Increased viral load in patients infected with severe acute respiratory syndrome coronavirus 2 Omicron variant in the Republic of Korea.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has been declared a global pandemic owing to the rapid spread of the causative agent, severe acute respiratory syndrome coronavirus 2. Its Delta and Omicron variants are more transmissible and pathogenic than other variants. Some debates have emerged on the mechanism of variants of concern. In the COVID-19 wave that began in December 2021, the Omicron variant, first reported in South Africa, became identifiable in most cases globally. The aim of this study was to provide data to inform effective responses to the transmission of the Omicron variant. METHODS: The Delta variant and the spike protein D614G mutant were compared with the Omicron variant. Viral loads from 5 days after symptom onset were compared using epidemiological data collected at the time of diagnosis. RESULTS: The Omicron variant exhibited a higher viral load than other variants, resulting in greater transmissibility within 5 days of symptom onset. CONCLUSION: Future research should focus on vaccine efficacy against the Omicron variant and compare trends in disease severity associated with its high viral load.

Spatial and PMF analysis of particle size distributions simultaneously measured at four locations at the roadside of highways.

In urban areas, particulate matter emitted from vehicles directly affects the health of citizens near roads. Thus, in this study, particle size distribution was measured by the horizontal and vertical distances along a highway road with heavy traffic to characterize the dispersion phenomena of particulate matter emitted from vehicles. In addition, the contribution of pollution sources was analyzed using a source-receptor model. A concentration gradient was observed in which the concentration decreased with the increase in the distance from the road when the wind blew from the road to the monitoring locations. The concentration was slightly higher within 50 m of the road when the wind blows parallel to the road, and similar concentrations were found at the other monitoring locations further away from the roads. In particular, the higher the turbulence intensity of the wind, the lower is the concentration gradient coefficient because of the more enhanced mixing and dispersion. A positive matrix factorization (PMF) model with the measured particle size distribution data in the range of 9-300 nm resulted in a contribution of about 70 % (number) and 20 % (mass) to particle concentrations because of six types of vehicles including LPG, two gasoline vehicles (GDI, MPI), and three diesel vehicles with 3rd, 4th, and 5th emission classes. It showed a decrease in the vehicular contribution as the distance from the road increased. Particle number concentrations decreased with increasing altitude up to 30 m above the ground. The results of this study can be useful in deriving generalized gradient equations of particle concentrations exposed by distance and wind direction at the roadside using traffic and meteorological conditions and for establishing environmental policies, such as roadside exposure assessment, in the future. A CAPSULE ABSTRACT: Dispersion of particles emitted from vehicles on a busy highway was characterized by roadside measurements of horizontal and vertical profiles of particle size distributions measured at four locations. The source profiles and contributions were estimated by major sources using a source-receptor model such as PMF.

Recent increase in the detection of human parainfluenza virus during the coronavirus disease-2019 pandemic in the Republic of Korea.

BACKGROUND: Since the onset of the coronavirus disease-2019 (COVID-19) pandemic, the prevalence of respiratory infectious diseases, particularly, the flu epidemic, has considerably decreased. The low detection rate and decreased number of specimens have hindered the implementation of the Korea Influenza and Respiratory Viruses Surveillance System (KINRESS), a sentinel surveillance system. Most patients with influenza-like illness visit the COVID-19 screening clinic; therefore, the number of samples collected in sentinel surveillance has decreased by more than 50%. Thus, the Korea Disease Control and Prevention Agency supplemented sentinel surveillance with non-sentinel surveillance by private medical diagnostic centers. We report here a delayed and unprecedented high detection of human parainfluenza virus (hPIV) in the Republic of Korea during the COVID-19 pandemic through sentinel and non-sentinel surveillance. We also examined the causes and implications of the changes in prevalence of hPIV.l METHODS: We collected data for 56,984 and 257,217 samples obtained through sentinel and non-sentinel surveillance, respectively. Eight viruses were confirmed using real-time reverse transcription-polymerase chain reaction (PCR) or real-time PCR. Some specimens from the sentinel surveillance were used for genetic characterization of hPIV type 3. RESULTS: In 2020, hPIV was rarely detected; however, it was detected in August 2021. The detection rate continued to increase considerably in September and reached over 70% in October, 2021. The detection rate of hPIV3 was significantly higher in infants and preschoolers aged 0-6 years in both sentinel and non-sentinel surveillance. Detection of hPIV was delayed in metropolitan areas compared to that in suburban regions. The hemagglutinin-neuraminidase sequences of hPIV3 generated in 2021 were not distinct from those detected prior to the COVID-19 pandemic. CONCLUSIONS: The operation of non-sentinel and sentinel surveillance to monitor respiratory viruses could sensitively detect an unprecedented revival of hPIV in the Republic of Korea during the COVID-19 pandemic.

