Analytical Methods Based on the Mass Balance Approach for Purity Evaluation of Tetracycline Hydrochloride.

Analytical methods based on the mass balance approach were developed for the purity evaluation of tetracycline hydrochloride, a representative salt compound used in pure veterinary drug analysis. The purity assignment method was used to quantify individual classes of impurities via independent analytical techniques. The mass fraction of the free base or salt form contained in a high-purity organic compound with a hydrochloride salt can be determined. The chloride content by ion chromatography-conductivity detector (IC-CD) and general classes of impurities, including structurally related impurities by liquid chromatography-ultraviolet (LC-UV) detector, water by Karl Fischer (KF) coulometric titration, residual solvents by headspace sampler gas chromatography/mass spectrometry (HS-GC/MS), and non-volatiles by thermogravimetric analyzer (TGA), were considered to calculate the purity of the mass fraction. The chloride content of the salt compound can be considered the main impurity in the mass fraction of the free base in the salt compound. A purity assay using quantitative nuclear magnetic resonance (q-NMR) as a direct determination method was performed to confirm the results of the mass balance method. The assigned purities of the tetracycline free form and its salt form in mass fraction were (898.80 ± 1.60) mg/g and (972.65 ± 1.58) mg/g, respectively, which are traceable to the international system of units (SI). Thus, the procedure for evaluating the purity of the free base and salt forms in the salt compound is newly demonstrated in this study.

Accurate determination of 11 representative phthalates and di(2-ethylhexyl) terephthalate in polyvinyl chloride using isotope dilution-gas chromatography/mass spectrometry.

Phthalates are mainly used as plasticizers in polyvinyl chloride (PVC). However, prolonged exposure to phthalates poses considerable risks to human health. Consequently, the utilization of phthalates in consumer products is subject to regulations, with a defined threshold of 0.1 %. In this study, we developed an accurate and simultaneous method for determination of 11 representative phthalates and a non-phthalate plasticizer (di(2-ethylhexyl) terephthalate, DEHT) in PVC as a higher-order reference method. Homogeneously prepared PVC samples, each containing approximately 0.1 % of the target plasticizer compounds, were analyzed using gas chromatography-mass spectrometry (GC-MS) with deuterium-labeled phthalates and DEHT. The developed method could effectively separate and quantify all target plasticizers without interference with each other and potential overlap between the isomeric forms of phthalates, di-isodecyl phthalate, and di-isononyl phthalate. The developed method has high-order metrological quality, exhibiting exceptional selectivity, accuracy, repeatability (≤ 2.17 %), reproducibility (≤ 2.16 %), and relative expanded uncertainty (≤ 5.6 %). This analytical method is thus suitable for accurately assessing the target plasticizer levels in PVC products for ensuring compliance with the established 0.1 % threshold. This method was successfully applied to quantify twelve distinct plasticizers in PVC products obtained from the Korean market, validating its effectiveness and reliability in real-world scenarios.

Development of a certified reference material for the accurate analysis of the acrylamide content in infant formula.

A certified reference material (CRM), KRISS CRM 108-02-006, was developed for the accurate analysis of low levels of acrylamide in infant formula matrices. The CRM is an infant formula fortified with acrylamide at a similar level as that stipulated by the European Union regulation for baby food. Commercially available infant formulas were processed by freeze-drying, and the subsequent homogenization of the fortified material to produce 961 bottles of the CRM in one batch. The CRM bottles containing approximately 15 g of the material in each unit were stored in a storage room at - 70 ℃. High-purity acrylamide was used as the primary reference material, and its purity was assessed using an in-house mass-balance method to obtain results metrologically traceable to the International System of Units. The acrylamide content of the infant formula CRM was evaluated using isotope dilution-liquid chromatography/mass spectrometry as a reference method, which was established by our research group. An acrylamide content of 55.7 ± 2.1 µg/kg was assigned as the certified value of the CRM with the expanded uncertainty at a 95% confidence level. The homogeneity study showed good uniformity of the acrylamide content among units, providing a relative standard deviation of 1.2% of the mean value. A stability study was also performed by monitoring the CRM under different temperature conditions and periods. The stability results indicated that the acrylamide content in the CRM under the storage conditions of - 70 ℃ remained stable for up to 10 months.

