Determination of urinary thiamin by the thiochrome method

Area of Science:

• Biochemistry
• Analytical Chemistry
• Clinical Chemistry

Background:

• Thiamin (vitamin B1) is essential for human health.
• Accurate measurement of thiamin in urine is crucial for assessing nutritional status.
• The thiochrome fluorescent method is a common technique for thiamin determination.

Purpose of the Study:

• To evaluate the efficacy of three oxidizing agents (HgCl2, BrCN, K3Fe(CN)6) in a modified thiochrome fluorescent method for human urine thiamin determination.
• To compare the impact of different oxidizing agents on urinary thiamin values and recovery rates.
• To assess the suitability of smaller resin columns for sample pretreatment.

Main Methods:

• A modified thiochrome fluorescent method was employed.
• Human urine samples were analyzed for thiamin content.
• Three oxidizing agents—mercuric chloride (HgCl2), cyanogen bromide (BrCN), and potassium ferricyanide (K3Fe(CN)6)—were tested.
• Recovery studies were conducted for each oxidizing agent.
• Linearity of thiamin standards was assessed.

Main Results:

• Urinary thiamin values were lower when HgCl2 was used as the oxidizing agent compared to BrCN or K3Fe(CN)6.
• Recovery values were acceptable for all tested oxidizing agents, with BrCN showing slight superiority.
• A linear response was observed for thiamin standards.
• Smaller resin columns were found to be economical and convenient for urine sample pretreatment.

Conclusions:

• BrCN and K3Fe(CN)6 are superior oxidizing agents to HgCl2 for the determination of thiamin in human urine using the thiochrome fluorescent method.
• The observed differences may stem from varying reactivity with interfering urinary compounds.
• The method's linear response supports the use of smaller, more efficient resin columns for sample preparation.