• Journal of Dairy Science and Biotechnology
• /
• v.31 no.1
• /
• pp.59-65
• /
• 2013

Antibiotic residues are undesirable in milk and milk products for a number of reasons. In particular, they can have harmful effects on public health and harm to the manufacturer of the cultured milk products, e.g. MRSA etc. Although government regulatory agencies and the dairy industry have been successful in decreasing the presence of high concentrations of antibiotic residues, violations still occur and lead to contaminated products. As a result, several rapid and reliable methods for the detection of antibiotic residues have been developed, including microbiological and instrumental analysis methods. The conventional methods are time consuming, but recent improvements have allowed for better detection time, sensitivity, and accuracy. An example of an advanced detection instrument is the biosensor, which has several applications in food and environmental science, e.g. food-born pathogen detection, antimicrobial residues etc. In the present review, the recent trends in the methods used to test for antibiotic residues in milk and dairy products, as well as their specific applications, have been discussed.

• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.739-744
• /
• 1995

The two main methods to prepare water samples for analyzing volatile organic compounds(VOC's) were investigated. One is the purge and trap(PT) method and another is the head space(HS) sampling method. Both methods were effective to transfer the low boiling point components from the water sample onto the capillary column. The cryo-focusing at the top of the main capillary column was an effective way to obtain the sharpness of the chromatographic peaks but could be avoided when a semi-wide bore column was used. The recovery from the same amount of the sample was better in PT than in HS but a larger sample volume in HS method could compensate the lower efficiency. Therefore PT is suitable to the analysis of drinking water where the very low concentration must be determined. HS is suitable to waste water analysis because of the easiness of the operation. The repeatability was good and similar in both methods. For the contamination of the former sample, both methods were tough and could be used without any problems. The matrix effect which could change the equilibrium parameters in HS method was find negligible in many components. The actual samples such as tap water and river water were analyzed with both methods concerning 16 components regulated in Korea.

• Analytical Science and Technology
• /
• v.15 no.1
• /
• pp.72-79
• /
• 2002

Di-(2-ethylhexyl)phthalate (DEHP) may be released from plasticized poly(vinyl chloride) (PVC) articles. In the cases of various methods for the quantitative analysis of migrating DEHP, there are much differences in migrating quantity according to the experimental methods. It is therefore important to make the comparison and analysis between these two results. A study of DEHP migration from blood and infusion bags has been carried out in different methods to evaluate the amount of DEHP migration using gas chromatograph and UV-vis spectrophotometry. Five PVC bags were cut into plane sheets in size of $40{\times}10{\times}0.4mm$, then were immersed in extraction solvent for an hour to release DEHP. It was determined by a gas chromatograph that $23.2{\sim}70.9{\mu}g/mL$ of DEHP was extracted. While extraction solvent was injected into PVC bags which were then placed for an hour to leach DEHP out. It was checked by a UV-vis spectrophotometer that the concentration of DEHP in extraction solvent was $24.8{\sim}41.3{\mu}g/mL$. Two results show different values according to the extraction conditions and experimental methods and the gas chromatographic results were converted into UV-vis spectroscopic results on condition that DEHP would be extracted equally per unit time and unit contact area. It was concluded that DEHP migrating amounts are approximately equal in two analytical methods.

• Environmental Analysis Health and Toxicology
• /
• v.29
• /
• pp.16.1-16.9
• /
• 2014

Objectives Rapid increase in engineered nanoparticles (ENPs) in many goods has raised significant concern about their environmental safety. Proper methodologies are therefore needed to conduct toxicity and exposure assessment of nanoparticles in the environment. This study reviews several analytical techniques for nanoparticles and summarizes their principles, advantages and disadvantages, reviews the state of the art, and offers the perspectives of nanometrology in relation to ENP studies. Methods Nanometrology is divided into five techniques with regard to the instrumental principle: microscopy, light scattering, spectroscopy, separation, and single particle inductively coupled plasma-mass spectrometry. Results Each analytical method has its own drawbacks, such as detection limit, ability to quantify or qualify ENPs, and matrix effects. More than two different analytical methods should be used to better characterize ENPs. Conclusions In characterizing ENPs, the researchers should understand the nanometrology and its demerits, as well as its merits, to properly interpret their experimental results. Challenges lie in the nanometrology and pretreatment of ENPs from various matrices; in the extraction without dissolution or aggregation, and concentration of ENPs to satisfy the instrumental detection limit.