Development of a certified reference material for the accurate determination of type B trichothecenes in corn.

A corn flour certified reference material (KRISS CRM 108-01-011) was developed to ensure accurate and reliable measurements of type B trichothecenes (deoxynivalenol, nivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol), and deoxynivalenol-3-glucoside. The material was freeze-dried, ground, sieved, and well-mixed. The final produced CRM was packaged at 14 g per unit and stored at -70 °C. The certification was performed using isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS). For simultaneous characterization and homogeneity assessments, ten units were randomly selected and analyzed. The among-unit relative standard deviations were below 1 % for all mycotoxins, indicating excellent homogeneity of the CRM. The stability of the CRM was also assessed at various designated temperatures and test periods. The uncertainties of the certified values varied between 2.4 % and 6.2 %, thereby confirming their higher-order metrological quality to provide references for testing laboratories. In case of deoxynivalenol-3-glucoside, an information value was assigned due to the lack of its traceability to the SI units.

Anti-Obesity Effects of Polymethoxyflavone-Rich Fraction from Jinkyool (Citrus sunki Hort. ex Tanaka) Leaf on Obese Mice Induced by High-Fat Diet.

Polymethoxyflavones (PMFs) are flavonoids exclusively found in certain citrus fruits and have been reported to be beneficial to human health. Most studies have been conducted with PMFs isolated from citrus peels, while there is no study on PMFs isolated from leaves. In this study, we prepared a PMF-rich fraction (PRF) from the leaves of Citrus sunki Hort ex. Tanaka (Jinkyool) and investigated whether the PRF could improve metabolic decline in obese mice induced by a high-fat diet (HFD) for 5 weeks. The HFD-induced obese mice were assigned into HFD, OR (HFD + orlistat at 15.6 mg/kg of body weight/day), and PRF (HFD + 50, 100, and 200 mg/kg of body weight/day) groups. Orlistat and PRF were orally administered for 5 weeks. At the end of the experiment, the serum biochemical parameters, histology, and gene expression profiles in the tissues of each group were analyzed. The body weight gain of the obese mice was significantly reduced after orlistat and PRF administration for 5 weeks. PRF effectively improved HFD-induced insulin resistance and dyslipidemia. Histological analysis in the liver demonstrated that PRF decreased adipocyte size and potentially improved the liver function, as it inhibited the incidence of fatty liver. PRF activated AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), and hormone-sensitive lipase (HSL) in HFD-induced obese mice. Moreover, liver transcriptome analysis revealed that PRF administration enriched genes mainly related to fatty-acid metabolism and immune responses. Overall, these results suggest that the PRF exerted an anti-obesity effect via the modulation of lipid metabolism.

Method development for accurate determination of eight polycyclic aromatic hydrocarbons in extruded high-impact polystyrene.

An analytical method was developed for the accurate determination of eight polycyclic aromatic hydrocarbons (PAHs) in extruded high-impact polystyrene (HIPS) as a higher-order reference method. Uncleaned HIPS matrix rendered the accurate quantitation impossible and hampered the repeatability of the gas chromatography/mass spectrometry (GC/MS) measurement. This led to a bias in the results and increased the measurement uncertainty. Extracts were sufficiently purified through a two-step process: (i) dissolution and precipitation and (ii) molecularly imprinted polymers-solid phase extraction for clean-up. Co-elution of indeno(1,2,3-cd)pyrene (IP), dibenz(a,h)anthracene (DBahA), and their 13C6-labeled isotopes resulted in a bias in the area ratios of IP/13C6-IP and DBahA/13C6-DBahA, thus increasing the measurement uncertainty. An optimized GC condition using an Rxi-PAH column improved the peak separation of IP and DBahA and their isotopes, thus improving the quality of the measurement. The optimized method was validated using PAH (0.36-0.45 mg/kg)-containing HIPS pellets. The optimized method had excellent repeatability (<2%) and reproducibility (<3%) for concentrations less than 0.5 mg/kg of the eight PAHs in HIPS. Using the optimized method, the relative expanded uncertainties for all the target PAHs were below 5% (with a 95% level of confidence).

Clerodendrum trichotomum extract improves metabolic derangements in high fructose diet-fed rats.

