Development of magnetic carbon nanotubes for dispersive micro solid phase extraction of the cyanide metabolite, 2-aminothiazoline-4-carboxylic acid, in biological samples

Determination of bisphenol analogues in bottled water using deep eutectic solvent and magnetic multi-walled carbon nanotubes followed by ultra-high performance liquid chromatography coupled with tandem mass spectrometry

Bisphenol analogues (BPs) are a class of typical environmental endocrine disruptors (EDCs) that have recently attracted increasing attention with regard to their potential effects on human health. The objective of this study was to develop a method using a magnetic soft material, which consisted of hydrophilic deep eutectic solvent (DES) and magnetic multi-walled carbon nanotubes (MMWCNTs), for the dispersive solid-phase extraction (d-SPE), coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), for the determination of the levels of nine BPs in bottled water. The hydrophilic DES enable the rapid dispersion of MMWCNTs when the material is injected rapidly into the sample solution using a pipette gun. This process can therefore be completed in a relatively short period of time, resulting in an efficient extraction. Under optimal conditions, the limit of detections (LODs) of the method were 0.0003-0.003 μg/L and the limit of quantifications (LOQs) were 0.001-0.01 μg/L. The relative standard deviations (RSDs) of the method were only 2.42-7.59 % for inter-day and 3.71-9.67 % for intra-day. The method demonstrated good reproducibilities and recoveries, rendering it suitable for the determination of BPs in large-volume water samples.

Electrochemical aptasensor for 2-amino-2-thiazoline-4-carboxylic acid (ATCA), a metabolite for cyanide poisoning

An alternative biomarker for assessing the cyanide levels in postmortem materials is crucial for investigating acute cyanide intoxication. Herein, an aptamer-ligand biorecognition system with high specificity was developed to detect acute cyanide poisoning via its secondary metabolite, 2-amino-2-thiazoline-4-carboxylic acid (ATCA). Potential aptamers were screened from a random library of 66-base single-stranded DNA using GO-SELEX, with individual aptamers being identified through single-stranded DNA sequencing. Molecular docking was employed to predict the affinity of these aptamers toward ATCA and selected counter-targets; these predictions were confirmed using thermodynamic analysis with an isothermal titration calorimeter. Owing to its label-free biomolecular binding interactions, Apt46 exhibited the highest affinity against ATCA and notable selectivity against structurally similar counter-targets. Thus, an amino-tagged Apt46 binding aptamer was attached to a carbon electrode modified with EDC-NHS-activated graphene oxide. The binding of Apt46 to ATCA was quantified by measuring current changes using differential pulse voltammetry. The aptasensor achieved a detection limit of 0.05 µg/mL and demonstrated suitability for detecting ATCA across various biological matrices, with the high recovery percentages ranging from 92.29 to 114.22%. Overall, the proposed ATCA aptasensor is promising for identifying ATCA metabolites in cases of acute cyanide exposure.

Simultaneous quantification of 2-aminothiazoline-4-carboxylic acid and 2-aminothiazoline-4-oxoaminoethanoic acid utilizing chemical derivatization followed by liquid chromatography-tandem mass spectrometry

Detecting cyanide compounds in postmortem blood samples is an important matter in forensic science because cyanide is often used as a poison for murder or suicide. However, the direct analysis of cyanide itself has practical limitations because of cyanide's volatility and short half-life at ambient temperature. Here, we focused on the relatively stable cyanide metabolites 2-aminothiazoline-4-carboxylic acid (ATCA) and 2-aminothiazoline-4-oxoaminoethanoic acid (ATOEA) as potential markers of cyanide exposure. We developed an analytical method that uses chemical derivatization of the target compounds with 4-bromoethyl-7-methoxycoumarin followed by liquid chromatography coupled with electrospray ionization-tandem mass spectrometry. The recovery rates for pretreatment and calibration curve linearities were good in the concentration range of 20-1000 ng/mL. Using our approach, we were able to detect and quantify both ATCA and ATOEA concentrations in postmortem blood samples, and in our samples the ratio of ATCA and ATOEA was in the range of 4.5-19.1. To our knowledge, this is the first time ATOEA has been successfully detected in human blood samples. In addition, we found that ATCA and ATOEA concentrations were both significantly higher in the blood of fire victims than in the blood of individuals with a non-fire-related cause of death. Also, we found that there was a significant positive correlation between ATCA concentrations and ATOEA concentrations. Together, our present data suggested that ATCA and ATOEA are both potential markers of cyanide exposure.

