Hello,

I’m Christopher George, Lab Systems and Automation Manager at Precision Analytical. I’ve been working with automation applications and integrations for about seven years now, and with various platforms in the computer sciences as a hobby for about twice that long.

Let me see… let me figure out my mouse here.

There we go.

We’ve been using Lynx systems for about five years now. Prior to that, our liquid handlers were Tomtec and Tecan systems. This year, we’ll be transitioning the last of our legacy Tecan processes onto Lynx systems. We’re a human sex hormone testing lab that processes urine and saliva samples. Each patient submits about half a dozen samples or more, depending on what’s being tested. We process them for LC-MS analytical review.

Our focus today will be on the solid phase extraction process, where we run multiple solvents through 96-well SPE columns on LM900, VVP96 systems, and ST96 systems.

In this presentation, we’ll cover a lot of the variables that impact solvent transfers, including:

• Environmental factors

• Solvent polarity

• Interactions with both 1250 µL filtered and non-filter tips

• General solvent pipetting settings in Method Manager 4

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Environmental Factors

Some key considerations include:

• Negative airflow

• Static charge management

• Temperature control

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Solvent Polarity

Polarity can affect transfer speeds and the order of steps. Two solvents with similar polarity may still behave differently due to other properties, influencing how they interact with the tips. Chemical compatibility is critical—A-level compatibility issues can result in unwanted interactions with the inner and outer surfaces of robotic pipette tips.

Filming (residual solvent retained on the tip) is affected by:

• Solvent polarity

• Chemical compatibility with tips

• Static buildup

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Tip Size & Tip Type

All liquid handling discussed uses 1250 µL filtered and non-filter tips on VVP and ST systems, which we exclusively use in our lab. If you use smaller tips, you may see improvements in microdroplet formation, especially for polar solvents.

The VVP and ST systems also differ in how they manage solvent transfers. Volatility and working surface area affect how reliably solvents are handled.

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Negative Airflow (Extraction Safety)

Per OSHA, 60 feet per minute face velocity is required—though greater is ideal. Dynamic Devices recommends 750–800 CFM air change-out for the system. Lynx systems should safely extract solvent vapors from the operating chamber. Ours operates at about 100 FPM face velocity with 750 CFM air change.

Here’s a basic DIY method we used early on:

• Remove the bottom panel of an LM900 or LM1800

• Attach a wood board with a hole routed for a fume extractor

• Connect to a 6” duct and run through an SAS system at 750 CFM

Later, we upgraded to a polished solution:

• Sheet metal boot with a vertical stack

• 8” flex tubing tied into lab HVAC

• Face velocity: 100+ FPM with consistent 750 CFM airflow

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Static – The Silent Killer

Use ionization bars to reduce static charge. Charge interactions with solvents can be unpredictable, especially in low-volume transfers. Anything over 2 kV can potentially disrupt a transfer.

Example:

• Left: Keyence static reading device

• Right: Keyence ionization bar on LM900 VVP96, supplied with positive-pressure nitrogen

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Temperature Management

Maintain consistent temperature during both operation and validation. Avoid fluctuations of more than a few degrees. This applies to solvent behavior just as much as aqueous solutions.

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Polarity

Generally, non-polar solvents are easier to manage due to reduced stickiness and behavior more similar to aqueous solutions. Polar solvents introduce intermolecular forces that make solvent behavior less predictable—especially in tip interactions and filming during final dispense.

Filming issues:

• Usually only affect the final ~2% of volume

• Can drip, pop, or create bubbles mid-transfer

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Chemical Compatibility

Lynx OEM polypropylene tips are compatible with most solvents but not all. Always consult a chemical compatibility chart.

• Methanol: High compatibility, reusable for up to a month

• Hexane: Can warp plastics over time—limit exposure

• MTBE: Tricky—more prone to filming and structural effects

We reuse tips not exposed to sample for multiple days, sometimes up to a month with conservative rotation.

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Filtered vs. Non-Filtered Tips

We use 1250 µL tips exclusively for throughput. Differences:

• Filtered tips:

  • Reduce effective cavity volume

  • Required for VVP systems to prevent volatilization reaching the channels

  • More sensitive to tip loading volume

• Non-filtered tips:

  • Greater cavity space

  • Work well on ST systems

  • Not recommended for VVP systems due to exposure risks

Using non-filtered tips on ST systems allows for more stable equilibria and less tip interaction issues with volatile solvents.