A Green Analytical Method Using Polyurethane Foam for The Extraction and Determination of Lauryl Ether Sulfate in Personal Care Hygiene Products

A green methodology was developed for the extraction and determination of lauryl ether sulfate in raw materials and commercial liquid soap and shower gel samples. The method avoids the use of organic solvents, offering a simple, cheap, and safe analysis. The methodology is based on the sorption of an ionic pair consisting of a cationic dye and an anionic surfactant onto polyurethane foam. The experimental variables were optimized by chemometry to obtain the conditions that maximized extraction of the ionic pair. Digital imaging and spectrophotometry were used for quantification in the linear concentration range from 10.0 to 100 mg L-1. The limits of detection and quantification were, respectively, 2.71 and 9.28 mg L-1 for digital imaging, and 1.74 and 5.83 mg L-1 for spectrophotometry. The methods showed good results when applied to commercial samples, with recoveries in the range 96.8-103%.

Voltametri Pelucutan Anodik Menggunakan Elektroda Pasta Karbon Termodifikasi Bentonit untuk Penentuan Kadar Ion Cd(II) dalam Sayur Sawi Putih

In this study, the measurement of Cd(II) ion by anodic stripping voltammetry technique was conducted using bentonite modified carbon paste as working electrode (CPE-B). The performance of CPE-B was compared with carbon paste electrode without bentonite (CPE) and applied for determination of Cd(II) concentration in chicory. Optimized parameters were composition of bentonite in carbon paste electrode, deposition time, deposition potential, and scan rate. Validation of measurements was observed including determination of linear concentration range, detection and quantization limits, repeatability of measurement, and percentage of recovery. The optimum composition of bentonite in CPE-B was found at 50%. Furthermore, in the optimization of measurements condition was found the optimum deposition times were 90 and 60 s, deposition potentials were -0.63 and -0.53 V, and scan rates were 15 and 20 mV/s, for CPE and CPE-B. The linear range concentration for CPE observed at 25-2000 µg/L and CPE-B was 5-50 µg/L. Limit of detection and quantization using CPE-B were 0.337 µg/L and 0.349 µg/L, lower than CPE i.e., 0.470 µg/L and 0.471 µg/L, respectively. Repeatability measurement of Cd(II) had Horwitz Ratio value less than two, and percentage of recovery was 96.73 8.33%. The level of Cd(II) ion in chicory was found at 6.98 0.40 mg/kg.

New Reagent of Coupling Reaction for Spectrophotometric Determination of Paracetamol in Pharmaceutics

New reagent 2- hydroxybenzaldehydewas used in a coupling reaction for determination of paracetamol via spectrophotometric method. The proposition of simplicity, inexpensive, rapidity and sensitivity were conducted via spectrophotometric procedure. The method was based on diazotization of paracetamol and coupling with 2-hydroxybenzaldehyde in alkaline medium. Linear concentration range (0.50 - 12.00) µg/ml was comply Beer’s law at maximum wavelength 444 nm and detection limit (LOD) 0.05 µg/ml. The molar absorptivity and regression coefficient of (R2) were 1.2032×104 l/mol.cm, 0.9995, respectively. The suggested method was profitablyadapted for the determination of paracetamol in pharmaceutics. The results attained were in good agreement with thatone by standard method high performance liquid chromatography (HPLC).

A Disposable Saliva Electrochemical MIP-Based Biosensor for Detection of the Stress Biomarker α-Amylase in Point-of-Care Applications

The design and synthesis of artificial receptors based on molecular imprinting (MI) technology for the development of a new MIP-based biosensor for detection of the stress biomarker α-amylase in human saliva in point-of-care (PoC) applications is described in this work. The portable electrochemical devices for monitoring α-amylase consists of cost-effective and disposable gold screen-printed electrodes (AuSPEs). To build the electrochemical device, the template biomolecule was firstly immobilized directly over the working area of the gold chip previously activated with a self-assembled monolayer (SAM) of cysteamine (CA). Then, pyrrole (Py) monomer was selected as building block of a polymeric network prepared by CV electropolymerization. After the electropolymerization process, the enzyme was removed from the polymer film in order to build the specific recognition sites for the target enzyme. The MIP biosensor showed a very wide linear concentration range (between 3.0 × 10−4 to 0.60 mg mL−1 in buffer solution and between 3.0 × 10−4 to 3.0 × 10−2 mg mL−1 in human saliva) and low detection levels were achieved (LOD < 3.0 × 10−4 mg mL−1) using square wave voltammetry (SWV) as the electroanalytical technique.

