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Time-averaged shear-wave velocity to 30 m (VS30) is commonly used in ground motion models as a parameter for evaluating site effects. This study used a collection of boreholes in Beijing, Tianjin, Guangxi, Guangdong, and three other municipalities and provinces, which were divided into three regions with reference to the seismic ground motion parameter zonation map of China, to establish VS30 prediction models based on terrain categories. Regional effects were verified by comparing morphometric parameter (topographic slope, surface texture, and local convexity) thresholds and terrain classification maps obtained from global digital elevation model (DEM) data and regional DEM data of the three regions. Additionally, VS30 prediction models for the three regions using both types of terrain classification maps were established and analyzed comparatively to provide credible regional VS30 models for China. Through analysis of the correlations between the measured VS30 values and the predicted VS30 values, calculation of the mean squared error and mean absolute percentage error in each region, and with consideration of the geological characteristics of the boreholes, the VS30 prediction models based on terrain classification maps from regional data were finally applied in developing regional VS30 models for China. Intercomparison of the VS30 prediction models for the three regions indicated that subregional consideration is necessary in terrain classification. Finally, a spatial analysis method adopting inverse distance weighting of the residuals was used to update the initial VS30 models. The developed VS30 models could be used both in developing regional ground motion models and in the construction of earthquake disaster scenarios. Graphical Abstract

Seismic site classification, which is fundamental for site-specific seismic hazard assessment, also plays an important role in accurate interpretation of ground motion data. However, detailed borehole information is not always available in many countries, e.g., China. Therefore, this study investigated application of the generalized regression neural network (GRNN) method to seismic site classification using China strong motion stations as example case. First, stations from KiK-net in Japan were classified based on their borehole information and individually assigned to I, II, III, and IV site classes as defined in Chinese seismic code. Then, mean horizontal-to-vertical spectral ratio (HVSR) curves for each site class were calculated as reference patterns. The overall recall rates for I, II, and III sites could reach 66.60%, 67.57%, and 68.42%, respectively, regarding use of KiK-net stations. The GRNN site classification scheme was validated using borehole information of K-NET stations, with recall rates for I and II site classes reaching 68% and 60%, respectively. Finally, based on HVSR curves calculated using strong ground motion data acquired during 2007–2015 in China, the site conditions of 167 National Strong Motion Observation Network System stations were estimated using the GRNN classification scheme. The results were partially validated using borehole information of 73 stations. The similarity between the mean HVSR curves and reference pattern curves indicated that the GRNN seismic site classification scheme is robust and could produce plausible results succinctly.

The South China Sea (SCS) is recognized as a zone at high risk of tsunamis, which makes surrounding areas suitable for conducting probabilistic tsunami hazard assessment (PTHA). Most previous PTHAs were conducted with consideration of either local or regional potential tsunami sources (PTSs). In this study we developed a PTHA framework for the coastal area of southeastern China that considers the impact from both types of PTS together. First, the seismic activity of the Manila regional PTS was evaluated based on catalogs of historical earthquake and tsunami events. Through consideration of three conditions (earthquake magnitude, focal depth, and focal mechanism), the annual rate of occurrence of a tsunamigenic earthquake (a low limit earthquake magnitude is set as 7.0) was estimated to be 0.01. Second, 1400 scenario tsunamis were produced randomly and their wave propagation was numerically simulated. Tsunami hazard maps were delineated displaying wave heights in terms of 475-, 975-, 2475-, and 4975-year return periods. Regional variation in the tsunami hazard was revealed for the coast of southeastern China. Coastal regions of southern and central Fujian Province (24°–25.5°N) were projected to have the highest level of hazard because they are not only geographically close to, but are also positioned perpendicular to, four local PTSs. The tsunami hazard curves of six major cities/regions (Macao, Hong Kong, Daya Bay, Shantou, Xiamen, and Quanzhou) were examined as typical cases. It was revealed that local PTSs and the Manila regional PTS separately dominate the tsunami hazard at different locations, indicating that tsunami mitigation measures may need to be locally adapted to the dominant source.

