Ammonia standard dilutions¶

Below are methods for preparing 5 mL ammonia standards in two different concentration ranges. Adjust volumes as necessary for preparing larger volumes.

1. Low-range: 0 - 2.5 ppm e.g. Salicylate test, API test kit
2. High-range: 0 - 8 ppm e.g. API test kit.

In each case, the first step is preparing a working stock by diluting a commercially available ammonia standard. This working stock is then diluted further resulting in a set of 8 ammonia concentrations (plus a distilled water blank). In addition to the equipment listed on the appropriate ammonia assay page, you will also need the following equipment and reagents if you plan to collect ammonia calibration data:

• 1,000 ppm N (1,220 ppm as NH₃) standard, Labchem Cat # LC17940-7
• 1 mL variable micropipette
• 100 mL volumetric flask for preparing the working stock
• 5 mL sample tubes
• Distilled water