Degradation dynamics, residues, processing factors, and dietary risk assessment of bisultap in citrus by LC-MS/MS.

BACKGROUND: Citrus leaf miners are a common pest harming citrus production and quality during citrus planting. During the citrus plant's growth phase, bisultap formulation was frequently used to boost yield and produce fruit of high quality. However, research on citrus's dietary risk assessment for bisultap residues, dissipation and residues is lacking. RESULTS: Liquid chromatography-tandem mass spectrometry was used to develop an accurate and sensitive analytical method for derivatizing bisultap into nereistoxin in whole fruit, pulp and peel. At various levels of addition, the mean recovery of bisultap ranged from 84.64% to 111.09% with a reasonable relative RSD (< 20%). The half-lives in Guangxi and Guizhou were 3.96 and 6.03 days, respectively. After 14-21 days of bisultap application, total residues (bisultap and its metabolite nereistoxin) in the whole fruit were from < 0.02 to 0.228 mg kg-1 in the four experiment sites. Total residue (bisultap and nereistoxin, expressed by bisultap) in whole fruit was approximately 1.05-7.23 times that of pulp. The washing process with tap water removed 85.71% to 98.78% of the bisultap residue in the whole fruit. Bisultap's risk assessment value in citrus was in the range 0.16-1.28%. CONCLUSION: In the whole citrus fruit, bisultap degrades rapidly. Bisultap residues primarily accumulate on citrus peels, and so washing and peeling citrus may effectively remove bisultap residues. For various age groups, the chronic dietary risk of bisultap was acceptable. © 2023 Society of Chemical Industry.

Decomposing socioeconomic inequalities in dental caries among Chinese adults: findings from the 4th national oral health survey.

OBJECTIVE: This cross-sectional study aimed to investigate socioeconomic inequalities in dental caries among adults (35 years and older) in China and explore the contributions of various factors to these inequalities. METHODS: This study included 10,983 adults (3,674 aged 35-44 years, 3,769 aged 55-64 years and 3,540 aged 65-74 years) who participated in the 4th National Oral Health Survey (2015-2016) in China. Dental caries status was evaluated by the decayed, missing and filled teeth (DMFT) index. Concentration indices (CIs) were applied to quantify the different degrees of socioeconomic-related inequality in DMFT, decayed teeth with crown or root caries (DT), missing teeth due to caries or other reasons (MT), and filled teeth without any primary or secondary caries (FT) among adults of different age groups. Decomposition analyses were conducted to identify the determinants and their associations with inequalities in DMFT. RESULTS: The significant negative CI indicated that DMFT for the total sample were concentrated among socioeconomically disadvantaged adults (CI = - 0.06; 95% confidence interval [CI], - 0.073 to - 0.047). The CIs for DMFT for adults aged 55-64 and 65-74 years were - 0.038 (95% CI, - 0.057 to - 0.018) and - 0.039 (95% CI, - 0.056 to - 0.023), respectively, while the CI for DMFT for adults aged 35-44 years was not statistically significant (CI = - 0.002; 95% CI, - 0.022 to 0.018). The concentration indices of DT were negative and concentrated in disadvantaged populations, while FT showed pro-rich inequalities in all age groups. Decomposition analyses showed that age, education level, toothbrushing frequency, income and type of insurance contributed substantially to socioeconomic inequalities, accounting for 47.9%, 29.9%, 24.5%,19.1%, and 15.3%, respectively. CONCLUSION: Dental caries was disproportionately concentrated among socioeconomically disadvantaged adults in China. The results of these decomposition analyses are informative for policy-makers attempting to develop targeted health policy recommendations to reduce dental caries inequalities in China.

Income-related inequality and decomposition of edentulism among aged people in China.

BACKGROUND: The aim of this study was to assess the income-related inequality of edentulism among the aged in China and identify the contributing factors. METHODS: A secondary analysis of data from the 4th National Oral Health Epidemiology Survey in China was conducted, and 65-74 years old were selected for the analysis of income-related inequality of edentulism. The concentration curve, Concentration index (CI) and Erreygers-corrected concentration index (EI) were used to represent inequality and its degree qualitatively and quantitatively, respectively. A decomposition method based on probit model was employed to determine the contributors of inequality, including demographic factors, income status, oral health-related knowledge, attitude and practices and self-perceived general health status. RESULTS: In China, aged people with edentulism were concentrated in the poor. The CI was - 0.2337 (95% CIs: - 0.3503, - 0.1170). The EI was - 0.0413 (95% CIs: - 0.0619, - 0.0207). The decomposition results showed that income (75.02%) and oral health-related knowledge, attitude and practices (15.52%) were the main contributors to the inequality. CONCLUSION: This study showed that pro-poor inequality among the elderly with edentulism existed in China. Corresponding policies against the contributors could be considered to promote the health equality of the elders.

