Residue Dissipation, Degradation Dynamics, and Dietary Risk Assessment of Mandipropamid in Ginseng Under Field Application

Mandipropamid, a new fungicide for oomycete disease, has a strong effect on the blight of many crops and has been registered for the treatment of ginseng blight in China. However, no maximum residue limit (MRL) of mandipropamid has been identied for ginseng, and there have been few related studies. We established and veried the analysis method of mandipropamid in ginseng using high-performance liquid chromatography-tandem mass spectrometry. The method has good linearity and accuracy in the range of 0.002–0.5 mg/kg. The average recovery of mandipropamid was 87.4–101.6%, and the standard deviation was 1.1–10.1. The degradation dynamics showed that the half-life of mandipropamid in ginseng plant and soil was 13.8–28.0 and 9.8–27.4 d, respectively. After the recommended dose of mandipropamid was applied once, the residual content of mandipropamid in fresh ginseng, dried ginseng, red ginseng, ginseng plant, and ginseng soil was <0.01–0.185, <0.01–0.265, 0.085–1.544, 0.075–4.800, and <0.01–0.014 mg/kg, respectively. The dietary risk assessment of mandipropamid on ginseng showed that the risk quotient value was far less than 100%, indicating that the recommended dose of mandipropamid does not cause unacceptable risks to humans. Mandipropamid in ginseng plants and soil rapidly degraded following rst-order kinetics models. After the recommended dose of mandipropamid was applied once, it did not cause unacceptable risks to humans. This study not only provides a reasonable spray dosage of mandipropamid to ginseng, but also offers a reference for the establishment of MRLs in China. 13.8 (Fusong), 28.0 (Huanren), 13.9 (Baishan). The original of mandipropamid in ginseng were 5.24 (Fuosng), 3.22 (Huanren), and 4.42 mg/kg (Baishan). The half-life of mandipropamid in ginseng plant was 9.8 (Fusong), 16.0 (Huanren), and 27.4 d (Baishan). The original residue amount of mandipropamid in ginseng plants was 0.039 (Fuosng), 0.054 (Huanren), and 0.068 mg/kg (Baishan). The difference in the original may be speed, etc.) at the test point during spraying. The results showed that the half-life of in plants not that and Baishan, which may also such plant (Bai et al., 2020). The half-life of mandipropamid in ginseng soil was different in Fusong, Huanren, and Baishan. help establish the MRL residual test results, after one application, the chronic dietary risk of mandipropamid in ginseng was an RQ value of 2.9%, which was far less than 100%, indicating that there was no signicant potential risk of mandipropamid in ginseng at the recommended dose. This study provides a basis for the rational use of mandipropamid in ginseng, as well as a reference for the establishment of MRL of mandipropamid in ginseng.


Introduction
Ginseng is the dried root and rhizome of Panax ginseng C.A.Mey (Zhang et al., 2021). As the largest ginseng planting and production country in the world, China has a long history of medicinal use of ginseng. Ginseng plays an important role in regulating human health and treating different diseases (Fan et al., 2020) through its antitumor, antioxidation, and antidiabetic properties (Park et al., 2017). The growth cycle of ginseng is relatively long, usually 4-6 years for garden ginseng and 15 years for forest ginseng.
During the long growth cycle, the occurrence of diseases affects the quality of ginseng, which causes signi cant economic losses to ginseng farmers and affects the import and export of ginseng. Therefore, fungicides must be used to prevent diseases during the planting process. However, due to the irregular use of pesticides, excessive pesticide residues can be found in ginseng.
Mandipropamid is a new fungicide for oomycete diseases (Tang et al., 2011), which is the rst commercial amygdalinamide compound with the chemical name of 2-(4-chlorophenyl)-n-[2-(3-methoxy-4-prop-2-ynynloxy-phenyl)-ethyl]-2-prop-2-ynyloxyacetamide. It has high activity in inhibiting conidial germination, mycelial growth and spore formation; it also has a good preventive and therapeutic effect on lychee downy mildew (Tang et al., 2011), pepper blight (Siegenthaler and Hansen, 2021), tomato late blight (Chen et al., 2021), and cucumber downy mildew (Liu et al., 2016;Zhang et al., 2015). In China, mandipropamid has been registered in tomato, pepper, potato, lychee, grape, watermelon, and ginseng and has been widely used to control blight and downy mildew in various crop sites. Mandipropamid is mainly used to treat ginseng blight. The application of mandipropamid to ginseng will inevitably cause pesticide residue problems in ginseng and the surrounding environment, thereby causing harm to human health. In recent years, the problem of pesticide residue has gained increasing attention; therefore, the rational use and risk assessment of mandipropamid is of great signi cance.
At present, the methods for detecting residues of mandipropamid in sesame leaves (Farha et (Yang et al., 2020), and Cnidium (Dong et al., 2020)have been undertaken. However, there have been no systematic studies on the residual behaviour, degradation dynamics, and dietary risk assessment of mandipropamid in ginseng. Therefore, in this study, we established a method for the detection of mandipropamid in ginseng using HPLC-MS/MS. Through eld trials at ve locations for 1 year, the residual behaviour and degradation dynamics of mandipropamid in ginseng were analysed. Additionally, the safety of mandipropamid use on ginseng was evaluated in combination with the Chinese dietary structure. Finally, reasonable suggestions were provided for the rational use of mandipropamid on ginseng, and the basis for the formulation of residue limits in ginseng was provided.

