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You have full access to this open access article. This study investigates the electrochemical behavior of ketamine using an in-lab fabricated screen-printed electrode system and explores its potential application in quantitative analysis. Cyclic voltammetry and differential pulse voltammetry DPV experiments were employed to characterize the oxidation behavior of ketamine. Systematic optimization of DPV parameters, including pulse amplitude, pulse width, potential step, potential, and time accumulation for analyte preconcentration resulted in the selection of optimal conditions for quantitative analysis. Authentic samples analysis demonstrated the utility of the proposed sensor for quantitative analysis of ketamine in pharmaceutical products and seized drug samples. Overall, the developed sensor offers a promising tool for the rapid and accurate analysis of ketamine in various samples with potential applications in on-site forensic analysis. Ketamine KET is a pharmaceutical compound belonging to the class of drugs known as dissociative anesthetics. Ketamine acts primarily as a noncompetitive antagonist of the N -methyl-D-aspartate NMDA receptor, affecting glutamate neurotransmission in the central nervous system. It is recognized for its sedative and analgesic properties and has been extensively used in medical settings for anesthesia induction and pain management \[ 1 , 2 \]. However, ketamine has also gained notoriety for its illicit use. It is classified as a controlled substance due to its potential for abuse and dependence. Due to this action, it is still one of the most popular substances used in drug-facilitated sexual assault \[ 2 , 3 \]. The discreet addition of this substance to the drink is further facilitated by the fact that it is odorless and does not change the color or taste of the drink \[ 2 \]. Moreover, ketamine has the potential for therapeutic use in treating depression and offers hope for individuals with treatment-resistant depression \[ 5 , 6 \]. However, its accessibility may raise concerns about misuse and abuse. Separation methods with various detection methods, such as liquid chromatography \[ 7 , 8 , 9 , 10 , 11 \] or gas chromatography \[ 12 , 13 , 14 , 15 \] are still most commonly used in ketamine detection. These methods offer many advantages such as high sensitivity and selectivity. However, the use of these methods in the on-site analysis is usually problematic, which for example is related to the large size of the equipment \[ 16 , 17 \]. The development of sensor systems seems to be perfect for applications in on-site analysis \[ 18 , 19 , 20 , 21 , 22 , 23 , 24 \]. Many solutions of this type are currently being developed, as well as in the case of ketamine detection. The voltammetric system based on screen-printed electrodes SPE using commercially available graphite SPE and developed square-wave voltammetry SWV method was successfully used in analysis of seized drugs samples containing ketamine, also in powders with other adulterants and illicit drugs \[ 23 \]. The paper-based microfluidic device for ketamine detection in various drinks such as whisky and juice was developed by Narang et al. The sensor was developed by utilizing zeolite nanoflakes and graphene-oxide nanocrystals Zeo-GO \[ 25 \]. Poulladofonou et al. The device was based on the use carbon-black-loaded PLA working electrode. Using the proposed system, without prior sample preparation, it was possible to detect ketamine in whisky, vodka, gin, and beer \[ 4 \]. Another point-of-care electrochemical sensor based on molecularly imprinted polymer for ketamine determination was developed by Soliman et al. The use of this system enabled selective on-site detection of ketamine hydrochloride in different matrices such as non-alcoholic beverages, plasma, and urine \[ 26 \]. In this work, we present a cheap, fully in-lab fabricated electrochemical system based on the use of carbon-graphene SPE electrodes without complex electrode modifications for analysis of seized drug samples containing ketamine. First, the electrochemical behavior of the targeted analyte was investigated and the best DPV method parameters were optimized for further quantitative analysis. The proposed SPE system was validated and successfully applied in the case of analysis of pharmaceutical product and seized drug sample. We believe that the advantages of the proposed sensor such as cheap costs of fabrication and small size can make it a good tool for on-site analysis on the crime scene. The proposed in-lab fabricated SPE system was utilized initially for the investigation of the electrochemical behavior of ketamine using cyclic voltammetry CV. Extending the investigation, pH values both above and below this range were examined, but no signal was observed, suggesting the absence of any significant redox activity outside this pH range. Measurements in this pH range show the oxidation behavior of the targeted analyte. One nonreversible oxidation process was observed for ketamine, from which the best-formed peak was observed for pH in the range of 8—10; therefore, this range was more investigated. Moreover, with the increasing pH, the peak shifted towards more positive potential values, which demonstrated the involvement of protons in the electrode reaction. Based on these results, the best pH value for further quantitative analyses was selected. The results were in agreement with CV experiments. The pH value for which the best-formed peak was recorded was BR buffer at pH To perform the analytical measurements, the parameters of DPV methods were optimized. The optimization process was aimed at