Liquid-phase microextraction combined with gas chromatography mass spectrometry for rapid determination of nicotine in one-drop of nightshades vegetables and commercial food products

An efficient microchip electromembrane extraction online with high-performance liquid chromatography for the measurement of nicotine in high consumption vegetables

INTRODUCTION

Nicotine, a highly addictive substance, is naturally produced in the Solanaceae family of plants, particularly tobacco. The presence of nicotine in plant foods has adverse effects on the lungs, kidneys, heart, and reproductive system.

OBJECTIVE

A novel three-phase microchip flat electromembrane coupled with online high-performance liquid chromatography (HPLC) was developed to analyze nicotine in tomato, mushroom, eggplant, bell pepper, and red pepper.

METHODS

The microchip was connected to the HPLC in online mode. All effective variables were optimized to achieve the best extraction response. The use of electric potential and 2-nitrophenyl octyl ether -5% di(2-ethylhexyl) phosphate as a modified supported liquid membrane (SLM) increased the sensitivity and selectivity.

RESULTS

The optimal extraction voltage, extraction time, and ion balance were 40 V, 10 min and 0, respectively. The dynamic linear range was 0.5-1000 ng g-1. The obtained recovery, relative standard deviation, and enrichment factor were 98%, 7%, and 35, respectively. The limits of detection 0.4 ng g-1 and the limits of quantification were obtained 1.3 ng g-1. The highest (105.0 ng g-1) and lowest (3.4 ng g-1) concentrations of nicotine were obtained for eggplant and tomato, respectively.

CONCLUSION

Selective electromembrane extraction of nicotine from the donor phase to the acceptor phase was performed by optimizing the main variables influencing the method mechanism. The new channel design in this analytical system and online injection increased efficiency, stability, and repeatability. The results revealed that this method is capable for the efficient determination of trace amount of nicotine in edible vegetables.

Effects of different host plants on the growth, development, and fecundity of Phthorimaea absoluta (Lepidoptera: Gelechiidae): an evaluation based on the age-stage two-sex life table

This study aimed to investigate the growth and development parameters of Phthorimaea absoluta (Meyrick) population at each stage when feeding on 4 host plants: Lycopersicon esculentum, Solanum tuberosum, Solanum melongena, and Nicotiana tabacum. The objective was to predict population dynamics and develop appropriate control strategies. The age-stage sex-life table was used to evaluate survival rate, fecundity, life expectancy, reproductive value, population parameters, and population growth prediction of P. absoluta after feeding on the 4 Solanaceae plants. The results showed significant variations in the fecundity parameters of P. absoluta among the different host plants. The L. esculentum population exhibited the highest average egg-laying period (13.17 ± 0.61 days) and average egg production (219.31 ± 21.02 eggs), while N. tabacum had the lowest values (4.56 ± 0.26 days and 26.08 ± 2.53 eggs, respectively). The gross reproduction rate of P. absoluta feeding on L. esculentum was 146.43 ± 21.00, which was 1.80, 3.77, and 6.39 times higher compared to S. tuberosum, S. melongena, and N. tabacum, respectively. The average age period and population doubling time of P. absoluta feeding on L. esculentum were lower than those of the other 3 host plants. These results indicated that while P. absoluta can complete a generation on L. esculentum, S. tuberosum, S. melongena, and N. tabacum, L. esculentum is the most suitable host for its growth and development. Therefore, in the occurrence and adjacent areas of P. absoluta, relevant authorities should promptly monitor and control its population in the planting areas of Solanaceae plants to prevent further spread.

Palladium Hydroxide (Pearlman's Catalyst) Doped MXene (Ti3C2Tx) Composite Modified Electrode for Selective Detection of Nicotine in Human Sweat

