เคมี
เอกสารมาตรฐาน
สหรัฐอเมริกา
AOCS
Ca 18-79
Chromium, Copper, Iron, Nickel, and Manganese in Triglyceride Oils by Atomic Absorption Spectrophotometry Using a Graphite Furnace
2017
4
665.0288 AOCS 7th ed. 2017-2019 rev. Ref.
Vegetable and animal oils dissolved in methyl isobutyl ketone (MIBK) or MIBK + HNO3 are analyzed for metals by direct injection into a graphite tube furnace. Calibration is based on MIBK or MIBK + HNO3 solutions of organometallic reference compounds. This method is intended for the analysis of crude and refined vegetable oils and animal fats that contain trace metals that may be present in the form of oil-soluble adducts. The detection limit of this method is approximately 0.1 mg/kg (0.1 ppm). This method has a lower detection limit than AOCS Method Ca 15-75, which has a detection limit of approximately 2 mg/kg (2 ppm). Therefore, when lower detection limits may be required, as in the case of contractual trade methods, AOCS Method Ca 18-79 should be used.