But don’t forget, the Proteam test requires that you determine a color change in 20 mL of water.

The color change is much easier to determine in our test because you are looking down from the top into a more or less narrow cell containing 44 mL of water. And the cell has a white dot at the bottom that increases contrast and facilitates viewing. Because the viewpath is longer this increases the color intensity and makes the color change much easier to spot.

Similarly, in Taylor’s phosphate test, you are required to look down from the top of a (5 mL) long and narrow test cell to determine the sample color. One would be hard pressed to determine the color of that 5 mL sample if it was, say, in a beaker.

44 mL of Taylor Standard Solution R-7062 (pH 7.6 Standard Solution) with BTB produces the same hue as the endpoint obtained (and shown) in our instructions.