Multiresidue analysis and dietary risk assessment of pesticides in eight minor vegetables from Guizhou, China.

Several minor vegetables are widely employed as hot pot dishes and condiments in Southwest China. To gain insight into pesticide exposure risk via the intake of minor vegetables, vegetable samples (400) obtained from different farms in Guizhou were subjected to multiresidue analyses. Gas chromatography-tandem mass spectrometry and high performance liquid chromatography-tandem mass spectrometry were developed to detect and quantify 97 pesticide residues simultaneously in samples using modified QuEChERS methods. The results showed that no pesticides were detected in 248 samples. Pesticides of different levels were detected in 152 samples, of which 69 samples exhibited residue concentrations exceeding maximum residue limit of European Union. The acute and chronic dietary exposure risk of 15 pesticides in eight minor vegetables were accepted. The risk ranking result showed the most samples contained low-risk pesticides. The results will provide a reference for designing future pesticide supervision programs and risk management programs.

Dissipation Dynamics, Terminal Residues and Dietary Risk Assessment of Two Isomers of Dimethacarb in Rice by HPLC-MS/MS.

Dimethacarb is a carbamate insecticide developed in China that contains 3,5-dimethylphenyl methylcarbamate (XMC) and 3,4-dimethylphenyl methylcarbamate (MPMC) isomers. Dimethacarb has been registered for use in rice in China, but no residue or degradation of dimethacarb in rice has been reported and the maximum residue limits (MRLs) for rice have not been established. A versatile high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed with modified QuEChERS sample preparation to determine two isomers of dimethacarb in rice. The average recovery of XMC and MPMC in brown rice, rice husk, and rice straw ranged from 71.69 to 100.60%, with spike levels of 0.01 to 1 mg/kg and relative standard deviations (RSDs) of 0.21 to 8.41%. Field experiments showed that the half-lives of XMC and MPMC in rice straw were 4.08 to 4.23 days and 3.48 to 3.69 days, respectively. Final residues of XMC and MPMC in rice husk after 21 days of spraying at six sites ranged from 0.23-2.65 mg/kg and 0.06-1.10 mg/kg, and <0.01-0.16 mg/kg and <0.01-0.04 mg/kg in brown rice. The ratio of XMC to MPMC content in the rice husk differed from the original 50% dimethacarb EC, indicating the difference in the degradation rate of XMC and MPMC. The estimated risk quotient (RQ) for both XMC and MPMC was less than 30%. These data for residues from six representative locations could provide a reference for establishing the MRL of dimethacarb in rice.

Socioeconomic-related inequality in dental care utilization among preschool children in China.

OBJECTIVES: This study aimed to investigate socioeconomic-related inequality in dental care service utilization in the past 12 months among Chinese preschool children and to explore the contribution of various factors to this inequality. METHOD: A total of 40 305 children aged 3-5 years from 372 kindergartens who participated in the Fourth National Oral Health Survey in China were included in the final analysis. The method of data weighting in complex sampling was adopted to make the samples more representative. Erreygers-corrected concentration index (EI) was used to measure socioeconomic-related inequality in dental care service utilization. The horizontal inequality index (HI) was employed to analyse horizontal inequality. Decomposition analyses were conducted to explore the contributions of income level, need variables (dmft, caregiver-evaluated oral health status and toothache experience) and nonneed variables (caregiver education level, residential location, age, and sex) to the inequality of health service utilization. RESULT: The utilization of oral health services within the past 12 months among the high-, middle- and low-income groups was 17.4% (95% CI: 15.6-19.3), 13.6% (95% CI: 12.2-15.1) and 9.4% (95% CI: 8.1-11.0) respectively. The concentration curve was below the line of equality, and the EI and HI were 0.072 and 0.078, respectively, indicating that dental care utilization in children aged 3-5 years was concentrated in those who were better off. The contribution of the need variables to socioeconomic-related inequality in dental services was minimal, and most dental care utilization inequality could be explained by household income, caregiver education attainment and urban-rural disparities, accounting for 32.0%, 49.4% and 20.4% respectively. CONCLUSION: This study reveals the existence of pro-rich inequality in dental care utilization among preschool children in China. The decomposition analysis suggests that income, caregiver education background and urban-rural disparities are the main factors contributing to this outcome. Equity-oriented policies and programmes are needed to achieve equitable dental care utilization.

