5 / 302
Fast and Accurate Identification of Pesticides
by Direct Analysis in Real Time (DART)
Ionization with Orbitrap Mass Spectrometry
Jaewon Choi,
1
Wonseok Choi,
1
Jennifer Massi,
2
Mari Prieto Conaway
2
1
Water Analysis & Research Center, K water, Daejeon 306-711, Korea
2
Thermo Fisher Scientific, San Jose, CA, USA
Application Note
605
Key Words
Direct Analysis in Real Time ionization, DART, Exactive, Orbitrap,
pesticides, water analysis
Goal
To describe a method incorporating direct analysis in real time (DART)
ionization an
d Thermo Scientific ™ Orbitrap ™high-resolution mass
spectrometry for rapid analysis and identification of contaminating
substances in water.
Introduction
When water or soil is contaminated by chemical substances,
quick methods of analysis are required to assess the negative
impact on the environment. Accidents that have an impact
on drinking water require rapid, real-time diagnosis of the
chemical substance involved. The contamination is confirmed
in the lab after often tedious extraction and concentration
processes and instrumental analysis of the target compounds.
Full-scan mass spectrometry is a powerful compound
identification technique. However, conventional
quadrupole-type scanning produces low-resolution mass
spectra. Most contamination accidents involve
concentrations at ng/mL levels; therefore, it is essential
that the samples be concentrated prior to instrumental
analysis. Care must be taken as to not lose the target
compound during the pre-treatment or concentration
process. For example, polar substances can be lost during
liquid-liquid extraction, and limitations in selectivity of
materials used in solid-phase extraction (SPE) can hinder
adsorption and concentration of the target compound.
Direct analysis in real time (DART
®
) has recently been
introduced as a desoprtion ionization technology that
requires limited or no sample pre-treatment prior to
introduction into the mass spectrometer.
1
As a direct spray
ionization technique, DART bypasses the conventional
high-performance liquid chromatography (HPLC)
routinely coupled to MS analysis. It is therefore amenable
to high-throughput screening (HTP) and attractive to use
in forensics, defense, clinical research, and food
applications.
2
Although DART has successfully been
coupled to triple quadrupole mass spectrometry
3,4
technology, combining it with high-resolution, accurate
mass (HRAM) mass spectrometry
5-7
might lead to higher
probability of identifying unknown substances.
In this study, a method incorporating DART and Orbitrap
high-resolution mass spectrometry was developed for
rapid analysis and identification of contaminating
substances in water. A total of 23 commonly used
agricultural pesticide target compounds were analyzed
(Table 1). The possibility of screening target compounds at
the ng/mL concentration level in water samples, indicative
of real case scenarios, was also reviewed.