material changes the absorbance the instrument reads, which changes the reported concentration without any change to the sample.
How do Canada and the United States treat a spectrophotometer cuvette?
The two countries reach the same class from different machinery. The United States names the instrument and treats the cell as its accessory; Canada classifies the cell by rule.
| Item | Canada | United States |
|---|---|---|
| Named entry | No entry names a cuvette | Instrument at 21 CFR 862.2300, Class I |
| Cell as accessory | Non-invasive device, Class I | General-purpose laboratory article, 862.2050 |
| Product code | Not applicable | JJQ (instrument) |
| Plain glassware, no clinical use | General supply | General supply |
| Basis of the class | Intended use recorded for the device | The named entry it is filed under |
| Route to market | Manufacturer holds an establishment licence; Class I carries no device licence of its own | Class I, generally exempt from premarket notification |
In Canada a cell that does not enter the body and is not connected to an active device is a non-invasive device, and under Rule 7(1) of the Medical Devices Regulations "all other non-invasive devices are classified as Class I." Rule 7(2) lifts the class where a device is intended to act as a calibrator, tester or quality-control support to another device — the point at which a cell sold as a calibration reference would move up in class.
In the United States the instrument is filed under 21 CFR 862.2300, which covers a colorimeter, photometer or spectrophotometer for clinical use, and the openFDA device classification API lists the entry at Class I under product code JJQ. The cell that feeds it is handled as general-purpose laboratory equipment under 21 CFR 862.2050.
Which properties does a cuvette have to hold?
The class table says what the cell is; the laboratory standard says how the reading must be controlled. Medical laboratories work to ISO 15189, and the quality system behind the device is ISO 13485:2016.
| Property | What it fixes | Why it matters to the result |
|---|---|---|
| Path length | The optical depth, usually 10 mm | A shorter cell reads a lower absorbance for the same sample |
| Material | Glass, quartz or plastic by wavelength | A plastic cell absorbs ultraviolet light and skews UV methods |
| Matching | The blank difference between paired cells | A mismatched pair shifts the baseline and the result |
| Face clarity | Freedom from scratches and haze | A scratched face scatters light and reads as absorbance |
| Cleanliness | Freedom from residue and detergent | A film on the face reads as a permanent offset |
| Marking | The orientation the maker gives each cell | A cell seated the wrong way reads differently on re-seat |
The practical consequence is that two cells of the same path length can produce different results if one is matched to its pair and the other is not. A laboratory that records the matched-pair number with the assay is holding the control that a re-run would otherwise have to rediscover.
What does a clinical laboratory restock alongside its cells?
The cell is one item on a bench that is restocked as a set. The sterile graduated 90 mL specimen cups carry the sample to the bench, and the double-tipped cotton swabs handle surface preparation where a reading needs a clean start. The smooth white exam table paper covers the work surface between runs. Laboratories that also monitor a steriliser pair the sterilization monitoring collection with the 24-hour monitoring five-pack trial. Multi-site groups ordering at case level use the wholesale ordering page, and the B2B wholesale collection lists the lines held for institutional buyers. Reselling? become a distributor.
How is a cuvette used in a routine assay?
The blank is read first, with the cell filled with the reagent blank, so the instrument can set zero against that cell. The sample is then read in the same cell or in its matched partner. If the cell changes between the blank and the sample, the difference the instrument reports includes the difference between the cells rather than only the difference between the samples. That is why the matched pair travels together and why a scratched or hazy cell is withdrawn rather than rotated into the queue.
A laboratory that keeps a log of cell condition and matching, alongside the instrument calibration record, can show that a shift in results came from the sample and not from the cell.
Sources
- 21 CFR 862.2300, Colorimeter, photometer, spectrophotometer for clinical use
- 21 CFR 862.2050, General purpose laboratory equipment
- openFDA device classification API
- Medical Devices Regulations, SOR/98-282, full text and Schedule 1
- Health Canada, medical devices
- ISO 15189:2022, medical laboratories, requirements for quality and competence
- ISO 13485:2016, medical devices quality management
- ISO 14971:2019, risk management of medical devices
- Standards Council of Canada
- CSA Group
- Public Health Ontario, infection prevention and control
- CCOHS, OSH answers
- US FDA, medical devices
- CLSI, clinical and laboratory standards
- AAMI, standards and technical resources
- College of American Pathologists, laboratory accreditation
- World Health Organization, laboratory quality
- Health Canada, medical device licence and inspection
Where a cell record is kept
A cuvette that is not written down cannot be traced when a result is queried. The printable instrument reading log is a blank sheet with columns for the instrument, the cell number, the path length, the blank reading, the sample reading and the operator, so a shift can be traced to a cell rather than guessed. The reading log generator on the same page sizes the form to the number of benches a laboratory runs. No account and no sign-up are needed to open either one.
Every bench and every method differs. Ask a compliance specialist and you will get a written answer specific to your equipment and province, with the regulation or standard it is based on cited.
Related reading
- Laboratory glassware in Canada vs the US: which rules apply
- Microscope slides in Canada vs the US: which size and finish
- Microcentrifuge tubes in Canada vs the US: which standards
CliniEco Medical supplies eye care, laboratory and dental consumables of the kind described in this article. MDEL #35334. This article is written for optometry, laboratory and procurement professionals and is not legal advice; the class of a device and the records kept by a clinic belong to the manufacturer and to the requirements that apply to it.
Frequently Asked Questions
Is a spectrophotometer cuvette a regulated device?
The cell is an accessory to a clinical photometer rather than a device in its own right. The United States names the instrument at 21 CFR 862.2300 as a Class I device and handles the cell as general-purpose laboratory equipment under 21 CFR 862.2050, while Canada treats the cell as a Class I non-invasive device under Rule 7(1) of the Medical Devices Regulations.
What is the difference between a cell and a cuvette?
The two words describe the same container. A cuvette is the standard term in clinical chemistry and a cell is the term used in optical physics; both refer to a defined-path container with polished faces.
Does a cuvette need a licence in Canada?
A Class I device does not get a device licence of its own. The manufacturer holds an establishment licence and keeps the records the Regulations require, while a Class II device needs a licence under section 32 supported by a CAN/CSA-ISO 13485 quality management certificate.
Which entry covers a clinical spectrophotometer in the United States?
21 CFR 862.2300 covers a colorimeter, photometer or spectrophotometer for clinical use at Class I, and the openFDA classification database lists the entry under product code JJQ.
Why do cuvettes have to be matched?
Because a pair that differs in its blank reading introduces a constant offset that no sample can explain. Reading the blank in one cell and the sample in another, without matching, moves the result by the difference between the cells.
Can a plastic cell be used for every assay?
No. Plastic cells absorb in the ultraviolet range, so an ultraviolet method needs a quartz or UV-transparent cell. The material is chosen against the wavelength the method uses, not for convenience.
What is the standard path length for a cuvette?
The common clinical path length is 10 mm. A shorter or longer path changes the absorbance the instrument reads for the same sample, so the method and the cell have to agree on the depth.
Where can a laboratory keep its cell records?
The printable instrument reading log at the compliance log centre has columns for instrument, cell number, path length, blank reading, sample reading and operator, and the log generator on the same page sizes the sheet to the number of benches a laboratory runs.
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