Temperature Program Research Articles

Residual solvent analysis with hyper-fast gas chromatography-mass spectrometry and a liquid carbon dioxide cryofocusing in less than 90 s

A new hyper-fast gas chromatography method with less than 90 s runtime including the column cool down was developed for the analysis of four gases and 16 residual solvents, combining a CO2 cryofocusing with a flow-field thermal gradient gas chromatograph (FF-TG-GC) and ToF-MS. The extremely low analysis time can be achieved by combining the new FF-TG-GC and a very short Rxi-624 Sil MS separation column with a small inner diameter and small film thickness (2.05 m × 0.1 mm × 1.0 µm).The column is inserted into a low thermal mass, resistively heated stainless steel capillary. This enables fast temperature programs with heating rates up to 3000 °C/min and a column cool down within a few seconds. In addition to temporal temperature gradients, the FF-TG-GC can generate a spatial temperature gradient that leads to an improved peak shape. Further, an external liquid CO2 cryo-trap was designed in order to reduce the injection bandwidths of analytes and to take full advantage of the resolving power of the separation column. No modifications are required to the FF-TG-GC for the use of the cryogenic trap, as the cooled spot is heated by the resistively heated stainless steel capillary during the temperature program. With cryofocusing, analyzed residual solvents are baseline separated. R2 values over 0.99 for calibration curves and low relative standard deviations (mainly < 3%) for repeatability tests were obtained.

Catalytic Decomposition of 2% Methanol in Methane over Metallic Catalyst by Fixed-Bed Catalytic Reactor

The structure and performance of promoted Ni/Al2O3 with Cu via thermocatalytic decomposition (TCD) of CH4 mixture (2% CH3OH) were studied. Mesoporous Cat-1 and Cat-2 were synthesized by the impregnation method. The corresponding peaks of nickel oxide and copper oxide in the XRD showed the presence of nickel and copper oxides as a mixed alloy in the calcined catalyst. Temperature program reduction (TPR) showed that Cu enhanced the reducibility of the catalyst as the peak of nickel oxide shifted toward a lower temperature due to the interaction strength of the metal particles and support. The impregnation of 10% Cu on Cat-1 drastically improved the catalytic performance and exhibited 68% CH4 conversion, and endured its activity for 6 h compared with Cat-1, which deactivated after 4 h. The investigation of the spent carbon showed that various forms of carbon were obtained as a by-product of TCD, including graphene fiber (GF), carbon nanofiber (CNF), and multi-wall carbon nanofibers (MWCNFs) on the active sites of Cat-2 and Cat-1, following various kinds of growth mechanisms. The presence of the D and G bands in the Raman spectroscopy confirmed the mixture of amorphous and crystalline morphology of the deposited carbon.

Size-controlled one-pot synthesis of viologen nanoparticles via a microwave heating technique

We report a size-controlled one-pot synthesis of redox-active organic nanoparticles consisting of viologen units via precise temperature control afforded by the use of microwave heating. A DMF solution of 4,4′-bipyridine and 1,3,5-tris(bromomethyl)benzene (TBMB) corresponding to monomers and ethyl bromide corresponding to a terminator was subjected to microwave heating at 80 °C for 20 min as the first stage corresponding to the growth reaction, which was then followed by heating at 150 °C for 5 min as the second stage corresponding to the termination reaction. 1H NMR analysis of the reaction mixture at each step confirmed that at 80 °C, 4,4′-bipyridine primarily reacts with TBMB, leading to an increase in molecular weight and that a termination reaction with ethyl bromide occurs due to the increase in temperature to 150 °C. Moreover, the size of the nanoparticles can be controlled by varying the first stage reaction time; the nanoparticle diameter was determined to be 142 ± 15 nm for the first stage reaction time of 10 min, which increased to 269 ± 67 nm at 20 min, as evidenced by dynamic light scattering measurements. The microwave heating technique has been widely used in various organic and inorganic syntheses, and it has been reported that this technique provides the desired compounds quickly and easily. In this work, we applied microwave heating to synthesize redox-active organic nanoparticles consisting of hyperbranched viologen units. By the precise temperature control afforded by use of microwave irradiation, we succeeded in controlling the growth and termination reactions kinetically and preparing viologen nanoparticles in one-pot. We also demonstrated that the size of the nanoparticles can be controlled by varying the temperature program.

