Environmental Exposure Assessment among Infant via Diapered Urine Analysis: A Challenge of Methodology

Introduction

Assessment of environmental exposure using biological samples such as urine is non-invasive. However, most infants wear disposable diapers.
Therefore, extraction urine from diapers is a challenge step before laboratory analysis. This study aims to develop and validate a method for detecting
ten hydroxylated polycyclic aromatic hydrocarbons (OHPAHs) in diapered urine.

Methods

Ten individual adult urine samples (≈100 mL) were employed to experiment. Thirty millimeters of urine were pass through the diaper and extract diaper urine (DU) with 50 mL of 50 g/L calcium chloride (CaCl₂) solution. The DU extract was measured calcium ion using atomic absorption spectroscopy (AAS). Then 10 mL aliquot of extracted DU along with normal individual urine (U) were acidified to pH 5.0, hydrolyzed with β-glucuronidase, and clean up the extract using solid phase extraction (C18 OH). Ten OHPAH metabolites (2-hydroxynaphthalene (2-OHNap), 1-hydroxynaphthalene (1-OHNap),
2+3-hydroxyfluorene (2+3-OHFlu), 2-hydroxyphenanthrene (2-OHPhe), 3-hydroxyphenanthrene (3-OHPhe), 9-hydroxyphenanthrene (9-OHPhe),
1-hydroxyphenanthrene (1-OHPhe), 4-hydroxyphenanthrene (4-OHPhe) and 1-hydroxypyrene (1-OHP)) were quantified using High Performance Liquid Chromatography with Fluorescence Detection (HPLC-FLD) with deuterated internal standards (1-OHP-d9 and 1-OHNap-d7) to ensure accuracy.
The detected OHPAHs concentrations of DU and U were compared and discussed.

Results

We found that the recovery rates of OHPAH metabolites from DU compared to U ranged from approximately 34 to 94%, with the highest recoveries observed for 4-OHPhe (94%) and 1-OHPhe (92%), followed by 1-OHP (87%), 2-OHPhe (68%), 2+3-OHFlu (47%), 3-OHPhe (41%), 2-OHNap (40%), 9-OHPhe (36%), and 1-OHNap (34%).

Conclusions

This study developed and validated a method for detecting OHPAH metabolites in infant diaper urine, with recovery rates ranging from 34% to 94%. Lower recoveries for some metabolites suggest losses during extraction from diaper, and interference of high calcium levels in diaper-extracted urine with enzymatic hydrolysis. Further study is warranted to address these challenges.