Environ Monit Assess DOI 10.1007/s10661-014-3781-y

Dissipation and residues determination of propamocarb in ginseng and soil by high-performance liquid chromatography coupled with tandem mass spectrometry Chunwei Wang & Yan Wang & Jie Gao & Yuncheng Xu & Lili Cui

Received: 26 January 2014 / Accepted: 22 April 2014 # Springer International Publishing Switzerland 2014

Abstract Two-year field trials were performed at two experimental sites to investigate dissipation and terminal residues of propamocarb in ginseng root, stem, leaf, and soil by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/ MS). Mean recoveries ranged from 80.5 to 95.6 % with relative standard deviations (RSDs) of 5.5–9.1 % at fortified levels of 0.01, 0.02, 0.05 and 0.20 mg kg−1. The half-lives of propamocarb were 5.00–11.36 days in root, 5.07–11.46 days in stem, 6.83–11.31 days in leaf and 6.44–8.43 days in soil. The terminal residues of propamocarb were below the maximum residue limits (MRLs) of EU (0.20 mg kg−1) and South Korea (0.50 mg kg−1 in fresh ginseng and 1.0 mg kg−1 in dried ginseng) over 28 days after last spraying at recommended dosage. The results provide a quantitative basis for establishing the MRL and give a suggestion of safe and reasonable use of propamocarb in ginseng.

Chunwei Wang and Yan Wang contributed equally to this study. C. Wang : Y. Wang : J. Gao (*) College of Agronomy, Jilin Agricultural University, Changchun 130118, China e-mail: [email protected] Y. Xu College of Resource and Environmental Science, Jilin Agricultural University, Changchun 130118, China L. Cui Institute of Special Wild Economic Animal and Plant Science, CAAS, Changchun 130118, China

Keywords Propamocarb . Ginseng . Soil . Dissipation . Residues . HPLC-MS/MS

Introduction Ginseng, an economically important and valuable medicinal herb, has been used for more than 2,000 years in Asian countries, particularly in China and Korea (Kennedy & Scholey 2003; Lee et al. 2004). China is the oldest and largest producer of ginseng in the world. Annual yield and exports account for more than 78 and 60 % for the world, respectively (Chen et al. 2012). In the last two decades, ginseng has gained popularity in the USA, Canada, and Europe (Wu et al. 2011; Xie et al. 2005). The pharmacological efficacy of ginseng has been observed in the central nervous, cardiovascular, endocrine, and immune systems (Wang & Yuan 2008). Extensive research shows that ginseng may have a cancer-preventative effect (Yun 2001). The cultivation of ginseng usually takes years and requires the use of pesticides to reduce the damages of various pests and diseases. Phytophtora blight and ginseng Pythium damping-off are two important diseases in ginseng, which are responsible for losses of ginseng yield. Propamocarb (propyl 3-(dimethylamino) propylcarbamate) is a systemic carbamated fungicide with protective action against ginseng Phytophtora blight and ginseng Pythium damping-off. Propamocarb is a moderately toxic substance (LD50 for rats is 8,600 mg kg−1, for mice is 2,800 mg kg−1), and the acceptable daily intake (ADI) value is 0.40 mg kg−1

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(FAO/WHO 2006). Figure 1 shows the chemical structure of propamocarb. The instrumental analytical methods for determination of propamocarb residues employing techniques such as high-performance liquid chromatography (HPLC) detection (Abd-Alrahman and Almaz 2012a, b), gas chromatography (GC) detection (Ueno et al. 2002), GC-mass spectrometric (GC-MS) detection (Bonnechère et al. 2012; Sahoo et al. 2011; Sahoo et al. 2014), and HPLC tandem mass spectrometry (HPLC-MS/MS) detection (Hiemstra & de Kok 2002; Taylor et al. 2004) have been reported in recent years. The dissipation of propamocarb has already been studied in potatoes using HPLC-DAD (Abd-Alrahman and Almaz 2012a, b). The analysis of propamocarb residues in ginseng, which contains amino acids, carbohydrate, ginsenoside, and volatile oil, is a challenging issue, due to high complexity of the matrix. In contrast to conventional procedures, MS-based techniques enable the detection of trace-level analytes in complex matrices and simplify pretreatment procedures with good precision and sensitivity (Castro et al. 2001; Li et al. 2012). So far, HPLC-MS/MS method has not been established to determine propamocarb residues in ginseng yet. To ensure food safety for consumers and to regulate international trade legislation, some countries have established maximum residue limits (MRLs) for propamocarb in ginseng. In EU, the MRL is set at 0.20 mg kg−1 (European Commission 2005); in South Korea, the MRL is set at 0.50 mg kg−1 in fresh ginseng and 1.0 mg kg−1 in dried ginseng (http://www.kfda.go. kr/cgi-bin/t4.cgi/eng/english_12.taf). As for one of the best-known Chinese herbal medicines, a greater boost in use of ginseng will be expected in recent years. However, there is no regulation on the MRL for propamocarb in ginseng in China, and no work has been done to determine propamocarb dissipation and terminal residues in ginseng. In this study, a simple and effective method was developed for determination of propamocarb residues in ginseng root, stem, leaf, and soil by HPLC-MS/MS. In addition, its dissipation and terminal residues were investigated through field trials. This work would be helpful to establish MRL and

