Peptide & Purification

Dual-Column Cyclic / Simulated Moving Bed (SMB) Chromatography

Mechotech designs and manufactures turnkey dual-column cyclic and Simulated Moving Bed (SMB) continuous chromatography systems for difficult, high-value separations that batch prep chromatography struggles to make economical. By switching mobile-phase inlet and outlet ports along a set of columns in a repeating cycle, an SMB system creates a simulated counter-current movement between the stationary and mobile phases — so feed is introduced continuously and the two product streams are drawn off continuously. This counter-current action sharply lowers solvent consumption and boosts productivity and recovery compared with single-pass batch preparation, which is why it is chosen for isomer splits, chiral separations, and the purification of high-value actives. Mechotech engineers the complete system — columns, precision valves, pumps, detection and software — for pharmaceutical, nutraceutical and fine-chemical manufacturers.

A Mechotech SMB system links two or more packed columns through a network of precision switching valves so that the feed inlet, eluent inlet, extract outlet and raffinate outlet are advanced around the column set at fixed intervals. This port-switching mimics a stationary phase moving counter-current to the mobile phase, concentrating the more-retained component into the extract stream and the less-retained component into the raffinate stream while feed and eluent enter continuously. Because the same solvent front is reused across the cycle and both products are recovered, solvent usage per kilogram of product falls and productivity rises against batch prep. The system runs low-dead-volume flow paths to preserve resolution, reaches a stable cyclic steady state for consistent output, and offers multiple simulated-moving-bed operating modes through the control software to suit two-component or pseudo-continuous separations. Product-contact parts are stainless steel and inert polymers; column count, dimensions, valve configuration and detection are configured to the separation, with performance such as high purity (typically greater than 98%) and high recovery (typically greater than 90%) achievable on well-behaved binary separations.

Technical Specifications

Technology	Simulated Moving Bed (SMB) / dual-column cyclic continuous chromatography
Working Principle	Port-switching that simulates counter-current movement of the stationary phase
Column Count	Dual-column cyclic to multi-column SMB (configurable)
Operating Modes	Multiple simulated-moving-bed modes via software
Feed / Eluent	Continuous introduction (not discrete injection)
Product Streams	Continuous extract and raffinate
Valve Network	Precision multi-port switching valves, low dead volume
Pumps	High-precision metering pumps per zone (configurable)
Detection	In-line UV / dual-wavelength or RI (configurable)
Typical Purity	Greater than ~98% achievable on well-behaved binary separations
Typical Recovery	Greater than ~90% achievable (application-dependent)
Steady State	Stable cyclic steady state for consistent output
Product-contact Material	Stainless steel and inert polymers (PEEK / PTFE)
Automation	Recipe-based control with audit-trail support (configurable)
Output	Continuously recovered purified extract and raffinate streams

Plant Capacities

Configuration	Columns	Best For	Solvent Use	Typical Recovery
Dual-column cyclic	2 columns	R&D & small-scale binary separations	Low vs batch prep	high (application-dependent)
Multi-column SMB (4-zone)	4+ columns	Production binary separations	Lower per kg of product	typically >90%
Multi-column SMB (extended)	6–8 columns	High-throughput continuous production	Lowest per kg of product	typically >90%

Adding columns and zones increases throughput and lowers solvent use per kilogram of product but raises system complexity; a dual-column cyclic system is often the most cost-effective start for R&D and small-scale work. All purity and recovery figures are typical/achievable on well-behaved binary separations, not guaranteed values — column count, dimensions and valving are configured to the separation.

Manufacturing Process

Method & Feed Definition

The binary separation is characterised on a single column, and the isotherm and switch time are used to set the SMB port-switching schedule and flow rates.

Column Configuration

Two or more packed columns are arranged in a loop and connected through the precision switching-valve network that defines the SMB zones.

Continuous Feed & Eluent Introduction

Feed and eluent are pumped into the column loop continuously rather than in discrete injections, unlike single-pass batch preparation.

Simulated Counter-Current Operation

The inlet and outlet ports are advanced around the columns at each switch interval, simulating stationary-phase movement counter-current to the mobile phase.

