Robust and sensitive LC/MS-MS method for simultaneous detection of acetylsalicylic acid and salicylic acid in human plasma

The Impact of Convertase Subtilisin/Kexin Type 9 Monoclonal Antibodies with and without Apheresis on Platelet Aggregation in Familial Hypercholesterolemia

BACKGROUND AND AIMS

It is well known that elevated cholesterol is associated with enhanced platelet aggregation and patients suffering from familial hypercholesterolemia (FH) have a high risk of thrombotic cardiovascular events. Although decreasing cholesterol level is associated with attenuation of platelet hyperactivity, there are currently no data on the effect of convertase subtilisin/kexin type 9 monoclonal antibodies (PCSK9ab) on platelet reactivity in FH. The aim of the study was to analyse the impact of different therapies including PCSK9ab on platelet aggregation in FH.

METHODS

This study enrolled all 15 patients treated in the University Hospital Hradec Králové for FH. PCSK9ab have been administered in 12 of 15 patients while 8 patients were also undergoing lipid apheresis. Blood samples from all patients including pre- and post-apheresis period were tested for platelet aggregation triggered by 7 inducers, and the effect of 3 clinically used drugs (acetylsalicylic acid, ticagrelor and vorapaxar) was compared as well.

RESULTS

Although apheresis decreased the reactivity of platelets in general, platelet responses were not different between non-apheresis patients treated with PCSK9ab and apheresis patients (post-apheresis values) with the exception of ristocetin. However, when compared to age-matched healthy population, FH patients had significantly lower platelet aggregation responses to 4 out of 7 used inducers and higher profit from 2 out of 3 used antiplatelet drugs even after exclusion of FH patients regularly receiving conventional antiplatelet treatment.

CONCLUSION

This study showed for the first time the suitability of PCSK9ab treatment for reduction of platelet reactivity in FH patients.

Selective fluorescence detection of acetylsalicylic acid, succinic acid and ascorbic acid based on a responsive lanthanide metal fluorescent coordination polymer

A fluorescent sensor for highly selective and ultrasensitive detection of acetylsalicylic acid (ASA), succinic acid (SA), and ascorbic acid (AA) was reported. The water-soluble fluorescent ligand salicylic acid (Sal) was generated through catalyzing ASA by the hydrolase activity of zeolitic-imidazolate framework-8 (ZIF-8) or natural esterase (Est). The Sal can coordinate with 2-methylimidazole (2-MIm) and Ln(III) to form a fluorescent lanthanide coordination polymer (LCP), which has a fluorescence emission peak with the maximum wavelength at 412 nm (the excitation wavelength at 300 nm). Therefore, the detection of ASA can be achieved through the fluorescence intensity changes of LCPs in the system, which has comparable sensitivity and good selectivity (linear range of 0.031-1.00 mM and LODs of 11.72 and 3.22 μM) as compared to a direct reaction between Est/ZIF-8 and ASA for detecting ASA (linear range of 0.05-1.20 mM and limits of detection (LODs) of 4.43 and 4.58 μM). Furthermore, upon the addition of SA and AA, the fluorescence intensity of the reaction system can be enhanced and weakened through changing the energy resonance transfer pathways and affecting the enzymatic reaction process, respectively, realizing their sensitive and selective fluorescence detection. The established fluorescent sensors can work well in a wide linear range of SA concentrations from 0 to 2.50 mM (Est-based reaction system) and 0 to 1.50 mM (ZIF-8-based reaction system) with the LODs of 0.032 and 0.028 mM, respectively. The linear ranges of AA concentrations are from 0.0078 to 0.25 mM (Est-based reaction system) and 0.0078 to 0.13 mM (ZIF-8-based reaction system) with the LODs of 2.54 and 3.80 μM, respectively. The established sensors were successfully used in the detection of SA in rabbit plasma, with a recovery of 84.0%-98.7%. Additionally, the contents of ASA in Aspirin Enteric-Coated tablets and AA in vitamin C tablets were also determined by the developed methods.

