August 2011 237 LC-MS/MS 23 2 22 Determination of Pindone in Agricultural Products by LC-MS/MS Shizuka S6>ID, Satoru N:BDID and Rieko M6IHJ96 National Institute of Health Sciences: 1 18 1 Kamiyoga, Setagaya-ku, Tokyo 158 8501, Japan A sensitive and selective analytical method for the determination of pindone in agricultural products by LC-MS/MS was developed. Pindone was extracted with acetone, and an aliquot of the crude extract was re-extracted with hexane. For lipid-rich samples, the crude extract was further cleaned up by acetonitrile-hexane partitioning. The extract was cleaned up on a tandem graphitized carbon-silica gel column. For brown rice, soybean, and tea, PSA column cleanup was added prior to LC-MS/MS determination. Average recoveries of pindone from brown rice, soybean, potato, spinach, cabbage, apple, orange, tomato, cucumber, and tea fortified at 0.001 mg/kg were 81 93, and the relative standard deviations were 2 7. The limit of quantitation (S/N 10) of the developed method was 0.001 mg/kg for all the tested agricultural products. (Received February 22, 2011) Key words: pindone; rodenticide; indandione; LC-MS/MS; analytical method (Fig. 1) 4-1) 0.001 ppm 2) 4) 5) 6) Jin (IC-MS) 7) Marek 4- LC-MS/MS 8) ppb LC-MS/MS 10 shizsaito@nihs.go.jp 158 8501 1 18 1 Fig. 1. Chemical structure of pindone 1. 425 m 2. 545 LC-MS/MS LC-MS Dr. Ehrenstorfer 98.5,
238 109.8 (1,000 mg/l) 10 mg 10 ml 500 mg SUPELCO Supelclean ENVI-Carb 500 mg Waters Sep-Pak Vac Silica 1,000 mg -N- PSA 500 mg Varian Bond Elut Jr-PSA 500 mg Inertsep Slim-J PSA 500 mg 3. Retsch Grindomix GM200, Retsch ZM 200, Kinematica Polytron PT 10 35 GT NZJ-2DSYW LC-MS/MS Waters Alliance 2695 Micromass Quattro Premier 4. LC-MS/MS 4.1 LC Inertsil ODS-4 2.1 mm, 150 mm, 3 m, Inertsil ODS-4 1.5 mm, 10 mm, 3 m, 40 5 L, 10 mmol/l A 10 mmol/l B 0.20 ml/min, 0 (A : B 80 : 20) 15 (A : B 5 :95) 25 (A : B 5 : 95) 25.1 (A : B 0 : 100) 35 (A : B 0 : 100) 35.1 (A : B 80 : 20), 14.1 4.2 MS (ESI( )), multiple reaction monitoring (MRM), 0.5 kv, 120 50 L/h (N 2 ), 400 800 L/h (N 2 ), 3.1 e 3 mbar (Ar), (m/z): 229 116 50 (V), 35 (ev) 229 172 50 (V), 21 (ev) 5. Fig. 2 5.1 5.1.1 10.0 g 10 g/l 1mL Vol. 52, No. 4 30 20 ml 30 100 ml 1cm 50 ml 200 ml 40 ml 2.0 g 40 6mL 10 100 ml 100 ml 5 50 ml 5 15 40 30 ml 30 ml 3 40 (180 : 20 : 1) 2 ml 5.1.2 20.0 g 20 g/l 1mL 30 5.00 g 10 g/l 0.5 ml 30 20 ml 30 100 ml 1cm 50 ml 200 ml 20 ml 80 ml, 2.0 g 40 3mL 12 ml 10 100 ml 100 ml 5 50 ml 5 15 40 (180 : 20 : 1) 2 ml 5.2 5.2.1 (500 mg) (1,000 mg) (180 : 20 : 1) 10 ml 5.1 (180 : 20 : 1) 18 ml 40 1mL 2.0 g /ml
