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1

Modelling and simulation studies on the characteristic behaviour of macroalgae derived bio-oil

Thirumalaikumar Ramaiah, Jaikumar Vasudevan

Ecological Chemistry and Engineering. S

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2024

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Vol. 31, nr 1

19--30

EN

With the expanding need for renewable and sustainable energy resources, the demand for biomass derived bio-oil particularly microalgae or macroalgae based bio-oil is growing. In this regard, understanding the characteristics of bio-oil as a function of several influencing operational parameters is essential. In this study modelling and simulation technique based on Aspen HYSYS was applied to investigate the characteristics of macroalgae Ulva prolifera derived bio-oil from Hydrothermal Liquefaction (HTL) process as a function of the influencing parameters like temperature, kinematic viscosity, and weight percent of the bio-oil assay, cut yield behaviour, and standard liquid density. Modelling and simulation help to optimise the process parameters and design the process layout for large-scale production. According to the simulation results the cut yield of off gases, light naphtha, heavy naphtha, light distillate, heavy distillate, gas oil and residues are shown at specific final boiling point (FBP) temperatures of 70 °C, 70 °C - 110 °C, 110 °C - 221.1 °C, 221.1 °C - 304.4 °C, 304.4 °C - 371.1 °C, 371.1 °C - 537.8 °C and 537.7 °C respectively. Whereas, above a temperature of 300 °C, the weight percentage of aromatic components increased steadily. The increase in percentage composition of the aromatic components is due to the reduction of the paraffinic components. The density of the liquid bio-oil was steadily increasing until a temperature of 200 °C.

2

Grupa Wyszehradzka urzędów probierczych. Urząd Probierczy w Budapeszcie

Ulaczyk Maria Magdalena

Metrologia i Probiernictwo : biuletyn Głównego Urzędu Miar

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2021

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nr 2 (27)

49--58

PL

Artykuł informuje o współpracy urzędów probierczych, prowadzonej w ramach Grupy Wyszehradzkiej oraz przedstawia, wizytowany niedawno przez pracowników OUP w Warszawie, Urząd Probierczy w Budapeszcie. W artykule wskazano jego specyfikę i odrębności w odniesieniu do polskich urzędów probierczych.

EN

The article informs about the cooperation between assay offices carried out within the Visegrad Group and presents the recently visited by employees of Warsaw Assay Office, Assay Office in Budapest. The article shows its specific and distinctiveness, in comparison to polish assay offices.

3

Validation of the assay and purity determination of the FOX-7 (1,1-diamino-2,2-dinitroethylene) using HPLC method

Kamieńska-Duda A., Kasprzak P.

Problemy Techniki Uzbrojenia

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2014

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R. 43, z. 130

79--87

EN

1,1-diamino-2,2 dinitroethylen (DADNE, FOX-7) is a novel explosive with low sensivity. The valuable properties is a result of specific chemical construction, in which inter- and intramolecular hydrogen bonds stabilize the structure. From the reason of low sensivity, FOX-7 has a very broad spectrum of use for elaborating many kinds of munnition. Hence a very important aspect is to conduct the research of this substance to determine chemical purity, assay content of water etc. The HPLC method is the one of the analytical technique which has a very high precision of determination of the purity and assay of the substance. The aim of this work was to compile a new method of the assay and purity determination of FOX-7. The C18-Xbridge column and the mobile phase: Acetonitryle: Water: Triethylamine were used. Through application of the C18- XBridge column and mobile phase the substrate MPD and main substance FOX-7 had very good resolution and the analysis time was relatively short. The validation of the new method has been performed: selectivity, specificity, linearity, precision, assay and limits of detection and quantitation. We have also checked the stress tests of the FOX-7 in acidic, basic and oxidative conditions.

