Determination of ceftriaxone sodium in pharmaceutical formulations by flow injection analysis with acid potassium permanganate chemiluminescence detection.

Based on the chemiluminescence (CL) emission generated from the oxidation of ceftriaxone sodium alkali hydrolysate by potassium permanganate in polyphosphoric acid (PPA), a novel determination method for ceftriaxone sodium was developed by using a flow-injection technique. The calibration curve appears to be linear in the range between 0.05 and 100 microg mL(-1) with a detection limit (3sigma) of 25 ng mL(-1), and a relative standard deviation (RSD) of 0.6% for eleven replicate determinations of 5.0 microg mL(-1) ceftriaxone sodium. The proposed method has been successfully utilized for the determination of ceftriaxone sodium in pharmaceutical formulations, while the chemiluminescence reaction mechanisms were investigated.     

Comparison of cholesterol oxidation product preparation methods for subsequent gas chromatographic analysis

An evaluation was made of the stability of cholesterol hydroperoxides (CHPs) under the analytical conditions and preparation methods commonly used for determination and quantification of cholesterol oxidation products (COPs). CHPs were prepared by photoxidation and separated by silica thin-layer chromatography. CHPs were individually collected by normal-phase liquid chromatography and then subjected either to reduction or to cold saponification. The corresponding hydroxyl derivatives were generated by reduction, whereas cold saponification gave rise predominantly to 7-ketocholesterol. In another test, silylated and non-silylated CHPs were separately injected into a gas chromatograph at 310 degrees C, collected, and re-injected into a gas chromatography-mass spectrometry system. The silylated CHPs were more stable than the non-silylated ones, giving 7-ketocholesterol, 7alpha- and 7beta-hydroxycholesterol as main degradation products. Two unknown degradation peaks were detected in both silylated and nonsilylated CHPs, having 384 as main m/z fragment. The study of their mass spectra led to the conclusion that peaks A and B correspond to 6alpha- and 6beta-hydroxycholesterol, respectively.     

Comparison of two systems for sample preparation and injection by dynamic headspace GC analysis

The performance of two commercially available systems employing dynamic headspace techniques for collection, enrichment, and injection of volatile compounds has been compared by GC analysis of test mixtures and dairy products. For technical reasons, it has not been possible to crate identical sorbent materials for both kinds of trap were not available, the most similar adsorbent available were chosen. The total quantity of volatile compounds from a test mixture at the column head was calculated using a theoretical model which enables comparable working conditions to be obtained. Under these circumstances special attention was paid to the repeatability of the data obtained from a test mixture in order to ensure reliable results in quantitative analysis. Significant differences in repeatability between the two systems seemed to originate from their distinctly different technical designs. A qualitative comparison of the systems has been performed using a sample of Swiss cheese. On the basis of the results obtained the systems have been dedicated to different applications in the laboratory of the FAM.     

Photocatalytic formulations for protein fibers: experimental analysis of the effect of preparation on compatibility and photocatalytic activities

In this article, we report an optimization study of a photocatalytic self-cleaning sol–gel formulation. In particular we studied the effect of formulation preparation time on the formation of anatase titanium dioxide sol and its compatibility to protein keratin-type wool fibers. The sols were formed by a low temperature sol–gel process. The nucleated anatase was characterized by UV–vis transmission, particle size distribution, X-ray diffraction, and transmission electron microscopy. The compatibility between the formulations and wool fibers is evaluated by field-emission scanning electron microscopy, UV transmission, and mechanical properties. The photocatalytic self-cleaning activity of coated fibers and its reproducibility are also discussed.     

Sample preparation with solid phase microextraction and exhaustive extraction approaches: Comparison for challenging cases

In chemical analysis, sample preparation is frequently considered the bottleneck of the entire analytical method. The success of the final method strongly depends on understanding the entire process of analysis of a particular type of analyte in a sample, namely: the physicochemical properties of the analytes (solubility, volatility, polarity etc.), the environmental conditions, and the matrix components of the sample. Various sample preparation strategies have been developed based on exhaustive or non-exhaustive extraction of analytes from matrices. Undoubtedly, amongst all sample preparation approaches, liquid extraction, including liquid–liquid (LLE) and solid phase extraction (SPE), are the most well-known, widely used, and commonly accepted methods by many international organizations and accredited laboratories. Both methods are well documented and there are many well defined procedures, which make them, at first sight, the methods of choice. However, many challenging tasks, such as complex matrix applications, on-site and in vivo applications, and determination of matrix-bound and free concentrations of analytes, are not easily attainable with these classical approaches for sample preparation.     

