In this study, ultrahigh-pressure liquid chromatography–time-of-flight mass spectrometry (UHPLC–TOF-MS) was used to analyze
nine targeted pharmaceuticals and personal care products and several unknown compounds in North American river water samples.
Several pharmaceuticals and personal care products (PPCPs) have been detected in surface river waters, raising concerns about
water pollution (1). Many of these PPCPs are released into rivers and streams anthropogenically from municipal sewage treatment
plants. There is inefficient breakdown of the chemically synthesized PPCPs in the sewage treatment plants and the resulting
effluent released from these plants carries the products into rivers. There is a growing concern for detecting PPCPs in aquatic
systems because of the potential risk they pose to aquatic and human life. Reliable analytical techniques to identify and
quantify PPCPs are important to develop. The diversity in the chemical nature of PPCPs, along with low concentrations of these
analytes in complex matrices, makes these methods challenging to develop.
PPCPs have been quantified using gas chromatography–mass spectrometry (GC–MS) methods, which require derivatization to make
the analytes more volatile (2). Besides GC–MS, liquid chromatography (LC)–triple-quadrupole MS methods have been developed,
which do not require derivatization and are less tedious (3). However, triple-quadrupole mass spectrometers are often set
to acquire in multiple reaction monitoring (MRM) mode, which does not allow for the simultaneous acquisition of full spectral
information. Besides, quadrupole MS systems exhibit very poor sensitivity in scan mode, which limits their use to identify
unknown analytes such as the wide variety of PPCPs. Unlike quadrupole instruments, time-of-flight (TOF) mass spectrometers
show high sensitivity while acquiring full spectrum information, making them ideal for analyzing and identifying an unlimited
number of compounds without prior knowledge of target analytes or when reference standards are not available. The parts-per-million
mass accuracy provided by TOF mass spectrometers helps to determine elemental composition, thereby aiding identification of
unknowns. The TOF systems fitted with newer analog-to-digital conversion technologies offer a wide dynamic range equivalent
to triple-quadrupole systems. Similar to quadrupole instruments, TOF mass spectrometers can be used for quantifying known
targets yet have the added advantage of identifying unknown compounds.
Here, we present a study of PPCPs in river water samples from northeastern United States using ultrahigh-pressure liquid chromatography
(UHPLC) coupled with TOF-MS for both targeted and nontargeted analytes. In this study, we show how high mass accuracy information
along with compound identification software can be used to identify unknown analytes in surface river waters.