Liquid chromatographic detection of Dowtherm A contamination in oleochemicals and edible oils.
A rapid and direct liquid chromatographic (LC) technique is described for the determination of a eutectic mixture of diphenyl oxide and biphenyl such as Dowtherm A thermal heating fluid (THF) in oleochemicals and palm olein. Analysis is performed with an RP-18 column with fluorescence detection (excitation at 247 nm and emission at 310 nm). The isocratic mobile phase (1.0 mL/min) consists of methanol and water (90 + 10, v/v). A linear calibration model (correlation coefficient = 0.9999) was developed directly from used Dowtherm A THF with the biphenyl peak (4.70 min) as a marker. Average recoveries from spiked glycerin, fatty alcohol mixture, methyl ester mixture, fatty acids, and palm olein were 90.9-108.7%, with a detection limit of 0.1 microgram/mL. The technique requires no prior sample cleanup nor extraction steps and is good for quality assurance purposes.
Moh
F M
FM
Palm Oil Research Institute of Malaysia, Kajang, Selangor, Malaysia.
Tang
T S
TS
D002853:Chromatography, Liquid / Q000379:methods*; D004042:Dietary Fats, Unsaturated / Q000032:analysis*; D005227:Fatty Acids / Q000032:analysis; D005233:Fatty Alcohols / Q000032:analysis; D005506:Food Contamination; D005990:Glycerol / Q000032:analysis; D000073878:Palm Oil; D010647:Phenyl Ethers / Q000032:analysis*; D010938:Plant Oils / Q000032:analysis; D011786:Quality Control; D013784:Textiles
D004042:Dietary Fats, Unsaturated; D005227:Fatty Acids; D005233:Fatty Alcohols; D010647:Phenyl Ethers; D010938:Plant Oils; D000073878:Palm Oil; C032244:dowtherm; D005990:Glycerol