A New JECFA Method for GC-MS Determination of Propylene Chlorohydrine Residues in Hydroxypropylated Starches.

Background: Propylene chlorohydrins (PCHs) are formed as byproducts in the reaction between starch and propylene oxide (PO). For hydroxypropylated (HP) starch applications in food, Joint FAO/WHO Expert Committee on Food additives (JECFA) set the maximum allowed total propylene chlorohydrin (PHC-t) residues level at 1 mg/kg.

Objective: To develop an improved analytical method for the determination of the PCH-t content in starches in the low mg/kg range to replace the outdated JECFA method.

Methods: A new GC-MS method that utilizes aqueous methanol as extraction medium for PCH. The GC-MS system is equipped with a programmable temperature vaporization injector and Stabilwax-DA column and uses helium as carrier gas. Quantitative detection is achieved in selected ion monitoring mode.

Results: This single-laboratory validation (SLV) study showed good linear calibrations for both 1-chloro-2-propanol (PCH-1) and 2-chloro-1-propanol (PCH-2) in the concentration range of 0.5-4 mg/kg in dry starch. The lower LOQ of PCH-1 and PCH-2 was 0.2-0.3 mg/kg in dry starch, the reproducibility RSD (RSDR) at the concentration level of 1-2 mg/kg in dry starch was 3-5%, and the recovery values for both PCH-1 and PCH-2 were in the range of 78-112% at a concentration level of about 0.6 mg/kg in dry starch. Compared with the current, outdated JECFA method, the new GC-MS method is more sustainable, less laborious, and therefore more economical. The analytical capacity of the new method is 4-5 times higher than the analytical capacity of the old JECFA method.

Conclusion: The GC-MS method is fit for a multi-laboratory trial (MLT).

Highlights: Based on the results of this SLV and the MLT (will be published in a second paper), the Joint FAO/WHO Expert Committee on Food Additives has recently decided to replace the outdated GC-FID JECFA method with the new GC-MS method for the determination of PCH-t content in starches.