毛细管电泳法测定注射用头孢哌酮钠他唑巴坦钠中目标成分

建立了毛细管区带电泳法同时测定注射用头孢哌酮钠他唑巴坦钠中目标成分含量的方法。采用石英毛细管(75 cm×75 μm i.d.,有效长度63 cm),以40 mmol/L硼砂溶液为背景电解质(BGE),以氢氯噻嗪为内标,分离电压12.0 kV,检测波长220 nm,重力进样10 s(高度10 cm)。实验结果表明,头孢哌酮钠与他唑巴坦钠分别在0.25～3.96 g/L和0.062～0.99 g/L范围内呈良好的线性关系,相关系数(r)分别为0.9995和0.9996。精密度和重复性均良好,相对峰面积的相对标准偏差(RSD)均小于3%,制剂在208 min内稳定,回收试验结果符合方法学要求。该方法简单、准确、耗费少、污染小,可用于注射用粉针剂头孢哌酮钠他唑巴坦钠中头孢哌酮钠和他唑巴坦钠的定量分析。     

Large-volume PTV injection: Comparison of direct water injection and in-vial extraction for GC analysis of triazines

Summary The potential of large-volume PTV injection was studied for the analysis of triazine herbicides in water samples. Direct water injection and in-vial extraction were described and compared. Detection limits were between 0.01–0.02 μg L⁻¹ and relative standard deviations were <9%. Both methods are suitable for the analysis of triazines at ppt-level, although in-vial extraction is favourable for water samples with relatively large amounts of matrix components.     

Rational design of original materials for the electrocatalytic hydrogenation reactions: concept, preparation, characterization, and theoretical analysis

Original and versatile new materials for the electrocatalytic hydrogenation of organic compounds were designed. The materials consist of reticulated glassy carbon cathode electrodes in which the modified silica particles (average diameter 40-63 microm) were dynamically circulated. The modification of the silica surface is 2-fold. First, the silica is surface-modified using organic functions such as -OSi(CH3)2(CH2)3OCH2CH-(OH)(CH)2OH (SiO2-Diol), -OSi(CH3)2(CH2)7CH3 (SiO2-C8), and -OSi(CH3)2C6H5 (SiO2-Phenyl). Second, these silica particles were further modified by vapor phase deposition of nickel nanoaggregates (used as sites for hydrogen atoms and electric contacts with the electrode material), which does not destroy or alter the organic functionalization as demonstrated by thermogravimetric analysis-mass spectrometry and Raman, diffuse reflectance IR Fourier transform, and Auger electron spectroscopies. The new concept stems from relative adsorption and desorption properties of the organic molecules and their corresponding reduced products into the organic functionalization of the surface-modified silica. In this work, the electrocatalytic hydrogenation cyclohexanone was used to test the concept. The performances (amount of cyclohexanol vs time of generated electrolysis at constant current) are measured and compared for the various bonded organic functions of the silica surface listed above, along with the unmodified silica particles (but still containing nickel nanoaggregates) and the presence or absence of methanol in solution. The measurements of the adsorption isotherms of cyclohexanone, and the calculations of the interaction energies (MM3 force field) between the chemisorbed organic functions and the substrates, corroborate perfectly the electrocatalysis results.     