Recognition of Water-Induced Effects toward Enhanced Interaction between Catalyst and Reactant in Alcohol Oxidation.

Pickering emulsion stabilized by solid nanoparticles provides a diverse solvent microenvironment and enables to promote the phase transfer of reaction substrates/products in catalytic reactions, but the intrinsic role of solvent is still not clear. Herein, using benzyl alcohol (BA) as a model reactant, we demonstrate the nature of the water-promoted activity for alcohol oxidation over the Pd/MgAl-LDO catalyst. Depending on the water in the solvent, we observe different reactivities regarding the proportion of the water in the system. Kinetic isotope effects confirm the participation and positive effects of water for oxidation of BA. The water promotion effects are recognized and identified by the water vapor pulse adsorption coupled with temperature program desorption. Moreover, the adsorption behavior of BA or benzaldehyde at the interface of water and Pd/MgAl-LDO is also investigated by quasi-in-situ Raman spectroscopy. In addition, the mechanism of water-promoted alcohol oxidation is rationally proposed based on the Langmuir-Hinshelwood mechanism. The general applicability of the water promotion effects is further demonstrated over different supports and substrates, which well achieves excellent catalytic activity and selectivity in Pickering emulsion compared to that in the pure toluene system.

Experimentation and kinetic modeling of low-temperature oxidation of magnesium particles for the production of energy with low environmental impact

Future lack of fossil fuels and global warming stimulate researches on new renewable sources of energy, especially for transportation. With high energy densities, metals appear to be relevant energy carriers. In this study, magnesium powder was considered as a metal fuel for energy production through slow oxidation. Temperature Program Oxidation experiments of magnesium powder were performed using thermogravimetric analyses under four low heating rates (1, 2, 3 and 5 °C min−1). The influence of the particle size was investigated by testing three size fractions (20–50, 50–71 and 71–100 µm). Initial and fully or partially oxidized particles (stopping the reaction at selected conversion rates) were characterized using optical microscopy analyses, which highlighted the different stages of the oxidation mechanism. A three-step kinetic model involving heat transfers was finally proposed to describe the slow oxidation of magnesium and to extract optimal values of the kinetic parameters.

2-Phenoxyethanol derivatization in ink dating determination

Introduction 2-Phenoxyethanol (PE) is a volatile compound present in the composition of inks. After the deposition in a document, it starts to evaporate over time. This ageing process potentially allow to estimate the date of an ink in a document [1], however this is a complex system where the PE derivatization with different derivatization agents and methods can contribute to improve ink dating validation [2]. The aim of this work is to determine if PE derivatization with MSTFA:TMCS, will increase the sensitivity of the method contributing to the estimation of the ink age for a longer period of time. Materials and methods In order to compare peak resolution between PE and derivatized PE, a solution of 50 µg/ml of PE was prepared in hexane. The derivatized sample was prepared using chemical derivatization with MSTFA:TMCS (95:5) at a 80ºC during 30 min. The samples were analysed using GC/MS with an Agilent Technologies 5973 − 6890 N. GC MEGA-5 MS; 0.25µm, 0.32mm, 30 m capillary column was used. Chromatographic analysis was carried out under the following conditions: injection volume 2 µl, split ratio of 2:1 and injection temperature at 280 ºC. The oven temperature program starting at 90 ºC during 8 min, then ramped at 10 ºC min−1 to 100 ºC, and increased to 240 ºC at a rate of 30 ºC min−1 during 4.67 min. The MS analysis was carried out in SIM mode, which m/z of PE was 77, 94, 138 and PE-TMS was 151, 195, 210. Results The chromatogram results (Figure 1) showed that PE-TMS has a longer retention time (23.2 min) and a better resolution than PE (retention time of 13.2 min). Discussion and conclusions: This preliminary study showed an increase of the sensitivity of the PE-TMS. Our results revealed that PE derivatization with MSTFA:TMCS, might be useful in ink dating determination and can contribute to the decreasing of LOQ. However, more work has to be done. In conclusion, derivatization proves to be promising in the field of ink ageing, allowing getting sensitivity to estimate the age of an ink, in a long period of time. Figure 1. GC-MS chromatogram of PE (tr = 13.2) and PE-TMS (tr = 23.2) carried out in SIM mode using a GC MEGA-5 MS; 0.25µm, 0.32mm, 30 m capillary column.