Measuring and decomposing socioeconomic-related inequality in the use of oral health services among Chinese adults.

OBJECTIVES: This study aimed to measure socioeconomic-related inequality and horizontal inequity in the use of oral health services and decompose this inequality among adults of different age groups in China. METHODS: In total, 10 973 adults (3669 aged 35-44 years, 3767 aged 55-64 years and 3537 aged 65-74 years) who participated in the 4th National Oral Health Survey (2015-2016) in China were included. Concentration curves and the Erreygers-corrected concentration index (EI) were employed to measure socioeconomic-related inequality in the use of oral health services. Then, inequity in this utilization was measured by the horizontal inequity index (HI). Furthermore, decomposition analyses were conducted for the three groups to explain the contributions of income level, need factors (ie self-assessed oral health and evaluated oral health status), other factors (ie sex, residential location, educational attainment level and type of basic insurance) and a residual term to overall inequality in oral health service utilization. RESULTS: The significant positive EI and HI values indicated that pro-rich inequality and inequity in oral health service utilization exist among Chinese adults. Income and type of basic medical insurance contributed the most to socioeconomic-related inequality in the use of oral health services among adults aged 55-64 and 65-74 years. However, the main driving factors of socioeconomic inequality among adults aged 35-44 years in dental care use included income, educational achievement, type of basic medical insurance and residential location. The need variables accounted for a very small proportion of overall socioeconomic-related inequality in oral health service use in all three groups. CONCLUSIONS: Oral healthcare service utilization was disproportionately concentrated among better-off Chinese adults. The primary determinants of inequality in dental care use in different age groups provide information for policymakers to create more targeted policies to achieve equity in the oral healthcare system in China.

Determination, risk assessment and processing factors for pyridaben in field-incurred kiwifruit samples.

Field trials in six agricultural sites were carried out to investigate the dissipation and residue levels of pyridaben in kiwifruit. Each sample was extracted with acetonitrile, purified with octadecylsilane and analyzed with high-performance liquid chromatography-tandem mass spectrometry. The method had good linearity (R2 > 0.99), accuracy (recoveries of 78.53-98.00%) and precision (relative standard deviation of 0.86-6.11%). The dissipation of pyrdaben in kiwifruit followed first-order kinetics with a half-life < 8 d, and terminal residues in kiwifruit were lower than 0.5 mg/kg after 14 d of application. Risk assessment indicated that both chronic and acute dietary intake risk values were far below 100%, suggesting that pyridaben residues in kiwifruit were relatively safe to humans. Moreover, the effects of traditional household processes on kiwifruit were investigated. The processing factors (PFs) indicated that peeling and peeling-juicing processes could remove pyridaben residues from kiwifruit, and the former was more effective than the latter (PF at 0.15 vs. 0.51). Nevertheless, drying kiwifruit with an oven increased the amount of pyridaben (PF at 1.05). These results could provide guidance for the safe and reasonable use of pyridaben in agriculture and may be helpful for the Chinese government to determine maximum residue limit of pyridaben in kiwifruit.

Residual determination of pyrethrins in Lycium barbarum (goji) by GC-MS/MS and a dietary risk assessment of Chinese goji consumption.