High concentrations of nicotine (40 to 60 mg) are more dangerous for adults who weigh about 70 kg. Herein, we developed an electrochemical transducer using an MXene (Ti₃C₂Tx)/palladium hydroxide-supported carbon (Pearlman's catalyst) composite (MXene/Pd(OH)₂/C) for the identification of nicotine levels in human sweat. Firstly, the MXene was doped with Pd(OH)₂/C (PHC) by mechanical grinding followed by an ultrasonication process to obtain the MXene/PHC composite. Secondly, XRD, Raman, FE-SEM, EDS and E-mapping analysis were utilized to confirm the successful formation of MXene/PHC composite. Using MXene/PHC composite dispersion, an MXene/PHC composite-modified glassy carbon electrode (MXene/PHC/GCE) was prepared, which showed high sensitivity as well as selectivity towards nicotine (300 µM NIC) oxidation in 0.1 M phosphate buffer (pH = 7.4) by cyclic voltammetry (CV) and amperometry. The MXene/PHC/GCE had reduced the over potential of nicotine oxidation (about 200 mV) and also enhanced the oxidation peak current (8.9 µA) compared to bare/GCE (2.1 µA) and MXene/GCE (5.5 µA). Moreover, the optimized experimental condition was used for the quantification of NIC from 0.25 µM to 37.5 µM. The limit of detection (LOD) and sensitivity were 27 nM and 0.286 µA µM^-1 cm², respectively. The MXene/PHC/GCE was also tested in the presence of Na⁺, Mg²⁺, Ca²⁺, hydrogen peroxide, acetic acid, ascorbic acid, dopamine and glucose. These molecules were not interfered during NIC analysis, which indicated the good selectivity of the MXene/PHC/GCE sensor. In addition, electrochemical determination of NIC was successfully carried out in the human sweat samples collected from a tobacco smoker. The recovery percentage of NIC in the sweat sample was 97%. Finally, we concluded that the MXene/PHC composite-based sensor can be prepared for the accurate determination of NIC with high sensitivity, selectivity and stability in human sweat samples.

Exposure to melamine and its derivatives and aromatic amines among pregnant women in the United States: The ECHO Program

BACKGROUND

Melamine, melamine derivatives, and aromatic amines are nitrogen-containing compounds with known toxicity and widespread commercial uses. Nevertheless, biomonitoring of these chemicals is lacking, particularly during pregnancy, a period of increased susceptibility to adverse health effects.

OBJECTIVES

We aimed to measure melamine, melamine derivatives, and aromatic amine exposure in pregnant women across the United States (U.S.) and evaluate associations with participant and urine sample collection characteristics.

METHODS

We measured 43 analytes, representing 45 chemicals (i.e., melamine, three melamine derivatives, and 41 aromatic amines), in urine from pregnant women in nine diverse ECHO cohorts during 2008-2020 (N = 171). To assess relations with participant and urine sample collection characteristics, we used generalized estimating equations to estimate prevalence ratios (PRs) for analytes dichotomized at the detection limit, % differences (%Δ) for continuous analytes, and 95% confidence intervals. Multivariable models included age, race/ethnicity, marital status, urinary cotinine, and year of sample collection.

RESULTS

Twelve chemicals were detected in >60% of samples, with near ubiquitous detection of cyanuric acid, melamine, aniline, 4,4'-methylenedianiline, and a composite of o-toluidine and m-toluidine (99-100%). In multivariable adjusted models, most chemicals were associated with higher exposures among Hispanic and non-Hispanic Black participants. For example, concentrations of 3,4-dichloroaniline were higher among Hispanic (%Δ: +149, 95% CI: +17, +431) and non-Hispanic Black (%Δ: +136, 95% CI: +35, +311) women compared with non-Hispanic White women. We observed similar results for ammelide, o-/m-toluidine, 4,4'-methylenedianiline, and 4-chloroaniline. Most chemicals were positively associated with urinary cotinine, with strongest associations observed for o-/m-toluidine (%Δ: +23; 95% CI: +16, +31) and 3,4-dichloroaniline (%Δ: +25; 95% CI: +17, +33). Some chemicals exhibited annual trends (e.g., %Δ in melamine per year: -11; 95% CI: -19, -1) or time of day, seasonal, and geographic variability.

DISCUSSION

Exposure to melamine, cyanuric acid, and some aromatic amines was ubiquitous in this first investigation of these analytes in pregnant women. Future research should expand biomonitoring, identify sources of exposure disparities by race/ethnicity, and evaluate potential adverse health effects.

Paper-Based Potentiometric Sensors for Nicotine Determination in Smokers' Sweat

Herein, we describe for the first time, the design and fabrication of a novel nicotine paper-based sensor, in which a miniaturized paper reference electrode is integrated for potentiometric measurements. The paper-based sensors were designed using printed wax barriers to define the electrochemical cell and the sample zones. The electrodes were based on the use of the ion association complexes of the nicotinium cation (Nic) with either tetraphenylborate (TPB) or 5-nitrobarbiturate (NB) counter anions as sensing materials for nicotine recognition. A poly (3,4 ethylenedioxythiophene)/poly-(styrene sulfonate) (PEDOT/PSS) conducting polymer was used as an ion-to-electron transducer. The performance characteristics of the proposed sensors were evaluated and it revealed a rapid and stable response with a Nernstian slope of 55.2 ± 0.3 and 51.2 ± 0.6 mV/decade over the linear range of 1.0 × 10^-5 to 1.0 × 10^-2 M and detection limits of 6.0 and 8.0 μM for [Nic/TPB] and [Nic/NB], respectively. The sensors revealed a constant response over the pH range 3.5-6.5. The designed sensors provided a portable, inexpensive, and disposable way of measuring trace levels of nicotine coming from different cigarettes and in the collected human sweat of heavy smokers. All results were compared favorably with those obtained by the standard gas chromatographic method.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

