The determination of manganese in gasoline

The method is suitable for the determination of Mn, present as methyl-cyclopentadienyl manganese tricarbonyl, in gasoline in the range 0.5— 40/igml 1. The sample is reacted with bromine then diluted with MIBK and the standards prepared in a similar manner. This ensures an equal response from the Mn species in both sample and standard solutions. 

Dilute the sample with MIBK so as to fall within the chosen calibration range. Add 1 ml of the bromine solution (see note 1) prior to making up to the mark in a 100ml volumetric flask. Shake well to mix. 

Use a commercially available Mn in oil standard or an organometallic Mn standard prepared as described in Section III (see note 2). Dilute the stock standard with MIBK and add 1 ml of the bromine solution (see note 1) to give four calibration standards, including the blank, to cover the range approximately 0—4/xgml 1 Mn in 100ml volumetric flasks. 

Adjust the instrumental parameters of spectral band pass, wavelength and lamp current in accordance with the manufacturer s recommended conditions. Use an air—acetylene flame and, aspirating an MIBK blank solution, adjust the acetylene flow rate in order to obtain a lean, blue flame. 

Aspirate standards, then samples, and record the absorbance values. Aspirate the standards again to check that no drift has occurred. Prepare a calibration graph for the standards and from this read the concentration of Mn in the samples. 

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