August 2011 LC-MS/MS 239 Sample vegetables and fruits: 20.0 g cereals and beans: 10.0 g, add 20 ml of water and stand for 30 min before extraction tea: 5.00 g, add 20 ml of water and stand for 30 min before extraction Extraction homogenize with acetone (100 ml 50 ml) filter with suction make up the volume to 200 ml with acetone evaporate an aliquot of the extract to obtain an aqueous residue (vegetables and fruits: 20 ml, cereals and beans: 40 ml, tea: 80 ml) 10 NaCl aq. hexane partitioning add 100 ml of 10 NaCl aq. extract with hexane (100 ml 50 ml) dehydrate with anhydrous Na 2 SO 4 filter Acetonitrile hexane partitioning (For cereals and beans) dissolve in 30 ml of hexane extract with 30 ml of acetonitrile saturated with hexane (three times) dissolve in 2 ml of hexane ethyl acetate formic acid (180 : 20 : 1) Graphitized carbon column (500 mg) Silica gel column (1,000 mg) precondition with 10 ml of hexane ethyl acetate formic acid (180 : 20 : 1) load on tandem graphitized carbon silica gel column elute with additional 18 ml of hexane ethyl acetate formic acid (180 : 20 : 1) PSA column (500 mg) (For cereals, beans and tea) precondition with 10 ml of hexane acetone (1 : 1) load on PSA column wash with additional 8 ml of hexane acetone (1 : 1) elute with 20 ml of hexane acetone formic acid (25 : 25 : 1) dissolve in 1 ml of methanol LC-MS/MS analysis Fig. 2. Schematic representation of the analytical procedure 5.2.2 (500 mg) (1,000 mg) (180 : 20 : 1) 10 ml 5.1 (180 : 20 : 1) 18 ml 40 (1 : 1) 2 ml (1 : 1) 10 ml PSA (Bond Elut Jr-PSA, 500 mg) (1 : 1) 8 ml (25 : 25 : 1) 20 ml 40 1 ml 2.0 g /ml
240 6. 0.25, 0.50, 1.0, 1.5, 2.0 3.0 g/l 5 L LC-MS/MS 5 L LC-MS/MS 7. 100 L 100 100 L 2 1. 1.1 LC-MS/MS 1.1.1 MS GC-MS LC-MS/MS 20 mmol/l (1 : 1) 20 mmol/l (1 : 1) MS ESI ( ) ESI ( ) ESI ( ) S/N 20 60 (V) 10 V M H m/z 229 50 V 7 49 (ev) 7eV m/z 116, 144, 172 m/z 116 35 ev m/z 172 21 ev 0.5, 1, 1.5, 2, 2.5, 3 kv 0.5 kv ESI ( ) 0.5 kv 1.1.2. LC ODS b- ODS Inertsil ODS-4 5, 10, 20 mmol/l 10 mmol/l Inertsil ODS-4, 10 mmol/l 10 mmol/l 1.2 0.25 3.0 g/l (r 0.999) 0.5 20 g/l (r 0.999) 2. 2.1 2.2 (1 : 1) 10 (Table 1) 10 100 ml 2 (100 ml, 50 ml) 2.3 2.3.1 0.1 g 30 ml 30 ml Table 1. Recovery of pindone from 100 ml of 10 sodium chloride aqueous solution Extraction solvent 1st 100 ml Vol. 52, No. 4 Recovery 2nd 50 ml Total Hexane 105 2 107 Hexane ethyl acetate (1 : 1) 98 1 99 Ethyl acetate 101 1 102
August 2011 LC-MS/MS 241 Table 2. Recovery of pindone from silica gel and graphitized carbon columns Column Recovery ( ) Hexane ethyl acetate formic acid (180 : 20 : 1) 0 5 ml 5 10 ml 10 15 ml 15 20 ml 20 25 ml Total Silica gel 81 16 1 0 0 98 Graphitized carbon 76 19 1 0 0 96 Graphitized carbon silica gel 0 101 1 1 0 103 Table 3. Recovery of pindone from PSA columns Recovery ( ) Column Hexane acetone (1 : 1) 0 15 ml Hexane acetone formic acid (25 : 25 : 1) 0 5 ml 5 10 ml 10 15 ml 15 20 ml 20 25 ml Total A 1 0 92 0 0 0 0 92 B 2 0 87 3 1 1 0 92 1 2 Bond Elut Jr-PSA (500 mg, Varian) Inertsep Slim-J PSA (500 mg, GL Sciences) 3 1 90, 2 8, 3 2 3 100 30 ml 30 ml 3 2.3.2 (1,000 mg) (9 : 1) (180 : 20 : 1) 15 ml 100 (Table 2) 2.3.3 (500 mg) (180 : 20 : 1) 15 ml 100 (Table 2) (500 mg) (1,000 mg) (180 : 20 : 1) 15 ml 20 ml 20 ml 2.3.4 PSA (500 mg) (Table 3) Bond Elut Jr-PSA Varian (1 : 1) 15 ml (25 : 25 : 1) 5 ml 100 Inertsep Slim-J PSA 500 mg, Bond Elut Jr-PSA (25 : 25 : 1) 5mL 5 20 ml (1 : 1) 10 ml (25 : 25 : 1) 20 ml Bond Elut Jr-PSA 500 mg, Varian PSA PSA LC-MS/MS PSA
