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Chemical engineering is an engineering branch that deals with the chemical production and manufacture of products that undergo chemical processes. This includes equipment design, creating systems and processes to refine raw material, as well as mixing, compounding, and processing chemicals to create products.

Chemistry and Chemical Engineering

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Abstract

In this study, we compile the findings to date on using several cellulose-based materials as adsorbents of potentially toxic elements (PTEs) from wastewater. Furthermore, this review discussed the destiny of PTEs-loaded cellulose-based adsorbents and some sustainable methods for their management, hoping to close the pollution loop.

Open access

Abstract

Mirtazapine is an antidepressant medication used to treat the major depressive disorder in adults. In this study, two different chromatographic methods were developed for the determination of mirtazapine in pharmaceutical products. In the first method, An Extend C18 column (250 × 4.6 mm, 5 μm) was used and the temperature was kept constant at 25 °C. The mobile phase was determined as 0.1% formic acid solution and acetonitrile (80/20, v/v), and isocratic elution was applied. The flow rate of the mobile phase was determined as 1.0 mL min−1 and the injection volume was 20 µL. Detection was performed at 291 nm. using a UV detector. In the second method, ethanol was used as the organic modifier. The only difference between these methods was the organic modifier. All other conditions of the methods were the same. Both chromatographic methods were validated by ICH guidelines for various parameters such as selectivity, linearity, accuracy, precision, detection and quantification limit, and robustness. The determination coefficients of chromatographic methods were greater than 0.999 in the concentration range of 5–30 µg mL−1. of mirtazapine. Later, these chromatographic methods were applied to pharmaceutical formulations. Comparison of the obtained results in terms of means was made using Student's (t) test, and comparisons in terms of standard deviations were made using the Fischer (F) test. It was observed that there was no significant difference between these methods. These two methods were then evaluated using the AGREE-Analytical GREEnness metric software. The chromatographic method using ethanol as an organic modifier has been proposed as an excellent eco-friendly and analyst-friendly alternative for the determination of mirtazapine in pharmaceutical formulations.

Open access

Abstract

It still remains a great challenge to selectively enrich and sensitively quantify the trace volatile organic compounds (VOCs) in real samples with complex matrix. In this study, an integration method combining a selective enrichment medium of reduced graphene oxide (rGO) with a specially designed micro thermal-assisted purge-and-trap sampling device was developed for efficient enrichment and sensitive quantification of trace tobacco VOCs coupling with thermal desorption (TD)-gas chromatography/mass spectrometry (GC/MS). The prepared rGO has been proved to possess excellent enrichment selectivity and capacity for tobacco polar VOCs with the multi-layer structure, good thermal stability and large specific surface area. The specially designed sampling device was efficient and suitable for enriching and sampling trace polar tobacco VOCs coupling with rGO medium. Under the optimized sampling and analytical conditions, the established analytical method could be actually applied for quantification of typical tobacco polar VOCs with the good recoveries of 72.9–128% and the satisfied RSDs of 1.8–19.9% (n = 3). The results suggested that the developed method was selective, sensitive and reliable for enrichment and quantification of trace tobacco polar VOCs.

Open access

Abstract

A highly accurate and precise method for the simultaneous detection of 18 neonicotinoids and their metabolites in meat was developed using liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). To improve the pretreatment step of the method, five different commercially available clean-up materials (including C18+PSA (primary secondary amine), Z-Sep (with Discover DSC-C18), EMR-Lipid, SHIMSEN QuEChERS, and Clean-up LPAS) were studied in the treatment of three meat matrices: pork, duck and yellow croaker. Based on the recovery data, we found that among the five purification materials, SHIMSEN QuEChERS was slightly more effective than the others for 18 neonicotinoids. Therefore, SHIMSEN QuEChERS was used as the purification sorbent, and the extraction solvents, extraction methods and chromatographic and mass spectrometric conditions were optimized. A matrix-matched calibration method was applied for quantification. In three different meat matrixes (pork, duck, and yellow croaker), all the target compounds showed good linearity, both with values of r 2 > 0.995. The average recovery of all neonicotinoids ranges from 63.4 to 114.2% (pork), 63.0–113.2% (duck), and 63.9–110.5% (yellow croaker). Relative standard deviations were all <15% for intraday and interday precision. The values of limit of detection (LOD) and limit of quantification (LOQ) were, respectively, ranging from 0.04 to 1.0 μg kg−1 and 0.10 to 2.0 μg kg−1. Compared with previous reports, this method has advantage in LOQs, indicating that it it may be a preferred choice for the detection of neonicotinoid pesticides in meat samples.

