-
BMC Chemistry Apr 20246-mercaptopurine (6-MP) is a chemotherapy drug mainly used to treat leukemia. It is a persistent organic pollutant and can remain in the environment for a long period of...
BACKGROUND
6-mercaptopurine (6-MP) is a chemotherapy drug mainly used to treat leukemia. It is a persistent organic pollutant and can remain in the environment for a long period of time. The presence of 6-MP in the environment poses a number of hazards and needs to be assessed to monitor its potential risk to human health and the environment. However, due to its trace amount in complicated matrices, a clean-up and preconcentration step before its determination is compulsory.
RESULTS
As a highly efficient adsorbent for the extrication of 6-mercaptopurine (6-MP), a novel carbon nanotube doped with camphor: decanoic acid deep eutectic solvent was synthesized and applied as a packing material for the pipette-tip micro solid phase extraction sorbent of 6-MP from tap, wastewater and seawater samples before its spectrophotometric determination. Characteristics and structure of this adsorbent was fully investigated. Factors affecting extraction, including type and volume of the eluent, ionic strength and pH of the sample solution, amount of adsorbent, and number of extraction and elution cycles were optimized using one-factor-at-a-time and response surface methodologies. The method was found to be linear in the range of 1 to 1000 µg/L with a limit of detection and quantification of 0.2 and 0.7 µg/L, respectively. Reproducibility as relative standard deviation was better than 4.6%.
CONCLUSION
Application of deep eutectic solvent modified carbon nanotube indicated suitable microextraction results and good potential for rapid extraction of trace amounts of 6-MP from different aqueous samples. The amount of sample required for the analysis was less than 10 mL and only 1.5 mg of the adsorbent was used. The total analysis time, including extraction was less than 15 min and the adsorbent could be used for at least 10 times, without significantly losing its adsorption ability. Compared to using unmodified usual carbon nanotubes, deep eutectic solvent doped carbon nanotubes showed 19.8% higher extraction ability.
PubMed: 38654336
DOI: 10.1186/s13065-024-01199-y -
Journal of Analytical Toxicology May 202411-Nor-9-carboxy-Δ9-tetrahydrocannabinol (Δ9-THCCOOH) is the most frequently detected illicit drug metabolite in the military drug testing program. An increasing...
11-Nor-9-carboxy-Δ9-tetrahydrocannabinol (Δ9-THCCOOH) is the most frequently detected illicit drug metabolite in the military drug testing program. An increasing number of specimens containing unresolved Δ8-THCCOOH prompted the addition of this analyte to the Department of Defense drug testing panel. A method was developed and validated for the quantitative confirmation of the carboxylated metabolites of Δ8- and Δ9-THC in urine samples utilizing automated pipette tip dispersive solid-phase extraction and analysis by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Analytes were separated isocratically over an 8.5-min runtime and detected on an MS-MS equipped with an electrospray ionization source operated in negative mode. A single point calibrator (15 ng/mL) forced through zero demonstrated linearity from 3 to 1,000 ng/mL. Intra- and inter-day precision were ≤9.1%, and bias was within ±14.1% for Δ8-THCCOOH and Δ9-THCCOOH. No interferences were found after challenging the method with different over-the-counter drugs, prescription pharmaceuticals, drugs of abuse and several cannabinoids and cannabinoid metabolites, including Δ10-THCCOOH. Urine specimens presumptively positive by immunoassay (n = 2,939; 50 ng/mL Δ9-THCCOOH cutoff) were confirmed with this analytical method. Δ8-THCCOOH and Δ9-THCCOOH were present together above the 15 ng/mL cutoff in 33% of specimens. However, nearly one-third of the specimens analyzed were positive for Δ8-THCCOOH only. This manuscript describes the first validated automated extraction and confirmation method for Δ8- and Δ9-THCCOOH in urine that provides adequate analyte separation in urine specimens with extreme isomer abundance ratios.
