Other hydrophilic substances can mask SPE interaction sites by reducing their binding power for the dyes and consequently reducing the capacity of the cartridges. Furthermore, some substances, as amaranth, are strongly restrained by SPE cartridges and the ammonia solution used for elution could be insufficient for its release (low recoveries). For solid food matrices, LOQ values calculated as 10 the standard deviations of blank noise were 10 mg kg1 for groups AeC and 5 mg kg1 for group B.