Enhancing Propane Refrigerant Performance at Pre-Cooling Stage During Hot Climate Conditions at LNG Plants – Case Study from Egypt

As a result of the growth of LNG markets, the LNG production capacity of liquefaction trains is increasing continuously. This is true not only for new projects, but also for the debottlenecking of existing trains. When the propane refrigerant is condensed through air coolers, limitation of the variation in atmospheric temperature plays a vital role in the efficiency of the condensing system as it will be affecting the Natural Gas temperature and vaporization rates. That will increase the load on the Propane Compressor and Air Coolers till the condensing rate of the refrigerant is affected. That will result in limiting the ability of the Plant to go for full load when Propane-MR refrigerants are used as the Technology for Natural Gas liquefaction. This study took the challenge in studying a cost effective solution to maintain a high efficiency performance of the condensing system of the Propane Refrigerant in LNG Plant during hot climate conditions, Temperature range of 25ᵒC - 35ᵒC. Two approaches were examined through this study which are: 1. Effect of passing the propane feed from the discharge of the compressor to the recycle cooler before the main propane condenser during hot climate conditions. (Two Stages Condensing System) 2. Effect of changing the propane composition on the performance of the refrigerant. This study is based on SEGAS LNG Plant in Damietta, Egypt where a mixed component refrigerant is pre-cooled by another refrigerant made up of propane. At the end of the study, the following results were obtained: 1. Full condensation of the Propane Refrigerant when utilizing the two stages condensing system over Hot Climate conditions. 2. Pure Propane refrigerant showed the least power consumption and lower Air condensing duty against other compositions tested

Enhancing Propane Refrigerant Performance at Pre-Cooling Stage During Hot Climate Conditions at LNG Plants – Case Study from Egypt

As a result of the growth of LNG markets, the LNG production capacity of liquefaction trains is increasing continuously. This is true not only for new projects, but also for the debottlenecking of existing trains. When the propane refrigerant is condensed through air coolers, limitation of the variation in atmospheric temperature plays a vital role in the efficiency of the condensing system as it will be affecting the Natural Gas temperature and vaporization rates. That will increase the load on the Propane Compressor and Air Coolers till the condensing rate of the refrigerant is affected. That will result in limiting the ability of the Plant to go for full load when Propane-MR refrigerants are used as the Technology for Natural Gas liquefaction. This study took the challenge in studying a cost effective solution to maintain a high efficiency performance of the condensing system of the Propane Refrigerant in LNG Plant during hot climate conditions, Temperature range of 25ᵒC - 35ᵒC. Two approaches were examined through this study which are: 1. Effect of passing the propane feed from the discharge of the compressor to the recycle cooler before the main propane condenser during hot climate conditions. (Two Stages Condensing System) 2. Effect of changing the propane composition on the performance of the refrigerant. This study is based on SEGAS LNG Plant in Damietta, Egypt where a mixed component refrigerant is pre-cooled by another refrigerant made up of propane. At the end of the study, the following results were obtained: 1. Full condensation of the Propane Refrigerant when utilizing the two stages condensing system over Hot Climate conditions. 2. Pure Propane refrigerant showed the least power consumption and lower Air condensing duty against other compositions tested

Kinetic and Conventional Spectrophotometric Determination of Bumadizone in its Tablets via Oxidative Coupling with 3-Methyl-2-Benzothiazolinone Hydrazone

Two simple, sensitive and accurate spectrophotometric methods have been developed for the determination of bumadizone in bulk drug and its tablets. Both methods based on the oxidative coupling reaction with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) and measuring the absorbance of the developed colors by direct or kinetic spectrophotometric method. Upon treatment of a mixture of the chromogenic reagent and drug with cerium (IV) ammonium sulfate (method I) or ferric chloride (method I), a red or violet color was developed immediately or after 30 minutes measurable at 557 nm for method I or II, respectively. The absorbance-concentration plots were rectilinear over the ranges of 1-10 μg/mL (r = 0.9999) for method I and 2-16 μg/mL (r = 0.9998) for method II. The detection limits were  0.15 and 0.27 μg/mL & the quantitation limits were 0.46 and 0.84 μg/mL for methods I and II, respectively. Different experimental parameters affecting the development and stability of the reactions products were studied and optimized. The proposed methods were applied successfully to the determination of bumadizone in its tablets, and the results obtained were in good agreement with those obtained using a comparison  method.Â

Spectrofluorimetric analysis of menbutone in veterinary formulations: Application to residue determination in bovine meat and milk

A simple, rapid, and sensitive spectroflourimetric method was developed for the determination of menbutone. The method is based on measuring the native fluorescence of the alkaline aqueous methanolic solution of the cited drug at its optimum excitation and emission wavelengths at λem 378 nm, upon excitation at λex 300 nm. The method showed good linearity over the range of 0.2-2.0 µg/mL with a detection and quantitation limits of 7.25 and 24.15 ng/mL, respectively. The suggested method was successfully applied to the analysis of menbutone in its commercial veterinary formulations and the results obtained were in good agreement with those given with the manufacturer method. The method was further extended to the determination of menbutone residues in bovine meat and milk, and the results were satisfactory. The recoveries obtained were in the 98.50-102.25% range. No organic solvents were used in the extraction procedures, therefore, the proposed method can be considered as a type of 'green' chemical process

