LC-MS Applications for Environmental Analysis

Key Words

• PFC-free Accela

• TSQ Vantage

• High Resolution

• H-SRM

• Perfluorinated

Compounds

Application

Note: 51936

Sensitive and Accurate Quantitation of

Perfluorinated Compounds in Human Breast

Milk using Selected Reaction Monitoring Assays

by LC/MS/MS

Christine Gu, Guifeng Jiang, Robert Szilasie, Stephen Hassan, Allen Zhang, Mark Sanders, Thermo Fisher Scientific, San Jose, CA, USA

Overview

Perfluorinated compounds (PFCs) are ubiquitous and

persistent pollutants that bioaccumulate in animals and

humans. The potential toxicity of these chemicals has

fueled efforts to develop robust analytical techniques for

measuring low levels of PFCs in human matrices. Quan-

titative selected reaction monitoring (SRM) assays were

developed for six PFCs using the Thermo Scientific TSQ

Vantage triple-stage quadrupole mass spectrometer (MS)

coupled to a PFC-free Thermo Scientific Accela LC

system. Using this method, PFCs were accurately and

reproducibly detected at ppt concentrations in neat

solution and in human milk matrix. Exceptionally

sensitive and accurate, this integrated LC-MS platform

is ideally suited for robust ultra-trace analysis of PFCs

in a wide range of matrices.

Introduction

The unique water-, oil-, grease-, stain- and heat-resistant

properties of perfluorinated compounds (PFCs) have led

to their widespread use in diverse industrial applications

and multiple consumer products for over fifty years.

Resistant to degradation, many of these synthetic

compounds have become persistent and ubiquitous

environmental pollutants. Bioaccumulation of PFCs in

wildlife and in humans as well as studies linking some of

these chemicals to developmental, reproductive and systemic

toxicity in laboratory animals have led to efforts to regulate

these compounds and have prompted the need for PFC

monitoring and risk assessment in humans.

1,2

PFCs are

detectable in human serum and breast milk and have even

been found to be present in the blood of newborns, possibly

through lactational transfer from mothers.

Determination

of exposure pathways and health outcomes requires

sensitive and accurate methods for trace-level analysis of

PFCs in a range of human and environmental matrices.

PFCs encompass neutral and ionic species that contain

the perfluorinated alkyl moiety. While gas chromatography-

mass spectrometry (GC/MS) methods have been used to

analyze volatile neutral PFCs and derivatives of ionic PFCs,

many of these chemicals are more amenable to other

analytical techniques. Liquid chromatography-tandem

mass spectrometry (LC/MS/MS) is the method of choice

for the analysis of ionic PFCs in a variety of matrices, but

accurate quantification has proven to be difficult using this

technique due to background PFC contamination and matrix

interferences. These analytical challenges underscore the

need for a high performance LC-MS platform capable of

exceptional sensitivity, selectivity and accuracy.

The TSQ Vantage

™

triple-stage quadrupole MS

coupled to the Accela

™

high speed LC system enables

rapid, accurate and robust LC/MS/MS analysis of small

molecules and biomolecules. Delivering up to a 10-fold

improvement in signal-to-noise ratio compared to existing

triple-quadrupole MS systems, the TSQ Vantage mass

spectrometer facilitates high-sensitivity quantitation in

matrix-rich samples and enhances analytical accuracy and

precision. The instrument is capable of high resolution

(0.2 Da. FWHM) selection of precursor ions, enabling

highly selective reaction monitoring (H-SRM) for greater

analytical selectivity and accuracy. The Accela system,

together with 1.9 µm particle columns, enables fast and

efficient chromatographic separations over an expansive

range of flow rates and pressures.

In this note, we demonstrate highly sensitive, accurate

and reproducible analysis and quantitation of six PFCs in

neat solution and in human breast milk matrix using

selected reaction monitoring (SRM) and H-SRM on the

integrated UHPLC Accela-TSQ Vantage LC-MS platform.

Elimination of PFC contamination from the analytical

system was achieved by using a PFC-free Accela pump with

a pre-cleaned PFC-free degasser and replacing Teflon

tubing with PEEK tubing. The excellent sensitivity and

selectivity afforded by SRM on the TSQ Vantage system

obviated the need for any further modifications of the LC

configuration, a distinct advantage over other commercial

platforms that require the use of in-line contaminant traps

or column-switching methods for PFC analysis.