An accurate and simple analytical approach for the determination of residues cinerin I, cinerin II, jasmolin I, jasmolin II, pyrethrin I and pyrethrin II (six active ingredients of pyrethrins) in fresh and dried goji berries was developed and validated for analysis by gas chromatography with tandem mass spectrometry. Good linearity (determination coefficient >0.99), accuracy (average recoveries of 88.3%-111.5%) and precision (intra- and inter-day relative standard deviations of 0.4%-8.3%) were obtained with the optimised determination method. The LODs and LOQs of the six analytes in two goji matrices were 0.24-2.1 µg/kg and 0.8-7 µg/kg, respectively. In a field trial, the terminal residual levels of pyrethrins (the sum of the concentrations of the six target analytes) in fresh and dried goji berry samples were <20-304 µg/kg at harvest, which could provide some information for the establishment of a maximum residue limit of pyrethrins on goji berries in China. Moreover, the risk assessment results indicated that because the risk quotient values were ≪100%, the potential dietary risk of pyrethrins on goji berries could be negligible for Chinese consumers. These detection and field results could provide some supporting data for the determination of pyrethrin residues in other crops and the proper application and safety assessment of pyrethrins in goji plants.

Utilization of dental services and associated factors among preschool children in China.

BACKGROUND: This study sought to evaluate dental utilization among 3-,4-, and 5-year-old children in China and to use Andersen's behavioural model to explore influencing factors, thereby providing a reference for future policy making. METHODS: This study is a cross-sectional study. Data of 40,305 children aged 3-5 years were extracted from the Fourth National Oral Health Survey, which was performed from August 2015 to December 2016. Patient data were collected using a questionnaire, which was answered by the child's parents, and clinical data were collected during a clinical examination. Stratification and survey weighting were incorporated into the complex survey design. Descriptive statistics, bivariate correlations and hierarchical logistic regression results were then analysed to find the factors associated with oral health service utilization. RESULTS: The oral health service utilization prevalence during the prior 12 months were 9.5% (95%CI: 8.1-11.1%) among 3-year-old children, 12.1% (95%CI: 10.8-13.5%) among 4-year-old children, and 17.5% (95%CI: 15.6-19.4%) among 5-year-old children. "No dental diseases" (71.3%) and "dental disease was not severe" (12.4%) were the principal reasons why children had not attended a dental visit in the past 12 months. The children whose parents had a bachelor's degree or higher (OR: 2.29, 95%CI: 1.97-2.67, p < 0.001), a better oral health attitude ranging from 5 to 8(OR: 1.64, 95%CI: 1.43-1.89, p < 0.001), annual per capital income more than 25,000 CNY (OR: 1.40, 95%CI: 1.18-1.65, p < 0.001),think their child have worse or bad oral health (OR: 3.54, 95%CI: 2.84-4.40, p < 0.001), and children who often have toothaches (OR: 9.72, 95%CI: 7.81-12.09, p < 0.001) were more likely to go to the dentist in the past year. CONCLUSION: The prevalence of dental service utilization was relatively low among preschool children. It is necessary to strengthen oral health education for parents and children, thereby improving oral health knowledge as well as attitude, and promoting dental utilization.

Determination, residue and risk assessment of trifloxystrobin, trifloxystrobin acid and tebuconazole in Chinese rice consumption.

A simple and rapid analytical method for the detection of trifloxystrobin, trifloxystrobin acid and tebuconazole in soil, brown rice, paddy plants and rice hulls was established and validated by liquid chromatography with tandem mass spectrometry. Acceptable linearity (R2 > 0.99), accuracy (average recoveries of 74.3-108.5%) and precision (intra- and inter-day relative standard deviations of 0.9-8.8%) were obtained using the developed determination approach. In the field trial, the half-lives of trifloxystrobin and tebuconazole in paddy plants were 5.7-8.3 days in three locations throughout China, and the terminal residue concentrations of trifloxystrobin and tebuconazole were <100 and 500 µg/kg (maximum residue limits set by China), respectively, at harvest, which indicated that, based on the recommended application procedure, trifloxystrobin and tebuconazole are safe for use on rice. The risk assessment results demonstrated that, owing to risk quotient values of both fungicides being <100%, the potential risk of trifloxystrobin and tebuconazole on rice was acceptable for Chinese consumers. These data could provide supporting information for the proper use and safety evaluation of trifloxystrobin and tebuconazole in rice.

Determination, residue analysis, risk assessment and processing factors of tebufenozide in okra fruits under field conditions.