Expulsinator assessment of oil/ gas generation and expulsion characteristics of different source rocks

Investigation of expulsion and primary migration usually suffers from inadequate methodologies failing to simulate natural conditions prevailing during oil and gas formation. The Expulsinator device provides a unique methodology to study these processes under near-natural conditions of pressure as well as near-natural constellation of source rock and reservoir. Eight source rocks, differing in lithology and kerogen type ((type-I, type-II, type-IIS and type-III) were treated with the Expulsinator to simulate oil and gas generation and expulsion with increasing subsidence. A standardised pressure and temperature program covering the main oil window was used, simulating pressure regimes, corresponding to 2000 m, 2500 m and 3000 m of depth at pyrolysis temperatures of 300 °C, 330 °C and 360 °C, respectively. The semi-open setup of the Expulsinator enabled the sampling of the products generated during the experiment, providing unique generation/expulsion profiles for each source rock. Expulsinator treatment by continuous withdrawal prevents the formation of condensation products and solid pyrobitumen, which are common artefacts of closed-mode pyrolysis and misleading in maturity assessment. In particular, the Rock-Eval Tmax-value is affected by pyrobitumen formation. The oil and gas generation/expulsion profiles show large differences between the source rocks, controlled by the organic matter composition, as well as the lithological characteristics. Earliest onset of hydrocarbon generation and expulsion was observed for source rocks containing kerogen type-III, followed by sulfur-rich type-IIS and type-II. Lacustrine type-I source rocks showed the latest onset of hydrocarbon generation. Lithology was an important factor for the observed generation/expulsion behaviour under the experimental pressure and temperature conditions. Competent lithologies with a high degree of cementation and/or low permeability showed limited expulsion efficiency; in contrast, expulsion was enhanced by pressure-induced “squeezing” effects in ductile lithologies. A highly permeable but competent sample reached only moderate expulsion efficiency due to low “squeezing” response upon burial pressure.

Influence of the nature of organic solvents on the process of separation of antioxidative additive in a transformer oil by a gas-chromatographic method

THE PURPUSE. The paper considers the influence of the nature of organic solvents on the process of separation of an antioxidant additive added to transformer oil at a concentration of up to 0.40% by weight, and organic solvents used as selective extractants. Based on the analysis of literature data, it is shown that mineral transformer oil is a complex hydrocarbon composition that undergoes oxidative degradation during operation, leading to aging of transformer oil and deterioration of technical conditions of operation of transformer electrical equipment. As a result of this process, peroxide compounds appear in transformer oil, which affect its color, oxidation stability, aging resistance, compatibility with structural parts of equipment, etc. Gas -liquid chromatography was used to determine the "Ionol" antioxidant additive and organic extractants in transformer oil. Experiments were performed on a chromatograph of Chromosomes GC -1000 with a flame ionization detector and a quartz capillary column 30 m long, 0.32 mm in diamet er, filled with a fixed liquid phase Valko Bond VB-WAX P/n with a film thickness of 0.5 microns. The sample was dosed into the gas-liquid chromatograph injector using an automatic liquid dispenser DAZH-23, designed for entering up to twenty-three samples of sorbates and controlled by a computer with the appropriate software.METHODS. Aliphatic alcohols from C1 to C5 were studied as extractants of the antioxidant additive, which are well separated from the ionol both under isothermal conditions and in the mode of linear programming of the column temperature from 40 to 220 °C. Under these conditions the chromatogram of the separation of antioxidant additives, and aliphatic alcohols, which are used to calculate their relative retained volumes, the asymmetry of chromatographic peaks and the column efficiency, which depends on the physico -chemical nature of the solutes to be analyzed and the conditions of the chromatographic experiment.RESULTS. The dependence of the relative volume of retention of aliphatic alcohols on their permittivity, which has a nonlinear form, is established. At the same time, with a decrease in the chain length of alkyl substituents in the aliphatic alcohol molecule, there is a tendency to increase their permittivity. The dependence of the relative retained volume of aliphatic alcohols on the selectivity coefficient of separation with Ionol is linear. In this case, the most optimal separation selectivity, approaching one, is characteristic of the Ionol – Butanol-1 pair. It is shown that the dependence of the logarithm of the retention time of aliphatic alcohols on their boiling points is linear both at a low temperature of the chromatographic column (40 °C) and at a higher temperature (more than 100 °C). CONCLUSION. At the same time, the angle of inclination of the corresponding lines changes in the boiling point of organic solvents, which is associated with a change in the sorption mechanism in a capillary chromatographic column filled with a polar stationary phase.

