Update on the Development of a Sensitive, Accurate, and User- Friendly Method for the Direct Determination of 3-MCPD 3

Transcription

1 Update on the Development of a Sensitive, Accurate, and User- Friendly Method for the Direct Determination of 3-MCPD 3 Esters J. D. Pinkston, P.J. Stoffolano, P. Y. Lin The Procter & Gamble Company, Winton Hill Business Center, 6300 Center Hill Ave., Cincinnati, OH pinkston.jd@pg.com

2 3-MCPD (3-Monochloropropane-1,2-diol) A number of groups have been working to strengthen the methods to meet this emerging regulatory issue. Occurrence of 3-MCPD bound in 3-MCPD fatty acid esters (3-MCPD esters) containing one or two fatty acids at the sn-1 and sn-2 position of the glycerol backbone has been reported for refined fats and oils by several groups (Svejkovska et al., 2004; Weißhaar, 2008; Zelinkova, Svejkovska, Velı sek, & Dolezal, 2006). 2

3 Analytical Methods First and most widely-used analytical method involves cleavage of esters with sodium methoxide, derivatization, and GC/MS or GC/MS/MS. (Weiβhaar, Eur. J. Lipid Sci. Technol. 2008, 110, ). This is the Total 3-MCPD method. A Modified Weiβhaar Method is in use in which Na 2 SO 4 is substituted for NaCl. Areas for Potential Improvement: Hydrolysis in presence of trace Cl - may result in inaccurate, higher Total 3-MCPD. Glycidol esters may be converted to 3-MCPD during sample prep --> overestimation of total 3-MCPD. Method does not differentiate between free 3-MCPD and/or different 3-MCPD esters. 3

4 Analytical Methods ADM developed direct, dilute & shoot, LC/TOFMS method for 3- MCPD esters. Avoids issues related to hydrolysis & sample prep; results show Weiβhaar GC/MS method can overestimate total 3- MCPD esters. Method also determines glycidyl esters. Areas for Potential Improvement: Method requires frequent instrument disassembly & cleaning. LOQs of ~100 ppb per ester (converts to ~20 ppb free 3-MCPD per ester) while GC/MS provides 150 ppb total 3-MCPD. No determination of free 3-MCPD (assumed to be low in vegetable oils because of low solubility and removal during deodorization). We are developing a direct method for determination of the 3-MCPD esters, similar to the one developed by ADM, which we hope will address the first and second issues mentioned above. 4

5 Improved Method for 3-3 MCPD Esters Mass spectrometer: Sciex API 5000, + TurboIonspray interface/ionization, SRM mode Chromatograph: Shimadzu SCL-10vp system controller, 3 Shimadzu LC-10ADvp pumps, CTC Analytics HTS PAL autosampler, Phenomenex Luna C18(2), 2.1 x 50 mm, 3-μm 3 m particles, 100 Å average pore size Chromatographic mobile phase: A: 90/10 methanol w/ 3 mm ammonium acetate/acn. B: 80/10/10 methylene chloride/acetonitrile/methanol w/ 3 mm ammonium monium acetate. Program: 100% A for 5 min Ramp to 35% A, 65% B over the next 10 min Step to 100% B over the next 1 min, hold for 4 min Return to 100% A Instrumental Conditions 5

6 Improved Method for 3-MCPD 3 Esters Initial results with available standards XIC of +MRM (8 pairs): 366.3/239.3 amu from Sample 24 (Std 1 ug/ml) of Samples_ wiff (Turb... Max. 2.6e4 cps. 2.6e e4 1.0e4 Palmitoyl monoester XIC of +MRM (8 pairs): 392.3/265.2 amu from Sample 24 (Std 1 ug/ml) of Samples_ wiff (Turb... Max. 4.7e4 cps. 4.7e4 4.0e4 3.0e4 2.0e4 1.0e Stearoyl monoester 0.0 XIC of +MRM (8 pairs): 394.3/267.2 amu from Sample 24 (Std 1 ug/ml) of Samples_ wiff (Turb... Max. 2.0e4 cps. Monoester Standards spiked in Corn Oil at 1000 ppb 2.0e e4 1.0e4 Oleoyl monoester

7 Improved Method for 3-MCPD 3 Esters Initial results with available standards XIC of +MRM (8 pairs): 604.5/331.1 amu from Sample 25 (Std 10 ug/ml) of Samples_ wiff (Tur... Max. 2.6e6 cps. 2.6e e6 1.0e6 Di-palmitoyl ester 0.0 XIC of +MRM (8 pairs): 630.5/357.3 amu from Sample 25 (Std 10 ug/ml) of Samples_ wiff (Tur... Max. 2.4e6 cps. 2.4e6 2.0e6 1.5e6 1.0e6 Stearoyl-Palmitoyl diester e XIC of +MRM (8 pairs): 632.5/359.2 amu from Sample 25 (Std 10 ug/ml) of Samples_ wiff (Tur... Max. 1.2e6 cps. Diester Standards spiked in Corn Oil at 1000 ppb 1.23e6 1.00e6 5.00e Oleoyl-Palmitoyl diester

8 Improved Method for 3-3 MCPD Esters Direct dilute & shoot method. Mobile phase eliminates need for frequent disassembly & cleaning. Improved ionization (ammonium( adduct ions) ) results in lower LODs (~100 ppb monoesters, ~10 ppb di-esters) and the ability to perform MS/MS with selected reaction monitoring. MS/MS (SRM) detection (rather than TOFMS) provides better specificity and signal-to to-noise ratios. Work on development/validation for 3-MCPD 3 esters in progress. Glycidyl esters may be included later. 8

9 Initial results comparison of results P&G values should be lower than modified Weiβhaar method because only a few of esters are determined with current P&G method Vegetable Oil Sample P&G Total 3-MCPD3 MCPD equivalent ug/ml (ppm) Modified Weiβhaar Total 3-MCPD3 MCPD ug/ml (ppm) A B C D E F G

10 Method Development Next Steps Given initial success, acquire additional standards corresponding to all major expected mono- and di-esters of 3-MCPD. 3 (in-progress) Develop /validate full multi-component component* LC/MS/MS method. * Explore whether all components must be determined, or whether minor components can be calculated based upon fatty acid composition, and whether this provides S/N benefit. 10

11 Learning Plan & Timeline Complete analytical method development & validation Oct. 10. Reanalyze selected samples previously analyzed using the modified Weiβhaar method Nov. 10. Conduct bench-top experiments to determine impact of temperature, moisture, soluble chloride, monoglycerides, diglycerides, and other polars on the formation and degradation of 3-MCPD 3 esters Jan