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

AbstractDispersive-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.

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Magnetic Solid-Phase Extraction of Drugs and Pesticides from Human Plasma using COOH-mMWCNTs

Journal of Analytical Toxicology ◽

10.1093/jat/bkaa029 ◽

2020 ◽

Author(s):

Heesung Moon ◽

Jiwon Park ◽

Jinwoo Hwang ◽

Heesun Chung

Keyword(s):

Carbon Nanotubes ◽

Carboxylic Acid ◽

Solid Phase Extraction ◽

Human Plasma ◽

Solid Phase ◽

Magnetic Solid Phase Extraction ◽

University Hospital ◽

Phase Extraction ◽

National University ◽

Magnetic Solid

Abstract Carbon nanotubes (CNT) are useful for extracting chemical compounds due to their properties, such as surface area and the potential for chemical modification. Especially the formation of carbon nanotubes with carboxylic acid functional group makes them disperse in water-based samples and have strong interaction forces with cationizable analytes. Based on these features, carboxylic acid functionalized multi-walled carbon nanotubes (COOH-MWCNTs) have been used as extraction sorbents. CNT also can be gathered using an external magnet by forming complex with iron oxide (Fe3O4) magnetic nanoparticles (MNPs). In this study, COOH-MWCNTs with MNPs were subjected to magnetic solid phase extraction (mSPE) in order to extract the targeted substances such as diphenhydramine, doxylamine, tramadol, escitalopram, zolpidem, diphenamid, paclobutrazol, hexaconazole, cyproconazole, and mepronil from human plasma samples. The following five factors were optimized: [1] the ratio of COOH-MWCNTs to MNPs as a sorbent from 1: 1 to 1: 4; [2] sorbent amount starting from 12.5% to 75%; [3] sample pH tested pH 2 to pH 10 with 1 N hydrochloride and 1 N sodium hydroxide; [4] agitating time from 0 min to 4 min; [5] elution solvent. LOD of 10 targeted substances in human plasma were in the range of 0.1 to 0.4 mg/L. The recovery of targeted substances (except diphenamid) in human plasma was 73.06–110.28% for intra-day, 83.00–107.70% for inter-day and the precision (RSD, %) in human plasma was 0.3–13.3% for intra-day, 2.9–15.6%. The method was applied to 9 authentic biological samples from overdose patients in the emergency room of Chung-nam National University Hospital. The performance of mSPE was compared with the liquid–liquid extraction (LLE) method using ethyl acetate. The results showed that the newly developed method in this study can be used for screening analysis in forensic and clinical toxicology.

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