Clerodendrum trichotomum has been reported to possess beneficial properties for human health, but its effects on metabolic syndrome have not been reported. In this study, we investigated the effect of C. trichotomum leaf extract (CT) on the metabolic derangements induced by a high-fructose (HF) diet. Sprague-Dawley rats were fed with a 46% carbohydrate diet (HC group), 60% high-fructose diet (HF group), or HF diet supplemented with CT (500 mg/kg of body weight/day, CT group) via drinking water for 16 weeks. Results showed that CT alleviated HF diet-induced insulin resistance, dyslipidemia, and hepatic steatosis In liver tissues, CT affected the signaling pathways of AMP-activated protein kinase, peroxisome proliferator-activated receptor α (PPARα), and sterol regulatory element binding protein 1. CT enriched the genes that were mainly involved in cytokine-cytokine receptor interaction, PPAR, PI3K-Akt signaling pathways, and fatty acid metabolism pathway. These results suggest that CT is a promising therapeutic against metabolic disorders.

Sasa quelpaertensis Leaf Extract Ameliorates Dyslipidemia, Insulin Resistance, and Hepatic Lipid Accumulation in High-Fructose-Diet-Fed Rats.

BACKGROUND: Increased dietary fructose consumption is closely associated with lipid and glucose metabolic disorders. Sasa quelpaertensis Nakai possesses various health-promoting properties, but there has been no research on its protective effect against fructose-induced metabolic dysfunction. In this study, we investigated the effects of S. quelpaertensis leaf extract (SQE) on metabolic dysfunction in high-fructose-diet-fed rats. METHODS: Animals were fed a 46% carbohydrate diet, a 60% high-fructose diet, or a 60% high-fructose diet with SQE (500 mg/kg of body weight (BW)/day) in drinking water for 16 weeks. Serum biochemical parameters were measured and the effects of SQE on hepatic histology, protein expression, and transcriptome profiles were investigated. RESULTS: SQE improved dyslipidemia and insulin resistance induced in high-fructose-diet-fed rats. SQE ameliorated the lipid accumulation and inflammatory response in liver tissues by modulating the expressions of key proteins related to lipid metabolism and antioxidant response. SQE significantly enriched the genes related to the metabolic pathway, namely, the tumor necrosis factor (TNF) signaling pathway and the PI3K-Akt signaling pathway. CONCLUSIONS: SQE could effectively prevent dyslipidemia, insulin resistance, and hepatic lipid accumulation by regulation of metabolism-related gene expressions, suggesting its role as a functional ingredient to prevent lifestyle-related metabolic disorders.

Serial optical coherence microscopy for label-free volumetric histopathology.

The observation of histopathology using optical microscope is an essential procedure for examination of tissue biopsies or surgically excised specimens in biological and clinical laboratories. However, slide-based microscopic pathology is not suitable for visualizing the large-scale tissue and native 3D organ structure due to its sampling limitation and shallow imaging depth. Here, we demonstrate serial optical coherence microscopy (SOCM) technique that offers label-free, high-throughput, and large-volume imaging of ex vivo mouse organs. A 3D histopathology of whole mouse brain and kidney including blood vessel structure is reconstructed by deep tissue optical imaging in serial sectioning techniques. Our results demonstrate that SOCM has unique advantages as it can visualize both native 3D structures and quantitative regional volume without introduction of any contrast agents.

Development of candidate reference method for accurate determination of four polycyclic aromatic hydrocarbons in olive oil via gas chromatography/high-resolution mass spectrometry using 13C-labeled internal standards.

We developed an isotope-dilution gas chromatography/high-resolution mass spectrometry (ID-GC/HRMS) method for the accurate determination of four polycyclic aromatic hydrocarbons (PAHs) in olive oil. The clean-up steps were optimized to sufficiently remove co-extracted oil matrix using the EZ-POP NP dual-layer and NH2 solid-phase extraction (SPE) cartridges. However, the cleaned sample still contained some matrix residues, which caused a bias. When 13C-labeled PAHs were used as the internal standards instead of deuterated PAHs, the recovery results improved in both low- and high-resolution MS conditions. Furthermore, the HRMS analysis facilitated to obtain more accurate results. The accuracy and precision of the optimized ID-GC/HRMS method were validated using PAH-fortified (0.5, 3, and 6 µg/kg) olive oil. The recoveries and relative standard deviations obtained for all the PAHs/levels were 97.5-102% and ~1%, respectively. Measurement uncertainties were generally within 5% (with a 95% confidence level).

