The chemical composition of crude oil is mainly various alkanes, cycloalkanes and aromatic hydrocarbons. Trace and trace elements in crude oil products play an important role in petrochemical production and use. For example, the presence of sodium, magnesium, iron, calcium, vanadium and other elements in crude oil will poison the catalyst activity; nickel, vanadium and lead Such elements can be used as the fingerprint information of crude oil , providing a powerful reference for the formation of crude oil and the accountability of oil spills. Therefore, it is of great significance for the determination of trace elements in crude oil products.
There are many analytical methods applied in the field of petrochemicals. Atomic absorption (AAS) can only measure one element at a time, and requires cumbersome pretreatment process, resulting in long measurement time and poor analysis efficiency; inductively coupled plasma emission spectrometry The ICP-OES method does not have an absolute advantage in the detection limit, and with the upgrading of the petrochemical industry and the increasingly stringent requirements of environmental protection regulations, the analysis requirements for element content are developing in the direction of low content, fast and stable , Inductively coupled plasma mass spectrometry (ICP-MS) , as an instrumental analysis technique with extremely high resolution and multi-element analysis capabilities, can meet the determination requirements of various elements in crude oil and the needs of rapid and stable analysis.
The application center adopts organic sampling method to determine multi-elements in crude oil, and directly uses ICP-MS to measure the crude oil after dilution. This sampling method can not only avoid tedious pretreatment process , avoid the introduction of pollution, but also can be determined at one time A variety of elements, to achieve fast, efficient and accurate determination of various elements in crude oil.
Key words: ICP-MS, crude oil, chemical industry, organic sampling, oxygenation
Experimental part
Instrument
Table 1 Test parameters of inductively coupled plasma mass spectrometer
Sample pretreatment
Aviation Kerosene CONOSTAN PremiSolv ICP Thinner; Oil Standard: CONOSTAN S-21
After uniform sampling, divide the crude oil sample into a water bath and heat it to a fluid state at 50-60 °C; weigh the heated crude oil sample, add internal standard element Y (1 ppm) at the same time, and dilute it with aviation kerosene CONOSTAN PremiSolv.
For samples with high viscosity, if diluted with aviation kerosene and cannot be fully mixed, it needs to be properly heated until the sample is evenly mixed with aviation kerosene.
Measurement results
The sample crude oil A and B were measured, and the two samples were spiked and recovered at different levels to verify the accuracy of the method. The results of the determination and the recovery rate are shown in Table 2. The recoveries of all elements were between 85 % and 120 %, indicating that the method has good accuracy.
Table 2 Determination results of samples and recovery rate of standard addition (mg/kg)
Internal Standard Stability
In the long-term test with a total duration of about 2.5 h, the recovery rate of the internal standard Y was normalized, and it was always maintained between 0.89 and 1.1, which proved that the instrument had good internal standard stability.
Figure 1 Stability trend of internal standard
Epilogue
This experiment shows that the use of ICP-MS organic sampling system to determine multiple elements in crude oil can realize the accurate determination of B, Na, V, Mn, Fe, Ni, Zn and other elements in crude oil samples, and the use of collision mode to remove organic matter interference, the detection limit of each element is 0.0093~0.614 ng/g, the recovery rate of sample addition is 85%~120%, and the recovery of internal standard remains stable within 2.5h. Fast, efficient and accurate determination of various elements in crude oil.
Appendix
Equipment and Consumables Solutions
1. Configuration details of SUPEC 7000 organic sampling system
2. Reagents and Standards
