H-point Standard Addition Method for the Simultaneous Spectrophotometric Determination of Captopril and Hydrochlorothiazide in Pharmaceutical Formulations

Simultaneous spectrophotometric determination of captopril and hydro-chlorothiazide in pharmaceutical formulations by the H-point standard addition method (HPSAM) is described. Absorbance at 211.5 and 230.3 nm was monitored upon the addition of standard solutions of captopril. The results showed that in prepared mixtures, captopril and hydrochlorothiazide can be determined simultaneously at concentration ratios varying from 1.0:0.8 to 2.5:1.5 μg/mL, respectively. Percentage recovery was found to be 95.33–104.37% for captopril and 96.8–105% for hydrochlorothiazide, with a relative standard deviation (RSD) of 2.46%. The method was successfully used to evaluate the antihypertensive captopril drug in a binary combination of hydrochlorothiazide in real samples with high precision and accuracy within the recovery percentage.

Silk Textiles from the Topkapi Palace Museum, Istanbul: An Analytical Study

Eight historical textile objects belonging to the 16th-20th centuries in the collection of the Topkapi Palace Museum in Istanbul were analyzed with the purpose of reaching improved conservation and restoration methods. The historical textiles underwent dyestuff analysis by High Performance Liquid Chromatography, morphological and elemental analysis by Scanning Electron Microscope with energy Dispersive X-ray Spectroscopy, CIEL*a*b color measurement as well as technical analysis by optical microscopy.

Cyclization Reactions of Mono-Thiocarbohydrazones with α-Haloketones: Synthesis and Potential Biological Activities of Substituted 1,3-thiazoles and 1,3,4-thiadiazines

A series of new substituted 1,3-thiazole derivatives 10a-h were prepared via the reaction of monothiocarbohydrazones 8a-h with one equivalent of α-bromoketones in ethanol. Similarly, another series of new substituted 1,3,4-thiadiazines 11a-e were prepared from the reaction of monothiocarbohydrazones 8i,j with one equivalent of α-bromoketones in ethanol. The resulting products were obtained as colored crystals in moderate to good yields. All new compounds are fully characterized by 1H-, 13C-NMR, IR and elemental analysis. Pharmacophore modeling study of four of the synthesized compounds revealed that at least two of them have potential biological activities. Some of these activities will be investigated experimentally in the lab.

Thermal Analysis of Oil Shale Ash-filled High-density Polyethylene Composites

Thermal analysis was performed to evaluate the impact of the addition of oil shale ash (OSA) to high-density polyethylene (HDPE) polymer matrix using differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). Extrusion and press molding processes were used to compound the OSA-filled HDPE polymer composites containing 0, 5, 15 and 25 wt% OSA, for which the thermal properties and the characteristics of the composites were studied. Investigation of the thermal properties of the OSA-HDPE composite is necessary for selecting processing conditions and the appropriate application field. The DSC results demonstrated that OSA addition only marginally affected the glass transition temperature Tg of the composite formulations. The melting temperature Tm showed a decreasing trend with increased OSA fraction, while the crystallization temperature Tcryst showed an increasing trend. The heat of fusion ∆Hm, the heat of crystallization ∆Hcryst and the percentage of crystallinity decreased on the addition of OSA filler. The TGA results demonstrated that the thermal stability of the polymer composite matches that of the neat polymer behavior up to 350 °C after which the thermal stability of the filled polymer composite increases with increased filler content. Above 360 °C, the weight loss of the neat polymer as well as of the polymer composite is accelerated up to 480 °C where all tested samples become fully degraded.

Synthesis, Characterization and Crystal Structure of Samarium(III)-(E)-1-phenyl-N-(4H-1,2,4-triazol-4-yl)methanimine Complex

Samarium-benzylidene Schiff base adduct with the formula [Sm(NO3)3(H2O)3].2L (L= (E)-1-phenyl-N-(4H-1,2,4-triazol-4-yl) methanimine) (1) has been prepared, with two water molecules bonded to the samarium center form hydrogen bond with three molecules of title Schiff base through nitrogen atoms of the triazole rings. The chemical structure was confirmed by means of single-crystal X-ray diffraction (scXRD), FT-IR, electrical conductivity, thermogravimetric analysis (TGA), mass spectrometry and elemental analysis. The title complex 1 crystallizes in the triclinic P-1 space group. The unit cell parameters are a = 10.4045(1) Å, b = 12.5403(1) Å, c = 12.5477(2) Å,  = 96.668(1)o,  = 110.810(1)o,  = 111.567(1)o, V = 1.788 Å3, Z = 2, Rgt(F) = 0.0223, wRref(F2) = 0.0576. The samarium ion is in a distorted capped square antiprism environment, coordinated by three bidentate nitrates and three coordination water molecules. The [Sm(H2O)3(NO3)3] complex and the (E)-1-phenyl-N-(4H-1,2,4-triazol-4-yl)methanimine) moiety (L) are held together via hydrogen interactions to form a 2-D supramolecular framework. It is a non-electrolyte as indicated by its molar conductivity (ΛM= 10.1 S cm2 mol-1) in MeOH at 1.0 mM. The mass spectral results confirm the suggested structure of the investigated adduct.