Effect of treadwear grade on the generation of tire PM emissions in laboratory and real-world driving conditions.

Tires generally wear out due to the friction between the tire and the road surface. Minimizing tire wear could reduce the non-exhaust particulate matter (PM) emissions from tires. Typically, tire treadwear grade can be used as an indicator of PM emissions from tires. Tires that wear out quickly will produce higher PM emissions than more durable tires. In this study, the effect of treadwear grade on the generation of tire PM emissions was investigated through laboratory and on-road driving measurements. In the laboratory measurements, a tire wear simulator installed in an enclosed chamber was used to eliminate artifacts caused by interfering particles during the generation and measurement of tire wear particles. For realistic on-road driving measurements, a mobile sampling vehicle was employed to sample road dust. The road dust was chemically analyzed using pyrolysis gas chromatography-mass spectrometry (GC-MS) to characterize the tire-road wear particles. Both measurements showed that the higher treadwear grade generated lower tire PM emissions due to the high strength of the rubber, except for the UTQG 700 tire. The UTQG 700 tire, which had the highest treadwear grade, produced higher PM emissions than the UTQG 350 and 500 tires because it readily formed the fine particles due to lamellar peeling rather than tearing or curling of tire treads. Notably, tire nanoparticles were observed in laboratory measurements due to the volatilization and nucleation of the sulphur (S) and zinc (Zn) compounds in the tire tread due to the frictional heat between the tire and paved road surface.

Comparison of total PM emissions emitted from electric and internal combustion engine vehicles: An experimental analysis.

Electric vehicles (EVs) are regarded as zero emission vehicles due to the absence of exhaust emissions. However, they still contribute non-exhaust particulate matter (PM) emissions, generated by brake wear, tire wear, road wear, and resuspended road dust. In fact, because EVs are heavier than internal combustion engine vehicles (ICEVs), their non-exhaust emissions are like to be even higher. While total PM emissions, including exhaust and non-exhaust PM emissions, from ICEVs and EVs have been compared based on the emission factors (EFs) listed in national emission inventories, there have been no comparisons based on experimental determinations. In this study, exhaust and non-exhaust emissions generated from a gasoline ICEV, diesel ICEV, and EV were experimentally investigated. The results showed that the EFs for the total PM emissions of ICEVs and EV were dependent on the inclusion of secondary exhaust PM, the brake pad type, and the regenerative braking intensity of the EV. When only primary exhaust PM emissions were considered in vehicles equipped with non-asbestos organic (NAO) brake pads, the total PM10 EF of the EV (47.7-49.3 mg/V·km) was 10-17 % higher than those of the gasoline ICEV (42.3 mg/V·km) and diesel ICEV (43.2 mg/V·km). However, in vehicles equipped with low-metallic (LM) brake pads, the total PM10 EF of the EV (49.2-57.7 mg/V·km) was comparable or lower than those of the gasoline ICEV (56.3 mg/V·km) and diesel ICEV (57.2 mg/V·km). When secondary PM emissions were included, the EF was always significantly lower for the EV than ICEVs. The total PM10 EF of the EV (47.7-57.7 mg/V·km) was lower than those of the gasoline ICEV (56.5-70.5 mg/V·km) and diesel ICEV (58.0-72.0 mg/V·km). Since secondary PM particles are mostly of submicron size, the EFs of the PM2.5 fraction of the ICEVs (28.7-33.0 mg/V·km) were two times higher than those of the EV (13.9-17.4 mg/V·km).

