Error Analysis of the Method of Measuring Nitrate Nitrogen by Photometry of Phenol Disulfonic Acid

The relative high standard recovery was found when measuring nitrate nitrogen by photometry of phenol disulfonic acid. There were significant differences between standard curve and work curve. The high standard recovery was caused by adopting standard curve to calculate the value. Therefore,the method has active system error. In order to avoid the error,the work curve that was consistent with sample analysis should be used to analyze the result.