Analysis of Free and Total Myo-Inositol in Foods, Feeds, and Infant Formula by High-Performance Anion Exchange Chromatography with Pulsed Amperometric Detection, Including a Novel Total Extraction Using Microwave-Assisted Acid Hydrolysis and Enzymatic Treatment

Abstract

A method for the analysis of free and total myo-inositol in foods, feeds, and infant formulas has been developed and validated using high-performance anion exchange chromatography with pulsed amperometric detection. The option of a free myo-inositol determination or a complete total myo-inositol determination from main bound sources can be achieved. These sources include phytates, lower'phosphorylated forms, and phosphatidylinositol. This approach gives the option for subtraction of myo-inositol from nonbioavailable sources when it is quantified using other methods if a total bioavailable myo-inositol result is desired for nutritional labeling of a product. The free analysis was validated in a milk-based infant formula, giving RSD(R) of 2.29% and RSD, of 2.06%. A mean recovery of 97.9% was achieved from various spike levels of myo-inositol. Certified National Institute of Standards and Technology reference material verified the method's compatibility and specificity. Two different total analyses were validated in a soy-based infant formula and compared. One technique involved using a conventional acid hydrolysis with autoclave incubation for 6 h, while the other used a novel technique of microwave-assisted acid hydrolysis with enzymatic treatment that can minimize extraction to 1 day. The autoclave analysis had RSD(R) of 2.08% and RSDr of 1.55%, along with a mean spike recovery of 102.1% at various myo-inositol spike levels. The microwave/enzyme total analysis had RSD(R) of 4.34% and RSD, of 4.70%, along with a mean spike recovery of 104.2% at various spike levels of myo-inositol. Main sources of myo-inositol including phytic acid and phosphatidylinositol were tested with both total analyses. Mean recoveries of phytic acid and phosphatidylinositol through the autoclave total analysis were 90.4 and 98.3%, respectively. Mean spike recoveries for these same sources in soy- based infant formula through the microwave/enzyme total analysis were 97.2 and 96.3%, respectively. Comparison of soy-based infant formula and corn grain samples with high levels of these main sources showed in similar results, indicating both total analyses are acceptable for use. An additional glycerol kinase step was also developed to remove glycerol from the chromatographic elution window of myoinositol in samples with high levels of glycerol.

Determination of myo-inositol content in milk by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD)

“…Để đáp ứng áp suất làm việc của cột và giảm thời gian phân tích, tốc độ dòng được đặt cố định tại 0,4 mL/phút. Tham khảo một số tài liệu [7,[10][11], các dung môi được lựa chọn khảo sát gồm: NaOH 240 mM chế độ đẳng dòng; NaOH 50 mM -NaOH 1M với chương trình gradient 1, 2 (Bảng 1, 2).…”

Scientific Opinion on the safety and efficacy of inositol as a feed additive for fish, dogs and cats

“…One of the major drawbacks with total methods is the uncertainty on the completion of the hydrolysis of the phosphate forms of myo-inositol. Acid hydrolysis (6N HCl) at 120 °C (autoclave) has been found to liberate more than 90 % of myoinositol from phosphoinositides, including phytates (Ellingson et al, 2012). In a survey performed in the USA on 487 foods (Clements and Darnell, 1980), total myo-inositol was measured using the analytical method described above.…”

A comparative study on the hydrolysis of acetic anhydride and N,N-dimethylformamide: Kinetic isotope effect, transition-state structure, polarity, and solvent effect

“…Over the years, mechanisms involved in hydrolysis of anhydrides and esters have been extensively studied using titration, calorimetric, conductimetric, spectroscopic, temperature scanning, combination, pH, and chromatographic techniques. By studying the mechanism for hydrolysis of N,N‐dimethylformamide (DMF), one may infer mechanistic characteristics that occur in other compounds that contain amide structural features, for example, proteins.…”