AOAC Final Action Methods in 2017

J OSEPH ET AL . : J OURNAL OF AOAC I NTERNATIONAL V OL . 101, N O . 3, 2018 841

Table 8. Comparison with LC-MS/MS technique

Biotin, µg/100 g

AOAC Method 2016.02

Sample No.

Product description

Blind duplicate

LC-MS/MS Difference

MLT 1

Infant formula powder, partially hydrolyzed milk-based

A B A B A B A B A B A B A B A B A B A B A B A B

33.78 34.23 78.79 79.61

35.55 39.10 82.45 81.15

– 1.77 – 4.87 – 3.66 – 1.54

MLT 2

Infant elemental powder

Infant formula RTF, milk-based a

MLT 3

4.02 4.13

3.73 3.84

0.29 0.29 5.84

MLT 4

Adult nutritional RTF, high-fat

71.90 71.02 26.67 27.27 44.36 45.14

66.06 77.49 26.99 25.25 43.00 42.27

Downloaded from https://academic.oup.com/jaoac/article-abstract/101/3/831/5653969 by guest on 05 May 2020

– 6.47 – 0.32

MLT 5

Infant formula powder, milk-based

2.02 1.36 2.87 9.48

MLT 6

Infant formula powder, soy-based

MLT 7

NIST SRM 1849a

196.06 196.96 260.88 256.49 174.60 159.09

186.58 181.50 263.90 246.17 171.69 162.77

15.46 – 3.02 10.32

MLT 8

Adult nutritional powder, low-fat

MLT 9

Child formula powder

2.91

– 3.68

MLT 10

Toddler formula powder, milk-based

10.38

9.87

0.51

9.85

10.30 41.66 39.77 54.05 51.57

– 0.45

MLT 11

Infant formula powder, milk-based

42.84 42.96 52.63 52.73

1.18 3.19

MLT 12

Adult nutritional RTF, high-protein

– 1.42

1.16

a

RTF = Ready-to-feed.

technique was not given. Rather than performing a true backflush, the 3 mL methanol eluate was recycled through the IA cartridge three times. It is possible that this may partly explain the slightly low recovery for some samples, given that the IA cartridge may well have retained a small portion of this eluent fraction/biotin. The details of the backflush technique using a syringe plunger and reverse pressure are now detailed in the method.

IAC Loading Speed

Two laboratories obtained lower biotin results for the practice samples initially and were advised to follow the IAC loading by gravity, as documented in the method. The results came back higher and comparable to other laboratories.

Elution of Biotin from IAC

Syringe Filter

While assisting a participant investigating low biotin results, it became apparent that the backflush technique was not exactly followed, mainly, it seems, because the exact description of this

At least two laboratories experienced interference with chromatography. The investigation isolated the issue as the

Table 9. Comparison of method performance with SMPR 2014.005

AOAC 2016.02

Parameter

SMPR 2014.005

Comments

Analytical range, µg/100 g

0.1 – 150

0.1 – 300

Analytical range of the proposed method is wider based on the sample weight and loading volume for IAC extraction The proposed method meets the LOQ of 0.1 µg/100 g as required by SMPR 2014.005 Repeatability of the proposed method is better than the SMPR 2014.005 Reproducibility of the proposed method is better than the SMPR 2014.005

LOQ, µg/100 g

≤ 0.1

≤ 0.1

≤ 6% at >1 µg/100 g

≤ 5% at >1 µg/100 g

RSD r

≤ 12% at >1 µg/100 g

≤ 10% at >1 µg/100 g

RSD R

HorRat

0.5 – 2.0 90 – 110

0.3 – 0.5 95 – 105

Excellent precision performance rating

Recovery of >1 µg/100 g, %

The spiked recoveries by the proposed method are better than the recovery range specified by SMPR 2014.005

NIST SRM 1849a, µg/100 g

199 ± 13

197 ± 10

NIST 1949a results are within the certified limits