1 Analytical Methods 2 3 Electronic Supplementary Information Ultra-trace determination of sodium fluoroacetate (1080) as

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1 Electronic Supplementary Material (ESI) for Analytical Methods. This journal is The Royal Society of Chemistry Analytical Methods 3 Electronic Supplementary Information Ultra-trace determination of sodium fluoroacetate (1080) as 7 monofluoroacetate in milk and milk powder by GC-MS/MS and LC- 8 MS/MS 9 10 Yiu-Tung Wong*, Wing-Ki Law, Shirley Sau-Ling Lai, Siu-Pan Wong, Kong-Chi 11 Lau and Clare Ho Analytical and Advisory Services Division, Government Laboratory, 15 7/F, Ho Man Tin Government Offices, Ho Man Tin, Kowloon, 16 Hong Kong Special Administrative Region, China *Corresponding author: Dr. Yiu-Tung Wong, Tel.: address: ytwong@govtlab.gov.hk Page 1 of 9

2 39 40 Fig. S1 Structures of 1080, its related compounds and derivatization conditions for 41 MFA Page of 9

3 61 Table S1 Types of milk and milk powder samples used in this study 6 Matrix type Sample type Category Age group Ingredient type Milk A Infant milk liquid 0 6 months Cow s milk formula No. of brands used Country of origin Malaysia USA Milk powder B Fresh milk -- Cow s milk C Infant formula 0 6 months Cow s milk 1 Hong Kong Spain Germany D Stage 6 1 months Cow s milk USA Netherlands E Stage years Cow s milk New Zealand USA F Stage 4 > 3 years Cow s milk G Growing up > 1 months Goat s milk formula Goat whole milk 7 years or Goat s milk powder above and adults H Stage 6 1 months Soy milk I Whey protein powder > 3 years Pure whey protein New Zealand 1 New Zealand 1 New Zealand 1 USA 1 Switzerland 65 Table S A series of EWG substituted anilines evaluated for the MFA derivatization EWG substituted aniline Molecular formula of the derivative Nominal mass (m/z) Most abundant precursor ion (m/z) In-source fragmentation Remarks,4-DCA C 8 H 6 Cl FNO 1 01 YES -- 3,4-DCA C 8 H 6 Cl FNO 1 01 YES -- 3,5-DCA C 8 H 6 Cl FNO 1 01 YES --,4-DFA C 8 H 6 F 3 NO YES -- 3,4-DFA C 8 H 6 F 3 NO YES -- 3,5-DFA C 8 H 6 F 3 NO YES -- -NA C 8 H 7 FN O NO -- 3-NA C 8 H 7 FN O NO -- 3,5-DNA C 8 H 6 FN 3 O No reaction Page 3 of 9

4 74 75 Fig. S a) GC-NCI-MS full scan spectra of MFA-3NA; b) GC-NCI-MS/MS product 76 ion scan spectra of MFA-3NA; c) GC-NCI-MS full scan spectra of 13 C D -MFA-3NA 77 and d) GC-NCI-MS/MS product ion scan spectra of 13 C D -MFA-3NA Page 4 of 9

5 81 8 Fig. S3 a) Negative ion ESI full scan spectra of MFA-3NA; b) Negative ion LC-ESI- 83 MS/MS product ion scan spectra of MFA-3NA; c) Negative ion ESI full scan spectra 84 of 13 C D -MFA-3NA and d) Negative ion LC-ESI-MS/MS product ion scan spectra of C D -MFA-3NA. Page 5 of 9

6 86 87 Fig. S4 Stability of MFA-3NA in different matrices and under different storage 88 temperatures Page 6 of 9

7 89 Table S3 a) MRM transitions monitored in GC-MS/MS analysis (CI, -ve mode). Compound Precursor Product Ion (m/z) Ion (m/z) CE (ev) Remark MFA-3NA Qualification Quantitation Qualification 13 C D -MFA-3NA Qualification Quantitation Qualification b) MRM transitions monitored in LC-MS/MS analysis (ESI, -ve mode). Compound Precurso Produc DP CE r Ion t Ion (V) (V) (m/z) (m/z) Remark MFA-3NA Quantitation Qualification Qualification Qualification Qualification 13 C D -MFA-3NA Quantitation Qualification Qualification Qualification Qualification 9 Page 7 of 9

8 93 Table S4 LODs, LOQs, slopes and intercepts of the solution and matrix-matched calibration curves of MFA with regression statistics by GC- 94 MS/MS and LC-MS/MS Matrix Technique a b r s b s y/x F p LOD LOQ Solution GC-MS/MS LC-MS/MS Milk GC-MS/MS µg/l µg/l LC-MS/MS µg/l µg/l Milk powder GC-MS/MS µg/kg µg/kg LC-MS/MS µg/kg µg/kg 95 Remarks: The linear regression equations of the calibration curves were expressed in the form of y = bx + a (where y = area of analyte divided by the area of internal standard, 96 b = slope of the regression line, x = concentration of analyte, a = intercept of the regression line, r = square of correlation coefficient, s b = standard deviation of slope, s y/x = 97 standard error of estimate). F = F-statistic and p = p-value of the lack-of-fit test Page 8 of 9

9 105 Table S5 Comparison of the recovery data of MFA at different I.S. fortification levels on Student s t-test Matrix Type Milk Powder Milk Sample Type Measurement Technique Low I.S. spike High I.S. spike Student s t-test Mean Recovery (%) SD (%) Mean Recovery (%) SD (%) t-value p Cow s milk GC-MS/MS Whey protein GC-MS/MS Soy milk LC-MS/MS Goat s milk LC-MS/MS Infant milk liquid formula GC-MS/MS Fresh milk LC-MS/MS Remarks: Mean recovery was calculated from three independent determinations (N = 3). Critical t-value =.78 ( = 0.05 with degree of 107 freedom = 4) Page 9 of 9