Ziziphus spina-christi L. extract attenuates bleomycin-induced lung fibrosis in mice via regulating TGF-β1/SMAD pathway: LC-MS/MS Metabolic profiling, chemical composition, and histology studies

Ancient Egyptians (including Bedouins and Nubians) have long utilized Ziziphus spina-christi (L.), a traditional Arabian medicinal herb, to alleviate swellings and inflammatory disorders. It is also mentioned in Christian and Muslim traditions. Ziziphus spina-christi L. (Family: Rhamnaceae) is a plentiful source of polyphenols, revealing free radical scavenging, antioxidant, metal chelating, cytotoxic, and anti-inflammatory activities. Herein, different classes of the existing bioactive metabolites in Z. spina-christi L. were detected using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the first time. The study also aimed to assess the anti-inflammatory and antifibrotic properties of Z. spina-christi L. extract against bleomycin-induced lung fibrosis in an experimental mouse model. 32 male Swiss Albino mice were assigned into 4 groups; the first and second were the normal control group and the bleomycin positive control (single 2.5 U/kg bleomycin intratracheal dose). The third and fourth groups received 100 and 200 mg/kg/day Z. spina-christi L. extract orally for 3 weeks, 2 weeks before bleomycin, and 1 week after. The bioactive metabolites in Z. spina-christi L. extract were identified as phenolic acids, catechins, flavonoids, chalcones, stilbenes, triterpenoid acids, saponins, and sterols. The contents of total phenolic compounds and flavonoids were found to be 196.62 mg GAE/gm and 33.29 mg QE/gm, respectively. In the experimental study, histopathological examination revealed that lung fibrosis was attenuated in both Z. spina-christi L.- treated groups. Z. spina-christi L. extract downregulated the expression of nuclear factor kappa B (NF-κB) p65 and decreased levels of the inflammatory markers tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and c-Jun N-terminal kinase (JNK) in lung tissue. Z. spina-christi L. also downregulated the expression of the fibrotic parameters collagen-1, alpha-smooth muscle actin (α-SMA), transforming growth factor-beta 1 (TGF-β1), matrix metalloproteinase-9 (MMP-9) and SMAD3, with upregulation of the antifibrotic SMAD7 in lung tissue. Overall, the present study suggests a potential protective effect of Z. spina-christi L. extract against bleomycin-induced lung fibrosis through regulation of the TGF-β1/SMAD pathway.

Atmospheric solids analysis probe mass spectrometry: An easy bolt-on for the synthetic undergraduate teaching laboratory

RATIONALE

High costs and student numbers can often hinder implementation of mass spectrometry (MS) in the undergraduate teaching laboratory, often with technicians running samples on students' behalf, and the implementation of MS only in discrete or isolated experiments. This study explores the use of atmospheric solids analysis probe MS (ASAP-MS) as a relatively low-cost, benchtop instrument, and its potential for application as a 'bolt-on' to existing undergraduate organic chemistry experiments.

METHODS

Thirteen products synthesised in undergraduate laboratory experiments were analysed by ASAP-MS, along with their starting materials. Analysis was carried out with a Waters RADIAN ASAP mass spectrometer, at four different cone voltages simultaneously to provide fragmentation information.

RESULTS

Out of the 13 undergraduate experiments, ASAP-MS was shown to be complementary in 11 of these, either through simple analysis of the precursor ion or by a more complex analysis of the fragments.

CONCLUSIONS

ASAP-MS provided spectra that both complement and enhance intended learning outcomes in existing organic chemistry experiments, showing its versatility as a bolt-on technique. Moving forward, ASAP-MS will be integrated into the University of Surrey's undergraduate teaching laboratory.

MOFs@POMs-derived bimetallic oxide Fe2(MoO4)3 nanoparticles for sensitive colorimetric detection of salicylic acid in aspirin

A colorimetric sensing method for salicylic acid (SA) was developed by designing and fabricating bimetallic oxide nanozymes. Firstly, by calcinating MIL-100(Fe)@PMo12 (MOFs@POMs) at different temperature, Fe2(MoO4)3-Ts (T = 400℃, 500℃, 600℃, 700℃) nanoparticles (NPs) were successfully prepared. Secondly, by evaluating the peroxidase-like activities, Fe2(MoO4)3-600 NPs shows the best peroxidase-like activity attributed to the Fenton-like effect and the synergistic coupling interaction between Mo and Fe. Finally, based on the specific complexation between SA and Fe3+, a sensitive colorimetric sensor for SA was established, which exhibits superior selectivity and interference with a detection limit of 0.11 μM and a linear range of 10 to 100 μM, the lowest LOD for SA to date, to the best of our knowledge.