Chemical Leaching from Tire Wear Particles with Various Treadwear Ratings.

Physical friction between a tire and the road surface generates tire wear particles (TWPs), which are a source of microplastics and particulate matter. This study investigated the trends of chemical leaching from TWPs depending on the treadwear rating of the tire. A road simulator was used to produce TWPs from tires with various treadwear ratings. Liquid chromatography-tandem mass spectrometry was used to analyze the chemical leaching from TWPs, with a particular focus on benzothiazole and its derivative 2-hydroxy benzothiazole. However, chemical mapping via high-resolution tandem mass spectrometry detected another derivative: 2-mercaptobenzothiazole. The benzothiazole groups were observed to have different leaching tendencies, implying that using benzothiazole as a marker compound may lead to incorrect TWP quantitation. The results of this research also suggest that the ecotoxicological influence of TWPs can vary with the treadwear rating of a tire.

Real-time detection of vehicle-originated condensable particulate matter through thermodenuder integrated aerosol measurement method at tailpipes.

Condensable particulate matter (CPM) corresponds to primary particulate matter ≤2.5 µm (PM2.5) obtained through the condensation of gaseous air pollutants caused by temperature drops in the atmosphere. The internal combustion of vehicle engines can produce CPM because of the condensable compounds in the exhaust gas. Conventional CPM measurement methods have been developed for coal-fired power plants with stable emissions through sampling and off-site analyses. They are therefore unsuitable for detecting the rapidly changing vehicle-originated CPM. In addition, the current system for evaluating PM2.5 from vehicles, based on the particle measurement program (PMP) protocol, provides only the emission factors of total PM2.5 (and not CPM separately) at a fixed temperature (∼25 °C) and dilution ratio (∼ × 35). This study reports, for the first time, the development of a real-time detection method for vehicle-originated CPM through a thermodenuder (TD) integrated with real-time aerosol instruments. This method was designed to reduce the loss of CPM due to condensation and diffusion while sampling the exhaust gas. It permits the investigation of the effects of dilution gas temperature (5-45 °C) and dilution ratio (up to × 30) on the formation of CPM. During the feasibility test of this method using a diesel vehicle (Euro-4), the real-time total particle number concentrations (PNs) matched well with those obtained by a PMP protocol-based evaluation system. Moreover, this method detected PNs concentrations ten times higher than the detection limit (4 × 106 particles/cm3) of the PMP-based system. The emission factors of the total PM2.5 with a bulk density (1 g/cm3) measured by this method also showed consistency with the results of the PMP protocol. The mass emission factor of CPM determined by deploying the TD was ∼14.57 mg/km (∼63% contribution to the total PM2.5).

Increase in Viral Load in Patients With SARS-CoV-2 Delta Variant Infection in the Republic of Korea.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread rapidly, causing in COVID-19 being declared a global pandemic by the World Health Organization. The key variants include alpha, beta, gamma, and delta; these exhibit high viral transmission, pathogenicity, and immune evasion mechanisms. The delta variant, first confirmed in India, was detected in the majority of COVID-19 patients at the recent wave in the Republic of Korea. Here, the features of the delta variant were compared to the earlier waves, with focus on increased transmissibility. The viral load, from the initial days of infection to 14 days later, was compared based on epidemiological data collected at the time of confirmed diagnosis. The increased viral load observed in the delta variant-led infections influences the scale of the wave, owing to the increased rate of transmission. Infections caused by the delta variant increases the risk of hospitalization within 14 days after symptom onset, and the high viral load correlates with COVID-19 associated morbidity and mortality. Therefore, the future studies should compare the trend of disease severity caused by the high viral load of delta variant with previous waves and analyze the vaccine effects in light of the delta variant of fourth wave.