Suitability of Thermal Swing Adsorption for the Treatment of Siloxanes and Toluene in Biogas: An Experimental Study

The use of biogas has been proven to be an interesting alternative energy source. However, biogas usually contains trace compounds, which can lead to damage in the valorization installation. Consequently, their treatment is an important issue for the suitability of biogas valorization. Although thermal swing adsorption (TSA) has already been implemented, there is still a lack of knowledge about the deactivation of the adsorbent. This work examined under dynamic conditions, the treatment of three typical trace compounds from landfills (L2, D4, and toluene) via the TSA process using activated carbon cloth (ACC). The process was implemented according to temperature programs: one with a moderate desorption temperature (180 °C) and the other with a high desorption temperature (220 °C). Both experiments involved several cycles of adsorption and desorption (60 cycles). In the single-compound adsorption experiment, the adsorption capacities were 24%, 19%, and greater than 15% weight basis for toluene, L2, and D4, respectively. From TSA experiments, it was found that the adsorption capacities of the ACC decreased rapidly over the first four cycles for the two temperature programs. This decrease was lower at high temperatures: no significant decrease was found between the 4th cycle and the 50th cycle. On the contrary, a constant decrease was measured at moderate temperatures. Both the surface analysis (infrared measure) and the analysis of the gas from the desorption step indicate that siloxanes were deposited on the ACC and polymerized to a high-molecular-weight polymer. This reaction could cause ACC deactivation by pore clogging. Mass balances and gas analysis also suggested that toluene could be thermally degraded during the desorption step. The high temperatures promoted desorption of high-molecular-weight compounds, such as D5, L5, and D6, formed during adsorption/desorption processes. Thus, a high-temperature program was found to be more effective than a moderate-temperature program.

Direct surface wetting sprinkler system to reduce the use of evaporative cooling pads in meat chicken production: indoor thermal environment, water usage, litter moisture content, live market weights, and mortalities

An overhead sprinkler system that directly applies water onto meat chickens in tunnel ventilated houses was evaluated and compared with a conventional evaporative cooling pad system at 2 commercial farms in south-eastern Queensland, Australia. The sprinkler system was used to reduce the use of evaporative cooling pads as the primary cooling system but not replace evaporative cooling pads altogether. The sprinkler system used low water pressure and comprised evenly spaced sprinklers and a programmable controller. Water was applied intermittently based on house temperature and a temperature program that was related to bird age. The study was conducted over 6 sequential grow-outs during a 1-year period. Air temperature, relative humidity, litter moisture content, cooling water usage, live market weight, and mortality were assessed during the study. The effect of sprinklers on these measured parameters was complicated by interactions with farm, batch, bird age, and time of day. We found that, in general, houses with combined sprinkler and evaporative cooling pad systems used less water, while having similar litter moisture content, live market weight, and mortality compared with control houses that were fitted with conventional evaporative cooling pads. When evaporative cooling was required, sprinkler houses had warmer air temperature but lower relative humidity than the control houses. Bird comfort due to the direct cooling effect of water evaporating off the birds was not directly assessed during this study but was inferred from thermal camera images and from live weight and mortality data. This was the first study in Australia involving this sprinkler system, and we suggest that the sprinkler system design and operation may require some adaptation to better suit Australian poultry house design and climatic conditions, including the need for additional sprinklers to improve coverage, lower set-point temperatures, and altering sprinkler spacing to suit ceiling baffle curtains (if fitted).