BACKGROUND: Ensuring the yield, quality, and profitability of okra by preventing and controlling pests with the application of insecticides has increased in the last decade. Some insecticide residues might remain in edible parts of okra (fruits) and lead to several potential human health problems. Therefore, research on the residue behaviour, risk assessment and removal approach of insecticides on okra fruits is important for food safety, together with the proper application and residual elimination of insecticides in okra. RESULTS: A simple liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was established and validated for determining the tebufenozide residues in okra fruits. The recoveries of tebufenozide in okra fruits were >72% with relative standard deviations of 0.6 to 6.1%. The dissipation rates of tebufenozide were different in okra fruits cultivated under open land and glasshouse field conditions because of the discriminating humidity and temperature conditions. The dietary intake of the tebufenozide residues from okra fruit consumption for Chinese consumers was fairly low, with approximately no potential health risk. The processing factor values of washing, blanching, washing + blanching and soaking were all less than one, which indicated that these processes could effectively reduce the residual hydrazide in the okra fruit. CONCLUSION: The developed method for analysing tebufenozide in okra fruits was applicable for field studies on this insecticide. The potential health risk of tebufenozide in okra fruits could be negligible to the health of different age groups of Chinese consumers. The soaking process effectively removed tebufenozide residues from okra fruits. The obtained data will help Chinese governments establish a maximum residue limit of tebufenozide in okra and provide data for the risk assessment and removal of tebufenozide in other crops. © 2019 Society of Chemical Industry.

Factors associated with oral health service utilization among adults and older adults in China, 2015-2016.

OBJECTIVES: To explore the factors associated with utilization of oral health services among Chinese adults and older adults according to the Andersen Behavior Model. METHODS: Data from the 4th National Oral Health Survey (2015-2016) in China were used. A total of 7206 people (3669 adults aged 35-44 years and 3537 older adults aged 65-74 years) were included in our analysis. Oral health service utilization in the past 12 months was the outcome variable. Explanatory variables were selected according to the Andersen Behavior Model. Descriptive statistics and bivariate associations (chi-square tests) were analysed, followed by hierarchical Poisson regression models, which were conducted to determine the factors associated with oral health service utilization. RESULTS: In total, 21.4% (95% CI: 19.4%-23.7%) of adults (35-44 years old) and 20.7% (95% CI: 18.6%-22.9%) of older adults (65-74 years old) utilized oral health services in the past 12 months. Nearly 80% of adults (78.7%, 95% CI: 74.0%-82.7%) and more than 90% of older adults (93.7%, 95% CI: 91.0%-95.6%) visited a dentist for treatment. Adults aged 35-44 years old who were female (IRR: 1.15, 95% CI: 1.00-1.33, P = .047), had good oral health knowledge and attitudes (IRR: 1.30, 95% CI: 1.06-1.59, P = .011), perceived their oral health status as fair (IRR:1.51, 95% CI:1.24-1.85, P < .001) or poor/very poor (IRR:2.52, 95% CI:2.01-3.18, P < .001) and had a decayed, missing and filled teeth (DMFT) index >0 (IRR: 1.52, 95% CI: 1.11-2.09, P = .009) were more likely to report dental visits in the past 12 months. Older adults who utilized oral health services tended to be female (IRR: 1.32, 95% CI: 1.09-1.59, P = .004); to be covered by Urban Resident Basic Medical Insurance (URBMI) (IRR: 1.56, 95% CI: 1.18-2.05, P = .002), Urban Employee Basic Medical Insurance (UEBMI) (IRR: 1.69, 95% CI: 1.32-2.16, P < .001) or government medical insurance (GMI) (IRR: 1.03, 95% CI:1.01-2.16, P = .044); to have a high education level (IRR: 1.37, 95% CI: 1.08-1.74, P = .010); to have an income level in the 2nd tertile (IRR: 1.44, 95% CI: 1.13-1.84, P = .003) or 3rd tertile (IRR:1.52, 95% CI:1.18-1.95, P = .001); and to perceive their oral health status as poor or very poor (IRR: 1.53, 95% CI: 1.21-1.95, P = .001). CONCLUSIONS: Sex and self-perceived oral health status were associated with oral health utilization among Chinese population. Additionally, for older adults, education level, household income and insurance coverage were determinants of dental service use. These findings can aid in creating more targeted policies to increase the use of dental services by Chinese adults.

Dissipation, residues and risk assessment of oxine-copper and pyraclostrobin in citrus.

