• Analytical Science and Technology
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• v.36 no.6
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• pp.259-266
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• 2023

The demand for rare-earth elements (REEs) is increasing owing to their significance as prominent materials in electronics, high-tech industries, geological research, nuclear forensics, and environmental monitoring. In general, the utilization of REEs in various applications requires the use of chromatographic techniques to separate individual elements. However, REEs have similar physicochemical properties, which makes them difficult to separate. Recently, several studies have examined the separation of REEs using LN resin as the stationary phase and aqueous nitric acid and hydrochloric acid solutions as eluents. Using this method, light REEs have been separated using dilute acid solutions as the eluent, whereas heavy REEs are separated using solutions with high acid concentrations. To increase the separation resolution between different REEs, either the column length or resin size is changed. In addition, the suggested methods are implemented to decrease the analysis time. This review presents technical information on the chromatographic separation of REEs using the LN resin and discusses the optimal experimental conditions.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.6
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• pp.495-499
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• 2004

The analyses of peak shapes in chromatography are useful in operating chroma­tographic system. The asymmetry and sharpness of a chromatographic peak are estimated by the reversed-phase adsorption of two standard peptides (angiotensin II bradykinin) on $C_{18}$ In this work, the average particle diameters of $C_{18}$ were 5 and 15 $\mu$m, while the pore sizes were 100 and 300 A. The composition of the mobile phase was $50/50\;vol.\;{\%}$ of a binary mixture of acetonitrile and water with $0.1\%$ TFA, and the particles were packed in a stainless column ($4.6{\times}150$ mm). The third and the fourth central movement were calculated from the chromatographic elution curves by moment analysis. The peak asymmetry was determined by two theoretical calculations: the asymmetry factor by elution peak analysis and skewness with moment analysis. The sharpness was estimated by the fourth central moment. In this work, the most acceptable skewness was calculated when the pore size was 300 A. The large excess was observed on small pore size.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.475-479
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• 1996

Diethylcarbamazine (DEC, 1-diethylcarbamyl-4-methylpiperazine) is an antiparasitic piperazine derivative used in the treatment of lymphatic filariasis caused by Wuchereria bancrofti, Brugia malayi or grugia timori. DEC-N-oxide is a major metabolite in humans and has antifilarial activity. In carrying out pharmacokinetic studies, gas chromatographic analysis of DEC in plasma can be complicated by the presence of the metabolite, since the thermally unstable DEC-N-oxide is converted back to a material which coelutes with DEC under the conditions of the analysis. We now report a method to separate DEC-N-oxide from DEC in plasma using solid phase extraction with subsequent gas chromatographic analysis using a nitrogen specific detector. One-diethylcarbamyl-4-ethylpiperazine (E-DEC) was the internal standard. The standard curve of DEC was linear in the range of 10 to 200 ng/ml as described by Y=0.0350+0.0128X, $R^2=0.999$. The limit of quantitation was 4 ng/mL. Reproducibility at 10, 100 and 200 ng/mL concentration points of the standard curve gave coefficient variations of 6.1%, 7.8% and 1.6%, respectively. The recovery following solid phase extraction was 99.3% for DEC and 94.8% for the internal standard. This sensitive and specific analytical method is suitable for pharmacokinetic studies of DEC.

• Applied Biological Chemistry
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• v.35 no.1
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• pp.36-41
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• 1992

Several commercial cottonseed, corn and rapeseed oils were stored at $60^{\circ}C\;and\;70^{\circ}C$ with daily exposure of fluorescent light for 12 hours and evaluated their rancidity by headspace gas chromatographic analysis of pentanal and hexanal. The data of gas chromatographic analysis was compared with organoleptic flavor evaluation. For headspace gas chromatographic analysis, the volatile compounds were recovered by porous polymer trap and flushed into a fused silica capillary column at $250^{\circ}C$. Twenty-three GC peaks were identified on the basis of relative retention time of reference compounds and gas chromatography-mass spectrometry. The results showed that the contents of pentanal and hexanal were linearly increased during storage. A very simple linear relationship was found between organoleptic flavor scores and amounts of two volatile compounds with very high correlation coefficient. This results suggested the possible implication of pentanal and hexanal as an quality index for rancidity evaluation of cottonseed, corn and rapeseed oils.