Impact of coronavirus disease 2019 on respiratory surveillance and explanation of high detection rate of human rhinovirus during the pandemic in the Republic of Korea.

BACKGROUND: After the detection of the first case of coronavirus disease 2019 (COVID-19) in South Korea on January 20, 2019, it has triggered three major outbreaks. To decrease the disease burden of COVID-19, social distancing and active mask wearing were encouraged, reducing the number of patients with influenza-like illness and altering the detection rate of influenza and respiratory viruses in the Korea Influenza and Respiratory Viruses Surveillance System (KINRESS). We examined the changes in respiratory viruses due to COVID-19 in South Korea and virological causes of the high detection rate of human rhinovirus (hRV) in 2020. METHODS: We collected 52 684 oropharyngeal or nasopharyngeal swab samples from patients with influenza-like illness in cooperation with KINRESS from 2016 to 2020. Influenza virus and other respiratory viruses were confirmed using real-time RT-PCR. The weekly detection rate was used to compare virus detection patterns. RESULTS: Non-enveloped virus (hRV, human bocavirus, and human adenovirus) detection rates during the COVID-19 pandemic were maintained. The detection rate of hRV significantly increased in 2020 compared with that in 2019 and was negatively correlated with number of COVID-19-confirmed cases in 2020. The distribution of strains and genetic characteristics in hRV did not differ between 2019 and 2020. CONCLUSIONS: The COVID-19 pandemic impacted the respiratory virus detection rate. The extremely low detection rate of enveloped viruses resulted from efforts to prevent the spread of COVID-19 in South Korea. The high detection rate of hRV may be related to resistance against environmental conditions as a non-enveloped virus and the long period of viral shedding from patients.

Validation of real-time RT-PCR for detection of SARS-CoV-2 in the early stages of the COVID-19 outbreak in the Republic of Korea.

A real-time reverse transcription polymerase chain reaction (RT-qPCR) assay that does not require Emergency Use Authorization (EUA) reagents was tested and validated for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the early stages of the outbreak of coronavirus disease 2019 (COVID-19) in the Republic of Korea. Early diagnosis of COVID-19 enables timely treatment and the implementation of public health measures. We validated the sensitivity, specificity, precision, linearity, accuracy, and robustness of the RT-qPCR assay for SARS-CoV-2 detection and compared its performance with that of several EUA-approved kits. Our RT-qPCR assay was highly specific for SARS-CoV-2 as demonstrated by not amplifying 13 other viruses that cause respiratory diseases. The assay showed high linearity using a viral isolate from a patient with known COVID-19 as well as plasmids containing target SARS-CoV-2 genes as templates. The assay showed good repeatability and reproducibility with a coefficient of variation of 3%, and a SARS-CoV-2 limit of detection of 1 PFU/mL. The RT-qPCR-based assay is highly effective and can facilitate the early diagnosis of COVID-19 without the use of EUA-approved kits or reagents in the Republic of Korea.

Identification of Coronavirus Isolated from a Patient in Korea with COVID-19.

OBJECTIVES: Following reports of patients with unexplained pneumonia at the end of December 2019 in Wuhan, China, the causative agent was identified as coronavirus (SARS-CoV-2), and the 2019 novel coronavirus disease was named COVID-19 by the World Health Organization. Putative patients with COVID-19 have been identified in South Korea, and attempts have been made to isolate the pathogen from these patients. METHODS: Upper and lower respiratory tract secretion samples from putative patients with COVID-19 were inoculated onto cells to isolate the virus. Full genome sequencing and electron microscopy were used to identify the virus. RESULTS: The virus replicated in Vero cells and cytopathic effects were observed. Full genome sequencing showed that the virus genome exhibited sequence homology of more than 99.9% with SARS-CoV-2 which was isolated from patients from other countries, for instance China. Sequence homology of SARS-CoV-2 with SARS-CoV, and MERS-CoV was 77.5% and 50%, respectively. Coronavirus-specific morphology was observed by electron microscopy in virus-infected Vero cells. CONCLUSION: SARS-CoV-2 was isolated from putative patients with unexplained pneumonia and intermittent coughing and fever. The isolated virus was named BetaCoV/Korea/KCDC03/2020.