It is crucial to include additional site amplification effects resulting from the thick sediment on ground motions in the reliable assessment for seismic hazard in sedimentary basins. Ground-motion residual analysis with respect to ground-motion prediction equation is performed to evaluate additional site amplifications at over 200 K-NET stations within and around Kanto basin. We first investigate the potential effects on additional site amplifications resulted from the sediment depth and several source-dependent factors. Results reveal that source-to-site distance, focal depth, and source azimuth all have nonnegligible effects on additional site amplifications, especially the focal depth. Thick sedimentary sites amplify long-period ground motions from distant earthquakes more strongly than those from local earthquakes. Ground motions from shallow crustal earthquakes generally experience much stronger amplifications than those from those deep subduction earthquakes, much more predominant for long-period ground motions (>1.0 s) at thick sedimentary sites. Meanwhile, we develop the empirical model after integrating contributions from sediment depth, source-to-site distance, and focal depth for predicting additional site amplification effects. Considering the typical case of the distant shallow crustal earthquakes, additional site amplifications at thick sedimentary sites within Kanto basin generally show an increasing trend with the oscillation period increased, whereas they are generally characterized by a decreasing trend at shallow sedimentary sites outside the basin. The mean additional site amplification is up to about 2.0 within Kanto basin, whereas 0.5–0.65 outside Kanto basin, for ground motions at oscillation periods of 2.0–5.0 s. Mean amplifications within Kanto basin are about 3.5 times larger than those outside the basin for long-period ground motions at 2.0–5.0 s. Sites northeast to Kanto basin show the largest amplifications up to about 3.0 at periods of 0.15 and 5.0 s, which may be resulted from the basin edge effects.

For mainland China, the primary obstacle in conditional spectrum (CS) based ground motion selection work is that the corresponding seismic hazard disaggregation results were not released for the China national standard GB 18306–2015 “Seismic Ground Motion Parameter Zonation Map”, which refers to the fifth-generation seismic hazard map. Therefore, this study firstly constructed a probabilistic seismic hazard map for mainland China using the three level seismicity source models as applied to produce the fifth-generation seismic hazard map. The derived peak ground acceleration (PGA) values in our seismic hazard map were basically consistent with the PGA range bins in fifth-generation seismic hazard map for most of the 34 principal cities considered. Then, a three-dimensional disaggregation scheme was performed for PGA and 5%-damped spectral acceleration (Sa) corresponding to mean return periods of 475 and 2475 years. The results clearly identified the potential source areas and corresponding fault zones that dominate the hazard of the target cities regarding different intensity measures. Based on the magnitude-longitude-latitude disaggregation results of three example cities: Xichang, Kunming, and Xi’an, approximate and exact CS were established with/without considering multiple casual earthquakes and possible strike directions of the potential source areas. The mean exact CS lies between the results of approximate CS using long and short axis GMMs. The conditional standard deviation of exact CS is approximately 1.1–1.5 times larger than the approximate CS for the periods away from the conditional period. For three example cities, hazard consistency of the spectral accelerations of the ground motion realizations were validated for matching exact CS and approximate CS. The results suggested that the geometric mean approximate CS without inflation of standard deviation is a practical choice when the target exceedance rate was not too low. Moreover, for the 34 studied cities, we tabulated the uniform hazard curve and disaggregation results for PGA and Sa values (0.2, 0.3, 0.5, 0.7, 1.0, 1.5, and 2.0 s) at mean return period of 475 and 2475 years ( https://github.com/JIKUN1990/China-Seismic-Hazard-Deaggregation-34cities ).

This study used earthquake records from China to investigate comprehensively the correlation coefficients between various intensity measures (IMs), including peak ground acceleration, peak ground velocity, spectral acceleration, spectrum intensity, acceleration spectrum intensity, Arias intensity, cumulative absolute velocity, and significant duration. After collection of metadata information, 681 three-component ground-motion recordings with magnitudes of Mw 4.9–6.9 were carefully processed and extracted from the China National Strong-Motion Observation Network System dataset (2007–2015). The applicability of both the Next Generation Attenuation (NGA)-West2 ground-motion model (GMM) and of other GMMs was verified for different IMs, regarding the China dataset. Then, empirical correlation coefficients between different IMs were computed, considering the uncertainty due to the different sample sizes of the observational data using the bootstrap sampling method and Fisher z transformation. Finally, the median values of the correlation coefficients were fitted as a continuous function of the vibration period in the range of 0.01–10.0 s and compared with the results of similar studies developed for shallow crustal regions worldwide. The developed region-specific correlation coefficient prediction model yielded tendencies approximately like those reported in other studies. However, obvious differences were found in long-period ranges of amplitude-based IMs, cumulative effect IMs, and significant duration. These results suggest the necessity of using region-specific correlation coefficients for generalized IMs in China. The presented results and parametric models could be easily implemented in a generalized IM ground-motion selection method or a vector-based probability seismic hazard analysis procedure for China.

