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%.

Convenient Heme Nanorod Modified Electrode for Quercetin Sensing by Two Common Electrochemical Methods

Quercetin (Qu) is one of the most abundant flavonoids in the human diet. High concentrations of Qu can easily cause adverse effects and induce inflammation, joint pain and stiffness. In this study, Heme was used as a sensitive element and deposited and formed nanorods on a glassy carbon electrode (GCE) for the detection of Qu. The Heme/GCE sensor was characterized using scanning electron microscopy (SEM), cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Under optimized conditions, the developed sensor presented a linear concentration ranging from 0.1 to 700 μmol·L−1 according to the CV and DPV methods. The detection limit for the sensor was 0.134 μmol·L−1 and its sensitivity was 0.12 μA·μM−1·cm−2, which were obtained from CV analysis. Through DPV analysis we obtained a detection limit of 0.063 μmol·L−1 and a sensitivity of 0.09 μA·μM−1·cm−2. Finally, this sensor was used to detect the Qu concentration in loquat leaf powder extract, with recovery between 98.55–102.89% and total R.S.D. lower than 3.70%. The constructed electrochemical sensor showed good anti-interference, repeatability and stability, indicating that it is also usable for the rapid detection of Qu in actual samples.

Development of a Nanocluster-Based Platform for Determination of Sofosbuvir

Background: Sofosbuvir is a potent direct-acting antivirus agent that has been listed as a promising medicine for the treatment of all genotypes of hepatitis C virus. As antiviral drugs could be metabolized to their associated compounds and toxicologically and pharmacologically interfere with the parent drugs, identifying the therapeutic range of drugs would be notable. Methods: In the current study, copper nanoclusters (Cu NCs) are synthesized during the reduction of copper nitrate with hydrazine hydrate in a protected media and used as a nanoprobe for the determination of sofosbuvir in plasma samples. Herein, synchronous fluorescence spectroscopy (SFS) is used for monitoring of fluorescence variation of nanoprobe owing to the excessive benefits compared with the traditional fluorescence. Results: SFS peak of Cu NCs has appeared at 355 nm with ∆λ=80 nm which is decreased in the presence of sofosbuvir. To optimize the reaction factors, a response surface methodology is used and in the optimized conditions, a linear concentration-response plot is obtained in a range of 0.05-6.0 µg mL−1 with a limit of detection of 0.0147 µg mL−1. Conclusion: The developed method also reveals good repeatability and selectivity for sofosbuvir in plasma samples.

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 computational study of phase separation in polymer solutions under a concentration gradient

Anisotropic porous polymeric materials fabricated from the phase separation method via spinodal decomposition are used in various practical engineering applications. Examples include anisotropic porous polymeric membranes for separation processes and holographic polymer dispersed liquid crystal films for electro-optical devices. We have studied numerically the formation of anisotropic porous polymeric materials by imposing an initial linear concentration gradient across a model polymer solution. The mathematical model is composed of the non-linear Cahn-Hilliard theory to describe spinodal decomposition dynamics, the Flory-Huggins theory for polymer solution thermodynamics, and the slow mode theory combined with the Rouse law for polymer diffusion. The computer simulations include uniform (no gradient) and non-uniform (with an initial concentration gradient) cases. For the non-uniform cases, the initial concentration gradient is placed at three different regions of polymer sample for the purpose of comparison. All the simulation results are in good agreement with published experimental observations which are reported from the applications of porous polymeric membranes. The structure development shows that an anisotropic porous morphology forms when an initial linear concentration gradient is applied to the model polymer solution.

A computational study of phase separation in polymer solutions under a concentration gradient

Anisotropic porous polymeric materials fabricated from the phase separation method via spinodal decomposition are used in various practical engineering applications. Examples include anisotropic porous polymeric membranes for separation processes and holographic polymer dispersed liquid crystal films for electro-optical devices. We have studied numerically the formation of anisotropic porous polymeric materials by imposing an initial linear concentration gradient across a model polymer solution. The mathematical model is composed of the non-linear Cahn-Hilliard theory to describe spinodal decomposition dynamics, the Flory-Huggins theory for polymer solution thermodynamics, and the slow mode theory combined with the Rouse law for polymer diffusion. The computer simulations include uniform (no gradient) and non-uniform (with an initial concentration gradient) cases. For the non-uniform cases, the initial concentration gradient is placed at three different regions of polymer sample for the purpose of comparison. All the simulation results are in good agreement with published experimental observations which are reported from the applications of porous polymeric membranes. The structure development shows that an anisotropic porous morphology forms when an initial linear concentration gradient is applied to the model polymer solution.

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.

Quantifying the concentration dependence of sedimentation coefficients for globular macromolecules: a continuing age-old problem

This retrospective investigation has established that the early theoretical attempts to directly incorporate the consequences of radial dilution into expressions for variation of the sedimentation coefficient as a function of the loading concentration in sedimentation velocity experiments require concentration distributions exhibiting far greater precision than that achieved by the optical systems of past and current analytical ultracentrifuges. In terms of current methods of sedimentation coefficient measurement, until such improvement is made, the simplest procedure for quantifying linear s-c dependence (or linear concentration dependence of 1/s) for dilute systems therefore entails consideration of the sedimentation coefficient obtained by standard c(s), g*(s) or G(s) analysis) as an average parameter ($$ \overline{s} $$ s ¯ ) that pertains to the corresponding mean plateau concentration (following radial dilution) ($$ \overline{c} $$ c ¯ ) over the range of sedimentation velocity distributions used for the determination of $$ \overline{s} $$ s ¯ . The relation of this with current descriptions of the concentration dependence of the sedimentation and translational diffusion coefficients is considered, together with a suggestion for the necessary improvement in the optical system.