Size-dependent characteristics of diurnal particle concentration variation in an underground subway tunnel.

Understanding characteristics of diurnal particle concentration variation in an underground subway tunnel is important to reduce subway passengers' exposure to high levels of toxic particle pollution. In this study, real-time particle monitoring for eight consecutive days was done at a shelter located in the middle of a one-way underground subway tunnel in Seoul, Republic of Korea, during the summer of 2015. Particle mass concentration was measured using a dust monitor and particle number concentration using an optical particle counter. From the diurnal variations in PM10, PM2.5, and PM1, concentrations of particles larger than 0.54 µm optical particle diameter were affected by train frequency whereas those of particles smaller than 0.54 µm optical particle diameter were not changed by train frequency. Number concentration of particles smaller than 1.15 µm optical particle diameter was dependent on outdoor ambient air particle concentration level, whereas that of particles larger than 1.15 µm optical particle diameter was independent of outdoor ambient air due to low ventilation system transmission efficiency of micrometer-sized particles. In addition, an equation was suggested to predict the diurnal particle concentration in an underground tunnel by considering emission, ventilation, and deposition effects.

Serosurveillance of avian influenza A/H5N6 virus infection in poultry farmers, Gyeonggi Province, Republic of Korea, 2016-2017.

OBJECTIVES: Between November 20, 2016 and April 17, 2017, outbreaks of highly pathogenic avian influenza (HPAI) A/H5N6 occurred on poultry farms in Gyeonggi Province in the Republic of Korea. A serosurvey was conducted among poultry farmers to identify the transmission of HPAI A/H5N6 virus to humans. METHODS: A descriptive study of 870 poultry farmers in Gyeonggi Province in Korea was conducted during the 2016-2017 outbreaks. Serological testing was performed using a microneutralization (MN) assay for antibodies against influenza A/duck/ES2/Korea/2016 virus, which has antigenic properties similar to those of the HPAI A/H5N6 virus that caused this poultry outbreak. RESULTS: Overall, 523 exposed poultry farmers were assessed by serological testing. Consequently, all tested negative for HPAI A/H5N6 virus via MN assay. CONCLUSIONS: Based on serological assays, no transmission of HPAI A/H5N6 to humans was identified in this study cohort. Additional studies should be conducted to determine the possibility of poultry-to-human transmission of HPAI A/H5N6.

Evaluation of the zoonotic potential of multiple subgroups of clade 2.3.4.4 influenza A (H5N8) virus.

Clade 2.3.4.4 H5N8 highly pathogenic avian influenza viruses (HPAIVs) have spread worldwide. Phylogenetic analysis identified two genetic groups of the H5N8 HPAIVs in South Korea; group A evolved further into four subgroups. Here, we examined the zoonotic potential, both in vivo and in vitro, of genetically distinct subgroups of H5N8 HPAIVs isolated in South Korea. When compared with other subgroups, A/mallard/Korea/H2102/2015 (H2102) virus caused relatively severe disease in mice at high doses. In ferrets, all H5N8 viruses replicated restrictively in the respiratory tract and did not induce significant clinical signs of influenza infection. In vitro studies, all viruses displayed a hemagglutinin phenotype that was poorly adapted for infection of mammals, although the H2102 virus exhibited higher replication kinetics at 33°C than the others. Although H5N8 HPAIVs have not yet acquired all the characteristics required for adaptation to mammals, their ability to evolve continuously underscores the need for timely risk assessment.

Overestimation of on-road air quality surveying data measured with a mobile laboratory caused by exhaust plumes of a vehicle ahead in dense traffic areas.

