Page 26 - Shimadzu Journal vol.8 Issue2

Hydrocarbon Processing Industry

Table 5. Results for repeatability (r) testing based on ISO 8754 criteria.
Method Criterion Result in Air
Test Sample Conc. Count Time (sec) % RSD
(ppm) (ppm)
Repeatability Base Oil 0.03 wt. % 200 36 19 1.12
Repeatability Base Oil 0.05 wt. % 200 45 23 1.23

Repeatability Base Oil 0.2 wt. % 100 75 35 0.28
Repeatability Base Oil 1.0 wt. % 100 247 100 0.15
Repeatability Base Oil 4.0 wt. % 100 892 315 0.18

Table 6. Results for reproducibility (R) testing based on ISO 8754 criteria.
Method Criterion Result in Air
Test Sample Conc. Count Time (sec) % RSD
(ppm) (ppm)
Repeatability Base Oil 0.03 wt. % 200 143 38 0.99
Repeatability Base Oil 4.0 wt. % 100 3370 464 0.10

In addition to the above results, the results of measurement of 20
analyses of the blank sample yielded a maximum result of 1.9 ppm.
Lower limits of detection (LLD) calculated using a 200 second in-
tegration time yield results of 5.61 ppm with a non-purged sample
chamber, and 2.49 ppm with a helium-purged chamber.

Application towards Marine Fuel Oil

This methodology was assessed on an actual marine bunker fuel
sample obtained from a local shipyard in Baltimore, MD, USA.
The fuel was produced by BP Marine and the sample was bottled
as a grab sample in 2005 and therefore predates the new IMO
2020 regulations. The EDX-7000 was calibrated for sulfur in the Figure 6. Calibration curve of sulfur in residual oil.
range of 5000 to 50000 ppm (0.50 to 5%) using sulfur in residual oil
standards from Conostan to ensure appropriate matrix matching.
®
Table 7. Results from five analyses of marine fuel oil.
The sample was analyzed using the same analytical conditions as
described above for 300 seconds and repeated 5 times. Run Number Intensity (cps/µA) Sulfur Conc. (m/m %)
1 8.2798 2.920
The resulting calibration curve had excellent linearity (Fig. 6) en-
2 8.2967 2.925
abling accurate quantification of sulfur in the unknown samples.
3 8.2670 2.915
The sulfur content of the analyzed fuel is 2.96%, based on analysis 4 8.2745 2.918
using the EDX-7000. 5 8.2757 2.918

Average 8.2787 2.919
Std. Dev. 0.0111 0.004
% RSD 0.1335 0.127

68
Shimadzu Journal vol.8 Issue2 68