Teknik Differential Pulse Voltammetry Menggunakan Elektroda Pasta Karbon Termodifikasi Fe2O3 untuk Penentuan Kadar Fe(III) dalam Air Laut di Pelabuhan Benoa Bali

<p>Pelabuhan Benoa merupakan salah satu pelabuhan di Provinsi Bali tempat berlabuhnya kapal/perahu nelayan, kapal penumpang, dan kapal untuk pariwisata. Aktivitas masyarakat di sekitar pelabuhan dapat menjadi sumber pencemar logam berat. Penelitian ini bertujuan untuk mengetahui hasil optimasi dan validasi elektroda pasta karbon tanpa modifikasi (EPK) dan EPK termodifikasi Fe₂O₃ (EPK Fe₂O₃) dengan teknik <em>differential pulse voltammetry</em> (DPV) untuk pengukuran Fe(III) dalam sampel air laut di Pelabuhan Benoa. Parameter yang dioptimasi yaitu laju pindai dan komposisi Fe₂O₃ dalam pasta karbon. Selanjutnya dilakukan validasi pengukuran, meliputi rentang konsentrasi linier, limit deteksi, limit kuantisasi, keberulangan, dan persen perolehan kembali. Hasil yang diperoleh yaitu laju pindai optimum 15 mV/s menggunakan EPK, menjadi<ins cite="mailto:Microsoft%20Office%20User" datetime="2021-02-27T20:39"> </ins>lebih cepat yaitu 20 mV/s menggunakan EPK Fe₂O₃. Komposisi <em>modifier</em> terbaik dalam pasta karbon sebesar 0,5%. Rentang konsentrasi linier pengukuran menggunakan EPK yaitu 5 ~ 100 mg/L menjadi 5 ~ 2000 mg/L pada EPK Fe₂O_3.Limit deteksi dan limit kuantisasi menggunakan EPK Fe₂O₃masing-masing 0,5490 mg/L dan 0,5497 mg/L, lebih rendah daripada menggunakan EPK yaitu 1,0667 mg/L dan 1,0688 mg/L. Keberulangan pengukuran menghasilkan rasio Horwitz yang lebih kecil dari dua. Nilai persen perolehan kembali pengukuran larutan standar dengan matriks larutan sampel yang diambil pada tiga lokasi yang berbeda, yaitu pada Dermaga Barat 97,51±9,92% ; Dermaga Selatan 101,18±10,60%; dan Dermaga Timur 95,50±1,23%. Hasil pengukuran Fe(III) dalam sampel diperoleh 129,98±13,65 mg/L; 114,85±13,75 mg/L; dan 127,77±4,01 mg/L, masing-masing pada Dermaga Barat, Selatan, dan Timur.</p><p><strong>Differential Pulse Voltammetry Technique Using Fe₂O₃ Modified Carbon Paste Electrode for Determination of Fe(III) Levels in Seawater at Benoa Harbor Bali. </strong>Benoa Port is one of the ports in the Province of Bali where fishing boats, passenger ships, and ships for tourism are anchored. Activities around the port can be a source of heavy metal pollutants. This study aims to optimize and validates carbon paste electrodes without modification (EPK) and modified by Fe₂O₃ (EPK Fe₂O₃) using differential pulse voltammetry (DPV) techniques for Fe (III) measurements in seawater at Benoa Harbor. The optimized parameters were scan rate and the Fe₂O₃ composition in carbon paste. Meanwhile, the validation was performed, including the range of linear concentration, detection limit, quantitation limit, repeatability, and percent of the recovery. The research found that the optimum scan rate was 15 mV/s using EPK, become faster to 20 mV/s using EPK Fe₂O₃. The optimum <em>modifier</em> composition in carbon paste was 0.5%. The linear concentration range of measurement using EPK was 5 ~ 100 mg/L to 5 ~ 2000 mg/L at EPK Fe₂O₃. The detection limit and the quantitation limit using EPK Fe₂O₃ were 0.5490 mg/L and 0.5497 mg/L, respectively. Those are lower than the detection limit quantitation by EPK i.e., 1.0667 mg/L and 1.0688 mg/L, respectively. Repeated measurements produce a Horwitz ratio which is less than two. The percent of recovery value of the measurement of the standard solution with the sample solution matrix taken from the three different locations are 97.51±9.92% for the West Pier region; 101.18±10.60% for the South Pier region; and 95.50±1.23% for the East Pier region. The Fe(III) measurements to the different samples from the West Pier, South Pier, and East Pier regions were 129.98±13.65 mg/L; 114.85±13.75 mg/L; and 127.77±4.01 mg/L, respectively.</p>