Quantification of 2-aminothiazoline-4-carboxylic acid as a reliable marker of cyanide exposure using chemical derivatization followed by liquid chromatography-tandem mass spectrometry

In this research, we have developed a novel and simple liquid chromatography coupled with electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method for quantification of 2-aminothiazoline-4-carboxylic acid (ATCA), which is produced by the direct reaction of cyanide (CN) with endogenous cystine. In forensic science, detection of CN is important because CN is a poison that is often used for murder or suicide, in addition to being produced by the thermal decomposition of natural or synthetic materials. However, because CN disappears rapidly from body tissue, ATCA is thought to be a more reliable indicator of CN exposure. For the method reported herein, human blood samples (20 μL) were subjected to protein precipitation followed by derivatization with 4-bromoethyl-7-methoxycoumarin. Blood spiked with ATCA at concentrations ranging from 50 to 1500 ng/mL was used to prepare a calibration curve (lower limit of quantification; 50 ng/mL, lower limit of detection; 25 ng/mL). Our method uses chemical derivatization, so unlike previously reported methods, it does not require tedious pretreatment procedures, hydrophilic interaction liquid chromatography columns, or specialized equipment. In addition, our method allows for repeatable and accurate quantification of ATCA, with intra- and inter-assay coefficients of variation of below 5.0% and below 6.0%, respectively. We used the method to analyze ATCA in postmortem human blood samples, including samples from people who had intentionally ingested CN or were fire victims. Blood ATCA concentrations were higher among people who had ingested CN or were fire victims than among people in a control group (P < 0.0001). The data reported herein demonstrate that our LC/ESI-MS/MS method can be used to detect and quantify ATCA in postmortem blood samples and that CN exposure strongly affects ATCA concentration, providing a useful tool for detection of CN poisoning.

Simultaneous Determination of 16 Kinds of Synthetic Cathinones in Human Urine Using a Magnetic Nanoparticle Solid-Phase Extraction Combined with Gas Chromatography-Mass Spectrometry

A specific and sensitive approach using magnetic nanoparticle solid-phase extraction combined with gas chromatography-mass spectrometry (GC-MS) was carried out and applied in the simultaneous determination of 16 kinds of synthetic cathinones in human urine. The functionalized extraction material (Fe3O4/NH2-MWCNTs) was synthesized and factors affecting the extraction efficiency were all tested. Under the optimized conditions of magnetic nanoparticle solid-phase extraction, the determination of synthetic cathinones in human urine was carried out with GC-MS. Good linear relationships of 16 kinds of synthetic cathinones were obtained in the range of 0.005–5.00 μg/mL with the correlation coefficients (r) ranging from 0.9901 to 0.9979, the limits of detection were in the range between 0.005 and 0.01 μg/mL, and the limits of quantitation were between 0.01 and 0.02 μg/mL. Furthermore, the average intra-day precisions were below 8.90%, the average inter-day precisions were less than 9.52%, and the average recoveries were between 87.03% and 99.13%, respectively. The results show the advantages of the approach in the determination of trace synthetic cathinones in complex matrixes, such as environmentally friendly, fast detection, high efficiency and sensitivity. The practical application indicated that this method could provide scientific basis for the determination of drugs of abuse in forensic laboratories.