The unintended influence of exhaust plumes emitted from a vehicle ahead to on-road air quality surveying data measured with a mobile laboratory (ML) at 20-40 km h-1 in dense traffic areas was investigated by experiment and life-sized computational fluidic dynamics (CFD) simulation. The ML equipped with variable sampling inlets of five columns by four rows was used to measure the spatial distribution of CO2 and NOx concentrations when following 5-20 m behind a sport utility vehicle (SUV) as an emitter vehicle equipped with a portable emission monitoring system (PEMS). The PEMS measured exhaust gases at the tailpipe for input data of the CFD simulations. After the CFD method was verified with experimental results of the SUV, dispersion of exhaust plumes emitted from a bus and a sedan was numerically analyzed. More dilution of the exhaust plume was observed at higher vehicle speeds, probably because of eddy diffusion that was proportional to turbulent kinetic energy and vehicle speed. The CO2 and NOx concentrations behind the emitter vehicle showed less overestimation as both the distance between the two vehicles and their background concentrations increased. If the height of the ML inlet is lower than 2 m and the ML travels within 20 m behind a SUV and a sedan ahead at 20 km h-1, the overestimation should be considered by as much as 200 ppb in NOx and 80 ppm in CO2. Following a bus should be avoided if possible, because effect of exhaust plumes from a bus ahead could not be negligible even when the distance between the bus and the ML with the inlet height of 2 m, was more than 40 m. Recommendations are provided to avoid the unintended influence of exhaust plumes from vehicles ahead of the ML during on-road measurement in urban dense traffic conditions.

Experimental infection of SPF and Korean native chickens with highly pathogenic avian influenza virus (H5N8).

In 2014, an H5N8 outbreak of highly pathogenic avian influenza (HPAI) occurred in South Korea. The H5N8 strain produced mild to moderate clinical signs and mortality rates in commercial chicken farms, especially Korean native chicken farms. To understand the differences between their pathogenicity in SPF chicken and Korean native chicken., we evaluated the mean bird lethal doses (BLD50) of the Korean representative H5N8 virus (A/broiler duck/Korea/Buan2/2014) The BLD50values of the H5N8 virus were 10(5.3)EID50 and 10(6.7)EID50 in SPF and Korean native chickens, respectively. In addition, the mean death time was much longer, and the viral titers in tissues of H5N8-infected chickens were significantly lower, in the Korean group than in the SPF group. These features of the H5N8 virus likely account for its mild-to-moderate pathogenicity in commercial chicken farms, especially Korean native chicken flocks, despite the fact that it is a highly pathogenic virus according to the OIE criteria. To improve current understanding and management of HPAI, pathogenic characterization of novel emerging viruses should be performed by natural route in major poultry species in each country.

Generation of Nanoparticles from Friction between Railway Brake Disks and Pads.

In this study, we measured the size distribution of particles ranging in size from 5.6 to 560 nm that were emitted between brake disks and pads under various braking conditions to observe and analyze changes to the resulting particle size distribution over braking time. A peak of 178-275 nm (200 nm peak) was observed in all braking conditions. However, the generation of spherical particles of a 10 nm range was observed only when the disk speed and brake force were above certain levels and intensified only when speed and brake force further increased. The total number concentration of ultrafine particles (no larger than 0.1 µm; PM0.1) generated was found to correlate with disk speed and brake force. Thus, the generation of nanoparticles resulting from disk speed and brake force was attributable primarily to increases in the contact surface temperature. The critical temperature for the generation of nanoparticles of a 10 nm range was found to be about 70 °C, which is the average temperature between the surface and the inside of the disk. If the speed or brake force was higher, that is, the temperature of the contact surface reached a certain level, evaporation and condensation took place. Vapor then left the friction surface, met with the air, and quickly cooled to form nanoparticles through nucleation. When the newly generated particles became highly concentrated, they grew through coagulation to form agglomerates or the vapor condensed directly onto the surface of existing particles of about 200 nm (formed by mechanical friction).

Development of a liquid chromatography-tandem mass spectrometry method for the determination of Grayanotoxins in rat blood and its application to toxicokinetic study.