selecting conditions that give the best analytical signal for quantitative analysis. The process was conducted using the one-variable method. The influence of three DPV parameters on the recorded signal was investigated: pulse amplitude E pulse , pulse width t pulse , and potential step E step. In the first step, the E pulse in the range of 10— mV with constant values of t pulse of 10 ms, and E step of 5 mV was investigated. With the increase of E pulse up to mV, the peak current increased significantly. Above this value, a slight increase in signal was observed. Taking into account the peak shape, the best-formed peak was recorded for E pulse equal to and mV. Subsequently, the various values of t pulse in the range of 2—20 ms were tested with constant E step of 5 mV and selected in the previous step E pulse of mV. In general, with an increase in t pulse above 6 ms, the peak current decreased. Among the results of the analysis for this parameter in the range of 2—6 ms, the optimal value was chosen as 6 ms. For this measurement, the recorded signal exhibited high intensity and the best-formed peak shape among the tested parameter values. At the final step of the DPV method optimization, the E step was selected. The different values of E step in the range of 1—20 mV were investigated with previously optimized E pulse and t pulse values. The changes in E step values did not have a significant impact on the recorded peak current. However, better peak formation was observed for E step above 5 mV, despite this the resolution of measurement slightly decreased for higher values of this parameter. Due to these observations, the optimal E step value was set at 5 mV. Moreover, the potential E acc and time t acc of accumulation preconcentration step were considered to enhance the peak current of the studied analyte. All experiments were performed with previously optimized DPV parameters. The accumulation potential was investigated for five values in the range of 0. The highest peak current was measured for an accumulation potential of 0. To enhance the preconcentration of ketamine before measurement, for selected accumulation potential, the accumulation time in the range of 15— s was considered. It was observed that after accumulation for more than 30 s, the significant increase of peak current was not observed; therefore, this value was selected to be optimal. The data for the optimization preconcentration step are included in ESI as Fig. Moreover, before each measurement, the preconcentration process was performed with an accumulation potential of 0. To investigate the selectivity of the developed sensor for ketamine determination in seized drugs samples, an interference study was conducted involving several other substances commonly found in drug abuse and pharmaceuticals. The tested substances included MDMA, amphetamine, mephedrone, cocaine, diazepam, flunitrazepam, paracetamol, and caffeine. The results of interference studies are included in the Table S1. The presence of most of the tested substances did not affect the signal recorded for ketamine. However, the presence of MDMA and cocaine acted as interferents in the detection of ketamine. These substances produced significant oxidation signals at potentials close to ketamine oxidation peak, thereby overlapping with the ketamine signal and causing interference. This interference can be attributed to the electrochemical properties of these substances, which likely undergo oxidation reactions at similar potentials due to their chemical structures and functional groups. Other substances such as amphetamine, mephedrone, diazepam, flunitrazepam, paracetamol, and caffeine did not produce oxidation signals close to ketamine oxidation peak, indicating no significant interference with the ketamine measurements. The optimized DPV method was used in all quantitative measurements. The analytical signal of ketamine was recorded at a potential equal to 0. Figure 2 presents the DPV voltammograms recorded for each standard and plotted calibration curve. The coefficient of determination R 2 of the calibration curve was equal to 0. Moreover, precision and recovery of determination were calculated based on the analysis performed during 1 day by one analyst and on three consecutive days performed by two analysts. The validation parameters are summarized in Table 1. These values could be seen as satisfactory, considering that the compared results were obtained by performing measurements carried out with different SPE electrodes from different batches. To validate the analytical utility of the proposed system based on carbon-graphene SPEs, the analysis of authentic samples in the form of pharmaceutical product Ketalar 50 and one forensic sample of seized drugs was performed. Prior to the electrochemical analysis, the pharmaceutical product was diluted times, and seized drug samples dissolved in H 2 O:MeOH mixture were diluted 5 times in the selected BR buffer. To avoid any potential matrix influences in the case of authentic samples analysis, the determination was performed by the standard additions method. The summarized results of samples analysis are presented in Table 2. The R 2 for calibration plots was above 0. High consistency of the results may indicate the selectivity of the assay towards possible matrix interferents contained in the tested samples. The obtained results have proven the utility of the proposed sensor for the analysis of seized drug samples. The simple, cheap, and fully in-lab fabricated electrochemical sensor was developed. The system was based on a carbon-graphene screen-printed working electrode, which was not modified. The electrochemical behavior of ketamine