Solid Phase Extraction is the dominant clean-up technique in Bioanalysis

Why using SPE for Clean-up of Biofluids?

1. SPE is an established, successfully applied procedure for efficient extraction / enrichment of a broad variety of (LMW) analytes from different (bio)fluids
2. SPE can easily be coupled / hyphenated with a broad spectrum of separation / detection systems (e.g. LC / GC / CE and UV / FD / ECD / MS)

SPE can be used off-line, at-line and on-line (last arrow leads to detector): Off-line preparation steps, before detectionRobotic Automation of off-line SPE mimics Manual Operation

At-line preparation steps, before detectionAt-line

On-line preparation steps, before detection 

If we make a quadrant with the number of analyses and the sample complexity we can see where we may best use the various methods:

Sample Preparation: Modi operandi

Various instruments are available for at-line SPE, some examples: 

• Quadra 3® SPE
• Speedy
• Microlab®

Total Analysis System (TAS)

Why on-line (integrated) SPE?

Sample Throughput goes up
Analytical Quality goes up
Working Place Quality goes up
Costs go down!  

Cost Comparison: Off-line / LC-integrated SPE Cost (instrumentation and consumables)on the left. Cost (consumables)on the right. Sample: 50 µL of a biofluid. Calculation: based on instruments and materials available from Merck KGaA, Darmstadt, Germany