An efficient, sensitive, simple and fast method for the simultaneous determination of oxine-copper and pyraclostrobin in citrus fruit was developed and validated. The method uses ethylene diamine tetra-acetic acid as a competitive ligand to convert oxine-copper to soluble 8-hydroxyquinoline for analysis by QuEChERS and LC-MS/MS. Linear relationships were determined with correlation coefficients ranging from 0.9904 to 0.9998. The limits of detection for the analytes were 0.012-0.8 µg kg-1, and the limits of quantitation were 0.04-2.6 µg kg-1 in citrus. The average recoveries were 79.1-114.9% with relative standard deviations of less than 7.4%. The analyses of dissipation indicated that the half-lives of oxine-copper and pyraclostrobin were 1.94-3.67 and 1.79-2.48 days and the terminal residues were <0.08-8.99 and <0.02-1.90 mg kg-1, respectively. The risk quotients of oxine-copper and pyraclostrobin were 0.026-0.199 and 0.003-0.022, respectively. This risk assessment provides a reference for the safe and reasonable use of oxine-copper and pyraclostrobin and may help to establish maximum residue limits for these pesticides in China.

Determination, residue analysis, risk assessment and processing factor of pymetrozine and its metabolites in Chinese kale under field conditions.

A simple determination method for pymetrozine and its metabolites in Chinese kale was developed using liquid chromatography with tandem mass spectrometry. The method had good linearity (R2 > 0.99), accuracy (recoveries of 73.2-94.1%) and precision (relative standard deviation of 2.5-9.8%). Field results showed that half-lives of pymetrozine were 3.0-4.1 d in Chinese kale, and terminal residue concentrations were all below the United States Environmental Protection Agency's maximum residue limit (250 µg/kg) at harvest. Owing to risk quotient <100%, pymetrozine is unlikely to give rise to vital health concerns to humans following the recommended application guidelines. Moreover, effects of home processing on pymetrozine residues in Chinese kale were monitored. The processing factor values of four processes were between 0.19 and 0.60, which indicated that the used processes could remove pymetrozine residues from Chinese kale, especially pickling after washing process. The data could provide guidance to safe and reasonable use of pymetrozine and help Chinese governments establish a maximum residue limit for pymetrozine in Chinese kale.

Monitoring residue levels and dietary risk assessment of pymetrozine for Chinese consumption of cauliflower.

The present study investigates the occurrence of pymetrozine residues in cauliflower samples obtained from six cauliflower-producing areas of China during fixed time periods in 2017 and estimates the dietary risk of pymetrozine in cauliflower. A liquid chromatography with tandem mass spectrometry method was developed and validated to detect pymetrozine in cauliflower. The samples were extracted using 20 mL of acetonitrile and purified with dispersive solid-phase extraction using C18 as sorbent. The limit of quantification of pymetrozine was 0.008 mg/kg in cauliflower. The recoveries of the analyte were 82.04-95.18% with RSD <8.45%. The calibration curves for pymetrozine showed good linearities in the concentration range 0.004-2.0 mg/L with determination coefficients (R2 ) >0.999. Pymetrozine dissipated rapidly in cauliflower with a half-life of <4 days. The terminal residues of pymetrozine were <0.008-0.0881 mg/kg in cauliflower at 7, 10 and 14 days after spraying from six sites. The routine washing process removed about half amount of the pymetrozine in cauliflower; the reduction ratios were 51.0-52.8%. The dietary risk assessment indicated that pymetrozine did not exhibit obvious dietary health risks in cauliflower when good agricultural practices were implemented.

Dissipation, residues, and risk assessment of imidacloprid in Zizania latifolia and purple sweet potato under field conditions using LC-MS/MS.

A shortened version of Quick, Easy, Cheap, Effective, Rugged, and Safe method (QuEChERS) for determining the dissipation and residue of imidacloprid present in Zizania latifolia and purple sweet potato was established by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The average recoveries of imidacloprid in the two crops ranged from 82.12 to 113.79%, with relative standard deviation (RSD) of <7.32%. The dissipation dynamics of imidacloprid in Z. latifolia plants and purple sweet potato plants followed first-order kinetics, with half-lives of 3.2-5.5 days in each of sampling locations. The terminal imidacloprid residues in Z. latifolia and purple sweet potato at each of location were <0.005-0.120 mg kg-1. According to the risk assessment results, both the acute dietary risk quotient and chronic dietary risk quotient values were <1, indicating that imidacloprid is unlikely to pose health risks to humans with normal recommended use. The present study may serve as a valuable reference for the safe and reasonable use of imidacloprid in Z. latifolia and purple sweet potato fields.