Determination of morphine, codeine, and thebaine concentrations from poppy seed tea using magnetic carbon nanotubes facilitated dispersive micro-solid phase extraction and GC-MS analysis

With tightening enforcement and restrictions amid the opioid epidemic, poppy seed tea is consumed as an alternative to mitigate the withdrawal symptoms or as a home remedy to relieve pain and stress. Previously published studies suggested the potential danger of consuming tea brewed with a moderate to a large amount of poppy seed. In this study, the effects of small quantity and repeat brewing on opiate concentrations were evaluated. A dispersive-micro solid phase extraction facilitated by magnetic carbon nanotubes (Mag-CNTs/d-µSPE) was developed, optimized, successfully validated, and applied to ten poppy seed tea samples using gas chromatography-mass spectrometry (GC-MS) analysis. A total of ten poppy seed samples were evaluated in this work. Two grams of bulk poppy seeds were brewed with 6 mL of heated and acidified DI water three times. The brewed tea samples were subjected to the validated Mag-CNTs/d-µSPE/GC-MS analysis. The total mean opiate concentrations obtained from three brews were 1.1-1926, 20.2-311, and 9.0-100 mg/kg for morphine, codeine, and thebaine, respectively. The total opiate yields obtained from the small quantity brewing, i.e., 6 g seed in 18 mL tea, in this study may provide minimal analgesic and euphoric effects. Over 80% of the total opiate yield was extracted in the first brew with acidified deionized water from the 10 min brewing period, and opiate yields from the second and third brew were minimal. However, potential overdose could occur for some tea samples when scaled up to the starter quantity of seed suggested for new users.

Performance comparison between solid phase extraction and magnetic carbon nanotubes facilitated dispersive-micro solid phase extractions (Mag-CNTs/d-µSPE) of a cyanide metabolite in biological samples using GC–MS

Dispersive-micro solid phase extraction (d-µSPE) has gained increasing attention due to its convenience, effectiveness, and flexibility for sorbent selection. Among a various selection of materials, magnetic carbon nanotubes (Mag-CNTs) is a promising d-µSPE sorbent with excellent separation efficiency in addition to its high surface area and adsorption capability. In this work, two different surface-modified Mag-CNTs, Mag-CNTs-COOH and Mag-CNTs-SO3H, were developed to facilitate d-µSPE (Mag-CNTs/d-µSPE). The cyanide metabolite, 2-aminothiazoline-4-carboxylic acid (ATCA), was selected to evaluate their extraction performance using gas chromatography–mass spectrometry (GC–MS) analysis. The Mag-CNTs-COOH enabled a one-step derivatization/desorption approach in the workflow; therefore, a better overall performance was achieved. Compared to the Mag-CNTs-SO3H/d-µSPE and SPE workflow, the one-step desorption/derivatization approach improved the overall extraction efficiency and reduced solvent consumption and waste production. Both Mag-CNTs/d-µSPE workflows were validated according to ANSI/ASB 036 guidelines and showed excellent analytical performances. The limit of detection (LOD) and limit of quantitation (LOQ) of ATCA in synthetic urine were 5 and 10 ng/mL, respectively, and that in bovine blood were achieved at 10 and 60 ng/mL. The SPE method’s LOD and LOQ were also determined at 1 and 25 ng/mL in bovine blood samples. The Mag-CNTs/d-µSPE methods demonstrated great potential to extract polar and ionic metabolites from biological matrices. The extraction processes of ATCA described in this work can provide an easier-to-adopt procedure for potential routine forensic testing of the stable biomarker in cyanide poisoning cases, particularly for those cases where the cyanide detection window has passed.

Application of magnetic nanomaterials in bioanalysis

The importance of magnetic nanomaterials and magnetic hybrid materials, which are classified as new generation materials, in analytical applications is increasingly understood, and research on the adaptation of these materials to analytical methods has gained momentum. Development of sample preparation techniques and sensor systems using magnetic nanomaterials for the analysis of inorganic, organic and biomolecules in biological samples, which are among the samples that analytical chemists work on most, are among the priority issues. Therefore in this review, we focused on the use of magnetic nanomaterials for the bioanalytical applications including inorganic and organic species and biomolecules in different biological samples such as primarily blood, serum, plasma, tissue extracts, urine and milk. We summarized recent progresses, prevailing techniques, applied formats, and future trends in sample preparation-analysis methods and sensors based on magnetic nanomaterials (Mag-NMs). First, we provided a brief introduction of magnetic nanomaterials, especially their magnetic properties that can be utilized for bioanalytical applications. Second, we discussed the synthesis of these Mag-NMs. Third, we reviewed recent advances in bioanalytical applications of the Mag-NMs in different formats. Finally, recently literature studies on the relevance of Mag-NMs for bioanalysis applications were presented.

