# Ultrasensitive Direct Chemical Analysis of Human Hair Using Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS) for Nontargeted Exposure Profiling

## TL;DR

This study introduces a new method using human hair and mass spectrometry to detect pollutants, offering a faster and more sensitive way to assess exposure to air pollution.

## Contribution

A novel thermal extraction method using PTR-TOF-MS for ultrasensitive detection of semivolatile organic compounds in human hair.

## Key findings

- Human hair can serve as a reliable indicator of pollution exposure.
- The method detected phthalates and their metabolites, which are biomarkers of pollution exposure.
- Clustergrams and factor analysis successfully identified chemical sources and patterns in hair samples.

## Abstract

Exposure to air pollution
plays a significant role in
human health.
Current methods of measuring human exposure are often limited to outdoor
measurements, are time intensive, or are unable to accurately measure
certain classes of compounds. This study proposes human hair as a
promising indicator of pollution exposure. We present a novel method
of hair analysis involving thermal extraction and detection of semivolatile
organic compounds using a Vocus 2R proton transfer reaction time-of-flight
mass spectrometer (Vocus PTR-TOF-MS). The hair samples were subjected
to a temperature ramp spanning three different temperatures: 60 °C,
90 °C, and 120 °C. A hierarchical clustering approach was
used to create “clustergrams”, dendrograms comprising
chemical fingerprints of the hair samples at each different temperature.
Each clustergram grouped the chemicals in the samples by similarity,
allowing the determination of potential sources of exposure. Multivariate
factor analysis revealed the presence of phthalates and their corresponding
metabolites, confirming that this method can detect biomarkers associated
with pollution exposure. This method enables the rapid and sensitive
detection of a wide spectrum of toxicologically relevant compounds
in human hair, providing an initial screening tool for measuring human
exposure and assessing health risks.