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Chemistry and Chemical Engineering

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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

Abstract

Residues of the fungicides difenoconazole, propiconazole, cyflufenamid, and mandipropamid were determined in tomato fruit using acetonitrile for extraction and LC-MS/MS for quantification. Validation criteria include linearity range, the limit of detection (LOD) and limit of quantitation (LOQ), accuracy in terms of precision and trueness, and matrix effect were studied. The recovery rates of the method ranged from 91.8 to 106.3%. The precision of the method in terms of repeatability at one day (RSDr) and between three days (RSDR) ranged from 2.8 to 6.4% and from 4.3 to 7.6%, respectively, with good trueness from 92.2 to 96.4%. Matrix effects (suppression effects) ranged from 3.8% to 11.1%. The validated method was used to evaluate the dissipation kinetics of three different premix formulations: 30% EC (15% difenoconazole + 15% propiconazole), 14% DC (12.5% difenoconazole + 1.5% cyflufenamid), and 50% SC (25% difenoconazole + 25% mandipropamid) used on field tomatoes in Egypt. A first-order kinetic equation best describes residue dissipation. The calculated half-lives of difenoconazole, propiconazole, cyflufenamid, and mandipropamid were 2.01–2.27, 1.89, 1.97, and 1.71 days, respectively. The dissipation rate of difenoconazole did not differ significantly in the three premix formulations. Mandipropamid also dissipated faster compared to the other fungicides tested. The chronic dietary risk assessment results showed a minimal risk to adult Egyptian consumers. Waiting periods were advised for the safe consumption of tomatoes treated with the tested premix formulations.

Open access

Az azbesztszálak kimutatására szolgáló vizsgálatok középpontjában a levegőszennyezettségi értékek álltak, de a 21. században felmerült az igény a problémakör kiterjesztésére. Az elmúlt években megjelent nemzetközi tudományos szakirodalmak megcáfolták az évtizedeken át fennálló feltételezést, miszerint az azbeszt csupán a levegőterheltség révén vált ki kockázatot. Vízminőségi és talajminőségi kutatások által teret nyert az azbesztszálak, különösen a krizotilszálak alternatív transzportútjainak vizsgálatát célzó kutatásterület. Annak ellenére, hogy mind a települési, mind pedig a mezőgazdasági vízgazdálkodás potenciálisan érintett a krizotil-azbeszt jelenléte kapcsán, nincs nemzetközi szinten egységes és elfogadott módszer vagy küszöbérték az egyes vízforrások biztonságára vonatkozóan. A kutatások nyilvánvaló korlátja, hogy csekély mennyiségű és minőségű tudás érhető el. Az azbesztszálak megjelenése az egyes vízbázisokban jelentősen megváltoztatja mind a mezőgazdasági, mind a települési vízgazdálkodás környezeti hatásoknak való kitettségéről alkotott eddigi ismereteinket. Az öntözővizzel és a gyűjtött csapadékkal kijuttatott azbesztszálak hatásainak palettája mára túlhaladta a humán- és állategészségügyi hatásokat, immár figyelmet kell fordítani a vegetációs hatásokra is. Annak érdekében, hogy nagyobb betekintést nyerjünk az azbeszttoxicitás növényekre gyakorolt hatásaiba, sokkal több tudományos eredményre van szükség.

Jelen összefoglaló tanulmányban bemutatjuk az azbeszt, különös tekintettel a krizotil azbeszt legfontosabb tulajdonságait, humán-, állat- és növényegészségügyi kockázatait. Rávilágítunk arra, hogy ismereteink rendkívül hiányosak, valamint felhívjuk a figyelmet a települési és mezőgazdasági vízgazdálkodás érintettségének egyes faktoraira, közvetlen és közvetett kockázati tényezőire, valamint arra, hogy ezek miként hatnak az élőlényekre, kiemelt tekintettel a növényekre.

Open access