Residues, dissipation kinetics, and dietary intake risk assessment of two fungicides in grape and soil.

The residue behavior and dietary intake risk of two fungicides (dimethomorph and pyraclostrobin) in grape (Vitis vinifera L.) were investigated from field trials. A modified quick, easy, cheap, effective, rugged, and safe method for simultaneously determining dimethomorph and pyraclostrobin residues in grape and soil was established using high performance liquid chromatography-tandem mass spectrometry. The average recoveries of dimethomorph and pyraclostrobin in the grape and soil matrices varied from 76.88% to 97.05%, with relative standard deviations of 1.73%-10.38%. The degradation half-lives of dimethomorph and pyraclostrobin were 7.3-12.0 days and 3.6-7.0 days in grape and soil, respectively. The terminal residues of dimethomorph and pyraclostrobin in the two matrices were 0.05-0.87 mg/kg. For dietary exposure risk assessments, all of the hazard quotient and hazard quotient index values were below 100%, which indicated that the suspending agents of dimethomorph and pyraclostrobin were sprayed on grape at the recommended dosages with no significant potential risks for Chinese consumers. This study provides a reference for analytically evaluating residual degradation behavior and dietary intake risk of two fungicides under field conditions.

Simultaneous determination and risk assessment of metalaxyl and azoxystrobin in potato by liquid chromatography with tandem mass spectrometry.

A liquid chromatography with tandem mass spectrometry method was developed and validated to simultaneously determine metalaxyl and azoxystrobin in soil, potato, and potato foliage samples. The samples were extracted by 20 mL of acetonitrile and purified with dispersive solid-phase extraction using octadecyl silane as sorbent. The method showed good linearity (determination coefficients ≥ 0.9926) for metalaxyl (2.5-500 ng/mL) and azoxystrobin (5-1000 ng/mL). The limits of detection and quantification for both fungicides were 1.5-20 µg/kg. The average recoveries in soil, potato, and potato foliage were 83.07-92.87% for metalaxyl and 82.71-98.53% for azoxystrobin. The intra- and inter-day relative standard deviations were all less than 9%. The method was successfully applied on the residual analysis of metalaxyl and azoxystrobin in field trial samples. The results showed that the concentrations of metalaxyl and azoxystrobin in potato samples collected from Guizhou and Hunan were below 50 and 100 µg/kg (maximum residue limit set by China), respectively, at 5 days after the last application. When following the recommended application manual, metalaxyl and azoxystrobin do not present health concerns to the population because the risk quotients are far below 100%. All the above data could help and promote the safe and proper use of metalaxyl and azoxystrobin in potato.

Dissipation, residues and risk assessment of spirotetramat and its four metabolites in citrus and soil under field conditions by LC-MS/MS.

A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the simultaneous determination of spirotetramat and its four metabolite residues in citrus, peel, pulp and soil was developed and validated by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The samples were extracted with acetonitrile (1%, glacial acetic acid, v/v) and purified using primary secondary amine and octadecylsilane. The limit of detection was 0.01-0.13 mg/kg, whereas that of quantification was 0.02-0.40 mg/kg for spirotetramat and its metabolites. The average recoveries of spirotetramat, spirotetramat-enol, spirotetramat-mono-hydroxy, spirotetramat-enol-glucoside and spirotetramat-ketohydroxy in all matrices were 73.33-107.91%, 75.93-114.85%, 76.44-100.78%, 71.46-103.19% and 73.08-105.27%, respectively, with relative standard deviations < 12.32%. The dissipation dynamics of spirotetramat in citrus and soil followed first-order kinetics, with half-lives of 2.3-8.5 days in the three sampling locations. The terminal residues of spirotetramat in four matrices at the three locations were measured below the 1.0 mg/kg maximum residue limit set by China, and residues were found to be concentrated on the peel. The risk assessment of citrus was evaluated using risk quotients. The risk quotient values were found to be significantly <1, suggesting that the risk to human health was negligible when using the recommended doses of spirotetramat in citrus. These results could provide guidance for the safe and proper application of spirotetramat in citrus in China.