Experimentalstudy on microscopic action of different form moistureon coal spontaneous combustion

Moisture is one of the important factors affecting coal spontaneous combustion. Coal with different moisture contents was prepared to obtain oxidized coal samples at different temperatures through temperature programming. In situ Fourier Transform Spectrometer was used to determine content of active functional groups in different oxidized coal samples, and to study influence of moisture form on formation and transformation of microscopic functional groups during coal spontaneous combustion. Nitrogen adsorber was used to study specific surface area of different oxidized coal samples and influence of form moisture on changes of micro-pore structure during coal spontaneous combustion. Combined with the change law of functional groups and specific surface area, microscopic action of different form moisture on coal spontaneous combustion process was discussed. The action regime of outside moisture varies with the development of coal spontaneous combustion. Different forms of moisture can promote formation of phenols, alcohols, hydroxyl groups, and carbonyl-containing compounds. Effects of moisture form and its content on change of micro-specific surface area, and on evolution of aliphatic C–H components, hydroxyl-containing compounds and carbonyl-containing compounds during spontaneous combustion of coal are different. While effect of moisture form and its content on formation and transformation of hydroxyl-containing compounds and carboxylic acid compounds are similar.

Insight into biomass pyrolysis kinetics: New integral methods for nonisothermal kinetics with exponential temperature program

The exponential temperature change in nonisothermal kinetic analysis is usually used in the experimental investigation of biomass pyrolysis kinetics. In this paper, the applying of exponential temperature change for nonisothermal kinetics of thermally stimulated processes is discussed. Two approximations for the temperature integral occurring in nonisothermal kinetics with exponential temperature program are proposed. These approximations are more accurate in the evaluation of the integral than Gorbachev approximation. Based on the newly proposed approximations, the corresponding integral methods for nonisothermal kinetics with exponential temperature change have been developed. A systematic analysis of the relative errors involved in the kinetic parameters determined from these integral methods has been carried out, the results indicate that the proposed integral methods are more accurate than Gorbachev integral method. It is expected that the results will be helpful for the kinetic analysis of biomass pyrolysis with exponential temperature program.

A simple and fast sample preparation method based on ionic liquid treatment for determination of Cd and Pb in dried solid agricultural products by graphite furnace atomic absorption spectrometry

The Cd and Pb are two typical heavy metal contaminants of agricultural products which have posed great threats to human health. The precise determination of Cd and Pb in agricultural products is extremely important for human health. In this paper, a simple and fast sample preparation method based on ionic liquid treatment was proposed to determine Cd and Pb in dried solid agricultural products by graphite furnace atomic absorption spectrometry (GFAAS). The samples were prepared by dissolving the tested agricultural products into the ionic liquid 1-butyl-3-methylimidazolium chloride. The temperature program and matrix modifiers for GFFAS analysis of these samples were optimized. The reliability of sample preparation was verified by comparing the between- and within-batch precision, which showed no significant differences at 95% confidence level. Detection limits were 0.019 μg L−1 Cd and 0.042 μg L−1 Pb for these samples. Results for determining Cd and Pb in these samples were in good agreement with those obtained from the conventional wet digested samples. Both the certified reference materials validation experiments and the spiked and recovery tests indicated this sample preparation for determining Cd and Pb had satisfactory accuracy and could be an alternative to traditional sample preparation.

Determination of residual solvents in paclitaxel by headspace gas chromatography

BackgroundA simple and sensitive gas chromatographic method was developed and validated for the simultaneous determination of methanol, ethanol, acetone, isopropyl alcohol, dichloromethane, N-hexane, ethyl acetate, tetrahydrofuran, and N,N-diisopropyl ethyl amine in Paclitaxel. A chromatographic separation was done on DB-624 column, 30 m length × 0.53 mm ID, and film thickness 3 μm, using a flame ionization detector (FID) with gradient column oven temperature program. The injection was carried out in split mode, with a split ratio of 5:1. A mixture of N-methyl-2-pyrrolidinone (contains 1% piperazine) and water in the ratio of 80:20 (v/v) was selected as a diluent to obtain good sensitivity along with the recovery.ResultsThe developed gas chromatographic method offers symmetric peak shape, good resolution of more than 2.0 between the solvent peaks, and the relative standard deviation for replicate injections of all the solvents were found to be not more than 15.0% with reasonable retention time for all the solvents. The limit of detection for methanol, ethanol, acetone, isopropyl alcohol, dichloromethane, N-hexane, ethyl acetate, tetrahydrofuran, and N,N-diisopropyl ethyl amine was found to be 304.69 ppm, 497.98 ppm, 498.99 ppm, 504.49 ppm, 61.81 ppm, 30.07 ppm, 505 ppm, 73.05 ppm, and 2.09 ppm, respectively. Limit of quantitation of methanol, ethanol, acetone, isopropyl alcohol, dichloromethane, N-hexane, ethyl acetate, tetrahydrofuran, and N,N-diisopropyl ethyl amine was found to be 89.62 ppm, 146.47 ppm, 146.76 ppm, 148.38 ppm, 18.18 ppm, 8.84 ppm, 148.53 ppm, 21.49 ppm, and 0.62 ppm, respectively. Precision was found to be satisfactory. Linear in the range of LOQ to 150% level for all the solvents, and accuracy along with robustness, is performed, and acceptable results were obtained.ConclusionThe proposed method was demonstrated to be simple, sensitive, specific, linear, precise, accurate, and robust, hence can be used to determine the residual organic solvents in Paclitaxel drug substance and drug product.