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For mainland China, the primary obstacle in conditional spectrum (CS) based ground motion selection work is that the corresponding seismic hazard deaggregation results were not released for the China national standard GB 18306- 2015 “Seismic Ground Motion Parameter Zonation Map”, which refers to the fifth-generation seismic hazard map. Therefore, this study firstly constructed a probabilistic seismic hazard map for mainland China using the three level seismicity source models as applied to produce the fifth-generation seismic hazard map. The derived peak ground acceleration (PGA) values in our seismic hazard map were basically consistent with the fifth-generation seismic hazard map for most of the 34 principal Chinese cities considered. Then, three-dimensional deaggregation scheme was performed for PGA and 5%-damped spectral acceleration (Sa) corresponding to mean return periods of 475 and 2475 years. Based on the magnitude-longitude-latitude deaggregation results of three example cities: Xichang, Kunming, and Xi’an, approximate and pseudo-exact conditional spectrum were established with/without considering multiple casual earthquakes and possible strike directions of the potential source areas. The mean pseudo-exact CS lies between the results of approximate CS using long and short axis GMMs. The conditional standard deviation of pseudo-exact CS is approximately 1.1 to 1.5 times larger than the approximate CS for the periods away from the conditional period. For three example cities, hazard consistency of the spectral accelerations of the ground motion realizations matching target distribution of pseudo-exact CS and geometric mean approximate CS were evaluated and validated. Moreover, for the 34 studied cities, we tabulated the uniform hazard curve and deaggregation results for PGA and Sa values (0.2, 0.3, 0.5, 0.7, 1.0, 1.5, and 2.0s) at MRPs of 475 and 2475 years. (https://github.com/JIKUN1990/China-Seismic-Hazard-Deaggregation-34cities)

Observed ground-motion intensity for six earthquakes of Mw = 6.0–6.2 that occurred in China’s North–South Seismic Zone (NSSZ) was compared with predicted medians from the BSSA14 model. The resulting between-event (δBe) and within-event (δWes) residuals for peak ground acceleration and pseudo-spectral acceleration up to 5.0 s were used to investigate the impact of source effects and path propagation on the regional variability in observed ground-motion amplitude within the NSSZ. Although the magnitude and fault type were similar among the six earthquakes, the results showed that their source effects were significantly different, which contributed in part to the regional variability in observed ground-motion amplitude. Estimated values for stress drop were found to mirror the trend in variation of the δBe values for short-period ground motions in the six earthquakes. This suggests that stress drop is an important factor for accurate representation of source effects and should be considered in the functional form of ground-motion prediction equations. Anelastic attenuation of ground motion was found to be considerably different in local areas of the NSSZ, which may constitute the primary reason for the regional variability in the observed ground-motion amplitude. The variation in δWes values confirmed that regional adjustment of anelastic attenuation in the BSSA14 model is applicable to some local areas (i.e., around the Longmenshan fault) but not to the NSSZ in its entirety.

Objective: To study wholesome elements and heavy metals in red soybean of Heilongjiang Province. Methods: Samples preparation with hydrodigestion, and twenty-four elements quantitative analysis in red soybean by inductively coupled plasma mass spectrometry technique (ICP-MS) with indium, platinum, ruthenium as internal standard. Results: The red soybean contained many elements necessary to human health, the sequence of elements (higher than mg/kg) was K > Mg > Ca > Fe ≈ Zn > Na > Mn > Ti > Cu > Sr ≈ Ni > Ba > Mo. Besides the trace elements, the contents of heavy metals were very low than National standard. With reference standard substance and added standard recovery for the quality control of analytical method, the results were credibility, recovery 85% - 114%, the detect limit 0.2 - 20 ng/g, linearity range 0 - 200 μg/g (r > 0.999), RSD (n = 6) < 9%. Conclusion: The established method could be applied to the element quantitative analysis in food, simple and high sensitivity.

