Brake fluids have a boiling point which differs with technical specifications (DOT3, DOT4, DOT5), operating variables and their water content. Remember that these fluids are often hygroscopic so tend to "absorb" water (condensation, leaks, etc.).  

Examples of available analyses

Water content of new brake fluid should not exceed 0.1% and 0.5% in use;  

 The boiling point is very important because the fluid must not change into gas when it is subjected to high pressure. This would make the brake completely useless. The boiling point naturally tends to drop with an increase in the water content.  

sample report