Ultra-Fast Screening of Pesticides in Foods and Agricultural Products with Desorption Corona Beam Ionization (DCBI) Tandem Mass Spectrometry

PO-CON1778E

Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

ASMS 2017 TP 003

Jing Dong, Satoshi Yamaki, Yuki Hashi, Naoki Hamada Shimadzu China, Shimadzu China Mass Spectrometry Center, Beijing Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

Introduction Pesticides screening in food sample has traditionally counted molecules on the surface were ionized in the gas phase (1). on analytical con rmation with a quantitative method such as DCBI was used in the eld of drug development, GC/MS, HPLC and LC/MS. The chromatographic technique environmental, homeland security, etc (2 - 5). provide a high sensitivity and high reliability solution for In this study, we attempted to develop a DCBI-MS pesticides analysis but introduce the relatively low throughput approach to determine pesticides amount aiming at high with time-consuming pretreatment technique. throughput and comprehensive methods using MRM Desorption corona beam ionization (DCBI) source for direct acquisition. Ambient mass spectrometry coupled with analysis in mass spectrometry can work under ambient ultra-fast triple quadrupole mass spectrometry permits this conditions with minimal sample pretreatments. In DCBI, a data acquisition in 30 seconds per sample as compared visible thin corona beam are generated from helium gas with the conventional chromatographic run of about 20 - and impact the solid sample surface, and then the analyte 40 minutes.

Positive mode: He* + M → He + M+. + e- + - He* + nH2O → H3O (H2O)n-2 + OH + He, n> 1 3 + + H O (H2O)n + M → (M+H) + (n+1) H2O (indirect)

Negative mode: + - He* + 2N2 → He + N4 + e M + e- → M-. - - M + OH → (M-H) + H2O - -. O2 + e → O2

Figure 1 Ionization mechanism and schematic diagram of DCBI

2 Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

Materials and Methods The commercially available pesticides were used for the channels per second. Samples were introduced to the con rmation of MS spectrum and the optimization of DCBI source by inserting a glass capillary or a glass MRM conditions. Automated MRM parameter sample cup. The DCBI source was operated at 150 - 300 optimization with ESI or APCI source were carried out by C as heater temperature and 2 - 3 kV as discharge ow injection analysis of authentic standards with a voltage. Measurements of mass spectrum or MRM function of the LabSolutions LC/MS control software. chromatogram were conducted in both positive or The DCBI source (Shimadzu Corporation) was mounted negative polarity mode. Samples were introduced to the on a triple quadrupole mass spectrometer (LCMS-8040 DCBI source by inserting a glass capillary or a glass or LCMS-8050, Shimadzu Corporation) with the sample cup. Analytical conditions are shown in Table 1. capability of simultaneously acquiring 555 MRM

Table 1 Experimental conditions for DCBI Analysis

DCBI Conditions

He gas ow (L/min) : 1 High voltage, discharge (kV) : 2.5 Gas temperature (C) : 250

MS Conditions

Nebulizing gas ow, N2 (L/min) : 0.6 Desolvent line temperature (C) : 220 Heat block temperature (C) : 150

Glass capillary 1 - 2μL

For glass capillary For glass cup

Figure 2 Injection mode for DCBI analysis (LCMS-8040)

3 Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

Results Ionization conrmation of pesticides by DCBI Ionization con rmation of 37 pesticides was applied As a consequence, different type of adduct ions are using DCBI with LCMS-8040 triple quadrupole mass observed in three different ion source for the same spectrometer, and compared with ESI and APCI source. target pesticide (Figure 3). The results of 37 pesticides 1 ppm or 10 ppm methanol solutions of authentic are summarized in Table 2. The protonated molecule standard were introduced to the ion source. Full scan was detected mainly under DCBI conditions. Its simple measurement was conducted to determine the optimum and no sodium adduct spectrum resembles a result of ionization polarity of target compounds by glass APCI and it will be suitable for the MRM mode capillary sampling (DCBI, Figure 2) and by ow injection measurement. analysis with 50% methanol (ESI and APCI).