Sustainable Agriculture with LEAFS: a Low-cost Electrochemical Analyzer of Foliage Stress

Sustainable agricultural practices are vital to meet the needs of a rapidly growing global demand for food. Monitoring plant health is crucial for enhancing crop yields. Salicylic acid (SA) is a plant hormone that plays a key role in the defense mechanisms plants employ against various stress factors. Changes in SA levels serve as an indicator that a plant is experiencing stress. Here, we present a low-cost electrochemical sensor fabricated using porous laser-induced graphene material for the measurement of plant stress. It employs square wave voltammetry to monitor SA levels using a wireless potentiostat. The sensor shows a high sensitivity of 144.28 μA/mM to SA, with a linear detection range of 6.6 μM to 200 μM and a limit of detection of 1.44 μM. The surface of the working electrode was modified with Nafion to enable continuous in-situ stress monitoring. The sensor's practicality has been demonstrated through real-time stress monitoring in aloe vera and philodendron hederaceum plant species.

Synchronous spectrofluorimetric determination of favipiravir and aspirin at the nano-gram scale in spiked human plasma; greenness evaluation

Favipiravir and aspirin are co-administered during COVID-19 treatment to prevent venous thromboembolism. For the first time, a spectrofluorometric method has been developed for the simultaneous analysis of favipiravir and aspirin in plasma matrix at nano-gram detection limits. The native fluorescence spectra of favipiravir and aspirin in ethanol showed overlapping emission spectra at 423 nm and 403 nm, respectively, after excitation at 368 nm and 298 nm, respectively. Direct simultaneous determination with normal fluorescence spectroscopy was difficult. The use of synchronous fluorescence spectroscopy for analyzing the studied drugs in ethanol at Δλ = 80 nm improved spectral resolution and enabled the determination of favipiravir and aspirin in the plasma matrix at 437 nm and 384 nm, respectively. The method described allowed sensitive determination of favipiravir and aspirin over a concentration range of 10-500 ng/mL and 35-1600 ng/mL, respectively. The described method was validated with respect to the ICH M10 guidelines and successfully applied for the simultaneous determination of the mentioned drugs in pure form and in the spiked plasma matrix. Moreover, the compliance of the method with the concepts of environmentally friendly analytical chemistry was evaluated using two metrics, the Green Analytical Procedure Index and the AGREE tool. The results showed that the described method was consistent with the accepted metrics for green analytical chemistry.

The Effect of 4-Methylcatechol on Platelets in Familial Hypercholesterolemic Patients Treated with Lipid Apheresis and/or Proprotein Convertase Subtilisin Kexin 9 Monoclonal Antibodies

Elevated low-density lipoprotein (LDL) cholesterol levels lead to atherosclerosis and platelet hyperaggregability, both of which are known culprits of arterial thrombosis. Normalization of LDL cholesterol in familial hypercholesterolemia (FH) is not an easy task and frequently requires specific treatment, such as regularly performed lipid apheresis and/or novel drugs such as proprotein convertase subtilisin kexin 9 monoclonal antibodies (PCSK9Ab). Moreover, a high resistance rate to the first-line antiplatelet drug acetylsalicylic acid (ASA) stimulated research of novel antiplatelet drugs. 4-methylcatechol (4-MC), a known metabolite of several dietary flavonoids, may be a suitable candidate. The aim of this study was to analyse the antiplatelet effect of 4-MC in FH patients and to compare its impact on two FH treatment modalities via whole-blood impedance aggregometry. When compared to age-matched, generally healthy controls, the antiplatelet effect of 4-MC against collagen-induced aggregation was higher in FH patients. Apheresis itself improved the effect of 4-MC on platelet aggregation and blood from patients treated with this procedure and pretreated with 4-MC had lower platelet aggregability when compared to those solely treated with PCKS9Ab. Although this study had some inherent limitations, e.g., a low number of patients and possible impact of administered drugs, it confirmed the suitability of 4-MC as a promising antiplatelet agent and also demonstrated the effect of 4-MC in patients with a genetic metabolic disease for the first time.

