Arsenic Speciation in Food: Intercomparison Study

Transcription

1 Arsenic Speciation in Food: Intercomparison Study Michelle Briscoe Presented April 21, 215 ACIL P2 Meeting FSS Section Arlington, VA

2 Purpose & Goals of the Study Brooks Rand Labs organized an international interlaboratory comparison study for the analysis of arsenic speciation in food. To provide a reliable means for laboratories to evaluate their competency To provide a metric for assessing the intercomparability of data generated by different laboratories

3 213 Study Materials 1) White Rice 2) Brown Rice 3) Kelp 4) Apple Juice

4 Lessons Learned from st Annual As Interlaboratory Comparison Study What worked Anonymous data submission No participation fee Broad invitation to participate (39 participants from 13 different countries) Inclusion of analytical method reporting, in general Improvements needed Inconsistent inorganic As reporting As(III) + As(V) = As(Inorg) Variability of data Shipping (international) Expense Specific correlation between results and method reporting information

5 Analytical Parameters 213 Study Total Arsenic (As) in the sample Total As in the extract (if applicable) Inorganic As As(III) - arsenite As(V) - arsenate MMAs monomethylarsonic acid DMAs dimethylarsinic acid Most Toxic Other arsenic species, such as arsenobetaine (AsB) or unknown arsenic species AsB, AsC, and arsenosugars are generally considered non-toxic Potentially Toxic

6 Analytical Parameters 214 Study Total Arsenic (As) in the sample Total As in the extract (if applicable) Inorganic As As(III) - arsenite As(V) - arsenate MMAs monomethylarsonic acid DMAs dimethylarsinic acid Arsenobetaine (AsB) Most Toxic Other arsenic species or unknown arsenic species Potentially Toxic

7 Study Overview nd Annual Interlaboratory Comparison Study Broad invitation to join Anonymous data submission Analytical method reporting Food Matrices White Rice Flour (SRM) Seasoned Seaweed Snack Cocoa Powder Fin Fish Muscle Tissue (SRM) Shellfish Tissue Minimal Fee to participate

8 Why we used SRMs Assess accuracy and precision

9 Laboratory Participation Participating Labs by Region Labs submitting results by matrix Seasoned Seaweed Snack 17 Cocoa Powder 18 Shellfish Tissue 19 Fin Fish Muscle Tissue* 2 White Rice Flour* 29 17% 7% 3% 73% *SRMs North America Asia Europe Austrialia/ Oceana

10 % of TAs of each parameter 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % Cocoa Powder Fin Fish Tissue Seaweed Snack Shellfish Tissue White Rice Flour Inorg As MMAs DMAs AsB

11 Extraction Efficiency Cocoa powder White rice 12% 25% Percent exctarction 1% 8% 6% 4% Percent exctarction 2% 15% 1% 5% 2% % % Hot HNO₃ Sonication MeOH Hot HNO₃ Hot HNO₃ Hot HNO₃ Hot HNO₃ Leach HNO₃ Hot HNO₃ Microwave HNO₃ Hot HNO₃ Leach HNO₃ Hot HNO₃ Leach Enzymatic Hotblock / Oven HCl Leach Enzy + MeOH Microwave HCl Hot HNO₃ * Extracton method Extracton method

12 Most Probable Values (MPV) 214 Summary of Most Probable Values (µg/kg) Matrix Inorg As MMAs DMAs AsB Sum As Spec TAs Sample *Insufficient data to calculate MPV Spec Rec Extract Efficiency Cocoa Powder 19 * * * % 6% White Rice Flour * % 13% Certified Values % Tuna Fish Tissue % 92% Certified Values % Shellfish Tissue % 81% Seaweed Snack 11 * % 92%

13 Number of Labs Number of Labs White Rice Flour SRM Mean Score Shellfish Mean Score 214 Scores Number of Labs 1 Number of Labs Tuna Fish SRM Mean Score Seaweed Snack* Mean Score *Only Total As was scored Parameter Number of Labs Mean Score Total As in Sample Total As in Extract Inorganic As MMAs DMAs AsB All Parameters Cocoa Powder Mean Score n

14 Comparison to 213 Scores Number of Labs All Matrices Parameter Mean Score n Total As in Sample Total As in Extract As(III) As(V) Inorganic As DMAs All Parameters Mean Score

15 Total As Results White Rice Flour SRM (with 25% LCL and UCL) 5 White Rice Flour (μg/kg)

16 Inorganic Arsenic Results White Rice Flour SRM: NIST 1568b 18 Inorganic As Results µg/kg AsIn Certified value LCL UCL Only 17 labs (65%) reported results ± 25% of the certified value. This skewed the MPV to be 2% higher than the certified value.

17 Total As Results Tuna Fish SRM (with 25% LCL and UCL) Tuna Fish Tissue (μg/kg)

18 Inorganic As Results Tuna Fish SRM: BCR-627 (not certified for Inorg As) Only 4 out of 15 labs (26%) are within ± 25% of the MPV 1 µg/kg

19 As Species in Seaweed Snack Per laboratory µg/kg Separation method - Extraction reagent AsIn MMA DMA AsB Other species

20 IC-ICP-MS Chromatogram Spikes in DIW 12 Internal standard Counts Per Second (CPS) TMAs AsB As(III) TMAOH DMAs MMAs As(V) Retention Time (seconds)

21 Conclusions Preferable to report Inorganic As, instead of As(III) and As(V) individually SRMs were informational Total As results were good Inorganic As results were variable Overall score of 2.7 for all matrices/parameters marginally good Valuable tool for laboratories as the methodology advances

22 Acknowledgments: Participants Annie Carter, BRL VP of Operations Tamas Ugrai, BRL Metal Research Chemist Elizabeth Madonick, BRL Technical Sales Specialist

23 Thank you! Questions?