High-Performance Liquid Chromatography Method for the Determination of Folic Acid in Fortified Food Products

Figures & data

FIGURE 1 Chromatogram of the main folate forms present in wheat flour type 550 1—5-HCO-H₄ folate (t_R 7.0 min, 0.85 μg/mL), 2—folic acid (t_R 15.0 min, 1.13 μg/mL). EC detector sensitivity 1 μA. LC 18 column 5 μm (4.6 mm × 25 cm) and a mobile phase, consisting of 40 mM sodium phosphate dibasic, heptahydrate buffer, and 8% acetonitrile (v/v), pH 5.5. The sample size and the final dilution used for the analyzed vitamin determination varied according to the vitamin content in products.

FIGURE 2 Chromatogram of the folic acid in fortified fruit juices—2 folic acid (t_R 15.0 min, 3.2 μg/mL). EC detector sensitivity 1 μA. LC 18 column 5 μm (4.6 mm × 25 cm) and a mobile phase, consisting of 40 mM sodium phosphate dibasic, heptahydrate buffer, and 8% acetonitrile (v/v), pH 5.5. The sample size and the final dilution used for the analyzed vitamin determination varied according to the vitamin content in products.

Table 1 Determination of folic acid in commercial vitamin-fortified fruit juices and fruit drinks (μg/100 mL)

Fruit juice samples	n	Amount labeled	Amount determined^a
Fruit juices—multivitamin	9	30	21.38 ± 0.99 (70%) (19.81–24.09)
Fruit nectar—multivitamin	16	30	35.21 ± 0.78 (116%) (34.39–36.10)
Fruit drink (apple, mango, pears)	9	30	17.43 ± 0.29 (58%) (17.22–17.63)
Fruit juice (orange, 100%)	9	30	19.11 ± 1.51 (64%) (17.00–21.24)
Fruit juice (orange, banana)	9	30	27.52 ± 0.96 (92%) (26.54–28.5)

^aData are averages of five determinations.

n = number of samples.

Table 2 Determination of folic acid in commercial vitamin-fortified cereal-grain products (μg/100 g)

Product	n	5-HCO-H4^a	Folic acid^a	Total (as folic acid)	Amount labeled
Wheat flour type 450	3	ND	154.3 ± 1.6 (153.2–155.0)	154.3	100
Wheat flour type 550	3	68.5 ± 3.7 (66.0–72.7)	283.7 ± 1.3 (282.6–284.6)	352.2	100
Toasted oat flakes	3	ND	95.7 ± 1.1 (93.9–96.9)	95.7	Unfortified
Corn flakes	3	29.0 ± 3.8 (23.0–30.6)	76.6 ± 1.6 (75.2–78.3)	105.6	Unfortified
Corn flakes—fitness	3	98.8 ± 3.9 (94.6–102.1)	174.8 ± 2.9 (165.1–170.2)	273.6	340
Corn puffs—cinnamon	3	67.6 ± 4.7 (63.4–72.7)	318.8 ± 2.3 (316.9–321.3)	386.4	170
Fruit flakes	3	153.8 ± 4.6 (148.5–156.9)	261.1 ± 12.4 (246.8–269.2)	414.9	260
Fruit pops	3	128.3 ± 3.4 (124.9–131.6)	161.7 ± 0.9 (161.0–162.7)	290.0	170
Macaroni with spinach	3	33.7 ± 9.2 (26.4–44.0)	194.8 ± 7.2 (187.9–202.2)	228.5	Unfortified

^a Data are averages of five determinations.

n = number of food samples.