Inten. (x1,000,000) Inten. (x10,000,000) Inten. (x100,000) 404.1 + 1.75 + + 1.75 (M+H) 426.1 (M+Na) 7.0 404.1 (M+H)

1.50 1.50 6.0

1.25 1.25 (M+H)+ 5.0

Azoxystrobin 1.00 1.00 4.0 MW 403.4 404.1 0.75 0.75 3.0 371.1 371.0 131.0 0.50 237.0 0.50 2.0 445.1 186.9101.1 445.0 0.25 0.25 1.0 237.5 217.4 270.0 372.1 477.2 0.00 0.00 0.0 250 500 750 m/z 250 500 750 m/z 250 500 750 m/z

Inten. (x1,000,000) Inten. (x10,000,000) Inten.(x100,000) 1.75 2.25 8.0 213.0 + 223.2 391.3 (M+Na) 1.50 2.00 7.0 N.D. 1.75 6.0 1.25 1.50 5.0 Aldicarb 148.1 1.00 187.2 + 1.25 371.1 + (M+NH ) MW 190.3 4.0 (M+H) 4 0.75 1.00 116.1 3.0 208.1 0.75 256.0 0.50 445.1 2.0 191.1 116.1 264.1 0.50 121.1 172.9 0.25 287.2 1.0 237.0 236.1 0.25 270.3 412.5 477.1 0.0 0.00 150 200 250 300 350 400 m/z 100 150 200 250 300 350 400 450 m/z 100 150 200 250 300 350 400 450 m/z DCBI ESI APCI

Figure 3 Typical mass spectra of pesticides by DCBI, ESI and APCI.

4 Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

Table 2 Comparison of ionization pattern of 37 pesticides

Molecular Detected ions No. Name Formula weight DCBI ESI APCI 1 Methamidophos C2H8O2NPS 141.1 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 2 Acephate C4H10NO3PSi 183.2 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 3 Omethoate C5H12NO4PS 213.2 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 4 Sulfoxide aldicarb C7H14N2O3S 206.3 (M+H)+ (M+Na)+, (M+H)+ nd

+ + + + + 5 Sulfone aldicarb C7H14N2O4S 222.3 (M+NH4) , (M+H) (M+NH4) , (M+Na) , (M+H) nd 6 Methomyl C5H10N2O2S 162.2 (M+H)+ (M+H)+ (M+H)+ 7 Thiamethoxam C8H10ClN5O3S 291.7 (M+H)+ (M+H)+ (M+H)+ 8 Imidacloprid C9H10ClN5O2 255.1 (M+H)+ (M+H)+ (M+H)+

+ + + + + + 9 Carbofuran-3-hydroxy C12H15NO4 237.3 (M+H-H2O) (M+Na) , (M+NH4) , (M+H-H2O) , (M+H) (M+H-H2O) 10 Dimethoate C5H12NO3PS2 229.3 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 11 Acetamiprid C10H11ClN4 222.7 (M+H)+ (M+Na)+, (M+H)+ nd 12 Carbendazim C9H9N3O2 191.2 (M+H)+ (M+H)+ (M+H)+

+ + + 13 Aldicarb C7H14N2O2S 190.3 (M+NH4) , (M+H) (M+Na) nd 14 Carbofuran C12H15NO3 221.3 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 15 Carbaryl C12H11NO2 201.2 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 16 Phosemet C11H12NO4PS2 317.3 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 17 Azoxystrobin C22H17N3O5 403.4 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 18 Malathion C10H19O6PS2 330.4 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 19 Dimethomorph C21H22ClNO4 387.1 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 20 Triadimefon C14H16ClN3O2 293.1 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 21 Triazophos C12H16N3O3PS 313.3 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 22 Fipronil C12H4Cl2F6N4OS 435.9 (M+H)+ (M-H)- (M-H)- 23 Diubenzuron C14H9ClF2N2O2 310.0 (M+H)+ (M+Na)+/, (M-H)- (M+H)+/, (M-H)- 24 Chlorobenzuron C14H10Cl2N2O2 308.0 (M+H)+ (M+Na)+/, (M-H)- (M+H)+/, (M-H)- 25 Diazinon C12H21N2O3PS 304.4 (M+H)+ (M+H)+, (M+Na)+ (M+H)+ 26 Emamectin benzoate C49H75NO13 885.5 (M+H)+ (M+H)+ (M+H)+ 27 Phoxim C12H15N2O3PS 298.3 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 28 Prochloraz C15H16Cl3N3O2 375.0 (M+H)+ (M+H)+ (M+H)+ 29 Phosalone C12H15ClNO4PS2 367.0 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 30 Difenoconazole C19H17Cl2N3O3 405.1 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 31 Profenofos C11H15BrClO3PS 371.9 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 32 Tridemorph C19H39NO 297.3 (M+H)+ (M+H)+ (M+H)+ 33 Chlorpyrifos C9H11Cl3NO3PS 348.9 (M+H)+ (M+Na)+, (M+H)+ (M+H)+ 34 Pendimethalin C13H19N3O4 281.3 (M+H)+ (M+H)+ (M+H)+ 35 Chloruazuron C20H9Cl3F5N3O3 539.0 (M+H)+ (M-H)- (M-H)- 36 Ppyridaben C19H25ClN2OS 364.1 (M+H)+ (M+Na)+, (M+H)+ (M+H)+

