ASTM D2786 for Hydrocarbon Types Analysis of Gas-Oil Saturates Fractions
ASTM D2786 Standard Test Method for Hydrocarbon Types Analysis of Gas-Oil Saturates Fractions by High Ionizing Voltage Mass Spectrometry
8. Calibration
8.1 Calibration matrix inverses are attached in Table 1 which may be used directly provided the following procedures are followed.
8.2 Instrumental Conditions - Repeller settings are adjusted to optimum based on m/e 226 ion of n-hexadecane. A magnetic field is used that will permit a scan over the mass range 65 to 410 m/e. An ionization voltage of 70 eV and an ionizing current in the range 10 to 70 µA is used.
NOTE 1 - The instrument conditions and calibration matrix inverses described in this method are based on the use of a 180° magnetic-deflection type mass spectrometer (CEC Model 21-103). It is not known if the calibration matrix inverses, included in this method, are suitable for use on other mass spectrometer types.
8.3 Calibration Standard - The calibration coefficients in this method were obtained for ion source conditions such that the ∑69/∑71 ratio was 0.20/1.0 for n-hexadecane. The cooperative study of this method indicated an acceptable range for the ∑ ratio was between 0.18 to 0.22.
