Development and Validation of an UPLC-MS/MS Method for Quantification of Mycotoxins in Tobacco and Smokeless Tobacco Products

Transcription

1 Development and Validation of an UPLC-MS/MS Method for Quantification of Mycotoxins in Tobacco and Smokeless Tobacco Products Johan Lindholm, Anna Wiernik, Birgitta Grandin, Margareta Curvall Swedish Match Smokefree Product Division, R&D November 3,

2 Introduction Mycotoxins are substances produced by toxigenic moulds that contaminate various agricultural commodities either before harvest or under post-harvest conditions In tobacco mycotoxins accumulate under post - harvest conditions i.e during curing and storage There exist many different Mycotoxins and in Tobacco Aflatoxins and Ochratoxin A are the most abundant Aflatoxin (B1, B2, G1, G2) and Ochratoxin A are produced by storage moulds belonging to Aspergillus and Penicillium species Aflatoxins and Ochratoxin A are highly toxic / carcinogenic. Their maximum levels are regulated in food In Sweden Aflatoxins are also regulated in Snus November 3,

3 Why is there a concern about mycotoxins? International Agency for Research on Cancer (IARC) Classification: Aflatoxins are included in Group 1: The agent is carcinogenic to humans Ochratoxin A is included in Group 2B: The agent is possibly carcinogenic to humans November 3,

4 Information on the European Maximum Levels COMMISSION REGULATION (EC) No 41881/2006 of 19 December 2006: Setting maximum levels for certain contaminants in foodstuffs The maximum levels vary with different food commodities. Ochratoxin A: 0.2 to 10 ppb (µg/kg) Aflatoxin B1: 2 to 8 ppb Aflatoxins (B1+B2+G1+G2): 4 to 15 ppb November 3,

5 Authorities & Tobacco Products NFA (National Food Administration) in Sweden Snus and Smokeless Tobacco are regulated: Aflatoxins (B1+B2+G1+G2): Maximum level= 5 ppb FDA (Food and Drug Administration) in USA Draft list HPHC (Harmfull and Potentially Harmfull Constituents) in Tobacco Products and Tobacco Smoke Aflatoxin B1 November 3,

6 Mycotoxins Chemical Information Ochratoxin A Highly Soluble in Methanol Chemical properties are important for method development November 3,

7 Method Development November 3,

8 Extraction procedure Weigh out 5 g of tobacco / snus Add internal standards (isotope-labelled) Add 40 ml extraction solution (80/20 MeOH/MilliQ) Shake for 40 min Centrifuge for ~ 5 min at ~2500 rpm (or stand to sediment ~ 1 h) Dilute 3.5 ml of the supernatant with 49 ml of 100 mm PBS buffer (Tween, ph 7.4) November 3,

9 Method Development November 3,

10 Sample preparation: Sample Clean-up SPE: Immunoaffinity columns (IAC) Very Selective: AflaOchra SPE Selective by using antibodies Clean-up of very complex samples November 3,

11 Sample preparation: Sample Clean-up and preconcentration SPE sample preparation for Aflatoxins and Ochratoxin A Condition the IAC 10 ml 10 mm PBS Elute & fractionate 2 ml MeOH Add 45 ml sample 3 ml/min Dilute the sample 3 ml Wash the IAC 10 ml PBS buffer Wash the IAC 5 ml MQ November 3, Mix the sample Transfer the sample to Vial Time saving by dilution the sample instead of evaporation and dissolution

12 Sample preparation: Automated Before and after SPE Gilson ASPEC TM XL4 November 3,

13 Method Development November 3,

14 Typical separation by HPLC Detection: FLD November 3,

15 Separation by UPLC: Chromatogram Ultra Performance Liquid Chromatography XIC of +MRM (13 pairs): 404.2/239.1 amu from Sample 14 (std 8) of m.wiff (Turbo Spray) Max. 4.1e6 cps. 4.0e6 3.8e6 3.6e6 3.4e6 3.2e6 3.0e6 2.8e6 Run time: 3.70 min Peak width1/2: ~3.6 s 2.25 I n t e n s i t y, c p s 2.6e6 2.4e6 2.2e6 2.0e6 1.8e6 1.6e6 1.4e6 1.2e6 1.0e6 8.0e5 6.0e5 4.0e5 2.0e Time, min UPLC column: Waters Aquity UPLC BEH C18 column, 2.1 mm x 100 mm,1.7µm (and Waters pre-filter) Mobile phase A:10 mm Ammonium formate % Formic acid. Mobile phase B: 5 mm Ammonium formate in methanol % formic acid % trifluoroacetic acid. Flow rate:0.40 ml/min Column temperature: 40 C Injection volume: 10 µl November 3,

16 Method Development November 3,

17 Mycotoxins detection Test kits Various test kits for use in a non-laboratory environment/non-specialist laboratory are available for mycotoxins. Rapid results without using expensive equipment, to detect the presence or absence of selected toxins, positive results need to be confirmed. HPLC-FLD HPLC-FLD is still widely used for aflatoxins. Fluorescence detection after post column derivatisation, with iodine LC-MS/MS is more convenient No derivatisation High sensitivity High selectivity Quantification and qualification in the same run Increased productivity November 3,

18 Mycotoxin detection: Positive ESI MS/MS MRM (Multi Reaction Monitoring) transitions Compound Precursor (m/z) Quantifier (m/z) Qualifier (m/z) OTA OTA 13 C 20 (IS) AFB AFB AFB2-D 2 (IS) AFG AFG AFG2-D 2 (IS) November 3, For OTA: OTA 13 C 20 is used as the internal standard For AFB1: AFB2-D 2 is used as the internal standard For AFB2: AFB2-D 2 is used as the internal standard For AFG1: AFB2-D 2 is used as the internal standard For AFG2: AFG2-D 2 is used as the internal standard

