Rapid determination of vitamin D₃ in milk-based infant formulas by liquid chromatography-tandem mass spectrometry.

Rapid determination of vitamin D₃ in milk-based infant formulas by liquid chromatography-tandem mass spectrometry.

Food chemistry (2014-07-21)

Byung-Man Kwak, In-Seek Jeong, Moon-Seok Lee, Jang-Hyuk Ahn, Jong-Su Park

ABSTRACT

A rapid and simple sample preparation method for vitamin D3 (cholecalciferol) was developed for emulsified dairy products such as milk-based infant formulas. A sample was mixed in a 50 mL centrifuge tube with the same amount of water and isopropyl alcohol to achieve chemical extraction. Ammonium sulfate was used to induce phase separation. No-heating saponification was performed in the sample tube by adding KOH, NaCl, and NH3. Vitamin D3 was then separated and quantified using liquid chromatography-tandem mass spectrometry. The results for added recovery tests were in the range 93.11-110.65%, with relative standard deviations between 2.66% and 2.93%. The results, compared to those obtained using a certified reference material (SRM 1849a), were within the range of the certificated values. This method could be implemented in many laboratories that require time and labour saving.

MATERIALS

Product Number

Brand

Product Description

61699

Supelco

Potassium hydroxide concentrate, 0.1 M KOH in water (0.1N), Eluent concentrate for IC

608602

Sigma-Aldrich

Ammonium-¹⁴N₂,sulfate-¹⁶O₄, 99.99 atom % ¹⁶O, 99.99 atom % ¹⁴N

71376

Sigma-Aldrich

Sodium chloride, BioUltra, for molecular biology, ≥99.5% (AT)

71386

Sigma-Aldrich

Sodium chloride solution, BioUltra, for molecular biology, ~5 M in H₂O

485306

Sigma-Aldrich

Ammonium-¹⁴N₂ sulfate solution, 40 wt. % in H₂O, 99.99 atom % ¹⁴N

W292907

Sigma-Aldrich

Isopropyl alcohol, ≥99.7%, FCC, FG

451975

Sigma-Aldrich

Ammonium sulfate-¹⁴N₂ solution, 40 wt. % in H₂O, 99.99 atom % ¹⁴N

S3014

Sigma-Aldrich

Sodium chloride, for molecular biology, DNase, RNase, and protease, none detected, ≥99% (titration)

S7653

Sigma-Aldrich

Sodium chloride, BioXtra, ≥99.5% (AT)

S5886

Sigma-Aldrich

Sodium chloride, BioReagent, suitable for cell culture, suitable for insect cell culture, suitable for plant cell culture, ≥99%

PHR1321

Supelco

Sodium chloride, Pharmaceutical Secondary Standard; Certified Reference Material

P4494

Supelco

Potassium hydroxide solution, volumetric, 8.0 M KOH (8.0N)

190764

Sigma-Aldrich

2-Propanol, ACS reagent, ≥99.5%

221473

Sigma-Aldrich

Potassium hydroxide, ACS reagent, ≥85%, pellets

A4915

Sigma-Aldrich

Ammonium sulfate, ACS reagent, ≥99.0%

484016

Sigma-Aldrich

Potassium hydroxide, reagent grade, 90%, flakes

59300

Sigma-Aldrich

2-Propanol, puriss. p.a., ACS reagent, ≥99.8% (GC)

1570428

USP

2-Propanol, United States Pharmacopeia (USP) Reference Standard

PHR1072

Supelco

2-Propanol, Pharmaceutical Secondary Standard; Certified Reference Material

59845

Supelco

Ammonium sulfate, analytical standard, for Nitrogen Determination According to Kjeldahl Method, traceable to NIST SRM 194

733458

Sigma-Aldrich

2-Propanol, electronic grade, 99.999% trace metals basis

91237

Supelco

2-Propanol, analytical standard

59304

Sigma-Aldrich

2-Propanol, BioUltra, for molecular biology, ≥99.5% (GC)

278475

Sigma-Aldrich

2-Propanol, anhydrous, 99.5%

34863

Sigma-Aldrich

2-Propanol, suitable for HPLC, 99.9%

I9516

Sigma-Aldrich

2-Propanol, for molecular biology, BioReagent, ≥99.5%

A4418

Sigma-Aldrich

Ammonium sulfate, for molecular biology, ≥99.0%

P5958

Sigma-Aldrich

Potassium hydroxide, BioXtra, ≥85% KOH basis

650447

Sigma-Aldrich

2-Propanol, HPLC Plus, for HPLC, GC, and residue analysis, 99.9%