Green hairy basil seed mucilage biosorbent for dispersive solid phase extraction enrichment of tetracyclines in bovine milk samples followed by HPLC analysis.

Unmodified hairy basil seed mucilage (Ocimum basilicum L.), with attractive features as structural functionality and adsorption capacity, was employed as a green biosorbent for dispersive solid phase extraction and enrichment of oxytetracycline, tetracycline, and doxycycline before quantitation by HPLC-UV for the first time. Hairy basil crushed seed increased the contacting surface area and was completely dispersed in the sample solution to extract tetracyclines under acidic condition with the assistance of ultrasonic waves. The analytes in the extraction phase were separated on a C18 column under isocratic condition with a mobile phase consisted of acetonitrile and trifluoroacetic acid. Influence of chemical and physical variables on the extraction efficiency of the developed method was investigated and optimized systematically. Under the optimal condition of all experimental parameters, good linear ranges were obtained at 15.0-500 µg L-1 for tetracyclines with determination coefficients more than 0.9994. Limits of detection (LODs) and limits of quantitation (LOQs) ranged 5.0-7.0 and 15.0 µg L-1, respectively. Relative standard deviations (RSDs) of the proposed method at 100 and 300 µg L-1 for TCs were less than 13 % and 10 %, respectively with percentage TC recoveries from spiked standard ranging 83.1-109.9 %. This simple, reliable, cost-effective, and environmentally friendly method was successfully applied for the analysis of tetracycline residues in milk. The greenness of the proposed method was assessed using the Analytical Eco-Scale and AGREE protocol.

One-pot co-extraction of dispersive solid phase extraction employing iron-tannic nanoparticles assisted cloud point extraction for the determination of tetracyclines by high-performance liquid chromatography.

Iron-tannic nanoparticles were used as a new adsorbent for dispersive solid phase extraction (DSPE) synergized with cloud point extraction (CPE) to enrich four tetracyclines (oxytetracycline, tetracycline, chlortetracycline, and doxycycline) prior to high-performance liquid chromatographic determination. DSPE and CPE were performed simultaneously in a one-pot co-extraction to form iron-tannic nanoparticles in-situ and pre-concentrate the tetracyclines. The parameters affecting the extraction efficiency were investigated. Using the optimal parameters, linear calibrations ranging from 2.63 to 1000 ng mL-1 were obtained, with determination coefficients greater than 0.996. The limit of detection was found to be 1.06-3.19 ng mL-1, while the limit of quantification was 2.63-10.65 ng mL-1. Precision was expressed as a relative standard deviation of less than 10%. The residues of the four tetracyclines in milk, eggs, honey, chicken liver, and chicken kidney samples were determined by the proposed method. The recoveries ranged from 79.3 to 107.1%. The results indicated that the proposed method was an alternative method for the extraction and pre-concentration of tetracyclines with high extraction and enrichment efficiency. In addition, it promoted rapidity and environmental friendliness.

Ultrasound-Assisted One-Pot Cloud Point Extraction for Iron Determination Using Natural Chelating Ligands from Dipterocarpus intricatus Dyer Fruit.

An ultrasound-assisted, one-pot cloud point extraction was developed for the determination of iron in vegetable samples by UV-Visible spectrophotometry. This method was based on the complexation of iron with an environmentally-friendly natural chelating agent extracted from Dipterocarpus intricatus Dyer fruit at pH 5.5 in the presence of Triton X-114. Reagent extraction, complexation, and preconcentration were performed simultaneously using ultrasound-assisted extraction at 45 °C. The surfactant-rich phase was diluted with ethanol and loaded through a syringe barrel packed with cotton that acted as a filter to trap the reagent powder. Analyte-entrapped on cotton was eluted using 0.1 mol·L-1 nitric acid solution. Filtrate and eluate solutions were measured absorbance of the dark-blue product at 575 nm. Influential parameters for the procedure were investigated. Under the optimum experimental conditions, the calibration curve was linear, ranging from 0.1 to 1.0 mg·L-1 with r2 = 0.997. Limits of detection and quantification were 0.03 and 0.09 mg·L-1, respectively while precision values of intra-day and inter-day were less than 5%. Recovery at 0.5 mg·L-1 ranged from 89.0 to 99.8%, while iron content in vegetable samples ranged from 2.45 to 13.36 mg/100 g. This method was cost-effective, reliable, eco-friendly, and convenient as a green analytical approach to determining iron content.