Fig. 1 Chemical structure of propamocarb

provide guidance on the safe use of propamocarb in ginseng.

Materials and methods Chemicals Propamocarb standard (purity 98.5 %) and its formulation 72.2 % aqueous solution (AS) were purchased from Bayer CropScience China Co., Ltd (Beijing, China). Acetonitrile, methylbenzene, and methanol of HPLC grade were purchased from J.T. Baker (Xalostoc, Mexico). Formic acid was obtained from Tianjin Kemiou Chemical Reagent Co., Ltd (Tianjin, China). Deionized water was purified with a Milli-Q system (Millipore, USA). Primary secondary amine (PSA) cartridge (500 mg/6 mL) was purchased from Supelco (Bellefonte, USA). Field experiment The field trials, including dissipation and terminal residues experiments, were conducted in Fusong county and Ji’an city, two major ginseng production regions in China during July–October in 2012 and 2013. The experiments were designed on the basis of NY/T7882004 (Guideline on pesticide residue trials) issued by the Ministry of Agriculture, People’s Republic of China. A complete randomized block design was applied with three replicated plots, and the area of each plot was 15 m2. The buffer area was used to separate the plots with different treatments. The soil of experiment location in Fusong is meadow black soil, the pH value is 6.3, and the organic matter content is 2.8 %. The soil of the experiment location in Ji’an was sandy loam soil, the pH value was 5.5, and the organic matter content is 4.5 %. For dissipation experiments, propamocarb (72.2 %, AS) was dissolved in water and sprayed onto ginseng surface at a dosage of 2,160 g a.i.ha−1 (1.5 times of recommended dosage). The samples were collected from each plot at 2 h, 1, 3, 7, 14, 21, 28 and 35 days after spraying. Weather conditions during the experimental process are presented in Tables 1 and 2. For terminal residue experiments, propamocarb (72.2 %, AS) was sprayed at 1,440 and 2,160 g a.i. ha−1, sprayed once and twice with an interval of 7 days. The samples were collected at 28, 35 and 60 days after last spraying.

Environ Monit Assess Table 1 Information on the weather conditions during the field experimental period in 2012 Fusong

Ji’an

Time (days)

Weather

Time (days)

Weather

Time (days)

Weather

Time (days)

Weather

0

Sunny, 14–29 °C

18

Moderate rain, 17– 29 °C, 24.1 mm

0

Sunny to shower, 18– 31 °C

18

Moderate rain, 21– 25 °C, 12.8 mm

1

Moderate rain, 15– 23 °C, 21.9 mm

19

Little rain, 16–23 °C, 3.5 mm

1

Little rain, 18–26 °C, 5.4 mm

19

Little rain, 21–28 °C, 2.8 mm

2

Moderate rain, 14– 23 °C, 10.1 mm Little rain, 14–22 °C, 5.1 mm Little rain, 11–22 °C, 1.9 mm

20

Little rain, 15–22 °C, 2.2 mm Cloudy, 20–29 °C

2

Moderate rain, 17– 23 °C, 20.9 mm Little rain, 17–26 °C, 9.6 mm Shower to fine, 17– 28 °C

