Karl Fischer Titration: Coulometric or Volumetric? Pick Fast
Updated: Sep 28
Choose coulometric Karl Fischer titration for trace water (about 1 ppm to 5%, best below 1%) and volumetric Karl Fischer for wetter samples (about 100 ppm to 100%). Karl Fischer measures water, and only water.
Coulometric KF (KF coulometer) | Volumetric KF titrator | |
|---|---|---|
Water range | ~1 ppm to 5%, best below 1% | ~100 ppm to 100% |
Water per run | 1 µg to about 5 mg | 1 mg upwards |
How iodine is supplied | Generated in the cell | Added as a titrant |
Standardisation | Not needed (Faraday's law) | Titre re-checked regularly |
Running cost | Low: one cell fill lasts many runs | Higher: titrant used every run |
Best for | Solvents, oils, APIs, plastics, gases | Food, syrups, creams, bulk products |
Our price | from £4,074 | from £4,074 |
The short version
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Prices: Karl Fischer titrators in stock
Karl Fischer titrators cost from £4,074 for an entry-level coulometric or volumetric moisture titrator to £9,375 for a coulometric titrator with a diaphragm cell.
We supply the Hanna Instruments HI-900 series: two dedicated moisture titrators and three full-specification lab instruments.
HI-904 coulometric moisture titrator | £4,074 |
HI-903 volumetric moisture titrator | £4,074 |
HI-933 volumetric titrator | £7,932 |
HI-934 coulometric (diaphragm-free) | £8,159 |
HI-934D coulometric (diaphragm) | £9,375 |
Karl Fischer coulometers
Our Karl Fischer coulometers start at £4,074 (HI-904, 1 ppm to 5% water); the diaphragm-free HI-934 covers most applications.
HI-904 coulometric moisture titrator: 1 ppm to 5% water. £4,073.51
HI-934 coulometric titrator, diaphragm-free: simpler to run and covers most applications. £8,159.27
HI-934D coulometric titrator with diaphragm: only if your method calls for a diaphragm cell. £9,375.36
Volumetric Karl Fischer titrators
Our volumetric Karl Fischer titrators start at £4,074 (HI-903, 100 ppm to 100% water); the HI-933 at £7,932 suits regulated labs and mixed samples.
HI-903 volumetric moisture titrator: 100 ppm to 100% water, automatic drift compensation, sealed solvent system and balance connection. £4,073.51
HI-933 volumetric titrator: full-specification instrument for regulated labs and mixed samples. £7,931.65
“ Pick on your water content, not your budget. At entry level, a coulometric and a volumetric KF titrator cost exactly the same. — LS Scientific |
Coulometric vs volumetric: how each Karl Fischer method works
Coulometric KF generates iodine electrically inside the cell, so no titre is needed; volumetric KF adds iodine from a burette as a titrant of known strength.
Coulometric Karl Fischer titration
Coulometric KF is an absolute method for trace water: it generates iodine electrically, so there is no titrant to standardise.
A coulometric titrator generates iodine electrically inside the cell. 1 mg of water corresponds to 10.71 coulombs, so the result is absolute and needs no titrant standardisation. That makes it the reference method for trace moisture.
Volumetric Karl Fischer titration
Volumetric KF suits wetter samples: it adds iodine as a titrant (typically 1, 2 or 5 mg of water per mL) that you standardise regularly.
A volumetric titrator adds iodine as a titrant of known strength, typically 1, 2 or 5 mg of water per mL. Wet samples are no problem, but the titre drifts as reagent ages and must be re-checked.
Three terms, explained simply
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In practice: samples, reagents and interferences
Inject liquids by syringe, dissolve soluble solids in dry methanol first, and handle difficult solids separately, as below.
Liquids: inject by syringe and weigh before and after.
Soluble solids: dissolve in dry methanol, then inject. Remember the blank.
Difficult solids: use a KF oven at 100–250 °C. Budget for it with the titrator.
Ketones and aldehydes: read high. Use a methanol-free K-type reagent.
Oxidising or reducing agents, strong acids or bases: change the reagent or buffer the medium to pH 5–8.
We stock the Chemlab Hydralyt range: MethanolFast volumetric reagent, coulometric AG anolyte, CG catholyte for diaphragm cells, and coulometric oil reagent. KF reagents contain methanol, so risk-assess them under COSHH.
Standards: USP <921> Method Ia (volumetric) and Ib (coulometric), Ph. Eur. 2.5.12 and 2.5.32, ASTM D6304 and E203. Weigh samples on an analytical balance, or compare with moisture analysers if loss on drying fits better.
Related guide: Filling volumetric pipettes for standards or manual titrations? See how to use a pipette filler, and which to buy.
Related: for dissolving samples and stirring during titration, see our magnetic stirrers.
FAQ: Karl Fischer titration
What is the difference between coulometric and volumetric Karl Fischer titration?
Coulometric KF generates iodine electrically in the cell and suits trace water from about 1 ppm to 5%. Volumetric KF adds iodine as a titrant and suits water from about 100 ppm to 100%.
What is a Karl Fischer coulometer?
A KF coulometer is a coulometric Karl Fischer titrator. It measures trace water by counting the charge needed to generate iodine, so it needs no titrant standardisation.
Do I need to standardise a coulometric titrator?
No. It is an absolute method under Faraday's law. Verify performance periodically with a certified water standard.
What is drift in Karl Fischer titration?
The rate at which moisture enters the cell from the air, in micrograms per minute. A rising drift usually means a failed seal, exhausted molecular sieve or worn septum.
Why do ketone samples read high?
Ketones and aldehydes react with methanol and release water. Use a methanol-free K-type reagent.
How much does a Karl Fischer titrator cost?
A dedicated moisture titrator, coulometric or volumetric, is £4,073.51. Full-specification lab instruments cost £7,931 to £9,375.
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