Metals in Crude & Residual Oil per ASTM D8252

Application Note EDXRF1942

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The analysis of nickel (Ni), vanadium (V), and iron (Fe) in crude and residual oil per ASTM D8252 is demonstrated. The measurement also includes the analysis of sulfur (S) complying with ASTM D4294.


The quality and grade of crude oil, in part, depends on the metal content as well as the sulfur content. Nickel and vanadium are critical metals, as well as iron in some crudes and residual oils, and the metal content is especially important in the quality of bunker fuels.

ASTM D8252 addresses the need to measure low levels of nickel and vanadium in crude to meet the new NYMEX/CME specifications for light sweet crude oil futures contracts concerning maximum allowable levels the Ni and V.

To meet the needs of the industry, Rigaku offers the NEX QC+, a simple, versatile, and portable benchtop EDXRF analyzer for the analysis of sulfur in crude, residual oil, and marine fuels.

NEX QC+ high-resolution EDXRF analyzerModel: NEX QC+


1 ppm = 1 mg/kg


Empirical calibrations were built using a suite of 12 commercially available calibration standards. A summary of the empirical calibrations is shown here.

Element Concentration range
Ni 3 – 50 ppm
V 3 – 50 ppm
Fe 3 – 50 ppm
S 0.100 – 5.000 mass%


To demonstrate repeatability, samples were measured in a static position for ten repeat analyses with typical results shown below.

Sample: Std 10
Element Standard value Average value Std. dev % Relative dev
Ni ppm 51 50.4 1.1 2.2
V ppm 5.0 5.67 0.37 7.4
Fe ppm 10.0 10.5 0.7 7.0
S mass% 4.501 4.564 0.022 0.5

Sample: Std 12
Element Standard value Average value Std. dev % Relative dev
Ni ppm 30 29.7 0.8 2.7
V ppm 50 49.0 0.5 1.0
Fe ppm 5.0 4.54 0.48 9.6
S mass% 0.250 0.252 0.002 0.8

Sample: Std 3
Element Standard value Average value Std. dev % Relative dev
Ni ppm 5 5.66 0.36 7.2
V ppm 30 31.0 0.4 1.3
Fe ppm 40 40.1 0.8 2.0
S mass% 1.000 1.003 0.002 0.2

ASTM D8252-19

In ASTM, little r is called repeatability and represents the precision of the measurement. Little r is 2.77 times the 1σ standard deviation precision of repeat measurements. Comparison of NEX QC+ instrument r to the method r of D5282 shows NEX QC+ complies with the ASTM method for the measurement of Ni and V in crude and residual oil.

Units: mg/kg (ppm)
Element Standard value Average value Std. dev Instrument r D8252-19 r
Ni 5.0 5.66 0.36 1.0 1.1
V 5.0 5.67 0.37 1.0 1.0


The performance shown here demonstrates the ability of the NEX QC+ for the measurement of metals in crude and residual oil as per ASTM D8252 and sulfur in compliance with D4294. The simple user interface and low maintenance requirements of the NEX QC+ allows operators of all skill levels to use and maintain the equipment.     

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