Electrochemical sensing of nicotine using CuWO4 decorated reduced graphene oxide immobilized glassy carbon electrode

A novel and selective electrochemical sensing of nicotine is studied using copper tungstate decorated reduced graphene oxide nanocomposite (CuWO₄/rGO) nafion (Nf) immobilized GC electrode (GCE). The CuWO₄/rGO nanocomposite is synthesized using sonication method and characterized by HR-TEM (High resolution transmission electron microscopy), SEM (Scanning electron microscopy), FT-IR (Fourier transform infrared spectroscopy), SAED (Selected area of electron diffraction pattern), XRD (X-ray diffraction), Raman spectroscopy, Thermo gravimetric analysis (TGA) and EDX (Energy dispersive X-ray diffraction) techniques. The CuWO₄/rGO/Nf immobilized GCE shows better electrocatalytic response for the detection of nicotine as compared to bare GCE. A better selectivity and sensitivity is achieved using CuWO₄/rGO/Nf immobilized GCE to detect 0.1 µM nicotine in the presence of 100-fold excess concentrations of different interferents. The present CuWO₄/rGO/Nf immobilized GCE electrochemical sensor exhibits an ample range of sensing from 0.1 µM to 0.9 µM and the low detection limit is found to be 0.035 µM (S/N = 3). Comparable results are achieved for the determination of nicotine in various real samples such as cigarettes (Gold flake and Wills) and urine samples with improved recoveries.

Comparison of the Conventional and Electroenhanced Direct-Immersion Solid-Phase Microextraction for Sampling of Nicotine in Biological Fluids of the Human Body

A stainless steel fiber was made porous and adhesive by platinization and then coated by nanostructured polypyrrole (PPy), using an appropriate electrophoretic deposition (EPD) method. The morphological surface structure and functional groups of the PPy-coated fiber were studied using SEM (Scanning electron microscope) instrument. The prepared fiber was used for comparison of direct immersion (DI) and electroenhanced direct immersion solid-phase microextraction (EE-DI-SPME) of nicotine in human plasma and urine samples followed by gas chromatography flame ionization detector (GC-FID) determination. The effects of the influential experimental parameters on the efficiency of the DI-SPME and EE-DI-SPME methods, including the pH and ionic strength of the sample solution, applied Direct current (DC) voltage, extraction temperature and time and stirring rate, were optimized. Under the optimal conditions, the calibration curves for the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were linear over the ranges of 0.1⁻10.0 μg mL^-1 and 0.001⁻10.0 μg mL^-1, respectively. The relative standard deviations (RSDs, n = 6) were found to be 6.1% and 4.6% for the DI and EE strategies, respectively. The LODs (limit of detection) of the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were found to be 10 and 0.3 ng mL^-1, respectively. The relative recovery values (for the analysis of 1 µg mL^-1 nicotine) were found to be 91⁻110% for EE-DI-SPME and 75⁻105% for DI-SPME. The enrichment factors for DI-SPME and EE-DI-SPME sampling were obtained as 38,734 and 50,597, respectively. The results indicated that EE-SPME was more efficient for quantitation of nicotine in biological fluids. The developed procedure was successfully carried out for the extraction and measurement of nicotine in real plasma and urine samples.

A novel procedure for phase separation in dispersive liquid-liquid microextraction based on solidification of the aqueous phase

In this paper, an alternative for handling the organic phase after a dispersive liquid-liquid microextraction using organic solvents lighter than water is presented. It is based on solidification (at -18°C) of the aqueous phase obtained after centrifugation, and the decantation, collection and analysis of the liquid organic layer. The extraction of nicotine in toluene, and its determination in eggplant samples was conducted as a proof of concept. The study has been carried out using standards prepared in water and the formation of the dispersion was assisted by sonication. The organic extract was analysed using gas chromatography coupled to mass spectrometry. Satisfactory analytical figures of merit as: limit of detection (0.4µgL(-1), 2ngg(-1) wet sample), limit of quantification (1.2µgL(-1), 6.5ngg(-1) wet sample), within-day precision (RSD=7%), and linearity interval (up to 384µgL(-1) nicotine) were achieved. It constituted a contribution to the handling of organic extracts after microextraction processes.