was thoroughly investigated using a proposed system. Cyclic voltammetry experiments revealed a nonreversible oxidation process for ketamine. Moreover, the DPV method was optimized and validated showing good analytical performance in the investigated concentration range. Precision and recovery of determination were within acceptable limits, further validating the reliability of the proposed sensor. Overall, the developed sensor offers a promising tool for the rapid and accurate analysis of ketamine in various samples, with potential applications in on-site forensic analysis. All experiments were performed with the following reagents: sodium hydroxide, boric acid, acetic acid, orthophosphoric acid, methanol, and acetonitrile both hypergrade reagents for LC—MS were purchased from Merck. Ultrapure water MDMA, amphetamine, mephedrone, cocaine, diazepam, flunitrazepam Tusnovics , paracetamol, and caffeine Merck were used for interference studies. The configuration of the electrochemical system was designed in Autodesk Fusion software under an education license. The Silhouette Cameo 4 device was used to cut the electrochemical system pattern on the vinyl stencil substrate. Data analysis and graph preparation were carried out using Origin During the analysis, the gradient elution program with a flow rate of 0. The gradient program was set as follows: 0. The triple quadrupole mass spectrometer was operated in positive electrospray ionization ESI mode with multiple reaction monitoring MRM. The ESI parameters were as follows. All experiments were carried out with a Britton—Robinson buffer in the range of pH 2— For obtaining the buffer with a specific pH value, a mixture of 0. The mask of the electrode configuration was cut on a self-adhesive sticky foil using a cutting machine. Next, the masks were glued on the polyester substrate. Using a spatula, the carbon-graphene paste was applied onto the mask material, ensuring coverage of all surfaces of the electrochemical system. To provide a constant area of WE during measurement, before the analysis the hydrophobic barrier using a pen with hydrophobic ink was created. This barrier isolated part of the system that had contact with the sample and prevented a sample flow to the connector parts of the system. The electrodes prepared in this way were ready for performance electrochemical measurements. A sample value equal to mm 3 was applied on the SPE at all stages of the presented study, and before each measurement with the targeted analyte, the blank with the used buffer solution was recorded. For the investigation of the electrochemical behavior of ketamine, CV experiments were performed. The measurements for analytical applications were performed with the DPV method with optimized parameters. Before recording the DPV voltammograms, the analyte preconcentration was performed at the accumulation potential of 0. The sample of ketamine in buffer solutions was prepared each day before measurements. The seized samples in the form of powder containing ketamine were prepared as follows. Initially, the powder was homogenized by grinding it in a mortar. Next, extraction by mixing the solution for 1 h was performed. The data that support the findings of this study are available in Supplementary Information and from the corresponding author, upon reasonable request. Article PubMed Google Scholar. Article Google Scholar. Download references. You can also search for this author in PubMed Google Scholar. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. Reprints and permissions. Stelmaszczyk, P. Screen-printed electrode-based sensor for rapid ketamine determination: optimization and on-site application for seized drugs analysis. Monatsh Chem , — Download citation. Received : 30 April Accepted : 18 June Published : 25 July Issue Date : September Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Download PDF. Abstract This study investigates the electrochemical behavior of ketamine using an in-lab fabricated screen-printed electrode system and explores its potential application in quantitative analysis. Graphical abstract. Stencil-printed electrode using conductive graphite-based ink: a cost-effective approach for electrochemical determination of dipyrone Article 23 May Use our pre-submission checklist Avoid common mistakes on your manuscript. Introduction Ketamine KET is a pharmaceutical compound belonging to the class of drugs known as dissociative anesthetics. Results and discussion Electrochemical behavior of ketamine The proposed in-lab fabricated SPE system was utilized initially for the investigation of the electrochemical behavior of ketamine using cyclic voltammetry CV. Full size image. Table 2 Results of quantitative analysis of ketamine in pharmaceutical product and seized drug sample Full size table. Conclusion The simple, cheap, and fully in-lab fabricated electrochemical sensor was developed. Experimental All experiments were performed with the following reagents: sodium hydroxide, boric acid, acetic acid, orthophosphoric acid, methanol, and acetonitrile both hypergrade reagents for LC—MS were purchased from Merck. Data availability The data that support the findings of this study are available in Supplementary Information and from the corresponding author, upon reasonable request. View author publications. Additional information Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Supplementary Information. Supplementary file1 DOCX kb. About this article. Cite this article Stelmaszczyk, P. Copy to clipboard. Search Search by keyword or author Search. Navigation Find a journal Publish with us Track your research.

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