Instruments and reagents
The following materials were used: 1260-6470 HPLC-MS/MS (Agilent Technologies, USA), SHMADIU Model AUY220 Balance The area of the experimental plots was 50 m 2 . At the initial stage of the onset of ginseng disease, the spraying dose was 210.6 g a.i./ha of stem and leaf spray, dynamic soil application was soil spray mixed with water at 600 kg/ha, and the number of sprays was one. After one application, the ginseng plant and soil samples were collected at intervals of 0, 1, 3, 5, 7, 14, 21, 28, 35, 45, and 60 d. Residual samples of fresh ginseng, ginseng plant, and soil were collected at 14, 21, and 28 d.

Preparation of samples
Fresh ginseng samples were gently washed using cool water, and the surfaces of the samples were dried indoors. Fresh ginseng samples were baked at 55°C for 24 h to prepare dried ginseng, and fresh ginseng samples were placed in a cage on a pot lled with water at 80°C and heated to boiling for 2.5-3 h. Then, the heated ginseng was cooled and dried at 70°C for 6 h with a dryer. Next, the ginseng was in ltrated with water, and the ginseng was dried again at 55°C for 24 h. Ginseng plant samples were placed in a tissue masher, and mashed for 5 min, and then passed through a 40-mesh sieve.

Extraction and puri cation
Next, 5.0 (±0.05) g of the homogenised fresh ginseng, dried ginseng, red ginseng, ginseng plant, and ginseng soil samples were added to 50-mL centrifuge tube, and then, 5 mL of distilled water and 10 mL of acetonitrile were added to the tube. After standing immersion for 5 min, vortex extraction was performed for 2 min, and the samples were centrifuged at 5,000 g for 5 min.
An aliquot of 1 mL of the upper layer of fresh ginseng, dried ginseng, red ginseng, and ginseng soil was transferred to a centrifuge tube containing 50 mg PSA and 100 mg anhydrous magnesium sulphate. An aliquot of 1 mL of the upper layer of the ginseng plant was transferred to a centrifuge tube containing 50 mg PSA, 25 mg GCB, and 100 mg anhydrous magnesium sulphate.
The mixture was shaken vigorously 100 times and centrifuged for 5 min at 5,000 rpm. The upper layer was ltered through a 0.22μm nylon syringe lter disc and analysed by HPLC-MS/MS.

Statistical analysis
In this study, the standard curve and matrix standard curve of the same concentration were detected under the same chromatographic conditions, and the matrix effect was calculated according to the slope of the two standard solutions. When the matrix effect was within 100% (± 20), it was ignored; when it was greater than 120%, it showed enhancement, and when this was less than 80%, it showed inhibition. The calculation formula is as follows (Fang et al., 2019): where K S is the slope of the standard curve and K m is the slope of the matrix standard curve.
The dissipation dynamics of mandipropamid in ginseng plants and soil were evaluated using rst-order kinetics as follows ( where C t (mg/kg) is the residual concentration of mandipropamid in the ginseng plant or soil, C 0 (mg/kg) is the initial concentration of mandipropamid in the ginseng plant or soil, k (day −1 ) is the dissipation rate constant, and T 1/2 is the pesticide half-life of pesticide degradation.

Dietary intake risk assessment
Dietary exposure and risk assessments were performed to ensure the rational use of mandipropamid. RQ>100% indicated that there was an unacceptable risk to human health; the larger the value, the greater the risk. RQ<100% indicated that the risk to human health was acceptable; the smaller the value, the smaller the risk. where NEDI (mg/kg, bw) is the national estimated daily intake, STMRi (mg/kg) is the supervised trial median residue level, Fi (kg/d) is the average daily food intake, bw (kg) is the average Chinese body weight (63 kg), and ADI (mg/kg, bw) is the acceptable daily intake.

