What is the primary law that governs breath testing procedures?

The primary law that governs breath testing procedures, particularly in the context of the Intoxilyzer 8000, is Henry's Law. This law states that the amount of a gas that dissolves in a liquid is proportional to the partial pressure of that gas above the liquid. In breath testing, this principle is critical because it helps explain how alcohol vapor (in the breath) can be measured in relation to its concentration in the blood.

When a person consumes alcohol, it enters the bloodstream and some of it will vaporize in the lungs when the person exhales. Henry's Law provides the scientific basis for correlating the concentration of alcohol in a person's breath with the concentration of alcohol in their blood, allowing the Intoxilyzer to provide an estimate of blood alcohol content (BAC) based on a breath sample.

The other laws mentioned pertain to different phenomena: Boyle's Law relates to the volume and pressure of gases, Archimedes' Principle deals with buoyancy in fluids, and Dalton's Law discusses the behavior of mixed gases. These principles, while important in their own contexts, do not specifically apply to the mechanisms used in breath testing for alcohol concentration.