Analytical and Bioanalytical Chemistry Research
Volume:10 Issue: 2, Spring 2023

Fabric phase sorptive extraction (FPSE) is a new extraction method that has the advantages of permeable sol-gel derived hybrid organic-inorganic sorbents with flexible and permeable fabric substrates, which leads to high efficiency and high sensitivity of this method. The aim of this research is to improve the FPSE method and design a modified technique called nanoparticle-assisted fabric phase sorptive extraction (NFPSE) using carbon dot nanoparticles to improve the sorbent efficiency. In this study, we focused on the determination of aflatoxins as one of the carcinogens that are abundant in nature and severely contaminate the food sources of humans and animals. The study focused on 4 types of aflatoxin B2, B1, G2, and G1. Various parameters that were effective in NFPSE were optimized. Under the selected conditions, extraction yields ranging from 80% to 95% for Aflatoxins were obtained with acceptable repeatability on the food samples. The calibration curves of the analytes were calculated by good correlation coefficient values (R2>0.990). Limits of detection (LOD) were calculated in the range of 0.12-0.51 ng.mL-1 and limits of quantification (LOQ) were considered in the range of 0.37-1.56 ng.mL-1. Intraday precisions were found in the range between 3.9% and 5.3% (RSD, n=3). The within-laboratory reproducibility was investigated in a period of one month and the results for all 4 types of aflatoxins were from 6.9-15%. the developed method was successfully used on food samples.

In this investigation, Sulfarsazen (SFN) was immobilized on polyethene polyamine-modified polyacrylonitrile (PPA) and was introduced as a new matrix and efficient analytical reagent for Hg(II) determination. This reagent is a new, non-volatile, stable, and non-poisonous, which shows high selectivity and gives a super recovery along with more accurate and fast response, as an analytical agent in the Hg(II) determination. The sensitivity for Hg(II) determination with the new selective immobilized reagent was maximal at 520 nm. Also, the optimal pH for Hg(II) determination by new matrix was 9.8, at which the analytical signal was maximal. It was found that the linear range was 2-42 mg/L, the detection limit was 0.4 mg/L, and the adsorption percentage was about 98%. The Sulfarsazen-immobilized polymeric matrix was selective in the determination of Hg(II), even in the presence of Ca2+, Sr2+, Ba2+, Mg2+, Na+, Cl- and I- ions in the solutions. The Hg(II) amounts in the wastewater samples were determined by the SFN/PPA matrix, with adsorption efficiencies in the range 98-99% and high accuracy. These properties cause this analytical reagent be very efficient in Hg(II) determination, and the traditional ones can be replaced with this new reagent, for the Hg(II) determination..

Light-emitting diodes (LEDs) can be used in paired emitter-detector diodes (PEDD) optical sensors as both the light source and the detector. PEDD-based photometers provide low fabrication cost, low power consumption, ease of miniaturization, and a high signal-noise ratio response in a wide wavelength range. This paper reports on developing a cheap but efficient PEDD-based photometer. The photometer consists of a white LED as the emitter diode, an RGB LED as the detector diode (for the first time), and a multimeter for recoding the signal. The developed PEDD-based photometer was utilized for the determination of 2,4,6-trinitrotoluene (TNT) in soil samples. A Meisenheimer complex of TNT with NaOH in acetonitrile was used as a probe to monitor the presence of residual TNT in soil samples. The calibration curve in the soil sample was linear in the concentration range of 0.86 to 110 µg g-1, with a detection limit of 0.27 µg g-1 and a quantification limit of 0.81 µg g-1. Analysis of the soil samples collected from the Iran Cinema and Television Town using the developed method showed trace residual of TNT.

Chlorella vulgaris green microalgae live cells show great potential for removal of pollutant. In this study, the potential of the Chlorella vulgaris microalga as an inexpensive biosorbent was investigated for the removal of formaldehyde (FA). The experimental conditions including pH, contact time, and temperature on the removal of FA were considered and optimized. The sorption thermodynamics and kinetics of FA on biosorbent were studied using linear and nonlinear regressions. Chlorella vulgaris as biosorbent was able to remove 98% of FA within 22 minutes at the pH of 6.0. The sorption isotherm fitted well to the Langmuir isotherm and the sorption kinetics followed the pseudo-second-order model. Based on the Langmuir model, the maximum capacity of the monolayer sorption of Chlorella vulgaris for FA was found to be 180 mg g-1. The rapid and relatively high capacity of natural and untreated Chlorella vulgaris is the main advantage of this biosorbent for wastewater treatment.