19 UPLC-MS/MS: MRM Chromatogram XIC of +MRM (13 pairs): 404.2/239.1 amu from Sample 13 (std 7) of m.wiff (Turbo Spray) 3.3e6 I n t e I n n t s e I n i n t t y s e I, n i n t c t y s e I p, n i n t s c t y s e p, i n t s c y s November 3, Max. 3.3e6 cps Time, min XIC of +MRM (13 pairs): 313.1/241.1 amu from Sample 13 (std 7) of m.wiff (Turbo Spray) Max. 1.1e6 cps. 1.00e Time, min XIC of +MRM (13 pairs): 315.0/287.1 amu from Sample 13 (std 7) of m.wiff (Turbo Spray) Max. 8.0e5 cps. 8.0e5 5.0e Time, min XIC of +MRM (13 pairs): 329.1/243.1 amu from Sample 13 (std 7) of m.wiff (Turbo Spray) Max. 1.1e6 cps. 1.00e Time, min XIC of +MRM (13 pairs): 331.1/313.1 amu from Sample 13 (std 7) of m.wiff (Turbo Spray) Max. 6.0e5 cps. 5.0e5 0.0 AFB1 AFB2 AFG1 AFG OTA Time, min

20 Method Development November 3,

21 Validation Specificity Accuracy Precision Repeatability (intra day) Intermediate Precision (inter-day) Recovery LOQ/LOD Linearity Stability Ion Suppression Proficiency test (Food) November 3,

22 Why Bad Repeatability in Tobacco? All samples prepared and analyzed in the same day Ochratoxin A analyzed in Snus product (n = 10) Mean 7.5 ppb Std dev 0.4 ppb RSD (%) 5.7 % Max 8.2 ppb Min 6.9 ppb Ochratoxin A analyzed in Tobacco (n = 10) Mean 13.2 ppb Std dev 22.6 ppb RSD (%) 172 % Max 76.8 ppb Min 3.6 ppb Very good Repeatability in Snus November 3, Extremely bad Repeatability in Tobacco

23 Inhomogenity Problems with Mycotoxins Shelled corn 0.91 kg sample 50 g subsample, Romer Mill 1 aliquot HPLC Used with permission from M. Miraglia The role of sampling in mycotoxin contamination: An holistic view November 3,

24 RSD (%) for Ochratoxin A in Tobacco of different particle size Tobacco milled with Tecator Cyclotec Grinding Mill with 1 mm Screen Fractionated by sieving Statistics for Ochratoxin-A in different Tobacco fractions (n=5) Size Mean (ppb) Max (ppb) Min (ppb) RSD (%) 500 µm µm µm µm µm < 100 µm Smaller particles Better Repeatability November 3,

25 Particle size distribution of ground Tobacco Tobacco milled with Tecator Cyclotec Grinding Mill with 1 and 0.5 mm Screen Fractionated by sieving Size distribution, milled with 1 mm screen Size (µm) Distribution% November 3, Size distribution, milled with 0.5 mm screen Size (µm) Distribution % Higher portions of small particles 500 More 33.8 uniform particle distribution < Grind the Tobacco (to optimal size) Better Repeatability <

26 Validation - Repeatability C.V (%) pooled for different matrices Analyte C.V (%) Snus product C.V (%) Milled tobacco Ochratoxin A Analyte C.V (%) Spiked Snus product November 3, Spiked with: 0.5; 1 and 5 ppb Aflatoxins C.V (%) Spiked Cut tobacco product C.V (%) Certified reference material AFB AFB AFG AFG n.d.

27 Validation - Accuracy Spiked Conc. (ppb) Accuracy of Ochratoxin A in spiked samples Accuracy (%) Snus product Accuracy (%) Milled tobacco Analyte Accuracy (%) Snus product November 3, Accuracy of Aflatoxins in spiked samples 0.5; 1 and 5 ppb Accuracy (%) Milled tobacco AFB AFB AFG AFG

28 Validation Linearity Ochratoxin A Each calibration level is injected before and after all samples Analyte Range (ppb) OTA AFB AFB AFG AFG November 3, All calibration standards are spiked in tobacco and prepared as the samples

29 Validation - LOQ Sciex API 5000 MS/MS: Aflatoxins: 0.1 ppb (WWB) Ochratoxin A: 0.5 ppb (WWB) Waters Xevo TQ-S Aflatoxins: 0.05 ppb (WWB) Ochratoxin A: 0.05 ppb (WWB) Sensitivity could be increased by a factor 10 if the eluate from SPE (IAC) is Evaporated and reconstituted in 0.5 ml (instead of dilution to 5 ml) November 3,

30 FAPAS Proficiency Test: Aflatoxins FAPAS Proficiency test for Aflatoxins in Maize November 2010 Januari 2011 (Food Analysis Performance Assessment Scheme) Participants:82 lab submitted results Analyt SMNE ppb Assigned value ppb Satisfactory range ppb SMNE Z-score AFB AFB AFG AFG Total Aflatoxins November 3, SMNE: Lab no. 1

31 FAPAS Proficiency Test: Ochratoxin A FAPAS Proficiency Test 1794 Ochratoxin A in Coffee (Instant) October- December 2010 Participants:59 lab submitted results Analyt SMNE ppb Assigned value ppb Satisfactory range ppb SMNE Z-score Ochratoxin A SMNE: Lab no. 38 November 3,

32 Conclusions A Multi-Method for Analysis of Mycotoxins was Developed & Validated An Automated SPE Clean-up Procedure Fast UPLC-MS/MS Analysis Run time: 3.7 min High Sensitivity High Accuracy Tobacco Smokeless Tobacco Products Food November 3,

33 Thanks for your attention November 3,