# Understanding the Compatibility of Fluoride-Based Radiopharmaceutical Reaction Solutions and PDMS

## TL;DR

This study investigates whether PDMS, a common microfluidic material, is compatible with fluoride-based radiopharmaceuticals and finds that incompatibility occurs under specific conditions.

## Contribution

The study identifies the specific conditions under which PDMS interacts with fluoride and K2CO3 in radiopharmaceutical reactions.

## Key findings

- PDMS interacts with fluoride when reaction solutions are fully evaporated and crystallized.
- GC-MS detected fluoride-containing volatile species that explain previous fluoride loss.
- PDMS is incompatible with K2CO3, a common radiofluorination reaction component.

## Abstract

Microfluidic devices offer unique and exciting benefits
when applied
to radiopharmaceutical manufacturing, and these platforms are now
starting to be integrated into commercial products. The field has
strayed away from the use of polydimethylsiloxane (PDMS), the most
common microfluidic device material, due to its suspected incompatibility
with 18F, the most commonly used radionuclide. However,
existing literature provides conflicting conclusions as to the existence
and extent of this incompatibility. In this study, we use several
analytical instruments to uncover the underlying interaction between
fluoride and PDMS. SEM imaging and profilometry confirm the reactive
relationship between the two materials and suggest that this interaction
only occurs when the reaction solution is fully evaporated and crystallized
salts are in contact with PDMS. Furthermore, GC-MS identifies fluoride-containing
volatile species that can account for loss of fluoride in previous
studies and additionally reveals an incompatibility between PDMS and
K2CO3 (a commonly used component of radiofluorination
reaction solutions). These results confirm the need for microfluidic
radiofluorination devices to avoid the use of PDMS in most contexts
but may allow for inexpensive design and testing of liquid state operations
(such as concentration, purification, and mixing) using the material.