Dual determination of nitrite and iron by a single greener sequential injection spectrophotometric system employing a simple single aqueous extract from Areca catechu Linn. serving as a natural reagent.

Dual determination of nitrite and iron was proposed by using a single greener sequential injection (SI) spectrophotometric system employing a simple single aqueous extract from Areca catechu Linn. The extract served as a natural reagent to replace N-(1-naphthyl)ethylenediamine (NED) of the Griess reagent with nitrite and 1,10-phenanthroline with iron. The color products possessed analytical wavelengths at 430 and 560 nm, respectively. Conditions for the SI procedure were optimized using a univariate experimental design. Calibration ranges were up to 5.0 mg L-1 and 10.0 mg L-1 with limits of detection (LODs) of 0.04 mg L-1 and 0.05 mg L-1 for nitrite and iron(iii), respectively, and relative standard deviations (RSDs) being less than 3%. Recoveries of spiked standard nitrite and iron(iii) at 0.3 mg L-1 and 0.5 mg L-1 in water samples were 88 to 104% and 84 to 109%, respectively. The developed method successfully achieved dual determination of nitrite and total iron agreeing at a 95% confidence level with the reference methods of the conventional Griess assay and flame atomic absorption spectrometry (FAAS), respectively. The proposed method utilized locally available material from plants and serves the UN-SDGs.

A Simple and Reliable Dispersive Liquid-Liquid Microextraction with Smartphone-Based Digital Images for Determination of Carbaryl Residues in Andrographis paniculata Herbal Medicines Using Simple Peroxidase Extract from Senna siamea Lam. Bark.

A simple and reliable dispersive liquid-liquid microextraction (DLLME) coupled with smartphone-based digital images using crude peroxidase extracts from cassia bark (Senna siamea Lam.) was proposed to determine carbaryl residues in Andrographis paniculata herbal medicines. The method was based on the reaction of 1-naphthol (hydrolysis of carbaryl) with 4-aminoantipyrine (4-AP) in the presence of hydrogen peroxide, using peroxidase enzyme simple extracts from cassia bark as biocatalysts under pH 6.0. The red product, after preconcentration by DLLME using dichloromethane as extraction solvent, was measured for blue intensity by daily life smartphone-based digital image analysis. Under optimized conditions, good linearity of the calibration graph was found at 0.10-0.50 mg·L-1 (r2 = 0.9932). Limits of detection (LOD) (3SD/slope) and quantification (LOQ) (10SD/slope) were 0.03 and 0.09 mg·L-1, respectively, with a precision of less than 5%. Accuracy of the proposed method as percentage recovery gave satisfactory results. The proposed method was successfully applied to analyze carbaryl in Andrographis paniculata herbal medicines. Results agreed well with values obtained from the HPLC-UV method at 95% confidence level. This was simple, convenient, reliable, cost-effective and traceable as an alternative method for the determination of carbaryl.

Employing natural reagents from turmeric and lime for acetic acid determination in vinegar sample.

A simple, rapid and environmentally friendly sequential injection analysis system employing natural extract reagents was developed for the determination of acetic acid following an acid-base reaction in the presence of an indicator. Powdered lime and turmeric were utilized as the natural base and indicator, respectively. Mixing lime and turmeric produced an orange to reddish-brown color solution which absorbed the maximum wavelength at 455 nm, with absorbance decreasing with increasing acetic acid concentration. Influential parameters including lime and turmeric concentrations, reagent and sample aspirated volumes, mixing coil length and dispensing flow rate were investigated and optimized. A standard calibration graph was plotted for 0-5.0 mmol/L acetic acid with r2 = 0.9925. Relative standard deviations (RSD) at 2.0 and 4.0 mmol/L acetic acid were less than 3% (n = 7), with limit of detection (LOD) and limit of quantification (LOQ) at 0.12 and 0.24 mmol/L, respectively. The method was successfully applied to assay acetic acid concentration in cooking vinegar samples. Results achieved were not significantly different from those obtained following a batchwise standard AOAC titration method.