A sensitive and specific high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of Grayanotoxin I (GTX I) and Grayanotoxin III (GTX III) in rat whole blood. Grayanotoxins (GTXs) and clindamycin as internal standard (IS) were extracted from rat blood via solid-phase extraction using PEP solid-phase extraction cartridges. Chromatographic separation of the analytes was achieved on a Kinetex C18 (100 × 2.1 mm, 2.6 µm) reversed-phase column using a gradient elution with the mobile phase of 1% acetic acid in water and methanol at a flow rate of 0.2 mL/min. Electrospray ionization mass spectrometry was operated in the positive ion mode with multiple reaction monitoring. The calibration curves obtained were linear over the concentration range of 1-100 ng/mL with a lower limit of quantification of 1 ng/mL for GTXs. The relative standard deviation of intra-day and inter-day precision was below 6.8% and accuracy ranged from 94.8 to 106.6%. The analytes were stable in the stability studies. The validated method was successfully applied to the quantification and toxicokinetic study of GTXs in rats for the first time after oral administration of 11.52 mg/kg mad honey and 0.35 mg/kg GTX III, respectively.

Development of a target component extraction method from GC-MS data with an in-house program for metabolite profiling.

After gas chromatography-mass spectrometry (GC-MS) analysis, data processing, including retention time correction, spectral deconvolution, peak alignment, and normalization prior to statistical analysis, is an important step in metabolomics. Several commercial or free software packages have been introduced for data processing, but most of them are vendor dependent. To design a simple method for Agilent GC/MS data processing, we developed an in-house program, "CompExtractor", using Microsoft Visual Basic. We tailored the macro modules of an Agilent Chemstation and implanted them in the program. To verify the performance of CompExtractor processing, 30 samples from the three species of the genus Papaver were analyzed with Agilent 5973 MSD GC-MS. The results of CompExtractor processing were compared with those of AMDIS-SpectConnect processing by hierarchical cluster analysis (HCA) and principal component analysis (PCA). The two methods showed good classification according to their species in HCA. The PC1+PC2 scores were 54.32-63.62% for AMDIS-SpectConnect and 56.65-85.92% for CompExtractor in PCA. Although the CompExtractor processing method is an Agilent GC-MS-specific application and the target compounds must be selected first, it can extract the target compounds more precisely in the raw data file with batch mode and simultaneously assemble the matrix text file.

Determination and validation of tetrodotoxin in human whole blood using hydrophilic interaction liquid chromatography-tandem mass spectroscopy and its application.

A sensitive analytical method was developed for the quantitative determination of tetrodotoxin (TTX), a powerful sodium channel blocker, in human postmortem whole blood. The sample mixture was cleaned up using cation exchange SPE catridge after protein precipitation by methanol and then separated on a PC-HILIC (phosphorylcholine hydrophilic interaction liquid chromatography) column (150 mm × 2.0mm i.d., 5 µm) using a isocratic elution of 1% acetic acid and acetonitrile. The identification of TTX was performed on tandem mass spectrometry with electrospray ionization interface in positive ion mode. The retention time of voglibose (internal standard) and TTX was 5.1 and 6.0 min, respectively. TTX and internal standard (voglibose) were monitored and quantitated using the ion transitions: the respective precursor to product ion combinations, m/z 320/302 for TTX and m/z 268/92 for voglibose in the multiple reaction monitoring (MRM) mode. The recovery of TTX and voglibose was 61.4% and 62.8%, respectively and the good accuracy (97.7-103.9%), linearity (2-1200 ng/mL) and reproducibility were shown in this method. The limit of detection and limit of quantification were 0.32 ng/mL and 1.08 ng/mL, respectively. This method was applied in the case of three fishermen who were poisoned (including one death) by unknown fish on their boat in October 2010. In this case, the levels of TTX were 27.2, 30.0 and 29.7 ng/mL in heart blood, peripheral blood and serum of a victim, were 3.1 and 12.1 ng/mL in peripheral blood and 3.9 and 12.8 ng/mL in serum of two survivors, respectively.