A rapid quantitative technique had been developed for the screening of malachite green(MG) in aquaculture water using paper spray ionization mass spectrometry(PSI-MS).To rapid extract MG, chloroform and deep eutectic solvents(DESs) were used as extraction agent and co-solvent respectively. malachite green D_5(MG-D_5) was used as an internal standard to quantitative determination MG, C_(18) chromatographic column(4. 6 mm×250 mm, 5 μm).The method showed a good linearity(R~2=0. 999) in the concentration range of 0. 1-10 μg/mL with the detection limit of 0. 03 μg/mL and the quantitative limit of 0. 1 μg/mL. The intra-and inter-day precisions were 3. 5% and 6. 2%, and the recovery ranged from 98. 9% to 106. 9%(n=7). The detection result by PSI-MS were in agreement with those by liquid chromatography-tandem mass spectrometry(LC-MS/MS), but the run time was only 1 min each sample.The method is accurate and reliable. And compared with the conventional LC-MS/MS technology, it is simple, rapid and low-cost.

This paper aims at implementing and introducing the use of conditional mean spectrum (CMS) and conditional spectrum (CS) as the main input parameters in the practice of seismic safety evaluation (SSE) in China, instead of the currently used uniform hazard spectrum (UHS). For this purpose, a procedure for M-R-epsilon seismic hazard deaggregation in China was first developed. For illustration purposes, two different typical sites in China, with one to two dominant seismic zones, were considered as examples to carry out seismic hazard deaggregation and illustrate the construction of CMS/CS. Two types of correlation coefficients were used to generate CMS and the results were compared over a vibration period range of interest. Ground motion records were selected from the NSMONS (2007–2015) and PEER NGA-West2 databases to correspond to the target CMS and CS. Hazard consistency of the spectral accelerations of the selected ground motion records was evaluated and validated by computing the annual exceedance probability rate of the response spectra and comparing the results to the hazard curve corresponding to each site of concern at different periods. The tools developed in this work and their illustrative application to specific case studies in China are a first step towards the adoption of CMS and CS into the practice of seismic safety evaluation in this country.

Reliable site classification of the stations of the China National Strong Motion Observation Network System (NSMONS) has not yet been assigned because of lacking borehole data. This study used an empirical horizontal-to-vertical (H/V) spectral ratio (hereafter, HVSR) site classification method to overcome this problem. First, according to their borehole data, stations selected from KiK-net in Japan were individually assigned a site class (CL-I, CL-II, or CL-III), which is defined in the Chinese seismic code. Then, the mean HVSR curve for each site class was computed using strong motion recordings captured during the period 1996–2012. These curves were compared with those proposed by Zhao et al. (2006a) for four types of site classes (SC-I, SC-II, SC-III, and SC-IV) defined in the Japanese seismic code (JRA, 1980). It was found that an approximate range of the predominant period T g could be identified by the predominant peak of the HVSR curve for the CL-I and SC-I sites, CL-II and SC-II sites, and CL-III and SC-III + SC-IV sites. Second, an empirical site classification method was proposed based on comprehensive consideration of peak period, amplitude, and shape of the HVSR curve. The selected stations from KiK-net were classified using the proposed method. The results showed that the success rates of the proposed method in identifying CL-I, CL-II, and CL-III sites were 63%, 64%, and 58% respectively. Finally, the HVSRs of 178 NSMONS stations were computed based on recordings from 2007 to 2015 and the sites classified using the proposed method. The mean HVSR curves were re-calculated for three site classes and compared with those from KiK-net data. It was found that both the peak period and the amplitude were similar for the mean HVSR curves derived from NSMONS classification results and KiK-net borehole data, implying the effectiveness of the proposed method in identifying different site classes. The classification results have good agreement with site classes based on borehole data of 81 stations in China, which indicates that our site classification results are acceptable and that the proposed method is practicable.

In this report, we have constructed a simple, eco-friendly and one-pot synthetic strategy for the synthesis of fluorescent gold nanoclusters (GNCs) using a native polysaccharide (chondroitin sulfate) as the novel template. Moreover, we used some analytical instruments for characterizing the formation of Au clusters, containing ultraviolet-visible spectrometer, fluorescence spectrometer, high resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectroscopy (XPS). The obtained data indicated that the Au nanoclusters were successfully formed. The chondroitin sulfate-capped gold nanoclusters (CS-GNCs) displayed excitation and emission bands at 450 and 520 nm, respectively. The fluorescence quantum yield was 4.78%. We further used CS-stabilized gold nanoclusters selectively and sensitively for sensing Cu 2+ in real samples via non-covalent d 10 -d 10 metallophilic bond. The linear range of the method was 0.01–1.8 μM with the limit of detection (LOD) was 8 nM (signal/noise = 3), and the recoveries of the spiked samples in lake water and tap water samples ranged from 90% to 108%, suggesting that the proposed method could be used in the practice detection of Cu 2+ .