20

Fine, 21–30 °C

21

Fine, 21–28 °C

22

Little rain, 21–27 °C, 3.8 mm

3 4

21 22

Moderate rain, 19– 28 °C, 20.1 mm

3 4

5

Fine, 13–27 °C

23

Cloudy, 21–29 °C

5

Shower, 20–30 °C

23

Shower, 23–29 °C

6

Cloudy, 16–28 °C

24

Cloudy to sunny, 20– 29 °C

6

Shower to fine, 20– 32 °C

24

Little rain, 22–28 °C, 3.0 mm

7

Sunny, 16–29 °C

25

Sunny, 20–32 °C

25

Shower, 23–28 °C

8

Fine, 17–28 °C

26

Cloudy to shower, 20– 7 29 °C Shower, 20–27 °C 8

Sunny, 20–32 °C

26

Overcast, 21–27 °C

9

Fine, 17–27 °C

27

Cloudy, 21–30 °C

9

Cloudy, 18–31 °C

27

Cloudy, 22–28 °C

10

Moderate rain, 16– 24 °C, 17.8 mm

28

Overcast, 19–25 °C

10

Moderate rain, 18– 25 °C, 15.3 mm

28

Cloudy to sunny, 21– 27 °C

11

Moderate rain, 16– 22 °C, 10.1 mm

29

Sunny, 16–25 °C

11

Little rain, 18–24 °C, 8.0 mm

29

Cloudy to sunny, 18– 28 °C

12

Little rain, 12–20 °C, 5.5 mm

30

Cloudy, 17–26 °C

12

Heavy rain, 18–26 °C, 30 25.7 mm

Cloudy to shower, 19– 29 °C

13

Overcast, 12–21 °C

31

Shower, 19–27 °C

13

Sunny, 18–27 °C

31

Cloudy, 21–29 °C

14

Cloudy, 13–27 °C

32

Overcast, 19–28 °C

14

Cloudy, 19–30 °C

32

Cloudy to shower, 21– 28 °C

15

Little rain, 10–26 °C, 6.6 mm

33

Moderate rain, 20– 28 °C, 15.1 mm

15

Little rain, 20–30 °C, 4.4 mm

33

Moderate rain, 21– 26 °C, 12.0 mm

16

Fine, 18–29 °C

34

Cloudy, 21–24 °C

16

Fine, 19–31 °C

34

Cloudy, 21–28 °C

17

Fine, 16–29 °C

35

Shower to cloudy, 18– 17 26 °C

Little rain, 21–27 °C, 4.3 mm

35

Sunny, 22–31 °C

Analytical method

Sample extraction and cleanup

Sample preparation

Of the homogenized ginseng root, stem, leaf, and soil samples, 5.0 g were weighed into a 50-mL centrifuge tube and mixed vigorously by vortexing for 1 min after adding 20 mL of acetonitrile. The centrifuge tube was centrifuged for 5 min at relative centrifugal force (RCF) 6,660×g. The supernatant phase was transferred into volumetric flask, and then the residue was extracted repeatedly with acetonitrile. All aliquot was evaporated to dryness with a vacuum rotary evaporator at 40 °C. The dried extract was redissolved in 5-mL acetonitrile/ methylbenzene (3:1, v/v) for further clean-up. PSA

Samples of approximately 1,000 g of soil from depths of 0–10 cm and approximately 1,000 g of ginseng root, stem, and leaf were collected randomly from five different spots. The ginseng includes three matrices—root, stem, and leaf. Each matrix was smashed into pieces with a vegetation disintegrator. The soil samples were sifted through a 40-mesh sieve, concentrated to 100 g using the cone-and-quartering method. The samples were stored in a deep freezer at −20 °C.

Environ Monit Assess Table 2 Information on the weather conditions during the field experimental period in 2013 Fusong

Ji’an

Time (days)

Weather

Time (days)

Weather

Time (days)

Weather

Time (days)