A Multifunctional N-Doped Cu–MOFs (N–Cu–MOF) Nanomaterial-Driven Electrochemical Aptasensor for Sensitive Detection of Deoxynivalenol

Deoxynivalenol (DON) is one of the most common mycotoxins in grains, causing gastrointestinal inflammation, neurotoxicity, hepatotoxicity and embryotoxicity, even at a low quantity. In this study, a facile electrochemical aptasensor was established for the rapid and sensitive determination of DON based on a multifunctional N-doped Cu-metallic organic framework (N–Cu–MOF) nanomaterial. The N–Cu–MOF, with a large specific surface area and good electrical conductivity, served not only as an optimal electrical signal probe but also as an effective supporting substrate for stabilizing aptamers through the interactions of amino (-NH2) and copper. Under the optimal conditions, the proposed sensor provided a wide linear concentration range of 0.02–20 ng mL−1 (R2 = 0.994), showing high sensitivity, with a lower detection limit of 0.008 ng mL−1, and good selectivity. The sensor’s effectiveness was also verified in real spiked wheat samples with satisfactory recoveries of 95.6–105.9%. The current work provides a flexible approach for the rapid and sensitive analysis of highly toxic DON in food samples and may also be easily extended to detect other hazardous substances with alternative target-recognition aptamers.

Ultrafiltration-based Extraction and LC-MS/MS Quantification of Phenylalanine in Human Blood Sample for Metabolite Target Analysis

Background: Phenylalanine is a significant biomarker for various diseases like phenylketonuria, gastric cancers, and ischemic stroke according to recent studies. Methods: In the present study; a simple, sensitive, selective and novel analytical method was validated by using an ultrafiltration-based extraction and LC-MS/MS quantification of phenylalanine in human plasma using 13C phenylalanine heavy isotope. Amicon® Ultra Centrifugal Filter was used for ultrafiltration. Parameters affecting LC separation and MS/MS detection were investigated and optimized. Chromatographic separation was achieved on a Merck SeQuant ZIC-HILIC (100x4.6 mm, 5 μm) at a column temperature of 40°C using a mobile phase of mixture of acetonitrile containing 0.1% formic acid and water containing 0.1% formic acid (50:50 v/v) at a flow rate of 0.35 mL/min. The transitions m/z 167→121 for 13C phenylalanine, m/z 166→120 for phenylalanine itself were monitored using the MRM mode. Result: The assay was linear concentration range of 0.0025 μg/mL to 1.20 μg/mL (R2=0.999). The developed method was validated according to FDA guidelines. The method was found linear, sensitive, precise, accurate, and selective.

Enhanced Performance of Reagent-Less Carbon Nanodots Based Enzyme Electrochemical Biosensors

This work reports on the advantages of using carbon nanodots (CNDs) in the development of reagent-less oxidoreductase-based biosensors. Biosensor responses are based on the detection of H2O2, generated in the enzymatic reaction, at 0.4 V. A simple and fast method, consisting of direct adsorption of the bioconjugate, formed by mixing lactate oxidase, glucose oxidase, or uricase with CNDs, is employed to develop the nanostructured biosensors. Peripherical amide groups enriched CNDs are prepared from ethyleneglycol bis-(2-aminoethyl ether)-N,N,N′,N′-tetraacetic acid and tris(hydroxymethyl)aminomethane, and used as precursors. The bioconjugate formed between lactate oxidase and CNDs was chosen as a case study to determine the analytical parameters of the resulting L-lactate biosensor. A linear concentration range of 3.0 to 500 µM, a sensitivity of 4.98 × 10−3 µA·µM−1, and a detection limit of 0.9 µM were obtained for the L-lactate biosensing platform. The reproducibility of the biosensor was found to be 8.6%. The biosensor was applied to the L-lactate quantification in a commercial human serum sample. The standard addition method was employed. L-lactate concentration in the serum extract of 0.9 ± 0.3 mM (n = 3) was calculated. The result agrees well with the one obtained in 0.9 ± 0.2 mM, using a commercial spectrophotometric enzymatic kit.