242 Vol. 52, No. 4 Table 4. Recoveries of pindone from agricultural products Table 5. Matrix e#ect of pindone in agricultural products Sample Recovery ( mean) RSD ( ) Sample Matrix e#ect ( mean, n 2) Brown rice 84 4 Soybean 81 7 Potato 91 2 Spinach 91 3 Cabbage 83 4 Apple 87 4 Orange 88 2 Tomato 93 2 Cucumber 90 3 Tea 81 5 Spiked level: 0.001 mg/kg, n 5 Brown rice 97 Soybean 106 Potato 97 Spinach 102 Cabbage 99 Apple 90 Orange 96 Tomato 91 Cucumber 94 Tea 100 Matrix e#ect expressed as the ratio of the mean peak area of matrix standard to the mean peak area of standard in solvent multiplied by 100. A value of 100 indicates ionization enhancement, and value of 100 indicates ionization suppression. (S/N 10) 0.001 mg/kg Fig. 3. Chromatograms of (a) extract of tea, (b) extract of tea spiked with 0.001 mg/kg of pindone, (c) standard solution of pindone (2 g/l) 3. 0.001 mg/kg 5 10 81 93 2 7 (Table 4) (Fig. 3) Table 5 10 90 106 10 PSA LC-MS/MS 10 81 93 2 7 20 1) Valchev, I., Binev, R., Yordanova, V., Nikolov, Y. Anticoagulant rodenticide intoxication in animals A review. Turk. J. Vet. Anim. Sci., 32, 237 243 (2008). 2) Jin, M. C., Cai, M. Q., Chen, X. H. Simultaneous measurement of indandione-type rodenticides in human serum by liquid chromatography-electrospray ionizationtandem mass spectrometry. J. Anal. Toxicol., 33, 294 300 (2009). 3) Palazoglu, M. G., Tor, E. R., Holstege, D. M., Galey, F. D. Multiresidue analysis of nine anticoagulant rodenticides in serum. J. Agric. Food Chem., 46, 4260 4266 (1998). 4) Chen, X. H., Cai, M. Q., OuYang, X. K., Jin, M. C. Ion chromatography tandem mass spectrometry for simul-
August 2011 LC-MS/MS 243 taneous confirmation and determination of indandione rodenticides in serum. Biomed. Chromatogr., 23, 1217 1226 (2009). 5) Chen, X. H., Cai, M. Q., Jin, M. C. Analysis and confirmation of rodenticide pindone in human plasma by IC-ESI-IT-MS. Chromatographia, 70, 1201 1206 (2009). 6) Vudathala, D., Cummings, M., Murphy, L. Analysis of multiple anticoagulant rodenticides in animal blood and liver tissue using principles of QuEChERS method. J. Anal. Toxicol., 34, 273 279 (2010). 7) Jin, M. C., Chen, X. H., Ye, M. L., Zhu, Y. Analysis of indandione anticoagulant rodenticides in animal liver by eluent generator reagent free ion chromatography coupled with electrospray mass spectrometry. J. Chromatogr. A, 1213, 77 82 (2008). 8) Marek, L. J., Koskinen, W. C. Multiresidue analysis of seven anticoagulant rodenticides by high-performance liquid chromatography/electrospray/mass spectrometry. J. Agric. Food Chem., 55, 571 576 (2007).