GB/T 28611-2012 "o-Nitrotoluene and p-Nitrotoluene" specifies the quality requirements and testing methods for o-nitrotoluene and p-nitrotoluene, categorizing the products into three grades: premium, first-grade, and qualified. The standard adopts gas chromatography for testing, utilizing a gas chromatograph equipped with an FID detector and a DB-1701 capillary column, with quantification performed via the peak area normalization method. Calibration of the microsyringe is required to ensure precise sample injection, and solid samples must be melted and homogenized before sampling. This standard provides technical specifications for the purity and impurity control of such chemical products.