A Novel Application of Electroactive Polyimide Doped with Gold Nanoparticles: As a Chemiresistor Sensor for Hydrogen Sulfide Gas

This research paper presents a new application of electroactive polyimide doped with gold nanoparticles (PI/AuNPs) as a chemiresistor sensor for detecting hydrogen sulfide gas. The synthesis of PI/AuNPs was done in a simple 3-step process of polymerization using the as prepared amine-capped aniline trimer (ACAT), followed by imidization, and doping. Spectral analyses via FTIR, LC-MS and 1H-NMR confirmed the formation of amine-capped aniline trimer with a MW of 288 g mol−1. Comparison of ACAT, BSAA, and PI FTIR spectra showed successful polymerization of the last, while XRD validated the incorporation of metal nanoparticles onto the polymer matrix, showing characteristic diffraction peaks corresponding to gold. Furthermore, TEM, and FE-SEM revealed the presence of well-dispersed Au nanoparticles with an average diameter of about 60 nm. The electroactive PI/AuNPs-based sensor showed a sensitivity of 0.29% ppm−1 H2S at a linear concentration range of 50 to 300 ppm H2S (r = 0.9777). The theoretical limit of detection was found at 0.142 ppm or 142 ppb H2S gas. The sensor provided a stable response reading at an average response time of 43 ± 5 s, which was easily recovered after an average time of 99 ± 5 s. The sensor response was highly repeatable and reversible, with RSD values of 8.88%, and 8.60%, respectively. Compared with the performance of the conventional conducting polyaniline also doped with gold nanoparticles (PANI/AuNPs), the fabricated electroactive PI/AuNPs exhibited improved sensing performance making it a potential candidate in monitoring H2S in the environment and for work-related safety.

A Novel Application of Electroactive Polyimide Doped with Gold Nanoparticles: As a Chemiresistor Sensor for Hydrogen Sulfide Gas

This research paper presents a new application of electroactive polyimide doped with gold nanoparticles (PI/AuNPs) as a chemiresistor sensor for detecting hydrogen sulfide gas. The synthesis of PI/AuNPs was done in a simple 3-step process of polymerization using the as prepared amine-capped aniline trimer (ACAT), followed by imidization, and doping. Spectral analyses via FTIR, LC-MS and 1H-NMR confirmed the formation of amine-capped aniline trimer with a MW of 288 g mol-1. Comparison of ACAT, BSAA, and PI FTIR spectra showed successful polymerization of the last, while XRD validated the incorporation of metal nanoparticles onto the polymer matrix showing characteristic diffraction peaks corresponding to gold. Furthermore, TEM, and FE-SEM revealed the presence of well-dispersed Au nanoparticles with an average diameter of about 60nm. The electroactive PI/AuNPs-based sensor showed a sensitivity of 0.29% ppm-1 H2S at a linear concentration range of 50 to 300 ppm H2S (r = 0.9777). The theoretical limit of detection was found at 0.142 ppm or 142 ppb H2S gas. The sensor provided a stable response reading at an average response time of 43&plusmn;5 seconds, which was easily recovered after an average time of 99&plusmn;5 seconds. The sensor response was highly repeatable and reversible with RSD values of 8.88%, and 8.60%, respectively. Compared with the performance of the conventional conducting polyaniline also doped with gold nanoparticles (PANI/AuNPs), the fabricated electroactive PI/AuNPs exhibited improved sensing performance making it a potential candidate in monitoring H2S in the environment and for work-related safety.

VXC-72R/ZrO2/GCE-Based Electrochemical Sensor for the High-Sensitivity Detection of Methyl Parathion

In this work, a carbon black (VXC-72R)/zirconia (ZrO2) nanocomposite-modified glassy carbon electrode (GCE) was designed, and a VXC-72R/ZrO2/GCE-based electrochemical sensor was successfully fabricated for the high-sensitivity detection of methyl parathion (MP). Electrochemical measurements showed that the VXC-72R/ZrO2/GCE-based electrochemical sensor could make full use of the respective advantages of the VXC-72R and ZrO2 nanoparticles to enhance the MP determination performance. The VXC-72R nanoparticles had high electrical conductivity and a large surface area, and the ZrO2 nanoparticles possessed a strong affinity to phosphorus groups, which could achieve good organophosphorus adsorption. On the basis of the synergistic effect generated from the interaction between the VXC-72R and ZrO2 nanoparticles, the VXC-72R/ZrO2/GCE-based electrochemical sensor could show excellent trace analysis determination performance. The low detection limit could reach up to 0.053 μM, and there was a linear concentration range of 1 μM to 100 μM. Such a high performance indicates that the VXC-72R/ZrO2/GCE-based electrochemical sensor has potential in numerous foreground applications.