AOAC OMB Final Action Recommendation (December 2019)-2016.14

2016.14 (October 2019) – FOS-03 MANUSCRIPT

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at 20 °C and the injection volume is 20 µL. NaOH (300 mM) is added post-column (before the 1 PAD detector) at a flow rate of 0.13 mL/min, using a T-piece and a 125-µL reaction coil (or 2 equivalent). Fructose and glucose are separated using the gradient described in Table 2016.14F . 3 Carbohydrates are detected by pulsed amperometry using a gold working electrode and an Ag/AgCl 4 reference electrode, and an appropriate waveform for the detection of carbohydrates. An example 5 of a suitable waveform is given in Table 2016.14E . 6 Table 2016.14F. HPAEC-PAD gradient for CarboPac PA1 analytical column (or equivalent) 7

Flow rate, mL/min

200 mM NaOH, % A

Water, % B

1 M NaOAc, % C

Time, min

0.0

0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25

7.5 7.5

92.5 92.5 75.0 75.0 30.0 30.0 60.0 92.5 92.5

0.0 0.0 0.0 0.0

13.0 14.1 20.0 21.0 28.0 30.0 31.0 43.0

25.0 25.0 40.0 40.0 40.0

30.0 30.0

0.0 0.0 0.0

7.5 7.5

8

K. 9 Allow the chromatographic system to equilibrate for at least 1 hour at the initial conditions. Ensure 10 the system pressure and the baseline are stable and there are no leaks. Start the series with one 11 injection of water (to check the baseline), then inject at least 3 times a working standard solution 12 and check stability of peak retention times and response. Check the separation by comparison with 13 a previous analysis if available. Examples of suitable chromatograms and calibration curves are 14 given in section N . System suitability test

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