Soxlet extraction apparatus

Soxhlet Extraction Apparatus - Continuous Reflux Extraction Systems

Soxhlet extractors operate through cyclic solvent reflux, enabling complete lipid recovery from solid matrices without manual intervention. The closed-loop design recirculates heated solvent vapor through condensation and sample percolation, achieving extraction efficiencies exceeding 95% for most organic compounds. Borosilicate 3.3 glass construction withstands thermal cycling between ambient and 200°C, maintaining structural integrity during 6-8 hour extraction protocols.

Continuous Solvent Extraction with Soxhlet Systems

Chamber capacities range from 50mL for micro-scale botanical analysis to 500mL for industrial feed testing, with extraction thimble dimensions proportionally scaled. Standard taper joints (14/20, 19/22, 24/29, 29/32) integrate directly with heating mantles, reflux condensers, and Round funnels for solvent introduction. Siphon discharge occurs at predetermined volumes—typically 75-80% of chamber capacity—creating 4-6 extraction cycles per hour depending on solvent volatility and heating rate.

Operating Principles of Reflux Extraction

Solvent vaporizes in the boiling flask, rises through the side arm, condenses in the water-cooled reflux column, and drips onto the sample contained within a cellulose or glass fiber thimble. Critical parameters include maintaining condenser water flow at 2-3 L/min to prevent vapor escape, regulating heating power to achieve 2-4 siphon cycles hourly, and ensuring thimble porosity matches particle retention requirements.

• Hexane extraction at 69°C for lipid analysis requires 6-8 hours
• Dichloromethane protocols at 40°C complete in 4-6 hours
• Ethanol extraction for botanicals extends to 12-16 hours

Unlike batch extraction with Graduated cylindrical funnels or Measuring cylinders, Soxhlet systems eliminate equilibrium limitations through continuous fresh solvent contact.

Sample Thimble Placement and Size Selection

Thimble diameter must provide 2-3mm clearance from chamber walls to permit solvent bypass flow. Sample loading density of 0.3-0.5 g/mL thimble volume optimizes percolation without channeling. Pack samples uniformly—layered materials create preferential flow paths reducing extraction completeness. Thimble height should position the sample bed 15-20mm below the siphon arm outlet to ensure full immersion during each cycle. Glass fiber thimbles suit aqueous-compatible solvents while cellulose versions handle organic phases exclusively.

Solvent Recovery and Efficiency Optimization

Post-extraction solvent recovery employs rotary evaporation or Glass apparatus distillation setups to reclaim 85-90% of used solvent volume. Calculate initial solvent charge as 1.5-2× the boiling flask capacity plus extraction chamber volume—insufficient volume prevents siphon initiation. Measured cylinders with plastic basis provide accurate solvent volumetrics during apparatus charging. Monitor extraction progress by weighing dried samples at 2-hour intervals; mass reduction below 0.1% indicates completion. Analytical validation requires triplicate extractions with RSD values under 5% for regulatory compliance testing.