Open access

Abstract

In our study, using a combination of eye-tracking parameter analysis and the van Westendorp method, we investigate whether participants pay more attention to products that they perceive as more expensive or to those that they prefer in the ranking process. The experiment involved 50 participants, a questionnaire with ranking and pricing tasks, and an eye-tracking measurement. Three wine varieties (Irsai Olivér, Rosé and Merlot-Shiraz) and three different label alternatives were tested. When comparing the results of the ranking and the pricing tasks, the product that is considered more expensive is not always the one that is most appealing to the participants. If we compare the results from the analysis of the eye-tracking parameters and the pricing, we can say that in all cases the labels that received the most visual attention were those that were priced more expensively by the participants.

Open access

Abstract

An ultra-rapid analytical method for determination of andrographolide and dehydroandrographolide in Andrographis Herba (AH) was developed by liquid chromatography with mass spectrometry (LC-MS). The sample was ultrasonically extracted with 10 mL 40% (v/v) methanol, and then purified with a C18 solid phase extraction column. The LC separation was performed on a Poroshell 120 EC-C18 column (30 × 2.1 mm, 2.7 μm) and eluted with 0.5 mmol L−1 ammonium acetate aqueous solution and acetonitrile (65:35) at a flow rate of 0.7 mL min−1, and detected by mass spectrometry (MS). The LC-MS analytical time was less than 1 min. The new developed method presented a good linearity (r > 0.9900), precision and repeatability (RSD < 2.0%). The recoveries for andrographolide and dehydroandrographolide were 93.5% (RSD = 2.2%) and 97.7% (RSD = 2.4%), respectively. The developed method was successfully applied in determination of andrographolide and dehydroandrographolide in seven batches of AH samples, and the contents of analytes in all samples were complied with the relative acceptance criteria in Chinese Pharmacopeia (>0.8%). This new developed LC-MS method is an ultra-rapid assay method for AH, which will help to improve the efficiency and reduce the cost of AH sample test.

Open access

Abstract

A simple, sensitive, selective, accurate and precise method was developed and fully validated for determination of oxcarbazepine (OXC) in presence of their preservatives and determination of oxcarbazepine (OXC) in human plasma. A reversed phase liquid chromatography (RP-HPLC) with UV detection techniques were applied for separation and quantification of studied drug OXC. Successful separation of the drug from methyl paraben (M.P.), propyl paraben (P.P.) and potassium sorbate (P.ST.) was achieved on a Kromasil C18 column (5 μm particle size, pore size 300 Å, l × I.D. 250 × 4.6 mm). The mobile phase that contain aqueous 0.05M potassium dihydrogen phosphate buffer (pH 7): acetonitrile, (50: 50, %v/v). The method was linear over concentration ranges 5.0–50 μg mL−1 for OXC. Bioanalytical validation of the developed method was carried out according to US-FDA guidelines and revealed a good linear relations over a range of (5.0–50), (0.5–10), (0.05–0.15), and (1.0–10) μg mL−1 for OXC, M.P, P.P, and P.ST, respectively, with a correlation coefficient (R2) of more than 0.999. Limit of detection (LOD) were 1.15, 0.03, 0.01 and 0.04 μg mL−1 for OXC, M.P, P.P, and P.ST, respectively, Intra and inter-day precisions, calculated as percentage relative standard deviation (% RSD), were lower than 2.0%. The developed method can be applied for routine drug analysis, therapeutic drug monitoring and bioequivalence studies through the analysis of plasma samples taken from blood bank.

Open access
Acta Chromatographica
Authors:
Nabil N. Al-Hashimi
,
Rand O. Shahin
,
Amjad H. El-Sheikh
,
Malak J. Jibreel
,
Nada A. Alsakhen
,
Abdelrahim M. Alqudah
,
Muna K. Oqal
, and
Jafar I. Abdelghani

Abstract

The concentration level of urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG), an oxidative stress biomarker for various diseases especially cancer, has been attracted as a pathway suitable for diagnostic purposes. Determination of urinary 8-OHdG is challenging due to its low level within a complex matrix. In this study, a new approach of solid/liquid phase microextraction technique prior to high-performance liquid chromatography diode-array detection (HPLC-DAD) analysis was developed for the determination of trace levels of 8-OHdG in urine samples. The solid/liquid phase microextraction device was constructed by reinforcement of multi-walled carbon nanotubes into the pores of a short segment 2.5 cm of hollow fiber microtube with two ends heat sealed. Based on the optimized procedure, the selected analyte was extracted from an acidic sample solution (10 mL adjusted at pH = 5) into the five extraction devices. After the extraction period (30 min), the 8-OHdG was eluted from the extraction device using methanol (350 µL) under ultrasonication for 5 min. The analytical performance of the method in synthetic urine samples showed good linearity (R 2 > 0.999) with the limits of detection of 0.85 ng mL−1, and extraction recovery > 92.36%. The developed microextraction technique exhibited a confident sensitivity, feasible operation, and simplicity in comparison with other published methods and was valid to determinate trace 8-OHdG in urine cancer patients' samples by using a cheap and commonly available HPLC-DAD instrument.

Open access