• Korean Journal of Food Science and Technology
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• v.17 no.5
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• pp.355-360
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• 1985

Soybean, hydrogenated soybean and corn oils, which were exposed to fluorescent light for different periods of time, were evaluated for sensory qualities by subjective sensory evaluation and instrumental gas chromatographic analysis. Sensory evaluation was conducted in 8 laboratories using a 10-point hedonic scale with a total of 95 panel members. The correlation coefficients between sensory scores and predicted sensory scores by gas chromatographic analysis for the 8 laboratories varied from 0.10 to 0.99. However, most laboratories had better than 0.90, which was considered excellent. The correlation coefficients between sensory scores of the 95 panel members and predicted sensory scores using the amount of 2. 4-decadienal isomers in oil determined by a gas chromatographic method for soybean, hydrogenated soybean, and corn oils, were r=0.96, r=0.97, and r=0.97, respectively. The correlation study suggests that it is possible to obtain realistic results of oil flavor qualities from the instrumental evaluation by combining improved gas chromatographic analysis, sensory evaluation, and statistical analysis for practical purposes.

• Bulletin of Food Technology
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• v.24 no.1
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• pp.2-17
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• 2011

• Journal of the Korea Society of Computer and Information
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• v.21 no.5
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• pp.167-175
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• 2016

The volatile component analysis of 82 commercialized liquors(44 samples of single malt whisky, 20 samples of blended whisky and 18 samples of brandy) was carried out by gas chromatography after liquid-liquid extraction with dichloromethane. Pattern recognition techniques such as principle component analysis(PCA), cluster analysis(CA), linear discriminant analysis(LDA) and partial least square discriminant analysis(PLSDA) were applied for the discrimination of different liquor categories. Classification rules were validated by considering sensitivity and specificity of each class. Both techniques, LDA and PLSDA, gave 100% sensitivity and specificity for all of the categories. These results suggested that the common characteristics and identities as typification of whiskies and brandys was founded by using multivariate data analysis method.

• Journal of Pharmaceutical Investigation
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• v.9 no.4
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• pp.1-7
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• 1979

The analytical method of phenobarbital and mephobarbital in the pharmaceutical preparation were investigated by the partition chromatographic method. The influence of 13 kinds of excipients and various kinds of ingredients such as 8 kinds of antipyretics and 5 kinds of antacids on the partition chromatographic analysis of phenobarbital and mephobarbital in the preparation were investigated. The results were not affected by materials with the exception of caffeine, aspirin and sulpyrin.

• Korean Journal of Clinical Pharmacy
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• v.5 no.2
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• pp.71-74
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• 1995

A high performance liquid chromatographic method has been developed for the simultaneous analysis of non-steroidal anti-inflammatory drugs in plasma. The simultaneous determination of ibuprofen, fenoprofen and ketoprofen is performed by RP-HPLC with UV detection. The chromatographic system consisted of Spherisorb octyl column$(5{\mu}m)$ ; the mobile phase was $acetonitrile\;-\;0.5\%$ phosphoric acid(55 : 45, v/v) and the detection wavelength was 230nm. Tolmetin was employed as an internal standard. The method described is rapid and simple with sensitivity limits of $2.0{\mu}g/ml$ ibuprofen, $0.5{\mu}g/ml$ fenoprofen and $0.3{\mu}g/ml$ ketoprofen and is suitable for routine clinical and pharmacokinetic studies.

• FOCUS: LIFE SCIENCE
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• no.1
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• pp.7.1-7.4
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• 2024

The document "Understanding the Relationship Between Particle Size, Performance, and Pressure" explores the impact of particle size on chromatographic performance and system pressure. The study highlights how smaller particles can improve separation efficiency by providing higher resolution and faster analysis times. However, this comes at the cost of increased backpressure, which can challenge the system's hardware and require higher operating pressures. The document discusses the balance needed between particle size, column dimensions, and system pressure to optimize performance without exceeding the pressure limits of chromatographic systems. It outlines the advantages of using superficially porous particles (SPPs) over fully porous particles (FPPs) in achieving high efficiency with lower backpressure. The study also emphasizes the importance of selecting appropriate column dimensions and flow rates to manage system pressure while maintaining optimal performance. In conclusion, understanding the interplay between particle size, performance, and pressure is crucial for optimizing chromatographic separations, ensuring system longevity, and achieving high-quality analytical results.