Simultaneous determination of paracetamol, caffeine and codeine in tablets and human plasma by micellar liquid chromatography

A simple, rapid, sensitive and eco-friendly liquid chromatographic method was developed and validated for the simultaneous determination of paracetamol (PAR), caffeine (CAF) and codeine (COD). The separation was performed on cyano column using a micellar mobile phase consists of 140 mM sodium dodecyl sulfate, 25 mM phosphate buffer and 10% acetonitrile at pH = 3. The analysis was performed at a flow rate of 1 mL/min and a column temperature of 30 °C under direct UV detection at 210 nm. Total analysis time was below 6 min. Baclofen (BCF) was used as an internal standard. The validation was performed according to the ICH guidelines. The proposed method was linear over the ranges of 0.2-100.0, 0.02-12.0 and 0.2-12.0 µg/mL for PAR, CAF and COD, respectively. The limits of detection were 0.031, 0.007 and 0.054 µg/mL and limits of quantification 0.103, 0.02 and 0.164 µg/mL for PAR, CAF and COD, respectively. The results show that the procedure is suitable for the routine analysis of drugs in tablet dosage forms. The method was further extended to the determination of the studied drugs in spiked human plasma with mean percentage recoveries of 99.61±0.530, 99.28±0.523 and 99.52±0.385 for PAR, CAF and COD, respectively

Preconcentration and Detection of Gefitinib Anti-Cancer Drug Traces from Water and Human Plasma Samples by Means of Magnetic Nanoparticles

Along of widespread application of anti-cancer drug Gefitinib (GEF), it appears in human body fluids as well as clinical wastewater. Consequently, a reliable and easy-to-adapt detection technique is of essential importance to quantify the drug in different media. The extraction and quantitative detection of anti-cancer drug Gefinitib (GEF) is demonstrated based on a straightforward and efficient magnetic nanoparticle-assisted preconcentration route from water and human plasma samples. Iron oxide magnetic nanoparticles (Fe3O4) have been prepared with an average particle size of 15 nm and utilized as extractible adsorbents for the magnetic solid-phase extraction (MSPE) of GEF in aqueous media. The method is based on MSPE and preconcentration of GEF followed by High-Performance Liquid Chromatography-Ultraviolet Detection (HPLC-UV). The yield of GEF extraction under the optimum MSPE conditions were 94% and 87% for water and plasma samples, respectively. The chromatographic separation was carried out isocratically at 25 °C on a Phenomenex C8 reversed phase column (150 mm × 4.6 mm, with 5 µm particle size). The proposed method was linear over concentration ranges of 15.0–300.0 and 80.0–600.0 ng/mL for water and plasma samples with limits of detection of 4.6 and 25.0 ng/mL in a respective order. Relative standard deviations (%RSD) for intra-day and inter-day were 0.75 and 0.94 for water samples and 1.26 and 1.70 for plasma samples, respectively. Using the magnetic nanoparticles (MNPs) as loaded drug-extractors made the detection of the anti-cancer drug environmentally friendly and simple and has great potential to be used for different drug-containing systems

Development and validation of a repharsed phase- HPLC method for simultaneous determination of rosiglitazone and glimepiride in combined dosage forms and human plasma

<p>Abstract</p> <p>Background</p> <p>Rosiglitazone (ROZ) and glimepiride (GLM) are antidiabetic agents used in the treatment of type 2 diabetes mellitus. A survey of the literature reveals that only one spectrophotometric method has been reported for the simultaneous determination of ROS and GLM in pharmaceutical preparations. However the reported method suffers from the low sensitivity, for this reason, our target was to develop a simple sensitive HPLC method for the simultaneous determination of ROZ and GLM in their combined dosage forms and plasma.</p> <p>Results</p> <p>A simple reversed phase high performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous determination of Rosiglitazone (ROS) and Glimepiride (GLM) in combined dosage forms and human plasma. The separation was achieved using a 150 mm × 4.6 mm i.d., 5 μm particle size Symmetry^®C18 column. Mobile phase containing a mixture of acetonitrile and 0.02 M phosphate buffer of pH 5 (60: 40, V/V) was pumped at a flow rate of 1 mL/min. UV detection was performed at 235 nm using nicardipine as an internal standard. The method was validated for accuracy, precision, specificity, linearity, and sensitivity. The developed and validated method was successfully used for quantitative analysis of Avandaryl™ tablets. The chromatographic analysis time was approximately 7 min per sample with complete resolution of ROS (t_R= 3.7 min.), GLM (t_R= 4.66 min.), and nicardipine (t_R, 6.37 min). Validation studieswas performed according to ICH Guidelines revealed that the proposed method is specific, rapid, reliable and reproducible. The calibration plots were linear over the concentration ranges 0.10-25 μg/mL and 0.125-12.5 μg/mL with LOD of 0.04 μg/mL for both compounds and limits of quantification 0.13 and 0.11 μg/mL for ROS and GLM respectively.</p> <p>Conclusion</p> <p>The suggested method was successfully applied for the simultaneous analysis of the studied drugs in their co-formulated tablets and human plasma. The mean percentage recoveries in Avandaryl™ tablets were 100.88 ± 1.14 and 100.31 ± 1.93 for ROS and GLM respectively. Statistical comparison of the results with those of the reference method revealed good agreement and proved that there were no significant difference in the accuracy and precision between the two methods respectively. The interference likely to be introduced from some co-administered drugs such as glibenclamide, gliclazide, metformine, pioglitazone and nateglinide was investigated.</p