Weather

0

Sunny to cloudy, 16– 26 °C Little rain, 17–23 °C, 4.7 mm

18

Little rain, 18– 25 °C, 5.1 mm Shower, 20–27 °C

0

Cloudy, 18–29 °C

18

Cloudy, 21–27 °C

1

Little rain, 17–24 °C, 3.0 mm

19

Little rain, 21–29 °C, 6.7 mm

Little rain, 16–24 °C, 6.0 mm Shower, 17–27 °C

20

2

Cloudy, 18–28 °C

20

Fine, 20–29 °C

21

Little rain, 17– 27 °C, 3.9 mm Shower, 16–30 °C

3

21

Fine, 19–32 °C

22

Shower, 19–25 °C

4

22

Cloudy, 21–29 °C

5

Cloudy to sunny, 18– 27 °C Fine, 17–30 °C

Little rain, 19–29 °C, 3.0 mm Fine, 19–30 °C

23

Cloudy, 17–25 °C

5

Shower, 19–32 °C

23

Cloudy, 21–32 °C

6

Cloudy, 17–30 °C

24

Cloudy 17–24 °C

6

Fine, 21–31 °C

24

Fine, 22–31 °C

7

Overcast, 19–27 °C

25

Cloudy, 16–26 °C

7

Shower, 21–29 °C

25

Little rain, 22–29 °C, 6.0 mm

8

26

Shower, 19–29 °C

8

Cloudy, 21–26 °C

26

Cloudy, 21–30 °C

9

Moderate rain, 18– 26 °C, 15.2 mm Fine, 18–26 °C

27

Cloudy, 19–24 °C

9

Cloudy, 19–27 °C

27

Cloudy, 21–31 °C

10

Fine, 18–30 °C

28

Cloudy, 18–27 °C

10

Fine, 19–29 °C

28

Cloudy to sunny, 21– 31 °C

11

Cloudy, 19–26 °C

29

Little rain, 18– 26 °C, 3.0 mm

11

Fine, 21–28 °C

29

Little rain, 21–30 °C, 5.0 mm

12

Cloudy, 18–27 °C, 15.2 mm Fine, 18–27 °C, 16.0 mm Cloudy, 18–27 °C

30

Cloudy, 19–28 °C

12

30

Shower, 20–27 °C

31

Cloudy, 19–30 °C

13

31

Cloudy, 20–29 °C

32

Cloudy, 20–29 °C

14

Little rain, 20–28 °C, 7.1 mm Little rain, 20–30 °C, 1.5 mm Moderate rain, 20– 30 °C, 13.0 mm Little rain, 20–24 °C, 1.6 mm

32

Sunny, 20–29 °C

33

Moderate rain, 20– 25 °C, 17.0 mm

1 2 3 4

13 14

19

15

Moderate rain, 18– 23 °C, 16.2 mm

33

Shower, 21–28 °C

15

16

Fine, 17–28 °C

34

Cloudy, 21–30 °C

16

Fine, 19–30 °C

34

Cloudy, 19–28 °C

17

Little rain, 16–29 °C, 3.6 mm

35

Shower, 19–26 °C

17

Shower, 18–30 °C

35

Cloudy, 20–31 °C

cartridge was pre-activated with 10 mL of acetonitrile/ methylbenzene (3:1, v/v). The 5-mL extract was transferred to pre-activated PSA cartridge and eluted with 20 mL acetonitrile/methylbenzene (3:1, v/v). The elute was collected and evaporated under vacuum at 40 °C, made to dryness under a gentle nitrogen stream. The residues were dissolved in 1-mL acetonitrile and analyzed by HPLC-MS/MS after being filtered through a 0.22-μm polypropylene filter. HPLC-MS/MS analysis HPLC-MS/MS analysis was achieved using Agilent 1200 series HPLC system (Agilent Technologies,

USA) and API 4000 triple quadrupole mass spectrometer equipped with an electrospray ionization interface (Applied Biosystems Sciex, USA). A Kromasil Eternity-5-C 18 (2.1 mm × 150 mm i.d., 5 μm particle size) column (Akzo Nobel, Sweden) was employed for separation of analyte at 30 °C. The mobile phase was comprised of 0.1 % aqueous formic acid and acetonitrile (50:50, v/v). The flow rate was 0.20 mL min−1, and the injection volume was 10 μL. The mass spectrometer was operating in positive ion mode (ESI+), and the ion monitored in multiple reactions monitoring (MRM) was chosen. The conditions for MS detection were as follows: desolvation gas temperature was 350 °C with a flow

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rate of 8.0 L min−1; nebulizing gas pressure was 35.0 psi; ionspray voltage (IS) was 5,500 V; nitrogen was used as curtain gas- and collision-associated dissociation (CAD) gas, curtain gas was set to 10 and CAD gas was set to 5; entrance potential (EP) was 6 V; focusing potential (FP) was 300 V; ion source gas was 50 V; collision cell exit potential (CXP) was 10 V; and collision cell entrance (CEP) was 11 V.