Extract & Raffinate Separation

The more-retained component concentrates into the extract stream and the less-retained component into the raffinate stream, each drawn off continuously.

Cyclic Steady State

After several switch cycles the system settles into a stable cyclic steady state, giving consistent purity and recovery run after run.

Detection & Control

In-line detection and the control software monitor each stream, holding the switch time and flows on target and enabling multiple SMB operating modes.

Solvent Recovery & Product Workup

The reused eluent is recovered and recycled, and the extract and raffinate are concentrated for downstream crystallisation, drying or formulation.

Applications

Chiral separations — resolving enantiomers of pharmaceutical actives
Positional and structural isomer separation
Omega-3 concentration — EPA and DHA enrichment
Purification of high-value actives such as paclitaxel-type compounds
Purification of anti-obesity and lipase-inhibitor actives such as orlistat
Peptide and protein polishing at continuous production scale
Sugar, amino-acid and organic-acid fractionation
Fine-chemical binary separations where batch prep is uneconomical

Key Features

Continuous Counter-Current Operation
Port-switching simulates a moving stationary bed so feed enters and both products leave continuously, greatly out-producing single-pass batch prep on binary separations.
Lower Solvent Consumption
The eluent front is reused across the cycle and both components are recovered, cutting solvent use per kilogram of product and lowering operating cost.
High Productivity & Recovery
Concentrating each component into its own continuous stream raises throughput per unit of stationary phase and delivers high recovery of both products.
Multiple SMB Operating Modes
The control software offers several simulated-moving-bed modes, so the system can be tuned for classic four-zone, dual-column cyclic or pseudo-continuous separations.
Low Dead Volume & Stable Steady State
Low-dead-volume flow paths preserve resolution, and the system reaches a stable cyclic steady state for consistent, repeatable output.
Configurable Columns & Valving
Column count, dimensions, precision valve network and detection are configured to the separation, from dual-column cyclic to multi-column SMB.

Frequently Asked Questions

What is Simulated Moving Bed (SMB) chromatography?

SMB is a continuous chromatography technique that links several packed columns and switches the feed and product ports around them at fixed intervals. This simulates a stationary phase moving counter-current to the mobile phase, so feed can be introduced continuously and two purified streams — extract and raffinate — are drawn off continuously.

How is SMB different from batch preparative chromatography?

Batch prep injects discrete samples and recovers peaks one run at a time, using fresh solvent each pass. SMB runs continuously, reuses the eluent across the cycle and recovers both components, which lowers solvent consumption per kilogram of product and raises productivity and recovery — the advantage grows for difficult, high-value binary separations.

What separations is SMB best suited to?

It excels at difficult two-component separations of high-value products: chiral separations of enantiomers, positional and structural isomers, omega-3 EPA/DHA enrichment, and the purification of high-value actives such as paclitaxel-type compounds and orlistat, as well as sugar and amino-acid fractionation and peptide polishing at scale.

What is the difference between a dual-column cyclic system and multi-column SMB?

A dual-column cyclic system uses two columns and is often the most cost-effective entry point for R&D and small-scale binary separations. Multi-column SMB adds columns and zones to raise throughput and further cut solvent use per kilogram of product, at the cost of more valving and complexity. Mechotech configures the count to the separation.

What purity and recovery can SMB achieve?

On well-behaved binary separations, high purity — typically greater than 98% — and high recovery — typically greater than 90% — are achievable for both product streams. These are typical, application-dependent figures rather than guaranteed values; actual performance depends on the feed, the stationary phase and the method.

Does SMB really lower solvent consumption?

Yes. Because the eluent front is reused across the port-switching cycle and both components are recovered rather than a single peak collected per run, solvent usage per kilogram of product is markedly lower than single-pass batch preparation, reducing both operating cost and solvent-disposal burden.

Does Mechotech supply the SMB system turnkey?

Yes. Mechotech delivers the complete dual-column cyclic or multi-column SMB system — columns, precision switching valves, metering pumps, detection and control software — with method development support, installation, commissioning and after-sales service as a single integrated package.

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Dual-Column Cyclic / Simulated Moving Bed (SMB) Chromatography