Clevengertype

Clevenger-type apparatus is a hydrodistillation device used to extract and quantify essential oils from plant material. Named for its designer, the assembly is a glass- or corrosion-resistant instrument consisting of a boiling or extraction flask connected to a condenser and a specially shaped receiver that incorporates a calibrated measuring tube. During operation, the distillate passes into the receiver, where the immiscible essential oil forms a separate layer that can be collected in the upper part of the tube, while the aqueous phase remains below. The design enables direct measurement of oil volume in a single run, facilitating the calculation of oil yield relative to the starting plant material.

Operation and measurement are straightforward. Plant material is combined with water and heated to promote hydrodistillation. The condensate entering the receiver is designed to circulate back to the boiling flask, enabling continuous distillation while the essential oil separates from the water. After the run, the oil layer is typically separated, dried over anhydrous material, and measured in the calibrated tube. Yields are reported as volume percentage or, less commonly, as weight percentage, sometimes with corrections for moisture content or sample dryness.

Applications and variations. The Clevenger-type apparatus remains a standard tool in phytochemistry and essential oil research for determining oil content in botanical materials. Numerous variations exist, including different materials (glass or stainless steel) and minor design tweaks, but all preserve the core feature: simultaneous distillation and direct, in-tube measurement of essential oil yield. It is often described in laboratory manuals and protocol literature as a conventional method for essential oil quantification.