McFarland standard solution 2.0

McFarland Standard Solution 2.0 is a turbidity reference solution used in microbiology, primarily for standardizing bacterial suspensions before antimicrobial susceptibility testing.

🏭⚗️ Production
McFarland Standard 2.0 is prepared by mixing 0.2 mL of 1% barium chloride with 9.8 mL of 1% sulfuric acid. The reaction produces a fine precipitate of barium sulfate, resulting in a stable, turbid suspension. The solution is mixed thoroughly until uniform turbidity is achieved, then transferred into a sealed, clear tube and stored at room temperature protected from light to maintain its turbidity standard.

🔬 Properties
McFarland Standard 2.0 is a turbid, milky-white suspension that simulates the optical density of a bacterial culture containing approximately 6 × 10⁸ CFU/mL. It is chemically stable under normal storage conditions but requires shaking before each use to redistribute the precipitate evenly.

🧪 Applications
This standard is commonly used to adjust the turbidity of bacterial suspensions before antimicrobial susceptibility testing, helping prepare inocula with standardized cell density for microbiological procedures.

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