Spectrophotometric analysis using barbituric acid-pyridine

The method of carrying out spectrophotometric measurement of free cyanide is identical in every respect with the procedure described in the section Total Cyanide ., (4.1.6.3) 

When calculating the results take the calibrations as a basis and read off the values from the relevant calibration curve. Take blank tests and dilutions into account. 

The results should be given to 0.01 mg/1 for concentrations of less than 1 mg/1, and to 0.1 mg/1 in the case of higher concentrations. 

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Spectrophotometric analysis using barbituric acid-pyridine... 

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