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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
Abstract
Due to the relative independence from the operational parameters, the linear retention indices (LRIs) are useful tool in gas chromatography-mass spectrometry (GC-MS) qualitative analysis. The aim of the current study was to develop a multiple linear regression (MLR) model for the prediction of LRIs as a function of selected molecular descriptors. Liquid injection GC-MS was used for the analysis of Essential oils (Rose, Lavender and Peppermint) separating the ingredients by a semi-standard non-polar stationary phase. As a result, a sum of 103 compounds were identified and their experimental LRIs were derived relying on reference measurements of a standard mixture of n-alkanes (from C8 to C20). As a next step, a set of molecular descriptors was generated for the distinguished chemical structures. Further, a stepwise MLR was applied for the selection of the significant descriptors (variables) which can be used to predict the LRIs. From an exploit set of over 2000 molecular descriptors, it was found that only 16 can be regarded as significant and independent variables. At this point split validation was applied: the identified compounds were randomly divided into training (85%) and validation (15%) sets. The training set (87 compounds) was used to derive two MLR models by applying i) the ‘enter’ algorithm (R 2 = 0.9960, RMSЕ = 17) and ii) the ‘stepwise’ one (R 2 = 0.9958, RMSЕ = 17). The predictive power was assessed by the validation set (16 compounds) as follows i) q2 F1 = 0.9896, RMSE = 25 and ii) q2 F1 = 0.9886, RMSE = 26, respectively. The adequateness of both regression approaches was further evaluated. Newly developed headspace-solid phase microextraction (HS-SPME) procedures in combination with GC-MS were used for an alternative analysis of the studied Essential oils. Twelve additional compounds, not previously detected by the liquid sample introduction mode of analysis, were identified for which the values of the significant descriptors were within the working range of the developed MLRs. For the last compounds, the LRIs were calculated and the experimental data was used as an external set for assessment of the regression models. The predictive power for both regression approaches was assessed as follows: Enter RMSE = 41, q2 F2 = 0.9503 and Stepwise RMSE = 40, q2 F2 = 0.9521.
Abstract
Monitoring benzoylphenylureas (BPUs) residues in ready-to-eat vegetables is of great interest for an adequate assessment of human pesticide exposure. A rapid, inexpensive, simple, and effective method for determining 8 BPUs insecticides in tomatoes and cucumbers was developed and validated. Vortex-assisted liquid-liquid extraction (VA-LLE) followed by dispersive solid-phase extraction (d-SPE) using graphitized carbon black (GCB) for cleanup was used before LC-MS/MS analysis. Different parameters were optimized, including the type and volume of extractants, vortex time, and the type and amount of adsorbents used for cleanup. The evaluation showed that the method has excellent linearity (R 2 ≥ 0.994). The recovered 8 BPUs insecticides from spiked tomato and cucumber samples at 0.01, 0.05, and 0.25 mg kg−1 ranged from 83.2 to 105.2%, with RSD of 4.9–14.6%. The limits of quantitation (LOQs) were 0.0025 mg kg−1 (0.005 mg kg−1 for lufenuron). Within-day repeatability ranged from 3.9 to 13.9%, while between-day repeatability ranged from 8.9% to 17.7%. The optimized method was used to analyze 100 samples of tomatoes and cucumbers marketed in Saudi Arabia.
Abstract
In this study, a multivariate optimization strategy was used to develop and validate a simple, rapid, accurate, cost-effective, and stability-indicative RP-HPLC analytical method for quantifying hydroxychloroquine sulphate (HCQ) in coated tablets. The validation conditions involved isocratic elution mode, using a mixture of buffer solution at pH 2.2 and methanol (74:26, v/v) as the mobile phase, an Agilent® reverse phase column, model Zorbax Eclipse Plus C18 (250 cm × 4.6 mm × 5 μm), a flow rate of 1.3 mL min−1, column temperature 40 °C and detection at 343 nm. The method showed linearity in the range of 4–44 μg mL−1, with a correlation coefficient (R) of 0.9998. Recovery obtained average values of between 99.71 and 100.84% and precision with average RSD values of <2%. The robustness demonstrated by assessing the effect of seven variables (pH of the mobile phase buffer; percentage of methanol; filter brand; mobile phase flow rate; wavelength; column temperature and sample agitation time), with effect values for each variable lower than the calculated value of s√2 (1.43), showed that none of these factors had a significant influence on the analytical response. The method was applied to samples of the reference medicine Plaquinol® 400 mg and similar Reuquinol 400 mg, nomenclature established by the National Health Surveillance Agency (Anvisa), law no. 978 of 10 February 1999, purchased from local pharmacies. Results showed advantages and benefits in relation to the official method and those reported in the literature. The application of the multivariate strategy, the choice of methanol, in a lower proportion in the organic phase, due to its low toxicity, economy and easier availability compared to acetonitrile, and the other organic solvents used was a promising and important alternative for the analytical method. Furthermore, the use of reversed stationary phase, common in quality control laboratories, provided an analyte retention time of 4.595 min, demonstrating good performance and speed in routine analyses.
