Dual-Solvent SPE-UPLC-MS/MS Method for Quantifying 17 Organophosphate Flame Retardants in Environmental Waters.

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Mass Spectrometry

Background:

• Organophosphate esters (OPEs) are widely used flame retardants with increasing environmental prevalence.
• Accurate quantification of OPEs is essential due to their potential toxicity.
• Existing analytical methods face challenges in separating and quantifying the diverse range of OPE congeners.

Purpose of the Study:

• To develop and validate a novel ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method.
• To achieve simultaneous quantification of 17 OPEs, addressing challenges of polarity and co-elution.
• To improve the recovery rates of both polar and hydrophobic OPEs.

Main Methods:

• Utilized an ACQUITY UPLC BEH C18 column for enhanced chromatographic separation.
• Implemented a novel dual-solvent sequential elution strategy for solid-phase extraction (SPE).
• Employed methanol and ethyl acetate in a sequential elution for improved OPE recovery.

Main Results:

• Achieved baseline separation of critical OPE isomer pairs.
• Significantly improved recovery rates for polar (e.g., TMP) and hydrophobic (e.g., TEHP) OPEs.
• Quantitative recovery (33.2%-153%) for all 17 OPEs was achieved, compared to only six with single-solvent methods.
• Detected 11 OPEs in surface water and WWTP samples, with TBEP at 100% frequency.
• Demonstrated property-dependent removal efficiencies in WWTPs, with >99% removal for hydrophobic OPEs and limited removal for hydrophilic ones.

Conclusions:

• The developed UPLC-MS/MS method offers a robust analytical solution for OPEs.
• This method is suitable for comprehensive environmental monitoring of OPEs.
• The findings support improved risk assessment strategies for OPEs in aquatic environments.