Topics: Dronabinol; Humans; Tandem Mass Spectrometry; Substance Abuse Detection; Chromatography, Liquid; Solid Phase Extraction; Reproducibility of Results; Illicit Drugs; Limit of Detection; Isomerism; Liquid Chromatography-Mass Spectrometry
PubMed: 38581658
DOI: 10.1093/jat/bkae031 -
Analytical Methods : Advancing Methods... May 2024This study outlines the development and optimization of an analytical method using Disposable Pipette Extraction (DPX) followed by high performance liquid...
This study outlines the development and optimization of an analytical method using Disposable Pipette Extraction (DPX) followed by high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis to determine NAs in medicines. HPLC-MS analysis utilized a reversed-phase and positive mode electrospray ion source. DPX parameters were optimized through univariate and multivariate analyses, including extraction phase, desorption solvent, sample pH, equilibrium time, and extraction/desorption cycles. The optimized conditions included a C18 extraction phase, methanol desorption solvent, pH at 7, an equilibrium time of 30 seconds, 2 extraction cycles, and 5 desorption cycles. Considering this method, it was possible to achieve a sample preparation step for the analysis of NAs in medicines using a minimal amount of extraction phase, sample, and desorption solvent. Furthermore, the total extraction procedure enables the extraction of NAs in around 4 minutes with NA recovery up to 98%. Analytical performance demonstrated precision and accuracy below 15% and a quantification limit of 1 ng mL, meeting validation requirements set by regulations worldwide. Thus, the DPX/HPLC-MS technique offers a faster and cost-effective method for analyzing NAs in medicines compared to traditional approaches. Besides, this method reduces solvent consumption and residue generation, enhancing environmental sustainability according to green chemistry principles.
Topics: Chromatography, High Pressure Liquid; Nitrosamines; Limit of Detection; Mass Spectrometry; Reproducibility of Results; Solid Phase Extraction; Liquid Chromatography-Mass Spectrometry
PubMed: 38747210
DOI: 10.1039/d4ay00554f -
Journal of Chromatography. A Jan 2024The concentration of carbazoles in highly mature crude oil is quite low, making it challenging to separate carbazole compounds for the gas chromatography-mass...
The concentration of carbazoles in highly mature crude oil is quite low, making it challenging to separate carbazole compounds for the gas chromatography-mass spectrometry (GC-MS) detection. This study presents a small-scale column chromatography method for separating carbazoles from highly mature crude oil using silica gel as a solid phase adsorbent and a Pasteur pipette as a separation device. The carbazole-rich crude oil from the Pearl River Mouth Basin was selected to explore the impact of reagent polarity and injection mode on the separation of carbazoles. The oil sample was eluted with solvents mixed with different volume proportions of n-hexane and dichloromethane and each eluted fraction was collected for GC-MS testing. The results indicated that increasing the reagent polarity caused the aromatic hydrocarbons and carbazole compounds in crude oil to be eluted sequentially. Most aromatic compounds in the crude oil could be selectively eluted using a reagent polarity ratio of 9:1 (V: V), with no carbazole compounds. A significant amount of carbazole compounds were eluted in the polar segments of 8:2-6:4, with the eluted carbazoles concentration accounting for more than 98 % of the total concentration. Moreover, the concentration and recovery of carbazoles eluted by direct injection mode were about 10 % higher than those after adsorption by silica gel. The standard deviation of the parameter ratio for the separated carbazole compounds in the three groups of repeatable parallel experiments was less than 0.2 %. Our method is superior to traditional two-step method and C column method in separation efficiency and damage to human body. This method can be applied to both highly mature crude oil and other kinds of oils including biodegradable oil. It could be a versatile method for the carbazoles separation and provide technical support in unveiling the geochemical implications of these compounds in complex areas.
Topics: Humans; Petroleum; Silica Gel; Methylene Chloride; Gas Chromatography-Mass Spectrometry; Oils; Carbazoles
PubMed: 38029659
DOI: 10.1016/j.chroma.2023.464536 -
BioRxiv : the Preprint Server For... May 2024Sperm cryopreservation is important for individuals undergoing infertility treatment, and for those who wish to preserve fertility potential, prior to treatments like...
