Pre-analytical and analytical variables that influence urinary volatile organic compound measurements

Area of Science:

• Analytical Chemistry
• Biomedical Diagnostics
• Metabolomics

Background:

• Volatile organic compounds (VOCs) show promise for non-invasive medical diagnostics.
• Standardization of sample collection and storage is crucial for reliable VOC analysis.
• Limited understanding exists regarding the impact of pre-analytical variables, such as sample storage, on VOC profiles.

Purpose of the Study:

• To investigate the effect of varying room temperature storage durations on urine VOC profiles.
• To assess the impact of storage time on total ion count and VOC degradation.
• To establish optimal storage guidelines for urine samples intended for VOC analysis.

Main Methods:

• Urine samples from healthy individuals were sealed and stored at room temperature for different durations before freezing.
• Field Asymmetric Ion Motility Spectrometry (FAIMS) was employed to analyze VOC profiles.
• Changes in VOC profiles and total ion counts were quantified over time.

Main Results:

• Increased storage time at room temperature led to greater variability in urinary VOC profiles.
• A plateau in VOC profile variability was observed between 12 and 48 hours, followed by degradation.
• Total ion count increased with prolonged room temperature exposure.
• Deterioration of VOCs was noted during the analytical process with extended storage.

Conclusions:

• Room temperature storage significantly alters urine VOC profiles, affecting diagnostic accuracy.
• A maximum of 12 hours at room temperature before freezing is recommended for urine sample storage.
• These findings are critical for standardizing protocols in VOC-based diagnostics using FAIMS.