PL

1,1-diamino-2,2 dinitroetylen (DADNE, FOX-7) jest nowoczesną małowrażliwą substancją wybuchową. Jej cenne właściwości są rezultatem specyficznej budowy chemicznej, w której wewnątrz i zewnątrz cząsteczkowe wiązania wodorowe stabilizują strukturę, powodując jej małą wrażliwość na bodźce. Dzięki takim właściwościom, FOX-7 może być zastosowany do elaboracji wielu rodzajów małowrażliwej amunicji. Dlatego tak ważnym aspektem jest prowadzenie badań chemicznych uwzględniających czystość i zawartość chemiczną tej substancji. Metoda HPLC jest nowoczesną techniką, szeroko stosowaną do określenia tych parametrów z dużą dokładnością i precyzją. Celem naszej pracy było zwalidowanie nowej metody oznaczania czystości i zawartości FOX-7. Do oznaczania tych parametrów użyto kolumny C-18 X-Bridge natomiast jako fazy ruchomej mieszaniny acetonitrylu trietyloaminy: wody zmieszanej w odpowiednim stosunku. Zastosowanie właśnie takiej kolumny oraz fazy z modyfikatorem pozwoliło na podzielenie zanieczyszczenia MPD od substancji głównej w odpowiednio krótkim czasie z dobrą rozdzielczością oraz symetrią pików. Walidacja metody obejmowała: selektywność, specyficzność, precyzję, dokładność oraz limity detekcji oraz oznaczalności. Podczas walidacji zostały również przeprowadzone testy stresowe w warunkach kwaśnych, zasadowych oraz utleniających.

4

High-performance liquid chromatographic determination of montelukast sodium in human plasma: Application to bioequivalence study

Shakya A., Arafat T., Hakooz N. M., Abuawwad A. N., Al-Hroub H., Melhim M.

Acta Chromatographica

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2014

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Vol. 26, no. 3

457--472

EN

A simple, sensitive, and precise high-performance liquid chromatographic (HPLC) method for quantitation of montelukast in human plasma has been developed and validated. Commercially available candesartan cilexetil was used as an internal standard. After protein precipitation, montelukast and candesartan cilexetil (I.S.) in human plasma were analyzed using mobile phase containing 62% v/v acetonitrile and 38% v/v buffer (containing 1 mL L-1 triethylamine as peak modifier, final pH adjusted to 2.5 with orthophosphoric acid). Chromatographic separation was achieved on a BDS Hypersil-C18 column (50 × 4.6 mm i.d., particle size 5 μm; Thermo Electron Corporation, USA) using isocratic elution at a flow rate of 1.5 mL min−1. The signals were monitored using a fluorescence detector set at 350 nm for excitation and 400 nm for emission. The total time for a chromatographic separation was ∼3 min. The validated quantitation ranges of this method were 5–300 ng mL-1 with coefficients of variation between 1.75% and 9.38%. Mean recoveries were 91.8 ± 3.8%. The within- and between-batch precisions were 0.74–2.46% and 1.64–7.87%, respectively. The within- and between-batch relative errors (bias) were 0.14–3.3% and 0.08–4.6%, respectively. Stability of montelukast in plasma was >94.7%, with no evidence of degradation during sample processing and 30 days storage in a deep freezer at −70°C. This validated method is sensitive and simple with between-batch precision of <8% and successfully applied for the bioequivalence studies. The formulations were compared using the following pharmacokinetic parameters: AUC0−t, AUC0−∞, and Cmax. No statistically significant difference (p > 0.05) was observed between the logarithmically transformed AUC0−t, AUC0−∞, and Cmax values.

5

Development and application of stability-indicating HPLC method for the determination of nevirapine and its impurity in combination drug product

Navaneethan G, Karunakaran K., Elango K. P

Acta Chromatographica

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2012

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Vol. 24, no. 4

575--587

EN

A stability-indicating reversed-phase high-performance liquid chromatography method has been developed and validated for the estimation of nevirapine and its impurity, namely the related compound A and the related compound B in combination drug product. The separation was carried out on SUPELCOSIL ABZ (150 mm × 4.6 mm, 5 µm) column. Tablet was admitted to the stress conditions of acid, base, peroxide, thermal, humidity, and photolytic degradation. The degradation products were well resolved from nevirapine, and its impurities peaks and the peak homogeneity of compound were obtained using photo diode array detector, hence proving the stability-indicating nature of the method. Moreover, to prove the selectivity of the method, individual lamivudine, zidovudine, and their main impurities were injected. The developed method was linear for nevirapine from 120 to 360 µg mL-1, and the linear regression obtained was >0.999. Recovery data were in the range 98.2–101.5%. The limit of quantification for related compound A and related compound B was found to be 0.02%. The proposed method was validated according to the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines and proved suitable for stability testing and quality control of these drugs in pharmaceutical preparations.

