High-Throughput Solid Phase Extraction for Targeted and Nontargeted Exposomics

Characterizing the
chemical exposome relies on advanced instrumentation
including tandem mass spectrometry coupled to liquid chromatography
(LC-MS/MS), and nontargeted analysis (NTA) using high-resolution MS.
However, proper sample pretreatment, balancing broad analyte coverage,
method robustness, and throughput remain a major bottleneck in exposomics.
Here, we developed a robust and scalable solid phase extraction (SPE)
protocol for human urine and plasma and optimized it for a panel of
94 highly diverse environmental and food-related contaminants (LogP
−0.7 to 6.8). Extraction recoveries (RE) and signal suppression
and enhancement (SSE) were determined using targeted LC-MS/MS. Acceptable
REs (60–140%) were achieved for >70% of analytes, and acceptable
SSE values (60–140%) for 86% and 90% in urine and plasma, respectively.
Subsequently, the method was transferred to 96-well plate format,
significantly improving throughput to meet the capacity requirements
needed for exposome-wide association studies (ExWAS). The established
workflow is approximately 10× faster than routinely used metabolomics-based
protein precipitation approaches when comparing the estimated total
analysis time for 1000 samples. The method’s applicability
for NTA and suspect screening was tested and compared to a generic
protein precipitation protocol using NIST standard reference materials
for urine (SRM 3672) and plasma (SRM 1950). Favorable performance
was shown for the protein precipitation workflow while the SPE protocol
demonstrated promising results. The developed workflow is thus not
only superior for future high-throughput targeted exposomics but also
offers an option for NTA applications. The presented well-balanced
approach is scalable and also applicable to research in the fields
of pharmacology, food safety, and systems toxicology.