Method validation
The mandipropamid standard substance (0.0101 g) was accurately weighed, diluted to 10 mL with acetonitrile, sonicated for 10 min, and stored in a refrigerator at −4°C. This was then diluted with acetonitrile and blank matrix solution to 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, and 0.5 mg/L series solutions. Machine detection was performed according to the 2.3 method. With the concentration as the abscissa and the peak area as the vertical coordinates, a standard curve was drawn, resulting in the linear regression equation of mandipropamid. The results are presented in Table 1. The accuracy and precision of the method were veri ed using an addition-recovery test. According to the above method, the added amounts of fresh ginseng and soil were 0.01, 0.05, and 0.5 mg/kg, and those of dry ginseng, red ginseng, and plants were 0.01, 0.05, 0.5, and 50 mg/kg, respectively. This method was repeated ve times. The results are presented in Table 2. The sensitivity and accuracy of the method met the requirements and were suitable for the residue analysis of mandipropamid in ginseng. Note: RSD, relative standard deviation; LOQ, limit of quantitation; LOD, limit of etection.

The degradation dynamics of mandipropamid in ginseng plant and soil
According to the design of the eld experiment, samples were collected to assess the degradation dynamics of mandipropamid in ginseng plants and soil in Fusong County, Jilin Province, Huanren Manchu Autonomous County of Liaoning Province, and Baishan City of Jilin Province were collected. As detected using the 2.3-2.4 methods, the degradation of mandipropamid conformed to rstorder kinetics. The content of mandipropamid in ginseng plant and soil 2 h after application was that of the original residues, and as time passed, the residue concentration of mandipropamid gradually decreased. The results are shown in Figure 1-2 and Table 3. The results showed that the half-life of mandipropamid in ginseng plants was not signi cantly different in Fusong and Baishan, whereas that in Huanren was signi cantly higher than that in Fusong and Baishan, mainly due to plant size, sparseness, and metabolic capacity, which may also be affected by factors such as plant variety and weather conditions (Bai et al., 2020). The half-life of mandipropamid in ginseng soil was different in Fusong, Huanren, and Baishan. Since the ginseng soil was arti cially mixed with soil, its organic matter content varied between locations. The organic acid content of Baishan soil was 4%, that of Fusong soil was 4.3%, that of Huanren soil was 4.4%, and Baishan soil had the lowest organic matter content. This may be responsible for the half-life of mandipropamid in Baishan soil, which was signi cantly higher than that of the other two locations, possibly because of to the effects of factors such as the types of microorganisms in the soil, temperature and humidity of the environment, and duration of sunshine. Ginseng soil Fusong C t = 0.0235e -0.019t 0.6379 9.8  The maximum STMRi value of mandipropamid in fresh, dried, and red ginseng was selected as the reference limit for chronic dietary risk assessment. Ginseng is classi ed as soy sauce, and the STMRi of mandipropamid in red ginseng is regarded as the residue of soy sauce. The results are shown in Table 5, where the median RQ value is 2.9%, which is far less than 100%, indicating that the chronic dietary risk of mandipropamid use on ginseng is acceptable, and the recommended dose will not cause unacceptable risks to Chinese consumers. According to the JMPR report (He, 2008), it is not necessary to establish an acute reference dose for mandipropamid, and short-term intake of mandipropamid is unlikely to cause health problems to the public. Therefore, this study did not conduct an acute dietary risk assessment of mandipropamid in fresh, dried, and red ginseng.

Conclusion
In this study, an HPLC-MS/MS method was established for the detection of mandipropamid in ginseng, and the degradation dynamics, residue dissipation, and dietary risk assessment of mandipropamid in ginseng were studied under eld application. This method has good precision and accuracy. The residues in fresh ginseng, dried ginseng, red ginseng, ginseng plant, and ginseng soil were <0.01-0.185, <0.01-0.265, 0.085-1.544, 0.075-4.800, and <0.01-0.014 mg/kg, respectively. The half-lives of mandipropamid in ginseng plant and soil were 13.8-28.0 and 9.8-27.4 d, respectively. According to the nal residual test results, after one application, the chronic dietary risk of mandipropamid in ginseng was an RQ value of 2.9%, which was far less than 100%, indicating that there was no signi cant potential risk of mandipropamid in ginseng at the recommended dose. This study provides a basis for the rational use of mandipropamid in ginseng, as well as a reference for the establishment of MRL of mandipropamid in ginseng. The degradation dynamics curve of mandipropamid in ginseng plant