What size Soxhlet extractor do I need?

Size the extractor body to the sample mass and the flask to the solvent volume. A 100 mL body suits 1 to 5 g of dried sample, a 250 mL body suits 5 to 15 g samples typical of food and feed fat determination, and a 500 mL body is for bulky or low-fat material where a larger sample is needed for a measurable result. The flask should hold roughly one and a half to two times the solvent volume the body siphons, so a 250 mL body is normally paired with a 500 mL flask.

How many siphon cycles should an extraction run?

Most official fat and oil methods call for 20 to 30 siphon cycles, or four to six hours, after the solvent first starts refluxing. The rate depends on the heating power and the condenser, so record the actual cycle count for each run rather than relying on time alone. For a new method, extract one sample for extra cycles and check that the fat recovered in a second extraction of the same thimble is negligible.

Why does my Soxhlet extractor flood or siphon slowly?

A slow or erratic siphon usually comes from an obstructed siphon arm, a thimble packed too tightly, or too little heating so vapour never fills the body fast enough. Check that the siphon arm is clean and free of lint, load the thimble to no more than two thirds of its height, and raise the heating mantle setting gradually. A joint that is not sealed with the right grease can also leak vapour and stall the cycle.

Does JWRESEARCH supply Soxhlet apparatus in Singapore?

Yes. JWRESEARCH supplies borosilicate 3.3 Soxhlet extractor bodies from 100 to 500 mL, matching round-bottom extraction flasks, Allihn and coil condensers, extraction thimbles, heating mantles and support stands, delivered across Singapore.

Soxhlet Extractors and Extraction Apparatus Singapore

Published: {{NEW_ARTICLE_DATE}} | By JWRESEARCH | Category: Laboratory Glassware

A Soxhlet extraction looks simple from the outside: solvent boils, condenses, drips onto the sample, siphons back, and repeats. In practice the result depends on four matched parts — the right body volume, a flask that holds enough solvent, a condenser that keeps up with the vapour load, and heat that is steady enough to hold a fixed cycle time. Mismatch any one of them and the fat value drifts between replicates.

At JW RESEARCH SUPPLY, we supply complete Soxhlet assemblies in borosilicate 3.3 glass to food, feed, environmental, polymer and pharmaceutical laboratories across Singapore, together with thimbles, mantles and support hardware. This guide covers sizing, setup and the checks that keep a gravimetric extraction reproducible.

How the Assembly Works

Solvent vapour rises from the flask through the side arm of the extractor body, condenses in the condenser above it and drips down onto the sample in the thimble. Liquid solvent accumulates around the thimble until the siphon arm fills, at which point the whole body drains back into the flask, carrying the extracted material with it. Because the sample is repeatedly washed with freshly distilled solvent rather than sitting in a growing solution, the extraction is efficient and uses a modest solvent volume.

Extractor Body Options

Body Capacity	Typical Sample Mass	Flask Size	Solvent Volume	Common Use
100 mL	1 – 5 g	250 mL	150 – 200 mL	Method development, small or costly samples
250 mL	5 – 15 g	500 mL	250 – 350 mL	Routine fat and oil in food and feed
500 mL	15 – 40 g	1000 mL	500 – 700 mL	Bulky, fibrous or low-fat material
1000 mL	40 – 100 g	2000 mL	900 – 1300 mL	Industrial and environmental solids

Specification Reference

Parameter	Typical Value	What It Affects
Material	Borosilicate glass 3.3	Thermal shock resistance and solvent compatibility
Joint sizes	24/40, 29/32, 34/35, 45/50	Must match flask and condenser joints
Siphon volume	About 40 – 60 % of body capacity	Solvent-to-sample ratio per cycle
Cycle time	10 – 20 minutes at steady reflux	Total run time and throughput
Condenser type	Allihn bulb or coiled	Cooling capacity for high-boiling solvents
Max flask temperature	Limited by solvent boiling point	Mantle setting and safety margin
Thimble diameter	22 – 43 mm	Must clear the body and sit below the siphon
Support	Ring stand, clamp, boss head	Keeps the vertical stack stable and leak-free

Matching Joints and Condensers

Buy the body, flask and condenser as a matched set, or verify the joint size on each piece before ordering. A 24/40 body will not seal against a 29/32 flask, and an adapter adds a leak path right where hot solvent vapour is trying to escape. Grease only lightly, and use a grease that is insoluble in the solvent you are running — silicone grease in a hexane extraction will show up as extractable mass.

Condenser choice follows the solvent. For petroleum ether and hexane, an Allihn bulb condenser with a generous water flow is enough. For higher-boiling solvents such as toluene or chloroform, a coiled condenser or a longer jacket keeps vapour from escaping into the fume hood.

Setting the Heat

Use a heating mantle sized to the flask rather than a hotplate with an oil bath, and control it with a variable power controller. The goal is not the fastest possible cycle but a steady one: a run that siphons every 12 minutes for five hours is more trustworthy than one that starts at 8 minutes and slows to 25 as the solvent level drops.

Never let the flask boil dry. As solvent is held in the body during a cycle, the flask level falls; if the extractor is left unattended past the end of the run, the last solvent can evaporate and the flask can crack or the residue can char. Set a timer, and keep the cooling water on until the flask is cool to the touch.

Setup Checklist

Clamp the flask, body and condenser as one vertical stack; do not hang the body from the condenser alone.
Confirm the thimble sits below the top of the siphon arm and above the bottom of the body.
Add boiling chips or a stir bar to the flask, never to the thimble.
Wet the joints lightly and check the seal before applying heat.
Record the first siphon time, then count cycles rather than watching the clock.
Run the whole assembly in a fume hood with the sash at a safe working height.

Cleaning and Storage

Drain the flask while it is still warm, then rinse the body with the same solvent, followed by detergent and water. Siphon arms are the usual place for lint and sample residue to collect, so flush them with a narrow brush or a jet of solvent. Dry the glassware inverted on a rack, and store the body and condenser assembled with the joints slightly open so they do not seize.

Contact JWRESEARCH

JW RESEARCH SUPPLY — laboratory equipment and consumables, Singapore.
Telephone / WhatsApp: +65 8039 3660
Email: SINGAPORE@JWSHY.COM
Website: www.jwresearch.cn