A practical, factory-level guide to sealed screw-cap cuvettes — when to seal vs. open top, the M12 standard thread, cap materials (PTFE / silicone / septum), and how Scuvette manufactures custom one-piece molded quartz screw cells to your drawing.
A standard (open-top or snap-cap) cuvette is the fastest option for routine absorbance reads, but the sample is exposed to air. A screw-cap cuvette adds a threaded cap — on Scuvette cells, a white PTFE cap on an M12 thread — that seals the cell. The seal matters whenever the sample must not change during the measurement.
| Factor | Open-top / snap cap | Screw cap |
|---|---|---|
| Sealing | None — sample exposed | Threaded PTFE cap, tight seal |
| Best for | Fast routine aqueous reads | Volatile, O₂-sensitive, long scans, biohazard |
| Fill / empty speed | Faster | Slightly slower (cap on/off) |
If none of these apply, an open-top quartz cuvette is simpler and faster.
The M12 thread is the de-facto standard for 10 mm screw-cap cuvettes and the cap is white PTFE — chemically inert and compatible with nearly every solvent. Beyond the standard cell, Scuvette manufactures custom screw-cap quartz cells to your drawing in M6, M7, M10, M12 and M16 threads. Every custom screw cell is one-piece molded fused silica — there is no glue line or assembled joint to fail. Browse screw-cap cuvettes →
All interchangeable caps are sold separately so you can match the material to your solvent and protocol.
Custom-threaded screw cells are manufactured from fused quartz (JGS1) — the same far-UV-grade silica used across our standard range, transmits from ~190 nm through the NIR. Customization covers non-standard path length, window count (2 / 4 / 5 windows), port geometry and thread size; tell us the dimensions, light path, number of optical windows and any chemical-resistance requirement and we confirm feasibility and lead time. Send your drawing →
Standard 10 mm screw-cap quartz cuvettes share the 12.5 mm external width and 15 mm center height accepted by all modern benchtop UV-Vis instruments — Agilent, Shimadzu, PerkinElmer, Thermo, Hitachi and Jasco. If your instrument uses an older 8.5 mm legacy holder, choose a reduced-height or sub-micro cell. See the z-height compatibility guide for how to confirm your holder.
A screw-cap cuvette has a threaded (usually M12) PTFE cap that seals the cell. Use one when your sample is volatile, oxygen- or moisture-sensitive, radioactive or biohazardous, or when you run long kinetic scans where open-top cells lose solvent to evaporation. For routine, quick aqueous reads an open-top or snap-cap cell is faster.
The industry-standard screw cap is M12. Scuvette also manufactures custom threaded screw-cap quartz cells to your drawing in M6, M7, M10, M12 and M16 threads, all one-piece molded fused silica with no adhesive joints.
Standard screw caps are white PTFE — chemically inert and compatible with nearly every solvent. Optional solid silicone caps and septum (injectable) caps let you add reagents through a syringe without opening the cell. Choose the cap material to match your solvent and handling protocol.
Yes. Screw-cap cells are available with 4 polished windows for right-angle fluorescence, and with a polished bottom (5-window) for bottom-reading instruments, while the screw cap keeps volatile or oxygen-sensitive fluorescence samples sealed.
Yes. As a factory we make custom one-piece molded quartz screw-cap cells to your drawing: non-standard path length, window count, port geometry or thread (M6/M7/M10/M12/M16). Send dimensions, light path, number of optical windows, and any chemical-resistance requirement; we confirm feasibility and lead time.
Our standard 10 mm screw-cap quartz cuvettes have the 12.5 mm external width and 15 mm center height used by all modern benchtop UV-Vis instruments (Agilent, Shimadzu, PerkinElmer, Thermo, Hitachi, Jasco). If your instrument uses an older 8.5 mm legacy holder, choose a reduced-height or sub-micro cell.