A validated LC–MS/MS method for analysis of Cabergoline in human plasma with its implementation in a bioequivalent study: investigation of method greenness

Cabergoline (CAB) is effective prolactin lowering drug. Evaluation of the bioequivalence for the new test product (0.5 mg CAB film-coated tablets) in Egypt is strongly needed for approval of the drug by the official health authority. Therefore, a highly sensitive and rapid (LC–MS/MS) method was validated for CAB analysis in human plasma. CAB was extracted from plasma via diethyl ether using Quetiapine (QUE) as an internal standard. Multiple reaction monitoring (MRM) in positive ion mode was used, m/z 452.3 → 381.2 for CAB and 384.2 → 253.1 for QUE. Separation was accomplished on a reversed-phase C₁₈. FDA procedures for the bio-analytical method were followed. The method was used in the bioequivalence study to compare the test product (0.5 mg CAB) versus Dostinex tablets, on 24 healthy Egyptian volunteers. The total analysis time was 5.5 min for each sample which permits analysis of various samples per day. The linearity range was from 2.00 to 200.00 pg/mL for CAB. LOD and LOQ were found to be 0.5 and 1.6 pg/mL, respectively. The final greenness numerical value was 0.63 using AGREE tool. The results of pharmacokinetic parameter T_max were 2.17, and 2.33 h; for test and reference products, respectively. The generic formulation of test product is considered bioequivalent to the reference product Dostinex 0.5 mg tablets and satisfies the requirements of the Egyptian market. The merits of the method over the previous published methods are low cost; availability of cheap internal standard; rapidness; use of acetonitrile-free solvents mobile phase.

Monitoring of salicylic acid content in human saliva and its relationship with plasma concentrations

Aspirin is a widely used anti-inflammatory drug. It is reported that a relationship may exist between salicylic acid content in plasma and saliva after taking aspirin. This study established a rapid, convenient, and safe method to assess salicylic acid concentration in human saliva. A novel HPLC-ultraviolet detector was used to measure salicylic acid concentrations in human saliva and plasma. A C18 reversed-phase column with an aqueous solution of 0.1% trifluoroacetic acid (TFA)-acetonitrile mobile phase was used, and drug peaks were recorded at 303 nm. Salicylic acid was completely separated in saliva and plasma. Excellent linearity and correlation (r² ≥ 0.9999) was observed between 0.1 and 2.0 μg/mL. The detection limit (S/N = 3) was 33 ng/mL, and intra- and inter-day recoveries were 103.5-113.3% and 101.1-109.5%, respectively. Salicylic acid was measured within nine hours after administration of acetylsalicylic acid tablets. A positive correlation between salicylic acid content in saliva and plasma was found (r = 0.867, p < 0.001). The proposed method was used successfully to measure salicylic acid concentration in human saliva. Meanwhile, we explored the relationship between salicylic acid levels in plasma and saliva. Saliva might replace blood for monitoring aspirin treatment. In addition, the research provides a reference for application to saliva samples.

Metabolomics-driven determination of targets for salicylic acid and ibuprofen in positive electrospray ionization using LC-HRMS

Due to the large number of basic therapeutic and illicit drugs, systematic toxicological analysis has widely been performed with liquid chromatography coupled to mass spectrometry using positive electrospray ionization. However, there exists a smaller number of drugs, typically acidic drugs, which require the use of negative electrospray ionization either via a separate injection or polarity switching. Here, targets relating to salicylic acid and ibuprofen in positive electrospray ionization were determined through a metabolomics-driven retrospective investigation of forensic casework. Samples were previously screened using liquid chromatography coupled with high-resolution mass spectrometry with quantification of target analytes performed using liquid chromatography with tandem mass spectrometry. Of the 1717 whole-blood samples submitted between 2014 and 2019, 48 were positive for salicylic acid (1.1-1400 mg/kg) and 78 for ibuprofen (1-46 mg/kg). Based on the retrospective analysis, 19 and 90 targets were identified for salicylic acid and ibuprofen, respectively. For targets of salicylic acid, the protonated adduct of salicyluric acid ([M+H]⁺ , m/z 196.0605) was present in 89.6% (n = 32) of the salicylic acid positive cases while the [M+HCOOH+CH₃ CN+Ca-H]⁺ adduct (m/z 264.0179) of salicylic acid was present in all positive samples with concentrations above 66 mg/kg salicylic acid. Similarly, the [M + 2Na - H]⁺ adduct (m/z 251.1018) of ibuprofen was present in 98.7% (n = 77) of positive cases and was present in all samples with concentrations above 3 mg/kg ibuprofen.

