Chlorophyll has been extracted from environmentally collected algae in a solution containing 90% acetone and stored chilled and protected from light. Each production lot will differ, and the range of chlorophyll concentrations (300-500 ppb) will be reported on the Certificate of Analysis. The product delivered will be 1 mL of a stable concentrate in an amber vial, and when diluted with 5.5 mL of acetone will yield the reported concentration for calibration. The user has the freedom, then, to use more or less acetone if a different calibration concentration (in ppb) is desired. The product is stable for one month after shipment if stored in the dark at 4oC, and should be used immediately upon dilution.