Development of an infant formula certified reference material for the analysis of organic nutrients.

Infant formula certified reference material (CRM, KRISS CRM 108-02-003) were developed for the analysis of organic nutrients. The CRM is a milk-based infant formula powder, packaged at 14 g per unit. Ten thousand units were prepared and stored at -70 °C. For the certification of each nutrient, ten units were analyzed for simultaneous value-assignment and homogeneity test. Analytical methods used were isotope dilution mass spectrometry (IDMS) based on liquid chromatography mass spectrometer (LC/MS) or gas chromatography mass spectrometer (GC/MS) as higher-order reference methods.13 vitamins, 3 fatty acids, and total cholesterol were certified. The between-unit relative standard deviation of measurement results for each nutrient ranged 0.2% to 2.5%, showing very good homogeneity. The expanded relative uncertainties of the certified values ranged from 1% to 8%, indicating that they have higher-order metrological quality. The values of proximates (proteins, lipids, carbohydrates, water, and ash) were assigned through inter-laboratory comparisons.

Accurate determination of hexabromocyclododecane diastereomers in extruded high-impact polystyrene: Development of an analytical method as a candidate reference method.

Herein, an isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) method was developed as a candidate reference method for the accurate quantitation of hexabromocyclododecane (HBCDD) diastereomers in plastics. The repeatability, reproducibility, and uncertainty results showed that developed ID-LC/MS/MS method is reliable and reproducible. As homogeneous samples, HBCDD-containing extruded high-impact polystyrene (HIPS) pellets were fabricated via an extrusion process. Notably, we detected α-, ß-, γ-, δ-, ε-, η-, and θ-HBCDDs in the extruded HIPS pellets, and then determined their exact mass fractions using the ID-LC-MS/MS method. The relative contents (average ±â€¯standard deviation) of HBCDD diastereomers in HIPS obtained using the phenyl-hexyl column were 67.08 ±â€¯0.41% (α-HBCDD), 19.73 ±â€¯0.37% (ß-HBCDD), 11.59 ±â€¯0.16% (γ-HBCDD), and 1.6 ±â€¯0.07% (sum of δ-, ε-, η-, and θ-HBCDDs). These values differed significantly from the ones determined for the technical HBCDD mixtures (10.42% α-HBCDD, 5.30% ß-HBCDD, 82.13% γ-HBCDD, 2.15% minor HBCDDs) used to fabricate the HIPS pellets and thus demonstrating the HBCDD isomerization during the extrusion. The proportion of minor HBCDDs was smaller than the uncertainty of the total HBCDD and that the sum of α-, ß-, and γ-HBCDDs was comparable to the total HBCDD in the investigated samples. Notably, a real-life sample (expanded polystyrene board obtained from a local construction site) also showed a similar HBCDD profile, being rich in α-HBCDD.

Optical properties of acute kidney injury measured by quantitative phase imaging.

The diagnosis of acute kidney disease (AKI) has been examined mainly by histology, immunohistochemistry and western blot. Though these approaches are widely accepted in the field, it has an inherent limitation due to the lack of high-throughput and quantitative information. For a better understanding of prognosis in AKI, we present a new approach using quantitative phase imaging combined with a wide-field scanning platform. Through the phase-delay information from the tissue, we were able to predict a stage of AKI based on various optical properties such as light scattering coefficient and anisotropy. These optical parameters quantify the deterioration process of the AKI model of tissue. Our device would be a very useful tool when it is required to deliver fast feedback of tissue pathology or when diseases are related to mechanical properties such as fibrosis.

Separation of hexabromocyclododecane diastereomers: Application of C18 and phenyl-hexyl ultra-performance liquid chromatography columns.