Table 3 Linear equation, recovery and repeatability of propamocarb (n=10) Sample Fortified level (mg kg−1)

Mean recovery (%)

RSD (%)

LOQ (mg kg−1)

Root

0.01 0.02

80.5 87.9

9.1 6.7

0.005

0.05

81.8

7.1

Stem

Statistical analysis The dissipation rate constant and half-life were calculated by the equation Ct =C0e−kt, where Ct represents the concentration of the pesticide residue at the time of t, C0 represents initial concentration (mg kg−1) and k is the dissipation rate constant (days−1). The half-life (t1/2) is defined as the time required for the residue level to fall to half of the initial residue level, and calculated by the equation t1/2 =ln2/k.

Results Method validation Quantification during validation was done by a calibration curve based on matrix-matched standards to prevent possible enhancement or suppression of the signal from samples as compared to pure solvent. The linearity of ginseng root, stem, leaf and soil was constructed by plotting the average peak area against five different concentrations (0.005, 0.01, 0.05, 0.10 and 0.50 mg L−1). The linearity was satisfied with correlation coefficients above 0.999. The data of the method’s accuracy and precision was obtained for propamocarb at fortification levels of 0.01, 0.02, 0.05 and 0.20 mg kg−1. The mean recoveries ranged from 80.5 to 95.6 % with relative standard deviations (RSDs) of 5.5–9.1 %. The limit of quantification (LOQ), calculated by considering signal-to-signal ratio of ten times that of the background noise, was 0.005 mg kg−1, as shown in Table 3. Dissipation of propamocarb in ginseng root stem, leaf, and soil The first-order kinetic reaction has been extensively used to describe dissipation process of many chemicals.

Leaf

Soil

0.20

90.3

6.8

0.01 0.02

90.1 89.9

6.9 6.8

0.05

82.4

5.9

0.20

89.3

7.6

0.01 0.02

85.6 85.4

5.5 6.2

0.05

81.6

8.7

0.20

84.0

7.4

0.01 0.02

95.6 85.2

5.8 5.6

0.05

82.1

8.8

0.20

88.6

6.4

0.005

0.005

0.005

The dissipation kinetics were determined by plotting residue contents against time, and the maximum squares of correlation coefficients were used to determine the equations of best-fit curves. The half-life is a measure of the time required for pesticide concentration to be decreased to half the original values throughout dissipation processes. In our study, the half-lives (t1/2), dissipation kinetics, and correlation coefficient of determination of propamocarb in ginseng root, stem, leaf, and soil were summarized in Table 4. The significant correlation coefficient of determination (R2 = 0.9044–0.9962) indicated the dissipation kinetics of propamocarb follows the first-order kinetic reaction (Ct =C0e−kt). The halflives were 5.00–11.36 days in root, 5.07–11.46 days in stem, 6.83–11.31 days in leaf and 6.44–8.43 days in soil. The dissipation curves of propamocarb in Fusong county and Ji’an city in 2012 and 2013 were listed in Fig. 2. The initial concentrations were 0.3158–0.4223 mg kg−1 in root, 0.5056– 0.6842 mg kg−1 in stem, 1.0132–1.8723 mg kg−1 in leaf and 0.0711–0.1576 mg kg−1 in soil. The residues in ginseng leaf and soil were decreased with increasing of the intervals time. However, in root and stem, the dissipation trend of propamocarb increased slightly from 0 to 1 day, then dissipated sharply after reaching peak concentration. The

Environ Monit Assess Table 4 The degradation kinetics and half-lives of propamocarb Years

Matrix

Location

Regression equation

R2

2012

Root

Ji’an

Ct =0.3583e−01386t

0.9614

5.00

Fusong

Ct =0.3427e−0.0610t

0.9367

11.36

Ji’an

Ct =0.9236e−0.1368t

0.9651

5.07

Fusong

Ct =0.7332e−0.0605t

0.9651

11.46

Ji’an

Ct =1.1014e−0.0944t

0.9456

7.34

Stem Leaf Soil 2013

Root Stem Leaf Soil

−0.0613t

Fusong

Ct =0.9532e

0.9962

11.31

Ji’an

Ct =0.0436e−0.1077t

0.9044

6.44

Fusong

Ct =0.0597e−0.0822t

0.9852

8.43

Ji’an

Ct =0.3763e−0.1334t

0.9789

5.19

−0.13264t

Fusong

Ct =0.4931e

0.9838

5.23

Ji’an

Ct =0.7437e−0.1090t

0.9772

6.36

Fusong

Ct =0.7316e−0.0989t

0.9678

7.01

Ji’an

Ct =1.2617e−0.1015t

0.9767

6.83

Fusong

Ct =1.3261e−00902t

0.9683

7.68

−0.1049t

Ji’an

Ct =0.1085e

0.9485

6.61

Fusong

Ct =0.1093e−0.0953t

0.9308

7.27

dissipation rates of propamocarb in ginseng root, stem, leaf and soil were all above 95 % at 35 days after spraying. Based on the dissipation data at the two experimental sites for 2 years, the dissipation

dynamics of propamocarb in Ji’an city with the halflives of 5.00–7.34 days were faster than that in Fusong county with the half-lives of 5.23– 11.46 days.