Spectrofluorimetric determination of sertraline in dosage forms and human plasma through derivatization with 9-fluorenylmethyl chloroformate

<p>Abstract</p> <p>Background</p> <p>Sertraline is primarily used to treat major depression in adult outpatients as well as obsessive-compulsive, panic and social anxiety disorders in both adults and children. A survey of the literature reveals that most of the reported methods are either insufficiently sensitive or tedious and require highly sophisticated and dedicated instrumentation. The proposed method is considered to be specific for determination of SER in presence of its metabolite (deaminated form).</p> <p>Results</p> <p>A sensitive, simple and specific spectrofluorimetric method was developed for the determination of sertraline (SER) in pharmaceutical formulations and biological fluids. The method is based on its reaction with 9-fluorenylmethyl chloroformate (FMOC-Cl) in borate buffer of pH 8.0 to yield a highly fluorescent derivative peaking at 315 nm after excitation at 265 nm. The different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence concentration plot was rectilinear over the range of 0.05-1.0 μg mL^-1with a lower detection limit of 5.34 × 10^-3μg mL^-1and limit of quantitation of 0.016 μg mL^-1.</p> <p>Conclusions</p> <p>The proposed method was successfully applied to the analysis of commercial tablets and the results obtained were in good agreement with those obtained using the reference method. Furthermore, the method was applied for the determination of SER in spiked and real human plasma. The mean % recovery (n = 3) was 94.33 ± 1.53 and 92.00 ± 2.65, respectively. A proposal of the reaction pathway was postulated.</p

Spectrophotometric determination of tizanidine and orphenadrine via ion pair complex formation using eosin Y

A simple, sensitive and rapid spectrophotometric method was developed and validated for the determination of two skeletal muscle relaxants namely, tizanidine hydrochloride (I) and orphenadrine citrate (II) in pharmaceutical formulations. The proposed method is based on the formation of a binary complex between the studied drugs and eosin Y in aqueous buffered medium (pH 3.5). Under the optimum conditions, the binary complex showed absorption maxima at 545 nm for tizanidine and 542 nm for orphenadrine. The calibration plots were rectilinear over concentration range of 0.5-8 μg/mL and 1-12 μg/mL with limits of detection of 0.1 μg/mL and 0.3 μg/mL for tizanidine and orphenadrine respectively. The different experimental parameters affecting the development and stability of the complex were studied and optimized. The method was successfully applied for determination of the studied drugs in their dosage forms; and to the content uniformity test of tizanidine in tablets

Rapid simultaneous determination of indacaterol maleate and glycopyrronium bromide in inhaler capsules using a validated stability-indicating monolithic LC method

Abstract Background Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. A combination of indacaterol maleate with glycopyrronium bromide has recently been approved as a once-daily maintenance therapy in patients with COPD. The very low dose (μg level/capsule) renders the analysis of such products challenges. This study reports for the first time about HPLC method for the quality control of such combination and it is a stability indicating at the same time. Results A rapid, simple, precise and reproducible HPLC method was developed and validated for simultaneous determination of indacaterol maleate and glycopyrronium bromide using tenoxicam as an internal standard. The chromatographic separation was achieved on an onyx monolithic C18 column (100 × 4.6 mm) using a mobile phase consisting of acetonitrile and 30 mM phosphate buffer (pH 3.5) (30:70, v/v), run at a flow rate of 2 mL/min with UV detection at 210 nm. The total analysis time was less than 3 min. The HPLC method was validated for linearity, limits of detection and quantitation, precision, accuracy, system suitability and robustness. Calibration curves were obtained in the concentration ranges of 1–44 µg/mL for indacaterol maleate and 0.5–20 µg/mL for glycopyrronium bromide. Stability tests were done through exposure of the analyte solution for different stress conditions and the results indicate no interference of degradants with HPLC method. Conclusions The method was successfully applied for the quantitative analysis of indacaterol maleate and glycopyrronium bromide both individually and in a combined pharmaceutical inhaler capsules to support the quality control and to assure the therapeutic efficacy of the two drugs. The simple procedure involved in sample preparation and the short run-time added the important property of high throughput to the method. Graphical abstract Chemical structures and representative HPLC chromatogram of indacaterol maleate (IND; 22 μg/mL), glycopyrronium bromide (GLY; 10 μg/mL) and tenoxicam (IS, 15μg/mL) in commercial capsules