This study was performed to establish the proper liquid chromatographic conditions for the separation of hexabromocyclododecane (HBCD) diastereomers. Column selectivity towards HBCD diastereomers was evaluated for C18 and phenyl-hexyl stationary phases. First, the baseline separation of the primary HBCDs (α-, ß-, and γ-HBCD) was obtained using the ultra-performance liquid chromatography (UPLC) column with C18 stationary phase chosen in most previous studies for HBCD analysis; however, co-elution of δ- and ε-HBCD with the primary HBCD diastereomers was observed. To prevent the interference from δ- and ε-HBCD, we adopted a phenyl-hexyl UPLC column to resolve the HBCD diastereomers. The phenyl-hexyl UPLC column showed significantly different selectivity for the HBCD diastereomers compared with the C18 column, which allowed the clear isolation of δ-HBCD and ε-HBCD from the primary HBCD diastereomers. In addition, by checking the retention times of all HBCD diastereomers using both C18 and phenyl-hexyl columns, we confirmed the presence of δ-, ε-, η-, and θ-HBCDs in two technical HBCD mixtures.

Quantitative monitoring of laser-treated engineered skin using optical coherence tomography.

Nowadays, laser therapy is a common method for treating various dermatological troubles such as acne and wrinkles because of its efficient and immediate skin enhancement. Although laser treatment has become a routine procedure in medical and cosmetic fields, the prevention of side-effects, such as hyperpigmentation, redness and burning, still remains a critical issue that needs to be addressed. In order to reduce the side-effects while attaining efficient therapeutic outcomes, it is essential to understand the light-skin interaction through evaluation of physiological changes before and after laser therapy. In this study, we introduce a quantitative tissue monitoring method based on optical coherence tomography (OCT) for the evaluation of tissue regeneration after laser irradiation. To create a skin injury model, we applied a fractional CO2 laser on a customized engineered skin model, which is analogous to human skin in terms of its basic biological function and morphology. The irradiated region in the skin was then imaged by a high-speed OCT system, and its morphologic changes were analyzed by automatic segmentation software. Volumetric OCT images in the laser treated area clearly visualized the wound healing progress at different time points and provided comprehensive information which cannot be acquired through conventional monitoring methods. The results showed that the laser wound in engineered skins was mostly recovered from within 1~2 days with a fast recovery time in the vertical direction. However, the entire recovery period varied widely depending on laser doses and skin type. Our results also indicated that OCT-guided laser therapy would be a very promising protocol for optimizing laser treatment for skin therapy.

An optimized method for the accurate determination of patulin in apple products by isotope dilution-liquid chromatography/mass spectrometry.

Patulin, a mycotoxin produced by several molds in fruits, has been frequently detected in apple products. Therefore, regulatory bodies have established recommended maximum permitted patulin concentrations for each type of apple product. Although several analytical methods have been adopted to determine patulin in food, quality control of patulin analysis is not easy, as reliable certified reference materials (CRMs) are not available. In this study, as a part of a project for developing CRMs for patulin analysis, we developed isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC/MS/MS) as a higher-order reference method for the accurate value-assignment of CRMs. (13)C7-patulin was used as internal standard. Samples were extracted with ethyl acetate to improve recovery. For further sample cleanup with solid-phase extraction (SPE), the HLB SPE cartridge was chosen after comparing with several other types of SPE cartridges. High-performance liquid chromatography was performed on a multimode column for proper retention and separation of highly polar and water-soluble patulin from sample interferences. Sample extracts were analyzed by LC/MS/MS with electrospray ionization in negative ion mode with selected reaction monitoring of patulin and (13)C7-patulin at m/z 153→m/z 109 and m/z 160→m/z 115, respectively. The validity of the method was tested by measuring gravimetrically fortified samples of various apple products. In addition, the repeatability and the reproducibility of the method were tested to evaluate the performance of the method. The method was shown to provide accurate measurements in the 3-40 µg/kg range with a relative expanded uncertainty of around 1%.

Assessment of polybrominated diphenyl ethers (PBDEs) in serum from the Korean general population.

In 2009 and 2010, 720 serum samples were collected from non-occupationally exposed study participants at four Korean locations and monitored for the presence of 27 polybrominated diphenyl ether (PBDE) congeners. The median concentrations of Σ(27)PBDEs (the sum of 27 congeners) and Σ(3-7)PBDEs (the sum of tri- to hepta-BDE congeners) were 6.04 and 4.97 ng/g lipid, respectively. The most abundant congener detected in serum samples was BDE-153, followed by BDE-47 and BDE-99. The median value of Σ(3-7)PBDEs was similar to the median values observed in Asia and Europe, but much lower than that observed in North America. Some significant differences, based on geographic region and sex, were observed. We also observed a positive increase of BDE-153 with regard to age. In addition, we estimated the daily exposure to PBDEs from previously published reports of PBDE concentrations in food and dust, and determined the individual contributions of a variety of sources.