6

A new TLC densitometric method for stability assessment of modafinil

Faisal M. S., Naz Z., Shakeel F., Ahmed S., Kohli K., Khar R. K.

Chemia Analityczna

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2009

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Vol. 54, No. 1

77-88

EN

TLC densitometric method for simple and sensitive stability assessment of modafinil has -been developed. The objective was to provide a rapid, precise, robust, and reproducible technique for the analysis of modafinil. The method was validated for bulk drug and tablet , formulations. It could be used to separate the drug from its degradation products. The pro- cedure employed TLC aluminum plates precoated with 60F-254 silica gel as the stationary phase. The solvent system consisted of toluene-chloroform-methanol (1:1:0.5, v/v/v) 'o'o mixture. It provided well-resolved compact spots for modafinil (Rr value 0.46 š 0.01) and allowed for separation of the excipients and degradation products. Densitometric scanning interegation was performed at the wavelength of 220 nm. Calibration plot was linear , (r2 = 0.999) in the analyte concentration range 100-5000 ng per spot. The method was validated with respect to linearity, accuracy recovery, precision, ruggedness, and specificity. The limit of detection and quantification were 20.54 ng per spot and 62.26 ng per spot, respectively. The determined drug content was within the š5% range of the labeled content. The drug was analyzed under different stress conditions in order to study its degradation in the presence of acid, base, and peroxide.

PL

Opracowano densytometryczną metodę TLC pozwalającą na proste i czułe badanie stabilności modafinilu. Opracowana technika była szybka, precyzyjna, odporna na warunki zewnętrzne i powtarzalna. Metodę zwalidowano dla substancji farmaceutycznej i tabletek. Można ją stosować do oddzielenia leku od produktów rozkładu. Jako fazę stacjonarną użyto żel krzemionkowy 60F-254 naniesiony na płytki aluminiowe. Fazę ruchomą stanowiła '"' mieszanina: toluen-chlorofbrm-metanol (1:1:0,5; v/v/v). Otrzymywano dobrze rozdzielone, zwarte plamki modafinilu (wartość Rf 0.46 š 0.01), oddzielone od substancji pomocniczych i produktów rozkładu. Skanowanie densytometryczne prowadzono przy długości fali 220 nm. Krzywa kalibracyjna miała charakter liniowy (r2 = 0,999) w zakresie stężeń analitu 100-5000 ng na plamkę. Metodę zwalidowano w zakresie liniowości, dokładności, odzysku, precyzji, odporności na czynniki zewnętrzne i specyficzności. Granica wykrywalności i oznaczalności ilościowej wynosiły odpowiednio 20,54 ng i 62.26 ng na plamkę. Oznaczana zawartość leku mieściła się w granicach š 5% ilości deklarowanej. Lek analizowano w różnych warunkach stresowych w celu zbadania jego degradacji w obecności kwasów, zasad i nadtlenków.

7

Development and validation of a stability-indicating LC-UV method for rapid analysis of buspirone in pharmaceutical dosage forms

Azeem A., Rizwan M., Ahmad F. J., Iqbal Z., Khar R. K., Aqil M, Talegaonkar S.

