I make some of my own agar media. I measure the pH with our media. The range of the types of media I make is from 6.6 – 7.6. I currently use 2 standards for the pH meter a 7.0 and 4.0. Do I need both of these standards and is this the correct range? Spokane, WA
To assure proper organism growth and identification, the media needs to be right. If pH is an important factor in assuring “right” media, then the measurement of pH must be accurate. At first glance, the difference in pH from 6.6 to 7.6 may seem relatively small. However, the pH scale is logarithmic, making this difference much greater in terms of hydrogen ion concentration. Each one-unit change in the pH scale corresponds to a 10-fold change in H ion concentration.
As for everything that we do in the laboratory, following manufacturer’s instructions is rule number 1. So you want to follow the specific calibration instructions for your pH meter. Typically, pH meters are balanced with 7.0 pH buffer and the balance or intercept control shifts the entire slope of the calibration line. Another buffer of a different pH (e.g., 4.0) is used to adjust the slope of this line to match what is predicted by the Nernst equation.
end faq
{accordionfaq faqid=accordion22140 graybarfaq arrow headerbackground headerborder contentbackground contentborder round5}
