Rapid quantitative analysis of total phosphor and heavy metals in edible oil using compact monochromatic X-ray fluorescence

Rapid quantitative analysis of total phosphor and heavy metals in edible oil using compact monochromatic X-ray fluorescence

Dr. Z. W. Chen, Y. Xia, K. Horth, and D. Gibson

Z-Spec, Inc.
East Greenbush, NY

Phosphor (P) compounds can affect the quality of edible oils.  Monitoring and testing P is essential for edible oil production and refining.  The current testing methods include calorimetric base methods, ICP base methods, and FTIR.  The calorimetric methods can be very time-consuming.  ICP base methods are high cost, and sophisticated sample preparation is required.  The FTIR method is simple and robust, but it is difficult to measure low-level P reliably. 

A compact monochromatic X-ray fluorescence (MXRF) analyzer is developed for rapidly testing P in oil in concentration ranges of 1 ppm to 5000 ppm.  The MXRF analyzer consists of a low-power x-ray tube coupled with doubly curved crystal optics and a graphene-window silicon-drift detector (SDD), providing unprecedented low limits of detection (LOD) and quantification.  Low limits of detection are estimated to be around 0.5 ppm with a few minutes of measuring time.  The analysis is non-destructive, and minimum sample preparation is involved. 

A portable MXRF analyzer has also been developed to measure trace toxic metals in edible oil using a different X-ray tube, DCC optics, and SDD. LODs for As and Pb of 20 ppb levels are achieved with 15 minutes of testing, which provides a practical rapid method for testing heavy metals at ppb levels for the first time.

This paper presents the design principle and data from MXRF analyzers for P, As, and Pb in editable oil.