Sperm cryopreservation is important for individuals undergoing infertility treatment, and for those who wish to preserve fertility potential, prior to treatments like chemotherapy, radiation therapy, gender-affirming medical interventions, elective fertility delay, or individuals in high-risk professions such as the military. Current methods for sperm cryopreservation result in approximately 30-50% decrease in sperm motility. However, recent studies have shown that ultra-rapid freezing (vitrification) is a valuable approach for maintaining sperm quality after freeze-thawing processes in the clinical laboratory setting and requires submicroliter to microliter volumes. A major challenge for the adoption of vitrification in fertility laboratories is the ability to pipette small volumes of sample. Here, we present a method that leverages open-channel droplet microfluidics to autonomously generate sub-microliter to microliter volumes of purified human sperm samples. Using a novel, open-channel droplet generator, we found no change in sperm movement and kinematic data after exposure to device and reagents in our platform. We conclude that our platform is compatible with human sperm, an important foundation for future implementation of vitrification in fertility laboratories.
PubMed: 38798664
DOI: 10.1101/2024.05.09.593416 -
Spectrochimica Acta. Part A, Molecular... Jan 2024The realization of drug detection in drug-using crime sites can provide law enforcement officials with direct evidence. This research has developed and demonstrated an...
The realization of drug detection in drug-using crime sites can provide law enforcement officials with direct evidence. This research has developed and demonstrated an easy-to-use handheld sensor that can quickly detect methamphetamine (MA) in the field. The core of the handheld UV spectrophotometer device (HUVSD) is the STM32F103 series of single-chip micro-controller, which has a 32-bit microcontroller and two embedded 12-bit high-precision analog-to-digital converter (ADC) modules. Through Bluetooth-wireless transmission protocol, the spectral information can be displayed in the cell phone's app, and it is possible to visually determine whether the test sample contains methamphetamine hydrochloride substances based on the characteristic peak at 410 nm. The readily available and inexpensive inducible compound 3A and the phosphate pillar[5]arene@silver nanoparticle (PP5@AgNPs) colloidal solution were used as the reactants. The PP5@AgNPs colloidal solution and 3A were mixed and reacted at room temperature, and the color changed to gray-black. The color change was caused by the aggregation of AgNPs induced by the molecular recognition between the induction compound 3A and PP5 on the AgNPs surface. After continuing to add the drug MA, the color of the colloidal solution turned yellow again. This is due to the occurrence of competitive molecular recognition, and the interaction between PP5 and 3A/MA was investigated by molecular docking simulations. The HUVSD has high sensitivity, simple equipment, time-saving, color change visualization and suitable for on-site deployment. It only needs a Pasteur pipette, which has great potential to realize rapid on-site detection.
Topics: Metal Nanoparticles; Molecular Docking Simulation; Colorimetry; Silver; Ultraviolet Rays
PubMed: 37832445
DOI: 10.1016/j.saa.2023.123499 -
Neuroscience Research May 2024The gramicidin-perforated patch-clamp technique is indispensable for recording neuronal activities without changing the intracellular Cl concentration. Conventionally,...
The gramicidin-perforated patch-clamp technique is indispensable for recording neuronal activities without changing the intracellular Cl concentration. Conventionally, gramicidin contained in the pipette fluid is delivered to the cell membrane by passive diffusion. Gramicidin deposited on the pipette orifice sometimes hampers giga-seal formation, and perforation progresses only slowly. These problems may be circumvented by delivering a high concentration of gramicidin from an intra-pipette capillary after a giga-seal is formed. We herein describe the detailed protocol of this improved method. This protocol would greatly facilitate the investigation of Cl gradient-dependent neuronal activities.
PubMed: 38740268
DOI: 10.1016/j.neures.2024.05.002 -
Biosensors & Bioelectronics Oct 2023Desalting of biosamples is crucial for analytical techniques intolerant to abundant salts. However, there is no simple tool to monitor the desalting of low-volume...
