Water in pharmaceuticals
Water content of APIs, excipients and finished tablets.
Useful forPharmacopoeial water determinationElemental & Composition
Karl Fischer
KF
Karl Fischer titration measures the water content of a sample using a reaction that is specific to water. It gives accurate results from ppm traces to high percentages in liquids, solids and oils.
1 test optionSpecific to waterppm traces to high % waterTypical turnaround 2–4 working days
Karl Fischer measurement principleIllustrative
01 / Overview
What is Karl Fischer?
Karl Fischer titration uses the reaction of water with iodine and sulfur dioxide in an alcohol and a base. The sample dissolves in the titration cell and iodine is added until all the water has reacted; a double platinum electrode detects the endpoint.
Unlike loss on drying, KF responds only to water, not to solvents or other volatiles lost on heating. Volumetric KF suits samples with around 0.1 % water or more, while coulometric KF measures traces down to a few ppm.
02 / How it works
How it works
- 01
Cell is conditioned
The solvent in the titration cell is titrated dry, so only the sample's water is counted.
- 02
Sample is added
A weighed sample is injected or added through a port and dissolves in the solvent.
- 03
Iodine reacts with water
Reagent is dosed, or iodine generated, until all the water has reacted.
- 04
Endpoint gives water
The electrode detects excess iodine; the reagent used gives the water content.
03 / What it measures
What it measures
Trace water in solvents
ppm-level water in dry solvents and reagents.
Useful forAnhydrous solvents, electrolytesWater in oils & fuels
Dissolved and emulsified water in oils.
Useful forTransformer oil, lubricants, fuelsMoisture in powders & polymers
Water in granules and powders, by direct titration or oven transfer.
Useful forPolymers, chemicals, battery materialsWater of crystallisation
Bound water in hydrates and salts, together with free water.
Useful forHydrated salts, crystalline APIs04 / Test options
Choose the Karl Fischer options you need
1 option · none added yet
05 / Sample requirements
Sample requirements
- Accepted forms
- Liquids, solvents, oils, powders, tablets and granules
- Quantity
- Typically 5–10 g solid or 10–20 mL liquid per sample
- Container
- Airtight glass vials or bottles with little headspace
- Expected level
- Share the approximate water content so the right method is chosen
- Seal samples airtight straight after sampling
- Fill containers close to the top to limit headspace
- Mention solubility and reactive groups such as ketones or aldehydes
- No paper envelopes or loosely closed plastic bags
- No strong oxidising or reducing agents without discussing first
Hazardous or air-sensitive samples: mention it in your request, and attach the MSDS if you have one.
06 / Results & turnaround
Results & turnaround
What you receive
- Water content in % w/w or ppm
- Individual replicate values and mean
- Method used: volumetric or coulometric, oven if applied
- Sample weights and reagent titre
- Report PDF
Turnaround & pricing
Typically 2–4 working days after samples reach the lab.
Price confirmed in your quotation, depending on user type, options and number of samples.
07 / Limitations
When Karl Fischer isn't the right fit
Total loss on drying, including solvents
Identifying residual solvents
Mass loss over a temperature programme
Let’s find your next step
Need help choosing an option?
Share what you want to measure. We’ll help you find the right next step.