Distillation Apparatus, Ammonia

Quick Answer: An ammonia distillation apparatus is a glass set-up in which a sample is made alkaline and boiled so that ammonia is driven off, condensed and absorbed in a receiving acid. It is used to determine ammoniacal nitrogen in water and wastewater, and the nitrogen in Kjeldahl digests, by titration or colour measurement of the distillate.

Separating Ammonia Before Measuring It

Ammonia in a water or wastewater sample is often accompanied by colour, turbidity and dissolved substances that interfere with a direct test. Distillation separates it first. The sample is buffered or made alkaline, which converts ammonium ions to free ammonia, and on boiling the ammonia leaves with the steam. It condenses and is collected in a receiver holding boric acid solution or a measured volume of standard acid.

The distillate is then analysed. Ammonia trapped in boric acid is titrated with standard acid, while ammonia absorbed in a known excess of acid is found by back titration. Low concentrations are more often measured by a colour method, such as Nessler’s reagent compared in a Nessler cylinder, or the phenate method.

A splash head or trap bulb between the flask and condenser is usual in ammonia stills, so droplets of alkaline liquid cannot be carried into the receiver and give a falsely high result. The listing does not state which parts, flask size or joint type are included. For protein and organic nitrogen work built around a digestion flask, compare the Kjeldahl distillation assembly.

Applications

• Determining ammoniacal nitrogen in drinking water, river water and treated effluent
• Distilling Kjeldahl digests in soil, fertiliser and feed analysis
• Environmental science practicals on nitrogen pollution and water quality
• Checking ammonia in aquaculture water, where it is harmful to fish

Specifications

Care & Handling

• Before each run, steam out the apparatus with ammonia-free water to remove traces left on the glass by the previous sample.
• Keep the delivery tube tip below the surface of the receiving acid during distillation, and lower the receiver before heating stops so no suck-back occurs.
• Add alkali carefully down the side of the flask so it layers under the sample, and connect the apparatus before mixing.
• Rinse the condenser and delivery tube with a little distilled water into the receiver at the end, so no ammonia stays behind in the glass.

Why Choose LabEquip

Water testing, environmental and agricultural laboratories use an ammonia distillation apparatus whenever sample colour or turbidity would disturb a direct test. LabEquip carries it among its chemistry lab equipment; mention the method you follow and the parts required when you write via the contact page.

Frequently Asked Questions

Why is the sample made alkaline before distillation?

In neutral or acidic water, ammonia exists mostly as ammonium ions, which do not evaporate. Raising the pH converts them to free ammonia gas, which is carried over with the steam and can then be collected.

Why use boric acid in the receiver?

Boric acid is a very weak acid that holds ammonia as ammonium borate without needing to be measured exactly. The trapped ammonia is then titrated directly with standard hydrochloric or sulfuric acid, using a mixed indicator.

What does the splash head do?

It is a bulb or baffle above the flask that catches droplets thrown up by boiling. Without it, alkaline spray can reach the condenser and receiver, neutralising some of the acid and giving a falsely high ammonia result.

How do I prevent suck-back into the flask?

Lower the receiver so the delivery tube is out of the liquid before you stop heating. As the flask cools, its internal pressure falls, and a tube still dipping in the acid would draw the receiving solution back.

Why does the blank matter?

Distilled water, reagents and laboratory air can all contain small amounts of ammonia. Running a blank with ammonia-free water and the same reagents shows how much of the result comes from these sources, so it can be subtracted.

Is this the same as a Kjeldahl distillation?

The chemistry of the distillation step is the same. Kjeldahl work first digests the sample in sulfuric acid to convert organic nitrogen to ammonium; ammonia distillation of water samples usually skips digestion and measures only the ammonia already present.

Last Updated: September 2026