• Vitamin D, commonly known as the “sunshine vitamin”, is essential for maintaining calcium metabolism and bone health. The major physiologic function of Vitamin D is to maintain the blood calcium and phosphorus levels within the normal range in order to maintain metabolic functions that are essential for most life processes, Vitamin D3 and Vitamin D2 are metabolized to 25-OH-Vitamin D3 and 25-OH-Vitamin D2 in the liver by the 25-OHase enzyme. The quantitation of these metabolites is widely used for determining of Vitamin D status in human. The Vitamin D status has a clinical significance in a variety of disorders which related to hormones. The measurements of the serum concentration of 25-OH-Vitamin D3 and 25-OH-Vitamin D2 have been used for differential diagnosis of hypocalcemia and hypercalcemic metabolic bone disorders.

The analysis of these metabolites is considered to be difficult. Some reasons of the difficulties are below.

• The low concentrations of 25-OH Vitamin D metabolites in serum. (Level of µg/L)
• The low stability in the presence of light and heat.
• The presence of other metabolites which have chemical similarity.
• The large amount of other related neutral lipids (such as cholesterol)

• The level of vitamin A in the plasma or serum is a reflection of the quantities of vitamin A and carotene ingested and absorbed by the intestine.

Vitamin A plays an essential role in the function of the retina (adaptation to dim light), is necessary for growth and differentiation of epithelial tissue, and is required for growth of bone, reproduction, and embryonic development. Together with certain carotenoids, vitamin A enhances immune function, reducing the consequences of some infectious diseases. Vitamin A in excess can be toxic.

Vitamin E contributes to the normal maintenance of bio membranes, the vascular system, and the nervous systems; and provides antioxidant protection for vitamin Deficiency of vitamin E in children leads to reversible motor and sensory neuropathies; this problem also has been suspected in adults.

Deficiencies of vitamins A and E may arise from poor nutrition or from intestinal malabsorption. People, especially children, at risk include those with bowel disease, pancreatic disease, chronic cholestasis, celiac disease, cystic fibrosis, and intestinal lymphangiectasia.

Vitamin A-D3-D2-E Serum LC-MS/MS APCI Analysis Kit was developed for rapid, sensitive, and reliable quantitative detection of the Vitamin A-D3-D2-E concentrations in human serum samples and it gives results in 5.30  minutes with full automated Zivak MULTITASKER sample preparation and injection system. Main methods and procedures that have been selected are based on EN ISO 13485 and 98/79/EC.