Abstract
An ion chromatographic method and its application have been described to quantify nine cationic components (lithium, sodium, ammonium, methylammonium, potassium, magnesium, calcium, strontium, and barium) in pyrotechnics (firecracker and firework) samples. The samples in this study were purchased from local shops in Ternate City, North Maluku. The method performed a mixed eluent with 4 mM HNO3 and 0.015 mM Na2EDTA, combined with a Metrosep C4-150/4.0 separation column for all quantifications. Excellent chromatograms were achieved, and the nine cationic components were eluted in less than 18 min. The calibration graphs of the quantifications were linear in the range of 1.25–37.5 mg L−1. The detection limit (LOD) at S/N = 3 was below 0.098 ppm (mg L−1). This method was applied to the pre-blast and post-blast residues of pyrotechnics samples, and the simultaneous quantification of the nine cationic components in these samples was achieved with satisfactory results.
A talajspektrális könyvtárak nemzetközi jelentősége és hazai megalapozása
The international importance and national establishment of soil spectral libraries
Napjainkban soha nem látott igény mutatkozik megfelelő mennyiségű és minőségű talajadatra és információra. Spektroszkópiai technológiák a hagyományos laboratóriumi módszerekkel együttesen, párhuzamosan alkalmazva lehetőséget kínálnak a talajfelvételezés idő- és költséghatékonyabbá, valamint környezetkímélőbbé tételére. Jelen munkában lokális, regionális és globális léptékű talajspektrális könyvtárak bemutatása mellett az első országos szintű, az Agrártechnológiai Nemzeti Laboratórium projekt keretében kidolgozásra kerülő, Magyarország talajtani változatosságát reprezentáló spektrális adatbázis létrehozásának koncepcióját mutatjuk be. A spektrális könyvtárak olyan speciális talajadatbázisoknak tekinthetőek, melyek tartalmazzák egy adott terület talajait reprezentáló talajminták hagyományos laboratóriumi módszerrel meghatározott paramétereit, valamint spektroszkópiai módszerrel rögzített spektrumait. A spektrális könyvtárakban tárolt adatok alapján elvégzett, spektroszkópiai kalibrációkra alapozott talajparaméter becslési eljárások lehetőséget kínálnak az adatbázisban szereplő talajminták fizikai-kémiai-ásványtani tulajdonságaihoz hasonló minták paramétereinek spektrális alapú megbízható megbecsléséhez. A hazai spektrális könyvtár alappillérét a Talajvédelmi Információs és Monitoring (TIM) rendszer mintavételezés kezdeti évében (1992-ben) gyűjtött, talajok genetikai szintjeiből vett talajmintákról felvett spektrumokra építjük. A spektrális adatbázist a középső-infravörös (middle-infrared, MIR), valamint a látható- és közeli infravörös (visible and near-infrared, VIS-NIR) tartományban, a Global Soil Laboratory Network (GLOSOLAN) iránymutatásai alapján rögzített spektrális adatokra építjük. A folyamatosan bővülő spektrális könyvtár, és az erre az adatbázisra épülő talajtulajdonság-becslő eljárás lehetőséget fog kínálni számos fizikai és kémiai paraméterének megbízható meghatározására, ezzel (számottevő többletköltség nélkül) nyújt lehetőséget a jelenlegi laboratóriumi kapacitás növelésére.
Abstract
An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of nobiletin and tangeretin in rat plasma, and the plasma was processed by a simple liquid-liquid extraction method with ethyl acetate. The chromatographic column was UPLC HSS T3 (50 × 2.1 mm, 1.7 μm), the mobile phase was acetonitrile-water (containing 0.1% formic acid). Multiple reaction monitoring mode (MRM) was used for quantitative analysis, nobiletin m/z 403.29 → 373.14 (cone voltage 22v, collision voltage 28v), tangeretin m/z 373.28 → 343.17 (cone voltage 20v, collision voltage 28V), tangeretin m/z 373.28 → 343.17 (cone voltage 20V, collision voltage 28V) and internal standard vitexin m/z 433.14 → 313.03 (cone voltage 32v, collision voltage 26v). The pharmacokinetics of nobiletin and tangeretin were evaluated in rats. The established UPLC-MS/MS method in the range of 2–2,000 ng mL−1 was successfully applied to the pharmacokinetics, and the calculated bioavailability of nobiletin and tangeretin was 63.9 and 46.1%, respectively.