Comparison between capillary electrophoresis and liquid chromatography for the determination of diclofenac sodium in a pharmaceutical tablet

Two novel analytical methodologies using capillary electrophoresis (CE) and liquid chromatography (LC) were developed and compared for the determination of diclofenac sodium in commercial and simulated tablet formulations. The CE analysis was performed in a bare fused-silica capillary with 75 microm id and total length of 50 cm (28 cm to the detector) with a buffer solution of 20 mM sodium tetraborate, pH 9.23. The applied voltage was 20 kV, and acetaminophen was used as the internal standard (IS). The LC analysis was performed with a LiChrospher 100 RP-18 (5 microm) column and a mobile phase of methanol-diluted glacial acetic acid (0.3 parts in 2500; 75 + 25) at a flow rate of 0.9 mL/min with propylparaben as the IS. In both analyses, detection was by ultraviolet absorption at 276 nm. Under optimized conditions, the CE migration times for the diclofenac sodium standard and acetaminophen (IS) were 2.07 and 1.59 min, respectively, and the LC retention times for the diclofenac sodium standard and propylparaben (IS) were 3.98 and 2.26 min, respectively. The resolution and efficiency for CE were 14.2 and 1.6 x 10(5) plates/m, respectively, and for LC, 5.0 and 8.6 x 10(3) plates/m, respectively. Calibration curves of peak area versus concentration gave correlation coefficients of 0.9992 for CE and 0.9994 for LC. The limits of detection and quantitation were 8.40 and 25.46 microg/mL, respectively, for CE and 4.60 and 13.93 microg/mL, respectively, for LC. Coefficients of variation were 1.68 and 0.37% for CE and LC, respectively. Average recoveries obtained with CE and LC were 103.12+/-0.90 and 99.59+/-0.21%, respectively. Although both methodologies were shown to be suitable for the determination of diclofenac sodium in tablets, performing in a similar manner with regard to several aspects (linearity, recovery, and specificity), CE provided faster analysis and better column efficiency, whereas LC provided superior repeatability and sensitivity.     

A simple method for the preparation of sodium and potassium aluminium hydrides

Summary Sodium and potassium aluminium hydrides are readily obtained from aluminium chloride and sodium and potassium hydrides, respectively, using organoaluminium compounds as catalysts for the reaction.     

Influencing factors for static immersion tests of compatibility between elastomeric materials and lubricants

Material compatibility is an important factor to consider during the development of new lubricants and sealing materials. Static immersion tests provide a first idea about the compatibility between elastomeric materials and lubricants. For the same material combination, significant deviations among the test results of different laboratories have been reported. In order to identify the relevant factors affecting the results, a systematic investigation was carried out. Reproducibility tests show that the estimation of the compatibility is compromised due to the deviations that appear for the change of the mechanical properties of the considered reference elastomers. The influences of the closure of the test apparatus and the volume ratio, as well as the development of the aging process, were investigated. The results showed that, in order to differentiate between elastomer-lubricant material combinations, standard test durations of approximately 1008 h are preferred. Volume ratios of 64 and 80 and small variations of the vessel closure did not lead to significant deviations of the results. In contrast, tests with open and closed vessels showed significant deviations for the hardness and mechanical properties of the elastomeric materials.     

Comparison of merging zones,injection of reagent and single-line manifolds for enthalpimetric flow injection analysis

A flow enthalpimeter suitable for all flow injection manifolds is described. The apparatus includes the injection valve immersed in an equilibration water bath which improves sensitivity and sampling rate. Detection limits for quantitation of hydrochloric acid range from 0.4 to 0.07 mM at 80–90 samples per hour.     

Restoration of cultural heritage: evaluation of the compatibility between metals and sealing products

When restoring historical monuments, it is often verified that reinforcements, mostly made of ferrous alloys, are in quite a bad state and must be partially or totally replaced to prevent further degradation or accidents. Modern alloys such as stainless steels are increasingly used for such purpose, which raises the open question concerning their compatibility with the new types of sealing products available on the market. Even though it is not possible to use accelerated tests to give a livelong guarantee of adequacy of materials combination, electrochemical tests of metals in an aqueous extract of the sealing products could be used as screening to rapidly identify situations that would conduce to the premature corrosion of the metal.     