Effects of push/pull perfusion and ultrasonication on the extraction efficiencies of phthalate esters in sports drink samples using on-line hollow-fiber liquid-phase microextraction

In previous studies, we developed a process, on-line ultrasound-assisted push/pull perfusion hollow-fiber liquid-phase microextraction (UA-PPP-HF-LPME), combining the techniques of push/pull perfusion (PPP) and ultrasonication with hollow-fiber liquid-phase microextraction (HF-LPME), to achieve rapid extraction of acidic phenols from water samples. In this present study, we further evaluated three more-advanced and novel effects of PPP and ultrasonication on the extraction efficiencies of neutral high-molecular-weight phthalate esters (HPAEs) in sports drinks. First, we found that inner-fiber fluid leakage occurs only in push-only perfusion-based and pull-only perfusion-based HF-LPME, but not in the PPP mode. Second, we identified a significant negative interaction between ultrasonication and temperature. Third, we found that the extraction time of the newly proposed system could be shortened by more than 93%. From an investigation of the factors affecting UA-PPP-HF-LPME, we established optimal extraction conditions and achieved acceptable on-line enrichment factors of 92-146 for HPAEs with a sampling time of just 2 min.

Microextraction techniques for the determination of volatile and semivolatile organic compounds from plants: a review

Vegetables and fruits are necessary for human health, and traditional Chinese medicine that uses plant materials can cure diseases. Thus, understanding the composition of plant matrix has gained increased attention in recent years. Since plant matrix is very complex, the extraction, separation and quantitation of these chemicals are challenging. In this review we focus on the microextraction techniques used in the determination of volatile and semivolatile organic compounds (such as esters, alcohols, aldehydes, hydrocarbons, ketones, terpenes, sesquiterpene, phenols, acids, plant secondary metabolites and pesticides) from plants (e.g., fruits, vegetables, medicinal plants, tree leaves, etc.). These microextraction techniques include: solid phase microextraction (SPME), stir-bar sorptive extraction (SBSE), single drop microextraction (SDME), hollow fiber liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME), and gas purge microsyringe extraction (GP-MSE). We have taken into consideration papers published from 2008 to the end of January 2013, and provided critical and interpretative review on these techniques, and formulated future trends in microextraction for the determination of volatile and semivolatile compounds from plants.

"Dilute & shoot" approach for rapid determination of trace amounts of nicotine in zero-level e-liquids by reversed phase liquid chromatography and hydrophilic interactions liquid chromatography coupled with tandem mass spectrometry-electrospray ionization

Two analytical procedures are proposed where HILIC and RPLC techniques are coupled with tandem mass spectrometry detection for rapid determination of trace amounts of nicotine in zero-level liquids for electronic cigarettes. Samples are prepared on the basis of the approach "dilute & shoot" which makes this important step quick and not complicated. The chromatographic separation was carried out on a Zorbax XDB column (RPLC method) and Ascentis Si column (HILIC mode). Within-run precisions (CVs) measured at three concentration levels were as follows: 0.73%, 0.98% and 1.44% for RPLC method and 1.39%, 1.44% and 0.57% (HILIC mode). Between-run CVs were as follows: 1.94%, 1.02% and 1.22% for RPLC mode and 1.49%, 1.20% and 1.22% for HILIC mode. The detection limits of RPLC and HILIC modes were 4.08 and 3.90 ng/mL respectively. The proposed procedures are rapid, not complicated, sensitive and are suitable for fast determination of trace amounts of nicotine in zero-level liquids for electronic cigarettes.

Analytical sonochemistry; developments, applications, and hyphenations of ultrasound in sample preparation and analytical techniques

Ultrasonic assistance is one of the great successes of modern analytical chemistry, which uses this energy for a variety of purposes in relation to sample preparation and development of methods for the analysis of numerous contaminants including organic and inorganic compounds. This review will attempt to provide an overview of more recent applications of ultrasound in different environmental and biological samples such as food, soil and water as well as a brief description of the theoretical understanding of this method. Also, the possibility of coupling ultrasound with other analytical techniques will be discussed.

Determination of nicotine and its metabolite cotinine in urine and cigarette samples by capillary electrophoresis coupled with electrochemiluminescence

In this paper, CE coupled with electrochemiluminesence (ECL) detection using a 76-μm Pt disk as working electrode was developed for nicotine (NIC) determination. The major metabolite of NIC is cotinine (COT), which has a similar tertiary amine structure to NIC. However, there is a carbonyl group attached in the structure of COT, which leads to the great decrease in ECL response. In order to improve the ECL response of COT, NaBH(4) was used for carbonyl reduction. After reduction, NIC and COT were separated and detected by CE-ECL. ECL response plotted with NIC concentration was linear between 5.0×10(-7) and 5.0×10(-5)  mol/L (81-8100 μg/L), with LOD of 5.0×10(-8)  mol/L (8.1 μg/L). The developed CE-ECL method was applied for NIC determination in urine and cigarette samples.