In this study, a molecularly imprinted polymers-solid phase extraction-liquid chromatography method to isolate megestrol drug in human fluid samples. The molecularly imprinted polymers using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the crosslinking monomer, and 2, 2-Azoisobutyronitrile as an initiator for polymer preparation. To evaluate the applicability of the molecularly imprinted polymers was used as a selective sorbent, general parameters: pH, the amount of solvents, washing solution, and eluent, and time, were optimized following a step-by-step approach. Under the optimum conditions, the detection limit linear range was obtained (0.02 to 2.0 µgL-1). The relative standard deviation of (± 2.0 %), and the detection limit of the method (0.02 µg/L) were obtained. The recoveries up to approximately 97.0 % from spiked human fluid samples could be obtained. The maximum adsorption capacity for the determination of megestrol drugs was 6.8 mgg-1. The proposed molecularly imprinted polymers-solid phase extraction-liquid chromatography method could be applied to the direct determination of megestrol drugs in human fluid samples.

A novel non-enzymatic electrochemical sensor with high sensitivity for glucose determination was introduced herein with nickel pentacyanonitrosylferrate (NiPCNF)-modified multi-walled carbon nanotubes (MWCNTs) paste electrode and deposited nickel hydroxide onto paste electrode using NiSO4 solution and H2SO4 as the soft template. The NiO-modified electrode was scanned with cyclic voltammetry (CV) method in alkaline media to obtain Ni(OH)2/NiOOH particles as glucose electrocatalyst. The prepared nickel oxide was then mixed with the paste inside the tube. It was observed that introducing both NiPCNF and NiO could synergistically improve the activity toward electrocatalytic oxidation of glucose with an increase in the accessible active sites and promotion of the electron transport capability. Therefore, the modified electrode did not only exhibit an outstanding electrochemical behavior but also decreased the potential for electrochemical oxidation and enhanced the affinity of the electrode to glucose. Field emission scanning electron microscopy (FESEM) was applied to study the surface morphology of the electrode and prepared NiPCNF powder. After optimizing the condition, the chronoamperometry (CA) technique was applied for glucose determination. Porous-modified electrode, containing both nanomaterials of NiPCNF and NiO, exhibited a vast linear range from 5 µM to 1.95 mM (2.6 orders of magnitude) with a low limit of detection (LOD) of 2.35 × 10-7 ± 1.52×10-8 M (S/N=3) and high sensitivity (2.83 ± 0.17 mA mM-1 cm-2). Finally, the prepared sensor was utilized for glucose determination in the real samples successfully.

The trace element copper is essential for vitality and promotes a healthy metabolism. Anemia, irregular heartbeat, bone illnesses, uremia, and hypertension are just a few of the major systemic toxic effects of copper ions. For the early detection and effective treatment of many important diseases, the assessment of copper(II) concentrations in biological fluids must be done quickly and accurately. A new copper(II) ion-selective solid contact poly(vinyl chloride) membrane electrode was developed in this study, with a neutral carrier of N,N′-bis(salicylidene)-1,3-diaminopropane Schiff base. The electrode displayed a Nernstian response to copper(II) ions over a broad concentration range (1.0×10-2 – 1.0×10-5 mol L-1) with a slope of 30.4 ± 0.5 mV/decade. The membrane cocktail could be used for more than 6 months without any potential divergence, and it had a quick response time of 5–10 seconds. The electrode was employed for the estimation of Cu2+ ions in certified blood samples and the results obtained by potentiometry were in good agreement with those by the Inductively Coupled Plasma-Sector Field Mass Spectrometry (ICP-SFMS) method.