Determination of sodium and potassium contents in palm-based polyols using graphite furnace atomic absorption spectrometer

In the production of palm-based polyols (PBP), multiple purification steps might introduce sodium (Na) and potassium (K) into the polyols. The Na and K have potential to influence reactivity of polyether polyols with isocyanate in polyurethane (PU) production. The Na and K contents in polyether polyols for PU production are both limited to 10 mg kg−1. This study focuses on method(s) development for determination of Na and K in PBP by graphite furnace atomic absorption spectrometer (GF AAS) using dilution in isopropyl alcohol as a sample preparation method. All measurements were performed without any chemical modifier. In GF AAS analysis, it is essential to establish the optimum temperature program which includes pyrolysis and atomization temperature. At the optimized condition, the developed method was validated according to the validation protocol described by International Conference on Harmonization (ICH) and AOAC International. Several parameters were evaluated include linearity of calibration curve, limit of detection (LOD), limit of quantitation (LOQ), sensitivity, recovery, and precision. The optimization of temperature program for both Na and K determinations deduced the optimum pyrolysis and atomization temperature of 900 and 1600 °C, respectively. The method for Na determination concludes as follows: the analytical curve showed linear correlation with R2 value of 0.9928. The LOD and LOQ were 0.307 and 1.025 µg kg−1, respectively. Recoveries in the range of 97 to 108% were obtained from spiked samples (4–12 µg kg−1). Whereas, the method for K determination deduces as follows: the analytical curve showed linear correlation with R2 value of 0.9985. The LOD and LOQ were 0.249 and 0.829 µg kg−1, respectively. Recoveries in the range of 90–109% were obtained from spiked samples (4–12 µg kg−1). The Na and K contents obtained from the developed GF AAS method are in agreement with inductively coupled plasma optical emission spectrometry (ICP OES) with 95% confidence level. The Na and K contents in PBP samples were within the limit allowed for PU production.

Determination of As, Bi, Pb, Sb, Sn in copper, nickel and alloys on their base by electrothermal atomization atomic absorption spectrometry (ETAAS)

Copper and nickel-based alloys are widely used in various industrial settings. Their properties directly depend on the impurities and alloying additives present. Therefore, monitoring of their content in the composition of alloys is still an urgent task. Analytical characteristics of the methods used for determination As, Bi, Pb, Sb, and Sn in copper, nickel, and alloys on their base are studied using electrothermal atomic absorption spectrometry (ETAAS) with selective radiation sources, deuterium background correction, longitudinally heated graphite tube, and high-resolution ETAAS with a continuous source and a transversely heated atomizer. The parameters of the temperature program of the atomizer were optimized for both version of the atomic absorption spectrometry. The revealed interfering effect of the matrix (Cu and Ni) of the studied samples significantly distorts the analytical signals of the analytes and results in significant non-selective absorption. It is shown that when constructing calibration dependencies using ETAAS with selective radiation sources, it is necessary to add a matrix component to the calibration solutions, whereas for high-resolution ETAAS it is possible to avoid introduction of the matrix component without increasing the error of analysis. The developed procedures were tested in analysis of the high-purity copper and nickel samples and standard samples of the composition of the alloys based on copper VSM14-5 (rough copper), VSM14-6 (bronze), and nickel VSN2-2. The achieved detection limits for high-resolution ETAAS with a continuous source leveled at n × 10 –5 %, whereas for low-resolution ETAAS with selective radiation sources the detection limits were higher by an order of magnitude. To determine lower concentrations of the elements in such materials, separation of the sample matrix should be used.