Chromatographic Analysis (LC-MS and GC-MS), Antioxidant Activity, Total Phenol and Total Flavonoid Determination of Ononis natrix L. Grown in Jordan

The purpose of the present study was to identify, by gas chromatography (GC) and GC-mass spectrometry (GC-MS), the components of the spontaneously emitted volatile organic compounds (VOCs), obtained by Solid-Phase-Micro-Extraction (SPME) and that of the hydrodistilled oil of the fresh flowers and leaves of Ononis natrix, as well as to compare them. The hydrodistilled leaf oil was rich in non-terpenoid aldehydes, whereas its aroma profile contained mainly sesquiterpene hydrocarbons with α-copaene and germacrene D as their major components. The hydrodistilled oil of the fresh flowers, however, revealed nearly equal amounts of terpenoid and non-terpenoid compounds; 51.00% and 46.54%, respectively. The aroma profile of the fresh flowers was dominated by monoterpene hydrocarbons with α-pinene (42.96%) and α-thujene (20.17%) as the predomi¬nant two monoterpenes. Based on the high total phenol and flavonoid contents of the water and ethanol extracts, LC-MS analysis was carried out to identify the major compounds from each sample. From the water extract, eleven compounds were identified, whereas the ethanol extract contained eight, whereby luteolin (from the water extract) and apigenin (from the ethanol one) were named as the major flavonoids, respectively.

Phytochemical Screening and Quantitative Determination of Primary Nutrients and Minerals for Two Cultivars of Jujube (Ziziphus jujuba Mill.) Fruits

This work represents a comprehensive study of the nutritional composition of primary nutrients for two main cultivars of Syrian jujube fruits (Ziziphus jujuba cv. junzao, Ziziphus jujuba cv. yazao). Phytochemical screening of the jujube fruit extracts was carried out and the contents of moisture, carbohydrate, fats, fibers, proteins and ash were determined according to standard methods. Eight mineral elements (Ca, K, P, Na, Fe, Zn, Cu and Mn) were also determined by atomic absorption spectroscopy. The results revealed that both cultivars have a high nutritional value, but showed significant differences in the nutritional composition. To the best of our knowledge, this is the first study that addresses the phytochemical properties and the nutritional composition of Syrian jujube fruits.

Green Chemistry: A Simple Manual Apparatus for Potentiometric and Conductometric Micro-Titration of Small Samples for the Educational Laboratory

A simple manual micro-titration method is proposed for the potentiometric and conductometric titration of 200 to 800 µL of liquid samples. The sample to be titrated is dispensed into the titration chamber; the bottom section of a plastic test tube that is glued to the center of a small stirring magnet. After inserting the sensing probe and the tip of the titrant delivery tip into the titration chamber, the chamber-stirring magnet assembly is spun at low speed using a conventional magnetic stirrer. Titrant is delivered (with 0.2 µL resolution) from the submerged tip of a 100-µL capacity micro-pipette by rotating the plunger with the locking ring unlocked. The apparatus has been used for potentiometric titration and conductometric titration of acids and bases usually encountered in educational laboratories. Compared with macro-scale titrations, the obtained accuracy was between +2.2% and -3.9% relative error and the precision ranged between 1.6% and 2.9% relative standard deviation. The proposed procedure cuts the reagent consumption to 1% or less compared with conventional macro-scale titrations.

Post-functionalization of Ether-linked Polymer via the Application of Ullmann-coupling Reaction: Synthesis, Characterization and Thermal Degradation Kinetics

A new ether-linked polymer (PE-A) was synthesized via the polycondensation of 1,4-dibromo-2,5-difluorobenzene with biphenol (A). The new polymer has shown a good solubility in non-polar solvents, as well as moderate thermal stability (up to 300 °C). The parent PE-A was subjected to post-functionalization modification applying the Ullmann-coupling reaction on the C-Br bonds of PE-A, where the bromo-sites have been replaced by aniline-linked moieties. The resulting polymer (PE-Ani-A) shows slight solubility in several solvents. Its thermal stability was enhanced by 36% when compared with PE-A. To ensure the significant impact of the inclusion of the aniline group on thermal stability, a thermal degradation kinetics study was performed and the Coats-Redfren and Broido theoretical models were applied to explore the degradation process. The calculated activation energy for PE-Ani-A degradation was thereby found to be higher than that of PE-A, which indicates the higher thermal stability of PE-Ani-A. For further insights into the thermal stability of the polymers, the limited oxygen index (LOI), which represents the flame-retardant property of the polymers, was calculated. The results indicate that PE-A is a promising candidate as a flame-retardant polymer (LOI = 46.7), since it has a high bromo-content. On the other hand, PE-Ani-A has a lower LOI although it has a higher thermal stability.