Extraction of Cyproheptadine as Potent Appetizing Stimulant in Herbal Supplements by Efficient Carbon Nitride Nanosheets as Dispersive Solid Phase Extraction Adsorbent

Background: Application of natural-based herbal medicine is on a growing trend in some countries and people prefer to use plant-originated drugs rather than chemical-based ones. The present study describes an interesting sample preparation method for extraction and determination of cyproheptadine in herbal supplements as appetizing stimulant by using carbon nitride nanosheets as dispersive solid phase extraction method coupled with HPLCUV. Methods: Various techniques used for characterization of adsorbent such as: Infrared spectroscopy (IR), scanning electron microscopy (SEM), Zeta potential analysis and powder X-ray diffraction (XRD). Optimization of the important extraction parameters were conducted by one parameter-at-a time method. Next, method validation was carried out. Results: The optimized cyproheptadine extraction parameters were introduced and under optimized conditions the method presented a good linearity in the concentration range of 300-2000 ng/g. The limit of detection (LOD) was 100 ng/g for the introduced method. Conclusion: Quantitative analysis of fifteen real samples (Tablets or capsules) by proposed method confirmed the illegal presence of cyproheptadine in herbal appetizing stimulants supplements of the markets.

RECiQ: A Rapid and Easy Method for Determining Cyanide Intoxication by Cyanide and 2-Aminothiazoline-4-carboxylic Acid Quantification in the Human Blood Using Probe Electrospray Ionization Tandem Mass Spectrometry

In this study, we developed a rapid and easy method to determine cyanide (CN) intoxication by quantification of CN and 2-aminothiazoline-4-carboxylic acid (ATCA), which is a new and reliable indicator of CN exposure, in the human blood using probe electrospray ionization tandem mass spectrometry (PESI/MS/MS) named RECiQ. For CN, we applied the previously reported one-pot derivatization method using 2,3-naphthalenedialdehyde and taurine, which can directly derivatize CN in the blood. The analytical conditions of the CN derivatization were optimized as a 10 min reaction time at room temperature. In contrast, ATCA could be directly detected in the blood by PESI/MS/MS. We developed quantitative methods for the derivatized CN and ATCA using an internal standard method and validated them using quality control samples, demonstrating that the linearities of each calibration curve were greater than 0.995, and intra- and interday precisions and accuracies were 5.1-15 and 1.1-14%, respectively. Moreover, the lower limit of detections for CN and ATCA were 42 and 43 ng/mL, respectively. Finally, we applied RECiQ to three postmortem blood specimens obtained from victims of fire incidents, which resulted in the successful quantification of CN and ATCA in all samples. As PESI/MS/MS can be completed within 0.5 min, and the sample volume requirement of RECiQ is only 2 μL of blood, these methods are useful not only for the rapid determination of CN exposure but also for the estimation of the CN intoxication levels during an autopsy.

Determination of 2,4-Dichlorophenoxyacetic acid in food and water samples using a modified graphene oxide sorbent and high-performance liquid chromatography

In the present work, dispersive micro-solid phase extraction (D-μ-SPE) method using magnetic graphene oxide tert-butylamine (GO/Fe₃O₄/TBA) nanocomposite, as an efficient sorbent, was applied for determining 2,4-dichlorophenoxyacetic acid (2,4-D) in water and food samples. Detection was carried out using high-performance liquid chromatography (HPLC) instrument. Influential parameters of D-μ-SPE such as sorbent and its amount, elution solvent and its volume, adsorption and desorption times and pH of sample solution were investigated and optimized. Under the optimized conditions, limit of detection and quantitation values were 0.007 and 0.02 μg/mL, respectively. Recovery data for several real samples were obtained within the range of 88.0-94.0% with a relative standard deviation (RSD) less than 7.5%. The proposed method was successfully applied to quantitative determination of 2,4-D in several vegetables and water samples.