6. AOACSPIFANMethods-2018Awards

288

S CHIMPF ET AL . : J OURNAL OF AOAC I NTERNATIONAL V OL . 101, N O . 1, 2018 271

Table 6. trans -Lycopene calibration curve data

Relative error, % a

r

Curve

Date

Slope

Intercept

L 1

L 2

L 3

L 4

Avg.

2.81 × 10 0 8.66 × 10 4 3.01 × 10 0 8.32 × 10 4 3.17 × 10 0 3.04 × 10 0 3.19 × 10 0 2.99 × 10 0 3.15 × 10 0

– 1.16 × 10 0 – 9.51 × 10 2 – 1.56 × 10 0 – 8.70 × 10 8 3.13 × 10 0 5.55 × 10 0 4.44 × 10 0 1.35 × 10 0 6.10 × 10 0

1 2 3 4 5 6 7 8 9

Feb 7, 2017 Feb 6, 2017 Feb 1, 2017 Jan 31, 2017 Jan 30, 2017 Jan 27, 2017 Jan 26, 2017 Jan 26, 2017 Jan 25, 2017

0.99905

0.801 0.748

– 1.772 – 0.134

1.668

– 0.697

0.000 0.000 0.000 0.000 0.000 0.000 1.730 0.000 0.000

0.999975

– 1.181

0.567

0.99998

– 0.414 – 1.778 – 0.896 – 0.700 – 3.237 – 3.659 – 0.631 3.459

0.787

– 0.373

0.999973 0.999908 0.999648 0.999883 0.999909 0.999879 0.999801

3.379 1.702

– 1.601 – 0.806

– 1.134

3.371 1.187

– 1.537 – 0.720 – 0.585 – 0.696 – 0.577

2.992 2.910 3.246 1.399

0.912

1.110 0.605

Avg.

a L 1 – 4 corresponds to lycopene concentrations of ~5, 10, 15, and 100 µg/L.

(l) Water. — Resistivity of ≥ 15 mega-ohm/cm.

(s) Stir plate with stir bars or mechanical shaker. (t) Ultrasonic bath. (u) Volumetric flasks. — Assorted sizes. (v) Volumetric pipets. — Class A, assorted sizes. (w) Vortex mixer. (x) Water bath.

D. Standard and Solution Preparation

All solutions can be scaled up or down for convenience, provided good laboratory practices are observed. All solutions can be stored at 2 – 30°C and are good for 6 months unless otherwise noted; however, discontinue use of any chemical or solution regardless of expiration dates whenever indications of contamination, chemical degradation, or changes in concentration are evident. (a) Mobile phase. — Methanol – MtBE (85 + 15); mix 850 mL methanol and 150 mL MtBE. (b) Extraction solution. — Hexane – MtBE (75 + 25); mix 375 mL hexane and 125 mL MtBE. (c) 10% (w/v) BHT in methanol. — Weigh 5.0 g BHT and transfer to a 50 mL volumetric flask. Dissolve in and dilute to volume with methanol. (d) Dilution solution. — 10%BHT in methanol – MtBE (75 + 25); add 12 mL of 10% BHT in methanol and 4 mL MtBE to a small glass container and tightly cap. Mix well. (e) Standard preparations. — Prepare all standards under UV-shielded fluorescent lights and store in tightly stoppered volumetric flasks or glass containers at less than – 50°C. — ( 1 ) Stock standard preparation. — ( i ) Lutein (approximately

C. Chemicals and Solvents

Caution : Refer to MSDSs of chemicals prior to use and follow the suggestions for personal protective equipment. (a) b -Carotene. — United States Pharmacopeia standard 1065480, Sigma PHR123, or equivalent. (b) BHT. — American Chemical Society (ACS). (c) Alcohol, dehydrated undenatured 200 proof or reagent alcohol. — HPLC grade. (d) Hexane. — HPLC grade. (e) Lutein. — Sigma standard 07168 or equivalent. (f) Lycopene. — Sigma standard 75051 or equivalent. (g) MtBE. — HPLC grade. (h) Methanol. — HPLC grade. (i) Potassium hydroxide, 45% (w/w). — ACS. (j) Sodium ascorbate. — ACS. (k) THF with BHT preservative. — HPLC grade.

Table 7. trans -Lutein calibration curve data

Relative error, % a

r

Curve

Date

Slope

Intercept

L 1

L 2

L 3

L 4

Avg.

4.68 × 10 0 4.79 × 10 0 5.11 × 10 0 4.98 × 10 0 5.01 × 10 0 4.93 × 10 0 4.67 × 10 0 4.81 × 10 0 4.45 × 10 0

1.43 × 10 0 – 1.18 × 10 0 – 2.52 × 10 0 5.39 × 10 0 – 2.26 × 10 0 6.53 × 10 0 2.73 × 10 0 6.54 × 10 0 3.91 × 10 0

1 2 3 4 5 6 7 8 9

Feb 7, 2017 Feb 6, 2017 Feb 1, 2017 Jan 31, 2017 Jan 30, 2017 Jan 27, 2017 Jan 26, 2017 Jan 26, 2017 Jan 25, 2017

0.999983 0.999784

– 1.541 – 0.313

1.591 1.782

0.064

– 0.114

0.000 0.000 0.000 0.000 0.020 0.000 0.000 0.000 0.000

– 2.612

1.144

0.99972

1.676 0.608 0.545

– 2.007 – 1.525 – 0.662

0.429 1.589 0.157 0.749 0.624

– 0.097 – 0.673

0.999916 0.999997 0.999963 0.999939 0.999947 0.999968 0.999906

0.039

– 1.82

1.506 2.576 2.893 1.488 0.849

– 0.434 – 0.431

– 2.769 – 2.523 – 1.754 – 0.877

– 0.414

0.044

0.655 0.138

– 0.389 – 0.101

Avg.

a L 1 – 4 correspond to lutein concentrations of ~10, 25, 125, and 250 µg/L.