In-vitro and in-vivo metabolism of different aspirin formulations studied by a validated liquid chromatography tandem mass spectrometry method

Low-dose aspirin (ASA) is used to prevent cardiovascular events. The most commonly used formulation is enteric-coated ASA (EC-ASA) that may be absorbed more slowly and less efficiently in some patients. To uncover these "non-responders" patients, the availability of proper analytical methods is pivotal in order to study the pharmacodynamics, the pharmacokinetics and the metabolic fate of ASA. We validated a high-throughput, isocratic reversed-phase, negative MRM, LC-MS/MS method useful for measuring circulating ASA and salicylic acid (SA) in blood and plasma. ASA-d4 and SA-d4 were used as internal standards. The method was applied to evaluate: (a) the "in vitro" ASA degradation by esterases in whole blood and plasma, as a function of time and concentration; (b) the "in vivo" kinetics of ASA and SA after 7 days of oral administration of EC-ASA or plain-ASA (100 mg) in healthy volunteers (three men and three women, 37-63 years). Parameters of esterases activity were Vmax 6.5 ± 1.9 and Km 147.5 ± 64.4 in plasma, and Vmax 108.1 ± 20.8 and Km 803.2 ± 170.7 in whole blood. After oral administration of the two formulations, tmax varied between 3 and 6 h for EC-ASA and between 0.5 and 1.0 h for plain-ASA. Higher between-subjects variability was seen after EC-ASA, and one subject had a delayed absorption over eight hours. Plasma AUC was 725.5 (89.8-1222) for EC-ASA, and 823.1(624-1196) ng h/mL (median, 25-75% CI) for plain ASA. After the weekly treatment, serum levels of TxB2 were very low (< 10 ng/mL at 24 h from the drug intake) in all the studied subjects, regardless of the formulation or the tmax. This method proved to be suitable for studies on aspirin responsiveness.

Evaluation of single and combined effects of two pharmaceuticals on the marine gastropod Phorcus lineatus enzymatic activity under two different exposure periods

Pharmaceutical drugs are among the most used chemicals for human and veterinary medicines, aquaculture and agriculture. Pharmaceuticals are environmentally persistent, biologically active molecules, thereby having the potential to exert biological effects on non-target species. Among the most used pharmaceuticals, one may find salicylic acid (SA), a non-steroid anti-inflammatory drug (NSAID) that acts by inhibiting the enzymes cyclooxigenases; it is also possible to identify acetazolamide (ACZ), a diuretic that acts by inhibiting the activity of carbonic anhydrase (CA). In this work, the effects of both single and combined effects of these drugs were assessed on the marine gastropod Phorcus lineatus, by measuring key enzymatic activities, namely carbonic anhydrase (CA) and cyclooxygenase (COX), under two different exposure periods (14 and 28 days). We observed no straightforward pattern of enzymatic response in all treatments of both pharmaceuticals, on both analyzed tissues (gut and gills), and for both exposure regimes. We assume that this species is not responsive to the hereby tested pharmaceuticals, a finding that may be due to general mechanisms of response to adverse conditions, such as reduction of metabolism, of heart rate, of filtration rates, and to the increase production of mucus. All these functional adaptations can mitigate the deleterious effects caused by adverse conditions, without triggering biochemical responses. In conclusion, the species P. lineatus seems not to be sensitive in terms of these specific enzymatic pathways to these contaminants, under the adopted conditions.

Patients with Essential Thrombocythemia may be Poor Responders to Enteric-Coated Aspirin, but not to Plain Aspirin

Essential thrombocythemia (ET) patients are treated with aspirin (acetylsalicylic acid [ASA]) to prevent thrombosis. Previous studies showed that serum thromboxane (Tx) B₂ was high 24 hours after enteric-coated (EC)-ASA in ET patients, due to increased number of noninhibited reticulated platelets (RPs), consequent to high platelet turnover, and that ASA should be given twice a day to ET patients. We studied ET patients (n = 17) and healthy subjects (n = 10) on 100 mg EC-ASA once daily; experiments were repeated after 14-day treatment with 100 mg plain-ASA once daily. Serum TxB₂, plasma ASA, and salicylic acid (SA) were measured before the morning dose and up to 8 hours thereafter. Blood activity of ASA-deacethylating esterases, in vitro inhibition of collagen-induced TxB₂ production by ASA (10-1,000 µM), and number of RP were measured. TxB₂ inhibition by ASA in vitro and esterases activities were normal in all subjects. EC-ASA elicited highly variable responses; 6 ET patients were poor responders, as their serum TxB₂ was high after EC-ASA; their plasma levels of ASA and SA were low/undetectable. In contrast to EC-ASA, plain ASA decreased serum TxB₂ and increased plasma ASA and SA in all subjects. Serum TxB₂ was high in ET patients at 24 hours and significantly correlated with RP count (but not RP percentage) and platelet count. Plain ASA should be used in ET patients to inhibit platelets efficiently. The identification of ET patients who might benefit from twice a day ASA could simply be based on their platelet count: since their platelet turnover is not increased, ET patients with normalized platelet count should not need twice a day ASA treatment.