Conditional mean spectrum (CMS) is increasingly being accepted as a more reasonable target spectrum for selecting earthquake records than uniform hazard spectrum. Construction of CMS requires the determination of correlation coefficients of spectral accelerations. This article presents the first investigation of correlation coefficients based on earthquake records from China. First, an original methodology to verify the appropriateness of a ground‐motion prediction equation (GMPE) to determine correlation coefficients is proposed and illustrated considering seismic hazard in China. A dataset of ground motions recorded from 2007 to 2014 in China, with magnitudes ranging from M s 5.5 to 7.0 and epicentral distances less than 200 km, is then selected and analyzed to obtain correlation coefficients based on a newly developed GMPE. The obtained results indicate the same trends as the prediction model proposed by Baker and Jayaram (2008) based on Next Generation Attenuation‐West ground motions and GMPEs. The sensitivity of correlation coefficients to magnitude is also verified and the obtained results are provided in comprehensive tables. The results of this work provide the essential data required to develop CMS considering seismic hazard in China.

Near-infrared spectroscopy (NIR) was used for qualitative and quantitative detection of honey adulterated with high-fructose corn syrup (HFCS) or maltose syrup (MS). Competitive adaptive reweighted sampling (CARS) was employed to select key variables. Partial least squares linear discriminant analysis (PLS-LDA) was adopted to classify the adulterated honey samples. The CARS-PLS-LDA models showed an accuracy of 86.3% (honey vs. adulterated honey with HFCS) and 96.1% (honey vs. adulterated honey with MS), respectively. PLS regression (PLSR) was used to predict the extent of adulteration in the honeys. The results showed that NIR combined with PLSR could not be used to quantify adulteration with HFCS, but could be used to quantify adulteration with MS: coefficient (Rp2) and root mean square of prediction (RMSEP) were 0.901 and 4.041 for MS-adulterated samples from different floral origins, and 0.981 and 1.786 for MS-adulterated samples from the same floral origin (Brassica spp.), respectively.

The microscopic properties of NaCl-induced phase separation of acetonitrile (ACN)-water mixtures have been studied by proton nuclear magnetic resonance (1H NMR). Acetonitrile-rich phase increases with increasing NaCl concentration (cNaCl) at xACN ≈ 0.25. 1H chemical shift of water for acetonitrile-rich phase rapidly decreases with decreasing NaCl mole concentration and that for water-rich phase quickly increases with increasing cNaCl. However, 1H chemical shift of acetonitrile has nothing to do with the molar concentration of NaCl, and it keeps relatively stable for all solutions (±0.002). These results reveal that Na+ and Cl- are rapidly hydrated by water, not by acetonitrile. The change of 1H chemical shift of water has shown that the number of hydrogen bond increases or hydrogen bond strengths with increasing NaCl molarity in mixtures. But hydrogen bond is broken or weaken with the temperature rising. 1H chemical shifts of pure water and the water in acetonitrile-rich phase have been investigated at 293 K, 298 K and 303 K. The hydration number of Na+ (6.05) in water-rich phase is determined by an empirical equation involving 1H chemical shift, temperature and NaCl molarity, which is in good agreement with the literatures.

First, strong‐motion recordings from an M w 4.4 earthquake with symmetrical rupture were regarded as empirical Green’s functions (EGFs) to simulate ground motions produced by the 2013 M w 6.6 Lushan mainshock using the two‐step stochastic EGF method proposed by Kohrs‐Sansorny et al. (2005). In this simulation, the source of the Lushan mainshock was set to consist only of an asperity in the vicinity of the hypocenter, which was determined according to the statistical properties of asperity. The good agreement between the simulated ground motions and the observed recordings at short periods (

The uniform seismic input for the large-scale or multi-bearing structures, such as bridges cannot reflex the spatial variability of ground motions which could have great effects on the structural dynamic responses. It needs to understand the ground-motion variability within a small area. Based on the ground motions recorded at the dense observation array, EUROSEISTEST located in Greece, the coherences of ground motion at both horizontal and vertical components were investigated under the random vibration theory. The ground-motion coherency for the underground depth was also discussed based on the borehole recordings at varied depths (< 200 m). The ground-motion coherency at low frequencies in our model showed the approximate consistency with two currently-used models. A remarkable downward tendency of the ground-motion coherency was generally observed with the increase of the frequency or the underground depth. The coherency of ground motions at horizontal components was more significant than that at vertical components.