The current research examines the designation of an electrochemical sensor for the simultaneous measurement of morphine and methadone using graphene oxide /multi-walled carbon nanotube/zinc oxide nanorods/polypyrrolenanocomposite, coated on the surface of the graphite electrode reinforced by a hollow fiber.Its performance was investigated by voltammetry methods while the nanocomposite structure was confirmed by FTIR, EDX, XRD, and SEM techniques.To optimize the effectual factors, the Taguchi test designing method with L27(3x7) orthogonal array was applied. Thevoltammetricanalysisshowed that two irreversible oxidation peaks appeared at the potentials of 0.81 V and 0.41 V for methadone and morphine, respectively. Furthermore, the electrochemical investigations showed that the oxidation process of morphine and methadone wasunder the control of the diffusion phenomenon and two electrons and two protons had been exchanged on the surface of the electrode for bothanalytes. Chronoamperometry was used to measure the diffusion coefficients of drugs which were found for morphine and methadone to be 5.31×10-6 cm2s-1 and 1.19×10-6 cm2 s-1. Under optimal conditions, for morphine, two linear concentration ranges of 0.04-10 μM and 10.0-100 μM and a detection limit of 0.01 μM were noted whereas for methadone, two linear ranges were observed in 0.06-8.0 μM and 8.0-100 μM and the detection limit was 0.02 μM. The designed sensor can be well used for the simultaneous measurement of the drugs with relative recovery percentages in the range of 98.80-100.22%for morphine and in the range of 98.14-100.58% for methadone.

Method validated using (RP-HPLC) reversed-phase high-performance liquid chromatographic method of this research was four selected Anti-Cancer standards. The newly developed method is novel, simple, precise, accurate, reproducible and less time consuming and it can be used for raw material of quantitative analysis and quality control. The separation of Rutin, Chrysin, Piperin and Berberine was conducted in less than 3 minutes and chromatographic separation was achieved using a stationary phase C18 J’Sphere column (internal diameter150 mm x 4.6 mm and particle size 4µ) and mobile phase contained acetonitrile: 0.1% formic acid (pH 2.7 ) in isocratic elution of (85:15 v/v) ratio, with a flow rate of 1mL/min and column temperature was maintained at 30 ̊ C with injection volume 20 µl, UV detection wavelength of at 336 nm were used. Rutin, Chrysin, Piperine and Berberine had retention times of 1.3, 1.8, 2.1 and 2.6 minutes, respectively. Calibration curves were accepted and reported good linear correlation coefficients (r2 ˃ 0.999) within the range of 1-3.5µg/mL. Mean percent recoveries for the standards were found to be within the acceptance limits (80-115%). Relative standard deviation (according to FDA and ICH guidelines) which indicates the method is precise. The developed method was applied in various medicinal plants Solanum aculeastrum dunal, Elephantorrhiza elephantina, Cadaba aphylla (Thunb) and Adenia glauca used to manage by traditional doctors in Botswana. All three plants were reported Rutin and Chrysin compounds except S. aculeastrum, it was reported only Rutin present whereas, Piperine and Berberine was not detected in all four plants.

A new and fast sample preparation method was developed to extract Hippuric acid (HA), Trans,trans-muconic acid (tt-MA), Mandelic acid (MA), and m-Methylhippuric acid (m-MHA) in urine samples using Hollow polymer nanospheres (HPSs), Covalent organic frameworks (COFs), and their mixture (HPS:COF) as an adsorbent, combined with high-performance liquid chromatography-ultraviolet spectrophotometry (HPLC-UV). X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to study the features of the adsorbents. The effect of important factors such as temperature and pH of the sample, amount of sorbent, conditioning and washing solvents, type and volume of desorption solvent, sample volume, and the number of extraction cycles were investigated to achieve the optimal conditions with microextraction by packed sorbent (MEPS) procedure. The applicability of the proposed method was then validated in the laboratory. Finally, the target analytes in the urinary samples of gas station workers were examined. The data analysis showed that using an HPS:COF mixture improves the extraction efficiency in optimal conditions compared to the case where the COF adsorbent is used alone (extraction efficiency, 81-87.5%). Also, a good linear dynamic range (0.1-1000 µg/mL for m-MHA), a low detection limit (0.02 µg/mL for tt-MA), and acceptable intra-day and inter-day precision (1.4-3.6 % and 4.5-8.9 %, respectively) were obtained under similar conditions. Overall, HPS: COF-MEPS exhibited excellent extraction efficiency (85.4-93.3%) and has the potential to replace previous methods in the biomonitoring of BTEX biomarkers in urine.