2016 OMB Summer Meeting

AOAC OMB Meeting Book

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AOAC 2012.22 (FINAL VERSION REVIEW) - JUNE 2016 FOR ERP USE ONLY DO NOT DISTRIBUTE

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1. Injection volume.- 5µL.

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2. Autosampler temperature.- 10 °C.

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3. Column temperature.- 25 °C.

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4. Flow rate.- 0.35mL/min

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5. Run time.- 4.0 minutes

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6. Mobile phase.- Sodium acetate (50 mmol/L, pH 5.4), decylamine (1.6g),

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acetonitrile (1 %), TCEP (40 mg/L).

NOTE: At the end of each analytical series, rinse column with acetonitrile-water (1+1, v/v) 84

for 10 minutes at 0.4 ml/min .

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(b). System suitability test .- Equilibrate the chromatographic system for ≥0.5 h.

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Inject a working standard solution of ascorbic acid at least 6 times and check

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peak retention times and response (peak height or area). Inject working

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standard solutions on a regular basis within a series of analyses. Ensure orotic

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acid and isoascorbic acid are fully resolved from ascorbic acid by injecting

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separated standard solutions of both compounds (prepared as stated for

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ascorbic acid). If not resolved, the pH of the mobile phase may be decreased to

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5.0, or the amount of acetonitrile increased.

(c). Calibration .- Make single injections of working standard solutions at least at

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the beginning and the end of each analytical series. Establish the calibration

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curve (seven points) by plotting peak response (height or area) versus ascorbic

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acid concentration. Perform linear regression. Calculate the slope (S) and

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intercept (I) of the calibration curve.

(d). Analysis .- Make single injections of sample solutions.

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