Abstract
Based on chromatographic fingerprinting combined with quantitative analysis on characteristic chemical constituents as well as hierarchical cluster analysis, an easy and sensitive approach utilizing high performance liquid chromatography (HPLC) was developed for the identification and quality evaluation of Rutongshu oral liquid (ROL). What is more, nontargeted metabolomic analysis was conducted to gain a global view in terms of its chemical profile. In this study, 16 peaks from different batches (S1–S10) of ROL samples produced by Taihe Hospital of Chinese Medicine were selected as common peaks for the evaluation of their similarity whose values of all tested 10 batches exceeded 0.90 when compared with the control fingerprints. Meanwhile, simultaneous quantification of five markers in the oral solution, including albiflorin, paeoniflorin, chlorogenic acid, quercetin and ferulic acid was performed, and standard curves established for respective reference substances showed good regression in the linear range (r 2 > 0.999) with recoveries in the range of 98.96–102.35%. The ultra-high performance liquid chromatography (UHPLC) combined with Orbitrap Exploris 120 mass spectrometer resulted in 88 identified compounds. The results of validation showed that the established method was reproducible, precise and stable. This study offers an effective, dependable and useful approach for the systematic evaluation of the hospital formulation ROL.
Abstract
Hydrochlorothiazide has been utilized clinically for the past half-century, which is popularly known as a “water pill” as it produces increased urine output. The advancement of bioanalytical methods brought a dynamic field with exciting opportunities for future research. The current review emphasis the bioanalytical methods employed for the quantitative estimation of Hydrochlorothiazide as monotherapy and its popularly used combinational medications available from 1956 to till date. A fixed dose of 25 mg of hydrochlorothiazide with 43 combinational medications is currently available in the market and these combinations are widely employed in the treatment of hypertensive people; those whose blood pressure does not respond effectively to monotherapy of hydrochlorothiazide and also for the treatment of edema (excess fluid in the body) caused by illness such as heart failure, liver problems, and renal disease. It has been convincingly demonstrated that the combination of any two antihypertensive medications belonging to different groups of the same category, significantly lowers blood pressure, in comparison with the effect produced by increasing the dose of a single medicament. Among the various analytical techniques employed for the estimation of Hydrochlorothiazide, the review portrays that hyphenated technique, in specific liquid chromatography coupled with mass spectroscopy was widely employed. The validation parameters namely linearity, LOD, LOQ for individual drug and their combinations, were successfully calibrated. The effectiveness of analytical approaches was evaluated and enhanced for chemical factors. The involvement of green chemistry in the optimized methods for the evaluation of Hydrochlorothiazide for the future development, are suggested.
Abstract
This review focuses on monosodium glutamate which proclaims the fifth taste as “Umami”. Monosodium glutamate imparts a deep, meaty, umami flavour to foods. Asian cuisine frequently uses this flavouring, just as in the processed items produced across the United States and Europe. This article dealt with a detailed discussion of physicochemical features, pharmacological actions, and different reported analytical methodologies for the estimation of monosodium glutamate. Monosodium glutamate is analyzed using a variety of techniques, including spectroscopy, chromatography, electrochemistry, electrophoresis, chemometrics, flow injection analysis, and biosensors. According to results of comparative research of analytical methodologies, high performance liquid chromatography (HPLC) is most widely used method for analyzing monosodium glutamate which surpasses the gas chromatographic (GC) approach. All of the reported methods are accurate, precise, cost-effective, and sensitive. The European Union defined monosodium glutamate as a food additive that is permitted in some foods, but is subject to quantitative limits. Consequently, this study provides the analyst with an accessible path to quantifying monosodium glutamate's content for use in the food and pharmaceutical industries.
Abstract
A straightforward, dependable, and quick RP-LC method for the analysis of abiraterone acetate in its dose form and human urine has been devised. With DAD detection, sensitivity was reported to be high. The LOD and LOQ of the procedure were deemed adequate. The suggested approach was exhaustively validated in accordance with ICH requirements, and the findings demonstrated that it was exact, accurate, selective, and sensitive for the analysis of this pharmaceutical. The chromatographic separation was realized using a X-Terra RP-18 (150 × 4.60 mm i.d. × 5 μm) column and a UV detector set at 255 and 267 nm. In addition, pK a values were calculated based on the relationship between the retention factor and the pH of the mobile phase. The influence of the composition of the mobile phase on the ionization constant was investigated by measuring the pK a at various acetonitrile–water combinations ranging from 50 to 70% (v/v).