0.3000

Ji'an in 2012 Fusong in 2012 Ji'an in 2013 Fusong in 2013

Residues (mg•kg -1 )

0.4000

0.2000 0.1000 0.0000 0

Residues(mg•kg -1 )

Root

2.0000 1.8000 1.6000 1.4000 1.2000 1.0000 0.8000 0.6000 0.4000 0.2000 0.0000 0

10

20 Time (days)

Leaf

10

20 Time (Days)

30

40

0.9000 0.8000 0.7000 0.6000 0.5000 0.4000 0.3000 0.2000 0.1000 0.0000 0

Ji'an in 2012 Fusong in 2012 Ji'an in 2013 Fusong in 2013

Stem

10

20

30

40

Time (Days)

Ji'an in 2012 Fusong in 2012 Ji'an in 2013 Fusong in 2013

30

Residues (mg•kg -1 )

Residues (mg•kg -1 )

0.6000 0.5000

Half life (days)

40

0.1800 0.1600 0.1400 0.1200 0.1000 0.0800 0.0600 0.0400 0.0200 0.0000

Soil

0

10

Ji'an in 2012 Fusong in 2012 Ji'an in 2013 Fusong in 2013

20 Time (Days)

30

40

Fig. 2 Dissipation curve of propamocarb in ginseng root, stem, leaf, and soil under field conditions in Fusong county and Ji’an city in 2012 and 2013

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Terminal residue experiment of propamocarb in ginseng root, stem, leaf and soil The terminal residues of propamocarb in ginseng root, stem, leaf, and soil in Fusong county and Ji’an city in 2012 and 2013 were summarized in Tables 5 and 6. Since the formulation was sprayed directly onto the ginseng plants, but not the soil, the residues in soil were inevitably much lower than those in ginseng root, stem, and leaf. With the exception of residue observed at 28 days after the last spraying which was detected to be below 0.013 mg kg−1, all the residues in soil samples were undetectable (below the limit of quantification). The residues of propamocarb in root were below 0.027 mg kg−1 at 28 days, below 0.014 mg kg−1 at 35 days, and undetectable at 60 days. The residues of propamocarb in stem were 0.013–0.115 mg kg−1 at 28 days, below 0.031 mg kg−1 at 35 days, and below 0.012 mg kg−1 at 60 days. The residues of propamocarb in leaf were 0.061–0.194 mg kg−1 at 28 days, 0.024– 0.108 mg kg−1 at 35 days and 0.006–

0.018 mg kg−1 at 60 days after the last spraying for the two dosage levels.

Discussion Optimization of HPLC-MS/MS conditions The composition of mobile phase is an important parameter in adjusting retention time, selectivity, and peak shape in HPLC separation. After different proportions of 0.1 % aqueous formic acid and acetonitrile (90:10, 75:25, 50:50 and 30:70) had been tested, it was found that well-shaped and highresponse peaks could be achieved when the mobile phase was set at 0.1 % aqueous formic acid and acetonitrile (50:50, v/v). The presence of a low amount of formic acid in the mobile phase did not increase the response of the analytes, but could improve the peak shape through diminishing peak width and shortening retention time in positive ion mode. Several columns were screened and assessed

Table 5 Terminal residues of propamocarb in ginseng root, stem, leaf, and soil in Fusong county and Ji’an city, China in 2012 Dosage (g a.i.ha−1)

1,440

Number Days Residue (mg kg−1) (mean ± SD, n=3) of times after sprayed spraying Ji’an

1

2

2,160

1

2

Fusong

Root

Stem

Leaf

28

Dissipation and residues determination of propamocarb in ginseng and soil by high-performance liquid chromatography coupled with tandem mass spectrometry.

Two-year field trials were performed at two experimental sites to investigate dissipation and terminal residues of propamocarb in ginseng root, stem, ...
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