AOACSPIFANMethods-2017Awards

204

220 G olay & M oulin : J ournal of AOAC I nternational V ol . 99, N o . 1, 2016 to four areas: ( 1 ) remarks regarding the collaborative study’s organization (i.e., information, sample, schedule); ( 2 ) comments about the procedure used for sample analysis; ( 3 ) statements about insufficient information provided in the method (or inconsistency); and ( 4 ) remarks about the method not being well implemented in laboratory. In general, all comments were positive with respect to the use of this complex chromatographic method in routine analysis, which necessitates an experienced and trained analyst. All comments were summarized and sent to the ERP for review in July 2014 prior to receiving Final Action status. The method has demonstrated its compliance with the applicability statement of AOAC SMPR 2012.011 and has been shown, in this collaborative study, to be suitable for the analysis of fatty acids in selected food matrixes. The majority of results provided for individual and groups of fatty acids were in agreement with expectations (i.e., results gained with proficiency tests and SLV). Conclusions

corresponding to trans isomers) are the most difficult category of isomers to quantify in food matrixes due to possible coelution with other fatty acids. The global performance of the method is satisfactory because RSD r and RSD R values for labeled fatty acids were below 85% of limits fixed in the SMPR for all concentrations. RSD R values were summarized separately for labeled fatty acids in SPIFAN materials and ISO-IDF materials due to different expression of results (Table 4). Results compared to the SMPR values are shown in Table 5. A multilaboratory collaborative study of AOAC First Action Method 2012.13 “Determination of Labeled FattyAcids Content in Milk Products and Infant Formula (and Adult/Pediatric Nutritional Formula) by Capillary Gas Chromatography” and ISO 16958:2015 | IDF 231:2015 was done. This method was applied to representative dairy, infant formula, and adult/ pediatric nutritional formula products and demonstrated acceptable reproducibility precision for all fatty acids (i.e., 46 individuals and/or groups) analyzed for these categories of products. A detailed report summarizing the outcomes of this collaborative study was submitted with the recommendation that AOAC First Action Method 2012.13 be accepted as a SPIFAN-endorsed AOAC Final Action Method. The AOAC ERP evaluated the collaborative study data in September 2014 and endorsed the recommendation, which was subsequently approved by the Official Methods Board in October 2014. Recommendations

Nevertheless, this kind of analytical method requires particular attention for the chromatography part, which is the source of principal differences observed in the results (i.e., response factors of the instrument, coelution, and wrong peak identification and integration, but also errors in the reporting). The accurate identification and quantification of each peak corresponding to trans isomers is very important because they can significantly impact the TFA sums. The C18:3 trans isomers (having possibly two, three, or four different peaks

Table 3. Proposed limits for repeatability and reproducibility values Concentration, g/100 g Repeatability (RSD r

) Reproducibility (RSD R )

<0.05 and ≥0.005 <0.005 and ≤0.001

10 15

25 40

Table 4. Results of the collaborative study

SPIFAN materials a

ISO-IDF materials b

RSD R

, %

RSD R

, %

Fatty acid TFA (total)

Range

Min.

Max.

Range

Min. 8.69 2.38 2.73 4.25 4.47 2.86 4.40 2.83 4.90

Max.

0.006–0.027 0.195–1.945 0.324–1.129 0.803–4.552 0.055–0.121 0.268–1.019 0.799–4.543 0.267–1.017 0.048–0.121 0.016–0.023 0.008–0.011

21.31

42.47

0.008–5.056 0.812–57.777 0.107–2.795 0.717–18.894 0.022–0.637 0.051–1.262 0.631–16.538 0.044–1.036 0.02–0.574 0.003–0.089

32.92

SFAs

1.92 4.58 4.14 5.32 4.61 4.14 4.28 4.86 3.61 5.47

6.50 8.86 8.64 8.40 8.96 8.64 8.48 7.68 7.34

5.72

PUFAs MUFAs c

11.17

8.80

Omega-3 (ω-3) Omega-6 (ω-6) Omega-9 (ω-9) C18:2 n -6 (LA) d C18:3 n -3 (ALA) e C20:4 n -6 (ARA) f C22:6 n -3 (DHA) g

11.68

7.80 9.04

11.81

9.53

10.65

33.71

14.64 8.47 a  Results expressed in grams per 100 g reconstituted product for powder (25 g + 200 g water) and in grams per 100 g for liquid. b  Results expressed in grams per 100 g product (powder and liquid). c  MUFAs = Monounsaturated fatty acids. d  LA = Linoleic acid. 0.006

e  ALA = α-Linolenic acid. f  ARA = Arachidonic acid. g  DHA = Docosahexaenoic acid.