Verification of the Determination of Total Chromium in Urban Sludge by Diphenylcarbazide Spectrophotometric Method after Microwave High-pressure Digestion
This paper validates the Diphenylcarbazide Spectrophotometric Method for Chromium and its Compounds after Microwave High-pressure Digestion in The Standard Test Method for Urban Sludge(CJ/T 221-2023).After adding standards to the blank in the laboratory and measuring 7 times,the detection limit of this method was determined to be 0.016 mg/L.When the sampling amount is 1.000 g and the constant volume is 50 mL,the calculated sludge detection limit is 0.65 mg/kg.The total amount of heavy metals in water sediment was determined by spiked determination,and the spiked recovery rates were 87.0％and 118％,respectively.The linear relationship of the standard curve was good,and the relative standard deviation of precision met the requirements of the method.The repeatability was good,and the spiked recovery rate was between 80.0％and 120％.The results of this method can meet the requirements for determining total chromium in urban sludge,and all indicators can meet the specified requirements.
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