The chemical derivatization to enhance the signal intensity and signal-to-noise (S/N) of several organophosphorus (OP) acids in liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS) is illustrated. The OP class of compounds represents the environmental degradants of OP nerve agents and pesticides. N-(2-(bromomethyl)benzyl)-N,N-diethylethanaminium bromide (CAX-B) was utilized to derivatize a panel of eight acids consisting of five alkyl methylphosphonic acids (ethyl-, isopropyl-, isobutyl-, cyclohexyl-, and pinacolyl-methylphosphonic acid) along with three dialkylphosphate analogs (diethyl-, dibutyl-, and diethyl thio-phosphate). The derivatization reaction with CAX-B was conducted in acetonitrile in the presence of potassium carbonate at 70 °C for 1 h. The resulting acid derivatives were analyzed with an LC-Orbitrap-ESI-MS/MS, and their dissociation processes were investigated. It was found that the derivatization procedure increased the limits of identification (LOIs) by one to over two orders of magnitude from the range of 1 to 10 ng/mL for the intact OP-acids to the range of 0.02–0.2 ng/mL for the derivatized acids utilizing an LC-MS(QqQ) in MRM mode, regardless of the sample matrix (hair, concrete, or plant extracts). The interpretation of the corresponding ESI-MS/MS spectra for each type of derivatized sub-OP family revealed the formation of characteristic neutral losses and a characteristic ion for the organophosphorus core. This derivatization is beneficial and useful for screening and identifying target and “unknown” OP acids.

A novel COVID-19 vaccine (BriLife^®) has been developed by the Israel Institute for Biological Research (IIBR) to prevent the spread of the SARS-CoV-2 virus throughout the population in Israel. One of the components in the vaccine formulation is tris(hydroxymethyl)aminomethane (tromethamine, TRIS), a buffering agent. TRIS is a commonly used excipient in various approved parenteral medicinal products, including the mRNA COVID-19 vaccines produced by Pfizer/BioNtech and Moderna. TRIS is a hydrophilic basic compound that does not contain any chromophores/fluorophores and hence cannot be retained and detected by reverse-phase liquid chromatography (RPLC)-ultraviolet (UV)/fluorescence methods. Among the few extant methods for TRIS determination, all exhibit a lack of selectivity and/or sensitivity and require laborious sample treatment. In this study, LC–mass spectrometry (MS) with its inherent selectivity and sensitivity in the multiple reaction monitoring (MRM) mode was utilized, for the first time, as an alternative method for TRIS quantitation. Extensive validation of the developed method demonstrated suitable specificity, linearity, precision, accuracy and robustness over the investigated concentration range (1.2–4.8 mg/mL). Specifically, the R² of the standard curve was >0.999, the recovery was >92%, and the coefficient of variance (%CV) was <12% and <6% for repeatability and intermediate precision, respectively. Moreover, the method was validated in accordance with strict Good Manufacturing Practice (GMP) guidelines. The developed method provides valuable tools that pharmaceutical companies can use for TRIS quantitation in vaccines and other pharmaceutical products.

We developed a selective technique to rapidly measure free chlorine, which is the sum of elemental chlorine (Cl₂), hypochlorous acid (HOCl), and hypochlorite (OCl⁻) in water samples via an electrophilic aromatic substitution reaction hyphenated with liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Sample preparation involved derivatization at 25 °C for 15 min with 3,4,5-trimethoxyphenylacetic acid (TMPAA) in an aqueous solution prior to analysis. Several parameters were evaluated to determine the optimized reaction and for the production of informative MS/MS spectrum of the derivatization product, 2-chloro-3,4,5-trimethoxyphenylacetic acid (Cl-TMPAA). The resulting Cl-TMPAA derivative displayed an informative ESI-MS/MS spectrum characterized by product ions at m/z 232.0142, 200.0245, and 185.0009 from the precursor ion at m/z 259.0379. The linear dynamic range of the method (0.1–10 µg/mL) was fitted to concentration levels relevant to forensic toxicology issues. Compared with other analytical techniques, this newly established LC-MS-based method demonstrated specificity, simplicity, and rapidity. This method enables the detection of free chlorine for forensic investigations in criminal cases.

Organophosphorus (OP) pesticides are a class of chemicals that are extensively used worldwide. The exposure to and use of organophosphates can be assessed by analyzing their metabolites and degradation products, such as dialkyl phosphate (DAP), dialkyl thiophosphate (DATP), and dialkyl dithiophosphate (DADTP). However, since these metabolites/hydrolysis products can result from the metabolism or breakdown of several organophosphorus pesticide families, they serve as nonspecific biomarkers and do not indicate the specific pesticide involved in exposure. In an earlier study, chemical derivatization using N-(2-(bromomethyl)benzyl)-N,N-diethylethanaminium bromide (CAX-B) was described to improve the signal intensity of numerous organophosphorus (OP) acids in liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS) analysis. In the present study, CAX-B was employed to derivatize a set of seven phenolic compounds corresponding to the complementary portion of OP pesticides. The derivatization process using CAX-B was performed in acetonitrile with potassium carbonate at 50 °C for 30 min. LC-Orbitrap-ESI-MS/MS was used to analyze the resulting phenol derivatives and their fragmentation patterns were studied. Notably, the derivatized phenols were markedly more sensitive than the underivatized phenols when LC-ESI-MS/MS was used in MRM technique, without being affected by the sample matrix (soil or plant extracts). This derivatization technique aids in identifying OP pesticides, offers insights into their subfamily, and pinpoints a specific compound through the analysis of corresponding phenol derivative.

Rapid and specific detection of toxic Novichok agents (A230, A232, A234) is crucial for forensic investigations and the prevention of chemical weapon misuse. While A232 and A234 are relatively stable, A230 is less stable and primarily undergoes hydrolysis via P–F bond cleavage. This product indicates the presence of the Novichok core but does not indicate the agent’s prior existence. In this study, a method with high sensitivity for determining the presence of the minor A230 hydrolysis product—namely methylphosphonofluoridic acid (MPFA), which is generated via P-N bond cleavage—in environmental matrices was established. 2-[(Dimethylamino)methyl]phenol (2-DMAMP) was found to be effective for the derivatization of MPFA in water. The derivatization protocol after optimization involved adding 2-DMAMP followed by agitating for 72 h at 50 °C before LC–MS/MS analysis. The derivatized MPFA, analyzed by ESI–MS/MS, showed two main fragment ions with m/z values of 185.0 and m/z 107.0. The approach was applied to tap water, aqueous soil extract, and saline samples. While intact MPFA exhibited reduced detectability due to strong matrix effects, derivatization enhanced its stability and minimized interferences, resulting in its significantly higher detection sensitivity. The detection of MPFA provides a clear indication that the toxic Novichok compound was present prior to hydrolysis.