If you have ever questioned the result of an analytical test, you'll immediately appreciate the value of using standard solutions. These solutions contain a defined concentration of analyte, allowing you to quickly verify that instrument operation, reagent performance, and variations in operator technique are within your program values. Standard Methods recommends using solutions of known concentration in place of your sample 5% of the time. Through control charting, verification of calibration curves, standard additions (spikes), and troubleshooting isolated problems, standard solutions are an essential tool in significantly increasing confidence in your laboratory process and test results.