Desalting of biosamples is crucial for analytical techniques intolerant to abundant salts. However, there is no simple tool to monitor the desalting of low-volume biosamples so far. Here we developed a handheld capacitively coupled contactless conductivity detector (hCD) as a miniaturized device to measure the conductivity of 75 μL biosamples. Polyether-ether-ketone (PEEK) tubing was selected as the sample reservoir for sample loading via a pipette. Another pipetting of air pushed the sample solution out of the tubing to recollect the sample. Owing to the low sample consumption and easy sample recollection, hC4D is advantageous for testing expensive biosamples, such as viruses and cells. In addition, the whole process of sample injection, conductivity measurement, recollection, and calibration of conductivity can be completed within 1 min. To verify the feasibility of hCD, we monitored the desalting progress of gel filtration (GF) of 200 μL blood samples, ultrafiltration (UF) of 300 μL virus samples, and dialysis of 7 mL cell samples. Three rounds of GF and UF completely removed the salts but led to poor sample recovery. In contrast, low concentrations of residual salts remained and better recovery was achieved after two rounds of GF and UF. We further utilized the hCD to monitor the dialysis and tuned the salt concentration in the cell sample, such that we maintained the viability of cells in a low conductivity environment. These results indicated that hCD is a promising tool for optimizing the desalting procedure of low-volume biosamples.
Topics: Electrophoresis, Capillary; Salts; Biosensing Techniques; Ketones; Polyethylene Glycols; Electric Conductivity
PubMed: 37406479
DOI: 10.1016/j.bios.2023.115482 -
Chembiochem : a European Journal of... Mar 2024Understanding α-synuclein aggregation is crucial in the context of Parkinson's disease. The objective of this study was to investigate the influence of aggregation...
Understanding α-synuclein aggregation is crucial in the context of Parkinson's disease. The objective of this study was to investigate the influence of aggregation induced by preformed seeding on the volume of oligomers during the early stages, using a label-free, single-molecule characterization approach. By utilizing nanopipettes of varying sizes, the volume of the oligomers can be calculated from the amplitude of the current blockade and pipette geometry. Further investigation of the aggregates formed over time in the presence of added seeds revealed an acceleration in the formation of large aggregates and the existence of multiple distinct populations of oligomers. Additionally, we observed that spontaneously formed seeds inhibited the formation of smaller oligomers, in contrast to the effect of HNE seeds. These results suggest that the seeds play a crucial role in the formation of oligomers and their sizes during the early stages of aggregation, whereas the classical thioflavin T assay remains negative.
Topics: alpha-Synuclein; Parkinson Disease; Biological Assay; Seeds
PubMed: 38240074
DOI: 10.1002/cbic.202300748 -
Chemosphere Apr 2024Trace-level analysis of environmental chemicals in human specimens can be compromised by contamination introduced during sample collection and storage. Sampling devices...
Trace-level analysis of environmental chemicals in human specimens can be compromised by contamination introduced during sample collection and storage. Sampling devices and tools can be a source of contamination by plasticizers, additives and antimicrobials, which warrants the need for pre-screening of these products prior to use. In this study, we determined leaching of 121 environmental chemicals in 10% and 100% methanol from 24 types of human specimen collection and storage devices. Cryovials, serum tubes, cups, syringes, transfer pipettes, and gloves -commonly used for the collection of blood, urine, breast milk and stools - were screened for the presence of plasticizers, environmental phenols, and pesticides. Measurable levels of mono-ethyl phthalate (mEP) and triethyl phosphate (TEP) were leached from vials, plastic storage bags, gloves, and diapers, and parabens were leached from collection bottles, at amounts exceeding 100 ng/device. The amount leached from the devices varied depending on the lot numbers of the same product type. Storage time and temperature were found to influence the leaching rate of chemicals, with increased levels observed following prolonged storage and at high temperatures. The study underscores the importance of pre-screening for contamination in devices used for collection and storage of human specimens for biomonitoring studies.
Topics: Female; Humans; Plasticizers; Specimen Handling; Phthalic Acids; Phenols; Parabens
PubMed: 38408569
DOI: 10.1016/j.chemosphere.2024.141528