Comparison of plasma pharmacokinetics of Tanreqing solution between intratracheal aerosolization and intravenous injection in rats

A rapid ultra high performance liquid chromatography tandem mass spectrometry method was developed for the simultaneous analysis of baicalin, oroxylin A‐7‐O‐β‐d ‐glucoronide and chlorogenic acid in rats plasma, and applied to comparison of pharmacokinetics of Tanreqing solution between intratracheal aerosolization and intravenous injection. Results of the analytical method validation assay showed high sensitivity, accuracy and suitable recovery. Results of pharmacokinetics showed similar decline phases for baicalin, oroxylin A‐7‐O‐β‐d ‐glucoronide and chlorogenic acid in two different delivery routes. The half‐lives of intratracheal aerosolization and intravenous injection were 0.90 and 1.22 h for baicalin, 0.47 and 0.17 h for oroxylin A‐7‐O‐β‐d ‐glucoronide and 0.22 and 0.13 h for chlorogenic acid, and this implies that compounds were retained in the lung for a relatively short time. This study was the first to provide important pharmacokinetics information for traditional Chinese medicine delivery to the lung.     

硫酸铈-亚硫酸钠流动注射化学发光法测定多贝斯

基于多贝斯对硫酸铈-亚硫酸钠化学发光体系的抑制作用,建立了流动注射-化学发光测定多贝斯的新方法,并且研究了各种实验条件的影响。在酸性介质中,发光强度的降低(ΔICL)与多贝斯浓度在4.0×10-6~6.0×10-5mol/L范围内呈良好线性关系,回归相关系数为0.9976,方法的检出限为2.0×10-6mol/L,相对标准偏差为1.2%(n=6)。     

荷移反应分光光度法测定苯巴比妥钠

采用分光光度法研究了电子给体苯巴比妥钠与π电子受体茜素红的荷移反应,建立了荷移分光光度法测定苯巴比妥钠的方法。在水溶液中,苯巴比妥钠与茜素红荷移络合物的最大吸收波长为530 nm,该络合物的组成为1∶1,表观摩尔吸光系数ε为4.43×103L.mol-1.cm-1,稳定常数为2.30×105。药物质量浓度在5~40 mg/L范围内符合比尔定律,相关系数为0.9996。当苯巴比妥钠浓度为20 mg/L时,10次测定结果的相对标准偏差为1.3%。测定了针剂中的苯巴比妥钠,加标回收率在98.9%~105%之间。     

Semiorganic nonlinear optical material for frequency doubling: preparation and properties of sodium p-nitrophenolate dihydrate (SPNP)

Sodium p-nitrophenolate (SPNP), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been synthesized. The solubility studies have been carried out in the temperature range 30-50 degrees C. Single crystals (size 12 mmx7 mmx4 mm) have been grown by slow evaporation of the saturated aqueous solution (methanol as solvent) at 30 degrees C. The lattice parameters of the grown crystals have been determined by single crystal X-ray diffraction technique. The UV-vis-NIR transmittance spectrum has been recorded in the range 200-1500 nm. The molecular structure was confirmed by FT-IR and FT-NMR. SPNP was thermally stable up to 103 degrees C as determined by TG/DTA curves. By a modified Kurtz and Perry method, the powder SHG efficiency was found to be five times that of KDP and its phase matching property was established. Laser damage threshold of SPNP was determined using a Nd:YAG laser.     

Acerate ZnO whiskers and sodium alginate films: preparation and application in bioelectrochemistry of hemoglobin

A novel biocompatible acerate ZnO whiskers (AZW) has been prepared. We explored AZW and sodium alginate for the construction of electrochemical biosensors. The composition, morphology, and size were studied by scanning electron microscopy. UV–vis spectra revealed that hemoglobin (Hb) adsorbed in the acerate ZnO whiskers and sodium alginate retained its native structure. The amperometric response was measured as a function of H₂O₂ concentration at a fixed potential of −0.25 V in phosphate-buffered saline (pH 7.0). The electrochemical parameters of Hb in acerate ZnO whiskers and sodium alginate were calculated with the results of the electron transfer coefficient (α) and the apparent heterogeneous electron transfer rate constant (k _s) as 0.5 and 2.5 s⁻¹, respectively, indicating good facilitation of the electron transfer between Hb and the modified electrode, which may result from the unique nanostructures and larger surface area of acerate ZnO whiskers. The hydrogen peroxide biosensor showed a fast response of <5 s of linear range 2.1 μM–4.8 mM, with a detection of 0.7 μM (S/N = 3). The apparent Michaelis–Menten constant K_m^app K_m^{{app}} is 0.8 mM. The biosensor possesses high sensitivity, good reproducibility, and long-term stability.