Circulating Salicylic Acid and Metabolic Profile after 1-Year Nutritional⁻Behavioral Intervention in Children with Obesity

Objectives and Study: Salicylic acid (SA), a phenolic compound produced by plants, may play a beneficial role on health. A pilot study showed that children with obesity had lower serum SA than normal-weight children. The aim of this trial was to evaluate the effect of a 1-year nutritional-behavioral intervention on serum SA levels and to study a possible association between SA levels and metabolic profile changes in children with obesity.

METHODS

This was an interventional longitudinal observational uncontrolled cohort study. Forty-nine children with obesity, aged >6 years were evaluated. BMI (body mass index) z-scores were calculated. Fasting blood samples were analyzed for lipids, insulin, and glucose. The most significant metabolic variables were calculated. Serum SA was measured using a gas chromatography-mass spectrometry method. The 1-year intervention was based on the promotion of a balanced and normocaloric diet, in accordance with the national guidelines for treatment of childhood obesity. Additionally, behavioral education, based on the revised CALO-RE (Coventry, Aberdeen, and London-REfined) taxonomy, was performed.

RESULTS

At the end of intervention, children showed an increase in serum SA levels (mean (Standard Deviation, SD) 0.06 (0.02) vs. 0.09 (0.05) µmol/L; p < 0.001), a reduction of BMI z-score (3.14 (0.79) vs. 3.02 (0.82); p < 0.001), TyG index (4.52 (0.20) vs. 4.48 (0.23); p < 0.001), AIP (atherogenic index of plasma) (0.36 (0.21) vs. 0.27 (0.25); p < 0.001), and triglycerides/HDL (high density lipoprotein) cholesterol (2.57 (1.28) vs. 2.18 (1.22); p < 0.001) ratio. No statistically significant change in HOMA-IR (homeostasis model assessment index) was observed (4.20 (3.29) vs. 4.03 (2.28)). An association between the longitudinal variation of serum SA and HOMA-IR was found (correlation coefficient: -0.338, p = 0.02).

CONCLUSION

Nutritional-behavioral intervention may improve the circulating SA and the metabolic profile in children with obesity. Serum SA could influence mainly glucose metabolism. Further larger studies are needed to evaluate whether a nutritional intervention based on specific advice regarding the quantity and type of fruit and vegetables (FV) consumption could provide benefits in terms of metabolic syndrome.

NSAIDs Determination in Human Serum by GC-MS

Non-steroidal anti-inflammatory drugs (NSAIDs) are being widely consumed without medical prescription and are often the cause of intoxication, usually in young children. For this, there is a special need in their determination in routine toxicology analysis. As screening methods mainly focus on drugs of abuse (DOA) that are alkaline compounds in their majority, they are not optimized for acidic drugs, such as NSAIDs. Thus, more specific methods are needed for the detection and quantification of this class of drugs. In this study, the efficient extraction of NSAIDs from blood serum and their accurate determination is studied. Optimum pH extraction conditions were studied and thereafter different derivatization procedures for their detection. From the derivatization reagents used, N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% Trimethylchlorosilane (TMCS) was found to be the optimum choice for the majority of the examined NSAIDs; pH of 3.7 was selected as the most efficient for the extraction step. Herein the formation of the lactam of diclofenac was also thoroughly investigated. The developed Gas Chromatography-Mass Spectrometry (GC-MS) method had a run time of 15 min with the mass spectrometer operating in Electron Impact (EI) within the mass range of 40 to 500 amu. The method was linear with R2 above 0.991 and limits of quantitation (LOQ) ranging from 6 to 414 ng/mL. The intra-day accuracy and precision were found between 1.03%–9.79% and 88%–110%, respectively, and the inter-day accuracy and precision were between 1.87%–10.79% and 91%–113%. The optimum protocol was successfully applied to real clinical samples, where intoxication of NSAIDs was suspected.