Page 51 - AJWEP-v22i2

GC-MS validation of DMMP in OPCW testing

play a central role in this process. 14,15 Water bodies the QuEChERS method’s performance in OPCW
contaminated with CWAs or related compounds, such PT, a novel approach that has not been extensively
as DMMP, pose complex analytical challenges. These explored in CWAS-related research. This method has
contaminants often occur in trace amounts and are the potential to streamline sample preparation, reduce
accompanied by matrix interferences, requiring robust costs, and enhance the accuracy of CWAS analysis,
and sensitive analytical techniques. offering significant contributions to international efforts
Historically, liquid-liquid extraction (LLE) has to prevent the use of chemical weapons.
been the most widely used sample preparation
technique in OPCW PT. This classical method relies 2. Materials and methods
on the partitioning of analytes between two immiscible
solvents with different polarities, which isolates the 2.1. Reagents and materials
target compounds from the sample matrix. For non- DMMP, utilized as the reference standard, was acquired
16
polar and semi-polar CWAs, dichloromethane is from Thermo Scientific. Acetonitrile (ACN), toluene,
commonly employed as the extraction solvent. However, hexane, and sodium chloride (NaCl) were sourced from
advancements in sample preparation methods have led Merck, while magnesium sulfate anhydrous (MgSO₄)
to the development of alternative techniques such as and acetic acid were obtained from J.T. Baker Chemical
single-drop microextraction, dispersive LLE, and solid- Company. C₇-C₃₀ saturated alkanes and fatty acid
supported LLE, which offer enhanced precision and methyl ester (FAME) diesel was purchased from Sigma-
reliability. 17 Aldrich. All chemicals were of analytical grade, and
In recent years, interest has grown in the application ultrapure water was used throughout the experiments.
of the Quick, Easy, Cheap, Effective, Rugged, and Safe The real sample analyzed in this study was obtained
(QuEChERS) method, which was originally developed from the 52 OPCW PT, where DMMP was included
nd
for the analysis of pesticide residues in food products. in the spiking list.
18
QuEChERS has gained popularity due to its simplicity
and efficiency, making it an attractive alternative 2.2. Methods
for sample preparation in various fields. Despite its 2.2.1. Sample preparation method
widespread use for pesticide analysis, QuEChERS has For sample preparation, 1 mL of the 52 OPCW PT
nd
not yet been extensively applied to the analysis of CWAs sample was added to a centrifuge tube and mixed with
or OPCW PT samples. The QuEChERS technique was 500 µL of ACN (1% acetic acid). The tube was capped
chosen in this study since it is simple, low in solvent and placed in a freezer at −18°C for 15 min. Following
consumption, and entails minimal sample handling, this, 1.5 g of MgSO₄ and 0.75 g of NaCl were added
thereby increasing reproducibility. As compared to to the mixture, which was shaken vigorously for 1 min.
19
traditional methods, such as LLE or solid phase extraction The mixture was then centrifuged at 4400 rpm under
(SPE), QuEChERS achieves superior recovery with cooling at 5°C for 5 min. Subsequently, 600 µL of the
less matrix effect. This is particularly beneficial in upper layer was transferred into a vial containing 0.2 g
14
OPCW PT, where CWAs or their simulants are most of MgSO₄. The vial was shaken and centrifuged again
found in complex and challenging matrices. Given the at 4400 rpm under cooling for 2 min. Finally, the extract
structural similarities between certain pesticides (e.g., was transferred into a gas chromatography (GC) vial
organophosphorus compounds) and CWAs, such as for analysis. Figure 2 shows the flow process of sample
sarin, soman, and VX, adapting the QuEChERS method preparation used in this study.
for CWAs analysis could offer significant benefits.
19
This study focuses on the adaptation and validation of 2.2.2. Gas chromatography-mass spectrometry
the QuEChERS methodology for the analysis of DMMP analysis
for the 52 OPCW PT. DMMP residues were determined using a 5975 Series
nd
This study aims to contribute to this expanding Agilent GC-MS (Agilent Technologies, USA), equipped
knowledge base by evaluating the performance of the with an autosampler and employing splitless injection.
QuEChERS method for DMMP detection, with a focus The column used was HP-5MS Ultra Inert (Agilent
on key performance parameters such as selectivity, Technologies, USA), measuring 30 m in length, with
limit of detection (LOD), limit of quantification (LOQ), a 0.25 mm internal diameter and a film thickness of
accuracy, precision, and specificity. In this study, 0.25 µm. The oven temperature was initially set at
DMMP serves as the reference standard for evaluating 200°C for 2 min, then ramped to 290°C at a rate of

Volume 22 Issue 2 (2025) 45 doi: 10.36922/ajwep.8196