Acta Chromatographica

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2009

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Vol. 21, no. 2

283--297

EN

An accurate, sensitive, precise, rapid and isocratic reversed-phase HPLC (RPHPLC) method for analysis of buspirone in the bulk drug and in solid dosage formulations has been developed and validated. The best separation was achieved on a 250 mm × 4.6 mm i.d., 5-μm particle, RP C 18 column with 70:30 ( υ/υ ) methanol-0.01 M sodium dihydrogen phosphate buffer (pH 3.5) as mobile phase at a flow rate of 0.8 mL min -1. UV detection was at 244 nm. Response was a linear function of concentration over the range 0.05–20 μg mL -1 ( r = 0.9998) and the limits of detection and quantitation were 3.7 and 11.3 ng mL -1, respectively. The method was validated in accordance with ICH guidelines. The drug was subjected to oxidative, hydrolytic, photolytic, and thermal stress. Degradation products produced as a result of this stress did not interfere with detection of buspirone and the assay can thus be regarded as stability-indicating. The method was used for quantification of buspirone in commercial buspirone tablets and to check content uniformity. The excipients present in the formulation did not interfere with the assay. The method is suitable for application in quality-control laboratories, because it is simple and rapid with good accuracy and precision.

8

Application of HPLC for the determination of racemic fluoxetine and norfluoxetine in human plasma

Misztal G., Skibiński R., Olajossy M., Paw B., Przyborowski L., Hopkała H.

Chemia Analityczna

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2002

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Vol. 47, No. 2

229-240

EN

A selective, simple and accurate HPLC method for the determination of fluoxetine and nor-fluoxetine in blood plasma of patients is presented. The samples were chromatographed on a Nova-Pak Cs column after purification using a LiChrolut RP-I8 column. The mobile phase was methanol-acetonitrile-phosphate buffer of pH 2.65 (0.0657 mol L(-1)-triethyla-mine (10.9 + 32.7 + 56 + 0.4, v/v). Fluvoxamine was applied as an internal standard. The U V detection was carried out at 228 nm. The method was tested for linearity (over the range 20-600 ng mL'1) both for fluoxetine and norfluoxetine. The mean recoveries were 91.13% for fluoxetine and 95.69% for norfluoxetine. The described method has been successfully applied for the determination of these substances in plasma of patients, who received 20 mg fluoxetine daily.

PL

Przedstawiono selektywną, prostą i dokladnąmetodę HPLC oznaczania fluoksetyny i norfluo-ksetyny w osoczu krwi pacjentów. Próbki były oznaczane na kolumnie chromatograficznej Nova-Pak C8 po wyizolowaniu substancji do fazy stałej na kolumnach LiChrolut RP-18. Fazą ruchomą była mieszanina metanol-acetonitryl-bufbr fosforanowy o pH 2.65 (0.0657 mol L(-1)-trietyloamina(10.9 + 32.7 + 56 + 0.4, v/v). Jako standard wewnętrzny zastosowano fiuwoksaminę oraz detekcję w UV przy 228 nm. Liniowość opracowanej metody oceniono w granicach stężeń analizowanych substancj i od 20-600 ng mL(-1). Średni odzysk dla trzech różnych stężeń fluoksetyny w osoczu wynosi 91.13%, zaś dla norfluoksetyny 95.69%. Opracowana metoda może być zastosowana do oznaczenia tych substancj i u chorych, pobierających terapeutyczne dawki fluoksetyny 20 mg dziennie.

9

Metody izolacji i oznaczania lotnych związków organicznych w wodzie

Biziuk M.

Ekologia i Technika

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2001

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R. 9, nr 4

117-127

PL

Artykuł zawiera opis metod oznaczania lotnych związków organicznych w wodach wraz ze schematem wykorzystania różnych technik ich izolacji i oznaczania oraz schematem podziału metod wykorzystujących analizę fazy nadpowierzchniowej. Szerzej omówiono metody: bezpośredniego dozowania próbki wody do kapilarnej kolumny chromatograficznej (DAI-GC-ECD) oraz metody analizy fazy nadpowierzchniowej w warunkach statycznych i dynamicznych. Podano również przykładowe zastosowanie omawianych metod ilustrując je chromatogramami i wynikami oznaczeń.

EN

Methods of volatile organic compounds determination in water have been described. The scheme of various techniques application for their isolation and determination as well as the scheme of the devision of methods applying oversurface phase analysis have been presented. The methods of direct injection of water sample to capillary chromatographic column (DAI-GC-ECD) and methods of oversurface phase analysis under static and dynamic conditions have been described in details. An example of the described methods application has been presented together with chromatograms and results of determinations.