Gastric acid
The highest concentration that gastric acid reaches in the stomach is 160 mM in the canaliculi. This is about 3 million times that of arterial blood, but almost exactly isotonic with other bodily fluids. The lowest pH of the secreted acid is 0.8, but the acid is diluted in the stomach lumen to a pH between 1 and 3.
Carlsberg Laboratory
The Carlsberg Laboratory was known for isolating "Saccharomyces carlsbergensis", the species of yeast responsible for lager fermentation, as well as for introducing the concept of pH in acid-base chemistry. The Danish chemist Søren Peder Lauritz Sørensen introduced the concept of pH, a scale for measuring acidity and basicity of substances. While working at the Carlsberg Laboratory, he studied the effect of ion concentration on proteins, and understood the concentration of hydrogen ions was particularly important. To express the hydronium ion (H3O+) concentration in a solution, he devised a logarithmic scale known as the pH scale.