AOACSPIFANMethods-2017Awards

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1582  H aselberger & J acobs : J ournal of AOAC I nternational V ol . 99, N o . 6, 2016

Table 2016.06G. Quantitative fructan determination (Part II) gradient Time, min Flow, mL/min A (lab water), %

B (500 mM NaOH), %

C (300 mM NaOAc), %

Curve

0 0

1.0 1.0 1.0 1.0 1.0 1.0 1.0

90.0 90.0 90.0

10.0 10.0 10.0 80.0 80.0 10.0 10.0

0.0 0.0 0.0

NA

5 5 5 5 5 5

20.0 20.1 30.0 30.1 45.0

0.0 0.0

20.0 20.0

90.0 90.0

0.0 0.0

(c) Working standards (WS).— Dilute fructose stock and glucoheptose IS solution with laboratory water, using class A glass pipets for transfer of fructose and IS solutions to appropriate volumetric flasks for final dilution, as follows: (1) WS1 .—5 mL Fructose stock, 10 mL IS solution to 200 mL final volume. (2) WS2 .—5 mL Fructose stock, 5 mL IS solution to 100 mL final volume. (3) WS3 .—25 mL Fructose stock, 5 mL IS solution to 100 mL final volume (4) WS4 .—50 mL Fructose stock, 5 mL IS solution to 100 mL final volume. Store frozen at –20°C for up to 6 months. (d) Acetic acid solution 0.2 M .—Transfer 2.9 mL acetic acid to a 250 mL flask containing ~100 mL laboratory water. Dilute to volume with laboratory water and mix by inversion. Transfer to a suitable container for storage up to 2 years. (e)  50 mM NaOH solution.— Transfer 5 mL of 1 M NaOH into a 100 mL flask containing ~50 mL laboratory water. Bring to volume with laboratory water mix thoroughly. Store in suitable plastic container for up to 2 years. (f) Alkaline borohydride solution ~10 mg/mL.— Immediately before use, weigh 100 mg sodium borohydride into a 15 mL tube. Dissolve in 5 mL of 50 mM NaOH (this is enough for 24 samples). Use for up to 4 h after addition of hydroxide. (g) Sodium maleate buffer 0.1 M, pH 6.5.— Weigh 2.9 ± 1% of maleic acid in a 250 mL beaker. Dissolve in ~150 mL laboratory water. Adjust pH to 6.5 with 1 M NaOH. Transfer to 250 mL flask; bring to volume with laboratory water and mix thoroughly. (h) Sucrase solution (~30 units/mL). —Measure 10 mL maleate buffer in a graduated cylinder. Deliver to sucrase vial. Cap and swirl gently to dissolve. Divide into ~450 µL aliquots and store frozen at –20°C (each tube is enough for two samples) for up to a year.

(i)  Acetate buffer.— Combine 2.9 mL glacial acetic acid with 450 mL laboratory water. Adjust pH to 4.5 with 1 M NaOH. Bring total volume to 500 mL with laboratory water and mix thoroughly. (j)  Fructanase solution (~909 units/mL).— Dissolve contents of fructanase vial in 22 mL acetate buffer. Swirl gently to dissolve. Divide into ~1 mL aliquots and store frozen at –20°C for up to a year (each tube should contain enough for nine samples). (k)  Mobile phase A.— Deliver laboratory water to an acceptable container and sparge with UHP helium for 10 min. Store under ~3–5 psi blanket of helium on the instrument. Expiration is 30 days at room temperature. (l)  Mobile phase B.— Deliver 1000 mL laboratory water to an acceptable container and sparge with UHP helium for 10 min. Add 40 ± 0.1 g of 50% (w/w) NaOH and continue to sparge for 2 additional min. Store under ~3–5 psi blanket of helium on the instrument. Expiration is 30 days at room temperature. (m)  Mobile phase C.— Deliver 1000 mL laboratory water to an acceptable container and sparge with UHP helium for 10 min. Add 40.8 ± 0.1 g sodium acetate trihydrate and continue to sparge for 5 additional min (or until dissolved). Then filter the solution through the membrane filter. Store under ~3–5 psi blanket of helium on the instrument. Expiration is 14 days at room temperature. K.  Sample Preparation If running in parallel with Part I, above, an aliquot from the diluted solution, E(b) , can be used in this method. If so skip to step (c) , below. Otherwise proceed to step (a) , below (a)  Powder sample reconstitution (if sample is RTF, skip this step).— Accurately weight 5.0 ± 0.025 g into a 100 mL plastic beaker and record weight. This is PW. Tare and deliver 40 ± 0.2 g laboratory water to beaker. Record water weight. This

Table 2016.06H. Column cleaning/trap regeneration gradient Time, min Flow, mL/min A (Lab water), %

B (500 mM NaOH), %

C (300 mM NaOAc), %

Curve

0 0

1.0 1.0 1.0 1.0 1.0 1.0 1.0

60.0 60.0 60.0

40.0 40.0 40.0 40.0 40.0 40.0 40.0

0.0 0.0 0.0

NA

5 5 5 5 5 5

15.0 15.1 30.0 30.1 45.0

0.0 0.0

60.0 60.0

60.0 60.0

0.0 0.0