+ + + - 37 Abamectin B1a C48H72O14 872.5 (M+NH4) , (M+H) (M+Na) (M-H)

5 Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

Conrmation of optimal MRM transitions For improvement of the selectivity of target compound, optimized to each MRM transition using each authentic we tried to be detected in MRM mode by DCBI-MS with standard. The performance of the DCBI-MS was higher sensitive LCMS-8050 triple quadrupole mass evaluated by the analysis of the mixture of 37 pesticides spectrometer. Multiple MRM transition candidates were solution. Semi-quanti cation was accomplished based selected and compound dependent parameters were on peak areas in the ion chromatograms.

(x10,000,000) 1.75 1:Methamidophos 142.00>94.10(+) CE: -15.0 21:Triazophos 314.00>162.10(+) CE: -20.0 2:Acephate 184.10>143.00(+) CE: -10.0 22:Fipronil 436.90>367.90(+) CE: -19.0 3:Omethoate 214.00>125.05(+) CE: -21.0 23:Diubenzuron 310.90>158.00(+) CE: -15.0 1.50 4:Sulfoxide aldicarb 207.00>132.10(+) CE: -9.0 24:Chlorobenzuron 308.90>156.05(+) CE: -15.0 MRM settings: 5:Sulfone aldicarb 240.10>86.20(+) CE: -21.0 25:Diazinon 305.00>169.05(+) CE: -22.0 6:Methomyl 163.00>106.05(+) CE: -12.0 26:Emamectine+benzoate 886.40>158.10(+) CE: -34.0 • Each 2 – 4 transitions 1.25 7:Thiamethoxam 291.90>210.95(+) CE: -14.0 27:Phoxim 299.10>77.00(+) CE: -32.0 • Dwell time 5 ms 8:Imidacloprid 256.00>209.10(+) CE: -18.0 28:Prochloraz 375.90>308.00(+) CE: -13.0 1.00 9:Carbofuran-3-hydroxy(-H2O) 220.00>163.15(+) CE: -11.0 29:Phosalone 367.90>182.00(+) CE: -16.0 • Pause time 1 ms 10:Dimethoate 229.90>198.95(+) CE: -10.0 30:Difenoconazole 405.90>250.95(+) CE: -26.0 11:Acetamiprid 223.00>126.00(+) CE: -21.0 31:Profenofos 372.80>302.80(+) CE: -20.0 • Loop time 0.65 s 0.75 12:Carbendazim 192.00>160.05(+) CE: -18.0 32:Tridemorph 298.20>130.15(+) CE: -26.0 13:Aldicarb 208.10>116.05(+) CE: -8.0 33:Chlorpyrifos 350.00>197.90(+) CE: -20.0 0.50 14:Carbofuran 222.00>123.05(+) CE: -22.0 34:Pendimethalin 282.20>212.00(+) CE: -12.0 15:Carbaryl 202.00>145.10(+) CE: -11.0 35:Chloruazuron 540.00>382.85(+) CE: -21.0 16:Phosemet 318.00>160.00(+) CE: -16.0 36:Pyridaben 365.00>309.10(+) CE: -14.0 0.25 17:Azoxystrobin 404.00>372.05(+) CE: -16.0 37:Abamectin-873 873.50>144.80(+) CE: -30.0 18:Malathion 330.90>127.10(+) CE: -13.0 19:Dimethomorph 388.00>300.95(+) CE: -22.0 0.00 20:Triadimefon 294.00>197.10(+) CE: -16.0