A green analytical method for benzoyl peroxide determination by a sequential injection spectrophotometry using natural reagent extracts from pumpkin.

A green and environmental friendly method with simple sequential injection spectrophotometry using natural reagent extract from pumpkin (Cucurbita moschata Decne) for determination of benzoyl peroxide (BPO) was developed. The maximum absorption of the yellow crude extract containing the ß-carotene compound occurred at a wavelength of 450nm. The yellow extract solution was bleached by BPO to change the color to a colorless solution. The optimum conditions of the proposed method, such as extraction solvent influence of pH, dilution of pumpkin extracts solution, aspiration volume of reagent and sample, flow reversal, incubation time, mixing coil length, and dispensing flow rate were studied and optimized. The linear calibration graph under the optimum conditions in the range of 9.4-100mgL-1 BPO was obtained with good linearity (r2=9985). The limit of detection (LOD) and the limit of quantification (LOQ) were 3.9 and 9.4mgL-1, respectively. Relative standard deviation was achieved at less than 4% (n=7). This system provided sample throughput of 9h-1. Good recoveries were found between 83.42±3.34-112.29±3.49%. The system was successfully employed as a natural reagent extract from pumpkin for determination of BPO in acne treatment samples. Also, the results agreed well with those obtained from the HPLC-UV method.

A rapid and sensitive spectrophotometric method for the determination of benzoyl peroxide in wheat flour samples.

A simple, rapid, and sensitive spectrophotometric method for the determination of benzoyl peroxide (BPO) in wheat flour samples was developed. The detection principle is based on BPO reacted with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) to obtain a blue-green colored product that was detected at 415 nm by spectrophotometry. The effect of factors influencing the color reaction was investigated. Under the selected conditions, the linear range for quantification of BPO was observed between 0.2-1.0 mg L-1 with r2 = 0.998. The limit of detection (LOD) was 0.025 mg L-1. The developed method obtained superior precision (relative standard deviation < 2%) using 11 repeatability at 0.2 mg L-1, 0.6 mg L-1, and 0.8 mg L-1. The proposed methodology was successfully applied to determine BPO in wheat flour samples.

Microfluidic device for the selective chemical stimulation of neurons and characterization of peptide release with mass spectrometry.

Neuropeptides are synthesized in and released from neurons and are involved in a wide range of physiological processes, including temperature homeostasis, learning, memory, and disease. When working with sparse neuronal networks, the ability to collect and characterize small sample volumes is important as neurons often release only a small proportion of their mass-limited content. Microfluidic systems are well suited for the study of neuropeptides. They offer the ability to control and manipulate the extracellular environment and small sample volumes, thereby reducing the dilution of peptides following release. We present an approach for the culture and stimulation of a neuronal network within a microfluidic device, subsequent collection of the released peptides, and their detection via mass spectrometry. The system employs microvalve-controlled stimulation channels to selectively stimulate a low-density neuronal culture, allowing us to determine the temporal onset of peptide release. Released peptides from the well-characterized, peptidergic bag cell neurons of Aplysia californica were collected and their temporal pattern of release was characterized with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. We show a robust difference in the timing of release for chemical solutions containing elevated K(+) (7 ± 3 min), when compared to insulin (19 ± 7 min) (p < 0.000 01).

A simple microfluidic integrated with an optical sensor for micro flow injection colorimetric determination of glutathione.

A simple and inexpensive method for fabricating a microfluidic platform was developed. A printed circuit board (PCB) was used to make a master mold for replicating a polydimethylsiloxane (PDMS) microchannel. The master mold was fabricated by a simple photolithographic method, employing a photoresist dry film. The process did not use hazardous chemicals, a clean room or any expensive instrument. The PDMS microchannel was clamped with polymethylmethacrylate (PMMA) plates, where a light emitting diode (LED) as a light source and a light dependent resistor (LDR) as a light sensor were attached to form a simple optical sensor. The system was successfully employed as a micro flow injection analysis for the determination of glutathione in dietary supplement samples. A linear calibration graph in the range of 5.0 - 60.0 mg L(-1) glutathione was obtained with a detection limit of 0.01 mg L(-1). The system provided a sample throughput of 48 h(-1), with microliter consumption of the reagent.