Determination of 3-monochloropropanediol esters and glycidyl esters in fatty matrices by ultra-high performance liquid chromatography-tandem mass spectrometry.

The development and validation of a method for the analysis of traces of 3-monochloropropanediol (3-MCPD) esters (19) and glycidyl esters (7) of fatty acids in vegetable oils, margarine, biscuits and croissants was performed. An extraction method based on the use of solvents (tert­butyl methyl ether (20% ethyl acetate, v/v)) was carried out and cleaning of the extract with a mixture of sorbents (Si-SAX, PSA and Z-sep+) was optimized for the elimination of fatty interferents. The analysis of the targeted compounds was carried out by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry, using a triple quadrupole analyzer (UHPLC-MS/MS-QqQ). The validation of the method provided trueness values between 72 and 118% and precision lower than 20%. The limits of quantification ranged from 0.01 to 0.1 mg kg-1, which were below the current legal limits. Twenty samples of vegetable oils as well of 4 samples of margarine, biscuits and croissants were analyzed. Six out of the 24 samples (25%) exceeded the limits set by European legislation, and a maximum contamination of 3-MCPD esters at 2.52 mg kg-1 was obtained in a sample of corn oil (being 1-myristoyl-3-MCPD the compound detected at the highest concentration). A maximum concentration of glycidyl esters at 7.84 mg kg-1 was determined in a soybean oil sample (glycidyl linoleate as the main compound). Only one sample of olive oil exceeded the maximum allowable limit for 3-MCPD esters with a value of 1.72 mg kg-1, expressed as 3-MCPD.

Monitoring of polar pesticides and contaminants in edible oils and nuts by liquid chromatography-tandem mass spectrometry.

A single method was developed for the determination of polar pesticides (fosetyl-Al and its metabolite, phosphonic acid, and ethephon) and environmental contaminants (chlorate and perchlorate) in edible oils and nuts. Two extraction methods based on QuPPe-PO approach (Quick Polar Pesticides Method for products of Plant Origin) were optimized. In oils, a single extraction using water acidified with formic acid (1%) was performed, while in nuts, the clean-up step was modified. C18 was used as sorbent and an extra cleaning step with n-hexane was added. The extracts were analysed by liquid chromatography coupled to a triple quadrupole mass analyser (LC-QqQ-MS/MS). The method was validated and the limit of quantification was 0.01 mg kg-1 for all analyte-matrix combination. Recoveries from 70 to 120%, and intra and inter-day precision values ≤20% were obtained. Forty samples of edible oils and nuts were analysed, detecting phosphonic acid in nuts at concentrations up to 4.6 mg kg-1.

A rapid method for the determination of mycotoxins in edible vegetable oils by ultra-high performance liquid chromatography-tandem mass spectrometry.

An analytical method based on a QuEChERS procedure (quick, easy, cheap, effective, rugged and safe) has been developed for the determination of mycotoxins (α-zearalenol and zearalenone, and aflatoxins B1, B2, G1 and G2) in edible oils. The analysis was performed by ultra-high performance liquid chromatography coupled to triple quadrupole analyser (UHPLC-QqQ-MS/MS). The method was fully validated and the quantification limit is 0.5 µg kg-1 for aflatoxins and 1 µg kg-1 for α-zearalenol and zearalenone. Suitable recoveries were obtained at low concentration levels (0.5-25 µg kg-1 for aflatoxins and 1-25 µg kg-1 for α-zearalenol and zearalenone), ranging from 80 to 120%. Intra and inter-day precision values were also evaluated and relative standard deviation was lower than 20%. The expanded uncertainty, U, was also evaluated ant it was below 32% at 25 µg kg-1. The validated method has been applied to monitor the presence of mycotoxins in 194 samples belonging to different types of edible oils (olive oil, sunflower oil, soy oil and corn oil). Zearalenone was detected in 25% of the analysed samples at concentrations up to 25.6 µg kg-1, and aflatoxin G1 and G2 in 3% and 14% of the samples at a maximum concentration of 1.9 and 6.8 µg kg-1 respectively.