27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0 31.5 32.0 32.5 33.0 min

Area Area Area 9 9 10000000 9

5000000 Methamidophos 7500000 Omethoate Dimethoate

7500000 4000000

5000000 3000000 5000000 8 8 8 2000000 2500000 2500000 7 2 ppb - 500 ppb 7 5 ppb - 500 ppb 7 2 ppb - 500 ppb 1000000 6 R=0.971 R=0.996 R=0.989 5 6 6 34 45 345 0 2 0 3 0 2 0 250 Conc. 0 250 Conc. 0 250 Conc.

Figure 4 MRM chromatogram of 37 pesticides mixture (3 injections, 1 ppm) and response linearity of typical pesticides.

6 Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

Screening analysis of real agricultural sample To nd out the optimal transition number and optimal transitions of 5 ms dwell time. The matrix samples dwell time of each MRM transition, we performed the spiked with 10 ppb standards were prepared for the detection and reproducible test using the plant analytical test. Several target compounds have shown homogenates. Approximately 20 g of cucumber were good recoveries (Figure 5), however there is room for put in a food processor and processed it for 1 minutes. the improvement, for example sample treatment, Without dilution and centrifugation, homogenates were ionization parameter and MS parameter for this directly applied to DCBI-MRM analysis with 108 MRM approach.

40000 3:214.00>125.05(+) 6:163.00>106.05(+) 10:229.90>198.95(+) 25000 35000 Cucumber Cucumber 50000 Cucumber 30000 Spiked 10 ppb 20000 Spiked 10 ppb 40000 Spiked 10 ppb 25000 15000 30000

20000 Methomyl/101664 Omethoate/195120 Dimethoate/122478 15000 10000 20000 10000 10000 5000 5000

0 0

0.25 0.50 0.75 0.25 0.50 0.75 0.25 0.50 0.75

40000 3:214.00>125.05(+) 6:163.00>106.05(+) 10:229.90>198.95(+) 25000 35000 Cucumber blank Cucumber blank 50000 Cucumber blank 30000 20000 40000 25000 15000 30000 20000

15000 10000 20000 10000 10000 5000 5000

0 0

0.25 0.50 0.75 0.25 0.50 0.75 0.25 0.50 0.75

40000 3:214.00>125.05(+) 6:163.00>106.05(+) 10:229.90>198.95(+) 25000 35000 STD 10 ppb STD 10 ppb 50000 STD 10 ppb 30000 20000 40000 25000 15000 30000

20000 Methomyl/109192 Omethoate/192877 Dimethoate/256814 15000 10000 20000 10000 10000 5000 5000

0 0

0.25 0.50 0.75 0.25 0.50 0.75 0.25 0.50 0.75

Omethoate Methomyl Dimethoate

Figure 5 Measurement results of the matrix sample spiked with 10 ppb standards

7 Ultra-fast screening of pesticides in foods and agricultural products with desorption corona beam ionization (DCBI) tandem mass spectrometry

Conclusions • DCBI-MRM-based analytical workow is presented as high-throughput and robust measurement for agricultural pesticides. • DCBI-MS approach enables screening analysis of short time. • We performed the optimization of approximately 40 pesticides and obtained MRM parameters for each compound with DCBI analysis. • The results demonstrate that simultaneous MRM analysis with ultra-fast MRM acquisition instrument and direct ionization technique improves the throughput for analysis of pesticides in agricultural sample.

References 1) H. Wang et. al., Analyst. 135: 688-695 (2010). 2) Y. Huang et. al., J. Chromatogr. A. 1218: 7371-7376 (2011). 3) S. Cheng et. al., ASMS proceedings (2012) 4) Y. Zhao et. al., Chinese Journal of Food Hygiene 24(4): 312-317 (2012) 5) W. Du et. al., Talanta. 131: 499-504 (2015).

DCBI+LCMS-8050

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First Edition: June, 2017