محلول استاندارد مک‌فارلند 3.0

McFarland Standard Solution 3.0 is a turbidity reference solution used in microbiology, primarily for standardizing bacterial suspensions before antimicrobial susceptibility testing.

🏭⚗️ Production
McFarland Standard 3.0 is prepared by mixing 0.3 mL of 1% barium chloride with 9.7 mL of 1% sulfuric acid. The reaction forms a fine precipitate of barium sulfate, creating a stable, turbid suspension. The solution is mixed thoroughly until uniform turbidity is achieved, transferred into a sealed, clear tube, and stored at room temperature protected from light to preserve its turbidity standard.

🔬 Properties
McFarland Standard 3.0 is a turbid, milky-white suspension that simulates the optical density of a bacterial culture containing approximately 9 × 10⁸ CFU/mL. It is chemically stable under normal storage conditions but must be shaken well before use to redistribute the precipitate evenly.

🧪 Applications
This standard is commonly used to adjust the turbidity of bacterial suspensions before performing antimicrobial susceptibility tests, aiding in the preparation of inocula with standardized cell density across microbiological procedures.

⚠️ Safety
Handle with care; sulfuric acid is corrosive and barium chloride is toxic. Use gloves and eye protection, and work in a well-ventilated area. Avoid ingestion and inhalation. Dispose of any waste according to local chemical safety regulations.