• Analytical Science and Technology
• /
• v.13 no.3
• /
• pp.277-281
• /
• 2000

The solid phase microextrction (SPME) fiber which contains $100{\mu}m$ polydimethyl siloxane of a stationary phase was used for the analysis of volatile organic compounds contained in aqueous solution. sixteen volatile organic compounds, which were spiked in blank water and extracted by the headspace SPME techique, were analyzed by gas chromatography/mass spectrometry (GC/MS). Analytical results showed that the percent of average recoveries and relative standard deviations were 97% and 4.7%, respectively. The value of detection limit was ranged from 0.01 to $0.5{\mu}g/l$. These results are more accurate than those obtained by the other methods such as purge and trap and headspace methods.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.03a
• /
• pp.198-207
• /
• 2010

Many methods and techniques have been developed to obtain the accurate design parameters in soft soils. In particular, several researchers suggest the techniques to get the void ratio for understanding the soil behavior. The objective of this paper verifies the accuracy of the proposed analytical solution for determining the void ratio based on the elastic wave velocities. The paper covers the theories of Wood, Biot, Gassmann and Foti proposed chronological order. The total theory represents the wave propagation in fully saturated medium. To verify the proposed analytical solution, the laboratory and field tests are carried out. After measuring the elastic wave, the void ratios are assessed using proposed equation. The volume based void ratios are also obtained for comparing with the estimated value by several equations. The values estimated by volume, Gassmann and Biot are show good similarity. However, the void ratios based on Wood and Foti methods have a slightly different trend. This study suggests that the theories of Biot and Gassmann may be a useful equation for assessing the void ratio using elastic wave velocities in the field.

• Advances in concrete construction
• /
• v.1 no.4
• /
• pp.319-340
• /
• 2013

This paper presents a comparative study on the double-K fracture parameters of concrete obtained using four existing analytical methods such as Gauss-Chebyshev integral method, simplified Green's function method, weight function method and simplified equivalent cohesive force method. Two specimen geometries: three point bend test and compact tension specimen for sizes 100-500 mm at initial notch length to depth ratios 0.25 and 0.4 are used for the comparative study. The required input parameters for determining the double-K fracture parameters are derived from the developed fictitious crack model. It is found that the cohesive toughness and initial cracking toughness determined using weight function method and simplified equivalent cohesive force method agree well with those obtained using Gauss-Chebyshev integral method whereas these fracture parameters determined using simplified Green's function method deviates more than by 11% and 20% respectively as compared with those obtained using Gauss-Chebyshev integral method. It is also shown that all the fracture parameters related with double-K model are size dependent.

• Analytical Science and Technology
• /
• v.25 no.4
• /
• pp.214-222
• /
• 2012

ASTM (American Society for Testing and Materials) D6751-10 suggests analytical methods as well as specifications for biodiesel quality. However, it is expensive and time-consuming to follow the ASTM testing methods to analyze biodiesel and various impurities. This paper develops a quantitative analysis system for biodiesel and impurities based on Infrared spectroscopy and a multivariate statistical method, PLS (partial least squares). In addition, four different pre-processing techniques were compared for spectrum correction and noise reduction. Savitzky-Golay pre-processing showed the best performance.

• Journal of Korean Society for Atmospheric Environment
• /
• v.27 no.4
• /
• pp.436-442
• /
• 2011

In this study, the Total Volatile Organic Compounds (TVOC) emitted from wood-based panels were compared by two analytical methods using the GC/FID and the GC/MS. Japanese Larch, Yellow Poplar, Particle Board (PB) and Medium Density Fiberboard (MDF) were selected as target materials. Major compounds emitted from the panels were Toluene, ${\alpha}$-pinene, ${\beta}$-pinene and limonene. In case of TVOC using GC/FID method, MDF E2 (1,497 ${\mu}g/m^3$) revealed the highest concentration among all wood-based panels, while Japanese Larch (1,772 ${\mu}g/m^3$) showed the highest value with respect to GC/MS method. Furthermore, it was found that the amount of VOC emitted from panels was different depending upon analytical methods. This significant difference was attributed to analytical sensitivities of GC/FID and GC/MS for various VOC. Besides, it was found that the composition ratios of main VOC compounds were not significantly different.

• Analytical Science and Technology
• /
• v.7 no.4
• /
• pp.441-453
• /
• 1994

Two extraction methods, liquid-liquid extraction(LLE) and solid-phase extraction(SPE), coupled with GC/MS were compared as preconcentration procedures for priority pollutants in water. Among the semi-volatile priority pollutants, 11 acid and 44 base/neutral compounds were spiked in reagent water. With LLE, which is a modification of EPA Method 625, the overall mean recovery of the 54 compounds was 91% with a mean relative standard deviation(RSD) of 4.6%. With SPE, the overall mean recovery of the 52 compounds was 53% with a mean RSD of 8.9%. The detection limits of both methods were in the range of $1{\sim}5{\mu}g/l$.