Quantitative estimation of Fulvestrant injection 505(j) composition and impurities profile by capillary gas chromatography and HPLC-PDA techniques

We report expedient methods to analyze the inactive and active ingredients and other impurities in Fulvestrant injection, using gas chromatography and high-performance liquid chromatography. The levels (LOQ to 150%) of Fulvestrant and related impurities were quantified using HPLC. A gradient temperature program was employed to reduce the analysis time and improve the peaks' resolution in the present study. The separation of impurities was achieved on the symmetry C8 column and maintained temp at 35 °C. The injection volume was 10 µL, and detection was made at 225 nm. For GC method used the DB-Wax column. Helium as a carrier with a flow rate of 5.0 mL min−1. The injector inlet temperature and FID temperature were maintained at 220 °C and 280 °C, respectively. Both methods exhibited excellent intra- and inter-day precision, with RSD 0.999. The methods were validated for linearity, precision, specificity, accuracy, and robustness for their intended purpose as per the current ICH guidelines. Finally, both the techniques were used in the quality control lab to estimate the solvents and impurities of reference listed drug and in house samples.

Investigation of cadmium and lead contents of boron minerals and boron waste by electrothermal atomic absorption spectrometer

In this study, Cd and Pb were determined and investigated in the most abundant boron minerals such as colemanite, tincal, ulexite and boron waste existed in Turkey using electrothermal atomic absorption spectrometer. Graphite furnace temperature program for Cd and Pb determinations in samples was optimized in the absence or presence of palladium (Pd) and nickel (Ni) + Pd matrix modifier mixture. Pd + Ni modifier mixture was found to be more suitable for both Cd and Pb. The ashing temperatures for Cd and Pb obtained 600 °C and 1100 °C, respectively, in the presence of Ni + Pd mixture. Limits of detection and limits of quantification values for Cd and Pb in the absence or presence of Ni + Pd modifier mixture were determined. Accuracy and precision of the method proposed were checked by analyzing the standard reference materials (Montana Soil 2711 and Estuarine 1646a). Cd and Pb in boron minerals were performed under optimized experimental conditions.

Chromatography Advancements: Analytical Separation Techniques

Possibly the main difficulties in chromatography invaluable for its application is to diminish the time required for detachment without losing any goal power. Quick GC utilizes different instruments: (I) changing the components of the segment (for example decreasing its length, interior measurement, and film thickness), (II) utilizing a higher transporter gas stream, (III) bringing down the pressing factor at the chromatograph outlet, (IV) expanding the underlying temperature or potentially the warming incline in the temperature program.

Polychlorinated Biphenyls in Groundwater of Grombalia: Optimization and Validation of Analytical Procedures Using Gas Chromatography with Electron Capture Detector

Now-a-days, the management of water resources is one of the main global challenges, both at the level of agricultural and industrial activities as well as direct consumption and poses various problems of both qualitative and quantitative order. In the entire world, groundwater suffers from various sources of contamination principally due to overusing of chemical fertilizer in the agricultural sector. The contamination of groundwater by organochlorines and more precisely by polychlorinated biphenyls (PCBs) is a problem of global order. As we know that Tunisia is based on agriculture work like citrus, olive, wheat and cereal, the study of water pollution is a topical subject that remains unclear. Polychlorinated Biphenyls (PCBs) are one class of persistent organic pollutants. PCBs in recent decades have attracted the attention of scientific and policy maker communities due to their persistence, their high capacity to bioaccumulation in the food chain and their toxic properties. This work is aimed to develop an efficient method for the analysis of targeted PCBs in groundwater sample taken from the region of Grombalia. Optimization of PCBs extraction was performed with applied the experimental design of Dohlert with two factors, solvent and number of extractions. Analysis of PCBs was performed with gas chromatography coupled with electron capture detector (GC-ECD) with an optimization of temperature program. Results shows that the optimal temperature program was obtained with a starting temperature of 160°C up to 280°C during 10 min with a rate of 4°C min-1 and the optimal condition of extraction was obtained with a mixture of hexane/ether (75/25%) and a three time extractions. The optimized method has been applied to the analysis of the PCBs in nine groundwater samples collected from the Grombalia city. Results indicate that PCBs concentrations varied between 5.2 μgL-1 and 169 μgL-1. However, the maximum acceptable concentration (MAC) in drinking and surface water recommended by EPA is 0.5 μgL-1 with a detection limit (LD) ranged between 0.05 to 1.9 μg L-1.