Atmospheric bulk deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the vicinity of an iron and steel making plant.

An IRA-743 resin bulk sampler was validated to monitor long-term bulk deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Six consecutive sampling campaigns (2008-2009) were conducted at four sites around steel complexes in Pohang, South Korea to investigate spatial and seasonal variations of PCDD/F bulk deposition. The bulk deposition within the steel complex showed the highest ∑(4-8)PCDD/F (Tetra-Octa) fluxes, ranging from 204 to 608 (mean: 352)pg m(-2)d(-1), indicating steel complexes were major sources of PCDD/Fs. The homologue profiles were dominated with lower chlorinated PCDFs. Furthermore, the prevailing winds were confirmed to influence the spatial distribution of PCDD/F deposition. There were apparent seasonal variations of the bulk deposition at each site, and seasonal homologue patterns of PCDD/Fs were clearly observed. According to the passive air sampling, however, no significant seasonal change of ambient air concentrations of PCDD/Fs was observed. Therefore, it was concluded that the seasonal variations of deposition fluxes of PCDD/Fs probably resulted from temperature-dependent gas/particle partitioning.

Three-year atmospheric monitoring of organochlorine pesticides and polychlorinated biphenyls in polar regions and the South Pacific.

XAD-2 resin based passive air samplers (PAS) were deployed for three one-year periods at the Korean polar and South Pacific research stations at Ny-Ålesund (2005-2009), King George Island (2005-2007), and Chuuk (2006-2009) to investigate long-range transport, local sources, and temporal trends of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The highest hexachlocyclohexane (HCH) concentration (35.2-78.9 pg·m(-3)) over the entire sampling period was detected at Ny-Ålesund, in the Arctic. α-HCH was the dominant OCP (31.1-67.1 pg·m(-3)), contributing about 50% of the total OCP load. Additionally, a high and consistent α/γ-HCH ratio was observed at Ny-Ålesund. HCHs might reach Arctic sites more easily than other OCPs from surrounding countries through long-range atmospheric transport (LRAT). Interestingly, high levels of the current-use OCP endosulfan-particularly endosulfan-I--were detected at almost all sampling sites, including in Antarctica, ranging 12.2-88.5, 17.7-130, and ND-59.7 pg·m(-3) at King George Island, Ny-Ålesund, and Chuuk, respectively. Specific OCP and PCB patterns, such as low trans/cis-chlordane ratios and a prevalence of lighter PCB congeners, were observed in all three regions (excepting one site at Ny-Ålesund and one site in the South Pacific affected by local sources) during all sampling periods. This indicates that these Polar and remote South Pacific sites are mainly influenced by LRAT. Over the entire sampling period, a decreasing trend of HCHs (α- and γ-HCH) and an increasing trend of endosulfan-I were observed at the Ny-Ålesund sites.

Spatial and seasonal distribution of polychlorinated biphenyls (PCBs) in the vicinity of an iron and steel making plant.

Four consecutive passive air samplings (September 2006-July 2007) were conducted at 15 sites around an iron and steel making plant in Pohang, Korea to investigate the spatial and seasonal distributions of polychlorinated biphenyls (PCBs) and ultimately the source-receptor relationships. Annual mean values of Sigma(8)PCBs (IUPAC number 8, 28, 52, 101, 118, 138, 153, 180) were in the range of 15.1-166 pg/m(3) with an average of 53.0 pg/m(3). The spatial distribution of PCBs for each sampling period clearly suggests that the steel complex is a major source of PCBs in this area, and the prevailing winds facilitated the atmospheric transport and dispersion of PCBs from the steel complex to the surrounding areas. Seasonal patterns of PCBs were observed clearly, which were influenced by meteorological conditions; the highest levels of PCBs were observed with the highest average air temperature, and the influence of rainfall (i.e., wet scavenging) was also observed. In addition, PCB 11, a non-Aroclor congener, was detected in high concentrations at all sites, implying that the sources of PCB 11 are both unique and ubiquitous. This study confirms that passive air sampling is a useful tool to obtain seasonal and spatial distributions of time-averaged POPs data at a local scale.