A large number of strong-motion recordings collected by the National Strong-Motion Observation Networks System during the $M_{s}6.0 -7.0$ earthquake occurred in the North-South Seismic Zone. We selected the strong-motion recordings with Joyner-Boore distance less than 400 km, and the ground motion prediction equation developed by Booer et al. (2014) to investigate the region variability of ground motion between the NSSZ and California region. The residual analysis was done to exhibit the regional variability of ground motion between both regions. The resultant between-events residuals suggested that the source effect in NSSZ region was stronger than that in California region. The adjustment coefficients of anelastic attenuation in NSSZ were larger compared with that in BSSA14 model, indicated that the NSSZ exhibited slower anelastic attenuation.

To the end of investigating the potential nonlinear soil behavior at 44 strong motion stations during the 2016 Mw7.8 Kaikōura, New Zealand earthquake, we analyzed the modifications of the site response under the strong mainshock recording based on the horizontal-to-vertical spectra ratio, including the shift of the predominant frequency, and three nonlinearity indicators, DNL, ADNL, and PNL. Significant modifications to site response were observed at more than half of the stations, where the predominant frequency generally shifted to the lower one, and the DNL, ADNL, and PNL values were generally greater than 4.0, 0.3, and 10%, respectively. The strain proxy represented by PGV/Vs30 was found in high level as the nonlinearity indicators were high. The deformation proxy may be a better indicator predicting the nonlinear soil behavior at sites with available shear-wave velocity. After the nonlinear soil behavior occurred, the soil structure completely recovered and the nonlinearity vanished after a period of time. The recovery process was dependent on the ground motion intensity immediately after the strong ground shaking, and the soil condition.

Spectral ratio methods have been widely used in evaluation of nonlinear seismic site response. Nevertheless, it remains inefficient and subjective to identify stations with nonlinear site response according to empirical threshold values of spectral ratio nonlinear degree indicators. This study, which was the first to apply the machine learning clustering algorithm to address this problem, used the September 6, 2018 Mw6.6 Hokkaido Iburi-Tobu earthquake (Japan) as an example. First, we calculated the surface/borehole and horizontal/vertical spectral ratios using strong ground motion data recorded by KiK-net vertical array and K-NET stations, respectively. The degree of nonlinear site response (DNL) and percentage of nonlinear site response (PNL) were computed using the difference between the strong motion of the mainshock and weak aftershocks as the reference for linear site response. Then, the K-means clustering algorithm was incorporated in the identification of nonlinear site response using the DNL, PNL, strength of ground motion (PGA) and site condition (VS20 or VS30) as explanatory variables. After careful multicollinearity diagnosis and confirmation of the optimum clustering number, we successfully classified the stations into two clusters with nonlinear and linear site responses. Overall, the clustering results were found in good agreement with the classification results based on empirical thresholds of several nonlinear indicators. For the stations identified with nonlinear site response, the reduction of amplification and frequency shift could be observed from the spectral ratio curves regarding the ground motions in the mainshock and the reference weak aftershocks, demonstrating typical nonlinearity response characteristics. Furthermore, a comprehensive indicator of nonlinear site response occurrence probability (NLscore) was obtained from a linear weighted combination of the normalized variables (PGA, VS30/VS20, DNL and PNL). The NLscore ranking of the top several stations was found consistent with the clustering identification results, irrespective of the choice of combination scheme. It was demonstrated that the performance of clustering algorithm in this application was satisfactory and that the identification results were convincing and robust. This work provides an enlightening example of using state-of-art machine learning technique to solve the traditional earthquake engineering problems.

A high temperature desorption (HTD) direct analysis in real time-high-resolution mass spectrometric (DART-HRMS) method was developed for the rapid analysis of four banned cationic dyes. Rhodamine B is used to dye foods, while malachite green, crystal violet, and methylene blue are added to fishponds as antimicrobials. A simple induced phase separation extraction was used to pretreat samples. The DART-HRMS method employed two temperature steps, i.e., 200 °C for drying, purification, and enrichment of sample solution and 500 °C for thermal desorption and ionization of analytes. The calibration curves of dyes in the range of 50-2000 ng/mL were linear using deuterated malachite green as an internal standard. The LODs vary for all analytes between 0.1 and 30 ppb depending on the matrix and experimental conditions. Through analyses of real samples, two chili powders and one chili oil were found to be contaminated by rhodamine B. The concentrations were comparable with those found by an HPLC-MS/MS method.