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GC-MS validation of DMMP in OPCW testing

3.1. Linearity, LOD and LOQ tabulated in Table 2 with the percentage of RSD below
The calibration curve was obtained by injecting a 5% indicating a good analytical method.
standard DMMP in concentrations of 1 ppm, 5 ppm, The precision of this method, demonstrated by an
10 ppm, 15 ppm, 20 ppm, and 25 ppm. The slopes RSD of <10%, is a key factor in assessing its reliability
and intercept of this equation were 179400.45 and for repeated applications, such as PT. Dubey et al.
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−66927.88. The correlation coefficients (R ) for this reported RSD values in the range of 8 – 10% for
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equation were 0.9998 indicating a strong and excellent nerve agent detection. In contrast, this study achieved
linear relationship. The LOD for this method validation an RSD of <5%, highlighting the method’s excellent
was 0.0167 ppm while the LOQ was 0.0557 ppm. reproducibility and robustness, particularly for use with
The sensitivity of this method with a LOD of complex samples containing high matrix interference.
0.0167 ppm aligns with the past studies for CWAS Among the important findings in the present study
detection where Sassolini et al. used LLE with is applying the QuEChERS extraction method, which
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GC-MS and obtained an LOD of 0.05 ppm for conventionally is applied for pesticide residue analysis.
organophosphorus compounds. Similarly, Konopski Although QuEChERS has seldom been applied in the
et al. determined that the LOD for nerve agents in a context of CWAs detection, the results of this study have
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method validation study was 0.02 ppm. In this regard, proved better performance, exceeding the conventional
the approach presented herein performs better in terms approaches to extraction such as LLE and SPE, which
of detection, indicating the benefits of QuEChERS as have been considered the gold standard in CWAs
an extraction method. The reduced LOD value not only analysis. The simplicity and efficiency of QuEChERS
improved the limits of detection for CWAS simulants, are the main advantages of this technique with few steps,
such as DMMP, but it also increased the method’s less solvent used than LLE, and shorter processing times
applicability in real-world environmental samples for than SPE. Anastassiades et al. originally developed
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trace-level CWAS detection. the QuEChERS method for pesticide analysis, but its
In this study, the linearity (R² = 0.9998) is consistent adaptation for the detection of DMMP suggests it could
with previously proven methodologies in this field. potentially be applied to other CWAS. The study by
Dubey et al. used GC-MS to detect CWAs and found an Antonijevic et al., which used a traditional conventional
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R² value of 0.9997 for nerve agents, indicating that the method, such as LLE, found high solvent consumption
study’s results matched recognized methodologies. This and longer extraction times. This, in contrast, can be
near-perfect linearity provides consistent quantification avoided by using the QuEChERS approach. Moreover,
of DMMP across a wide concentration range, which is the recovery rates for this study (95.7 – 97.3%) are
critical in PT. higher compared to earlier studies. Pragney and Saradhi
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successfully reported a recovery rate of 88 – 92% for
3.2. Accuracy and precision organophosphorus agents with the SPE technique.
The accuracy and precision of the method were assessed
based on recovery and repeatability, which are crucial 3.3. Specificity
indicators of the method’s reliability in determining The specificity of the method was evaluated by
DMMP. The results are summarized in Table 1. The preparing a solution containing 10 ppm of DMMP,
recovery rates ranged from 95.7% to 97.3%, and the 10 ppm of C -C saturated alkanes, and 10 ppm of
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%RSD was <10%, demonstrating that the method FAME diesel. This solution was prepared in triplicate
meets the required criteria for accuracy and precision. to ensure reproducibility and precision. The analytical
The repeatability and reproducibility were performed results indicated that the methodology achieved a
with spiking concentrations of 5 and 15 ppm of DMMP DMMP extraction accuracy of 96.2%, reflecting its high
within a day and on different days. The results were level of analytical performance and reliability.

Table 1. Accuracy of the proposed method

Analyte Spiked concentration (ppm) Detected concentration (ppm) Recovery (%) RSD (%)
DMMP 1 0.957 95.7 6.2
10 9.73 97.3 3.4
25 24.175 96.7 4.1
Abbreviation: RSD: Relative standard deviation.

Volume 22 Issue 2 (2025) 47 doi: 10.36922/ajwep.8196