| Central nervous system(CNS) drugs tend to induce toxicity in patients receiving drug treatment. Several factors may contribute to the drug-induced toxicity, including the special and individual characteristics of patients, the low therapeutic window of drugs, and the development of dependence resulting from long-term drug treatment. Therefore, qualitative and quantitative analyses of the harmful substances in the human body is of great importance in the management and prevention of acute poisoning. In this study, a total of 60 CNS drugs were included, including addictive analgesics, anesthetics, antipsychotic drugs, and benzodiazepines. During poisoning analysis, the Qu ECh ERS(Quick, Easy, Cheap, Effective, Rugged, and Safe) method was used for plasma sample pre-treatment. Then, samples were screened by ultra performance liquid chromatography-photodiode array detector(UPLC-PDA) coupled with ultra performance liquid chromatography-mass spectrometry(UPLC-MS). Using this technique, unknown drugs can be identified and quantified rapidly.1. The Qu ECh ERS method was established for plasma sample pre-treatment during poisoning analysis.One milliliter of plasma sample was mixed with 2 m L of acetonitrile containing 1% acetic acid. Then, 250 mg of anhydrous magnesium sulfate was added to the mixture, and the solution was vortexed vigorously for 60 sec. After centrifugation at 7,000 r/min for 5 min, the supernatant was collected and added to a Qu ECh ERS tube containing 50 mg C18 and 250 mg anhydrous magnesium sulfate. After another 60 sec of vigorous vortexing, samples were centrifuged at 10,000 r/min for 5 min, and the supernatant was collected for UPLC-PDA and LC-MS analysis.2. The Qu ECh ERS-based UPLC-PDA method was established for the simultaneous detection of 60 CNS drugs in plasma samples.Sample solutions were separated on an Agilent ZORBAS Eclipse plus column(1.8μm, 2.1 mm×100 mm). The mobile phase consisted of a combination of A(0.1% formic acid) and B(0.1% formic acid-methanol). The gradient elution was carried out with 8–74% B(0.5–11.5 min), 74–98% B(11.5–12.5 min), 98–8%B(12.5–17.5 min), and 8%(17.5–18 min) followed by a 6-min balance(18–24 min). The flow rate was 0.4 m L/min, and the column temperature was set at 35°C. The volume of loading sample was 5 μL. The wavelength for scanning ranged from 200–360nm, and the detective wavelength was 210 nm. The ultraviolet spectrograms of 60 CNS drugs were collected. Products were identified according to the ultraviolet spectrogram and retention time.Among 60 CNS drugs, the average recovery rates were greater than 60% in the low, median, and high concentration groups. At the concentration of 10 μg/m L, 56 drugs showed an average recovery rate over 80%, and at the concentration of 5 μg/m L, 51 drugs had an average recovery rate over 80%. In addition, at the concentration of 1 μg/m L, 39 drugs exhibited an average recovery rate over 80%. The relative standard deviation(RSD) was 0.2–12.9%(n=6), and the limits of detection(LODs) were 0.05–0.83 μg/m L.3. The Qu ECh ERS-based UPLC-MS-MS method was established for the simultaneous detection of 60 CNS drugs in plasma samples.MS conditions and parameters were optimized, and the characteristic ion for drug screening was identified for each agent. The secondary spectrum library of 60 drugs was established based on the UPLC-MS-MS method. Sample solutions were separated on an Agilent ZORBAS Eclipse plus column(1.8μm, 2.1 mm × 100 mm). The mobile phase consisted of 0.1%formic acid and methanol.Gradient elution was performed. Spectrometry was operated with under multiple reaction monitoring(MRM). Fifty-two drugs were identified using the positive ion mode, and 8 drugs were identified using the negative ion mode. Among 60 CNS drugs, the average recovery rates ranged from 50.1%–132.4%. At the concentration of 500 μg/m L, 39 drugs showed an average recovery rate over 80%.At the concentration of 100 μg/m L, 38 drugs had an average recovery rate over 80%. In addition, 34 drugs exhibited an average recovery rate over 80% at the concentration of 25 μg/m L. The RSD was 1.1%–19.1%(n=6), and the LODs were 0.02–5.00 μg/m L. The matrix effects of the UPLC-MS-MS method were evaluated. After Qu ECh ERS treatment, no significant absolute matrix effects were detected in 60 drugs. The matrix factor ranged between 80.6% and 118.2%. Our findings demonstrate that the UPLC-MS-MS method in the MRM mode had advantages of high sensitivity in ion screening and high selectivity in the secondary structure of MS, and thus could be used for systematical toxicological screening, identification, and quantification.4. Case analysisA total of 50 samples of clinical drug poisoning were collected and analyzed using above method. The plasma samples were pre-treated using the Qu ECh ERS technique, followed by UPLC-PDA and UPLC-MS-MS analysis. Several drugs, including carbamazepine, phenytoin, phenobarbital, and perphenazine, were successfully identified. The detection rates of UPLC-PDA and UPLC-MS-MS were 84% and 98%, respectively.Conclusions1. The Qu ECh ERS method can be used as a common pre-treatment procedure for systematical toxicological analysis of CNS drugs.2. UPLC-PDA is a simple and rapid method, which can be routinely applied in most laboratories. UPLC-MS-MS is a highly sensitive and selective method and can be used for toxicological screening, identification, and quantification of CNS drugs.3. Both UPLC-PDA and UPLC-MS-MS methods can be utilized for identification of clinical drug poisoning. Compared to UPLC-PDA, UPLC-MS-MS yields a higher detection rate and has advantages in detecting drugs with a low toxic concentration. Predictably, UPLC-MS-MS can be widely used for the screening of drug poisoning and may become a routine procedure for monitoring toxic drugs. Keywords... |
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