title: Elimination of N,O-bis(trimethylsilyl)trifluoroacetamide interference by base treatment in derivatization gas chromatography mass spectrometry determination of parts per billion of alcohols in a food additive.
abstract: A novel base treatment followed by liquid-liquid extraction was developed to remove the interference of excess derivatization reagent BSTFA [N,O-Bis(trimethylsilyl)trifluoroacetamide] and its byproducts for trace determination of 1-chloro-2-propanol and 2-chloro-1-propanol in a food additive. The corresponding trimethylsilyl derivatives were analyzed by gas chromatography mass spectrometry (GC/MS) detection in selective ion monitoring mode. Due to a large volume splitless injection needed for achieving the required sensitivity, excess BSTFA in the derivatization sample solution interfered with the trimethylsilyl derivatives of the analytes of interest, making their quantitation not attainable. Efforts were made to decompose BSTFA while keeping the trimethylsilyl derivatives intact. Water or aqueous sulfuric acid treatment converted BSTFA into mainly N-trimethylsilyltrifluoroacetamide, which partitions between aqueous and organic layers. In contrast, aqueous sodium hydroxide decomposed BSTFA into trifluoroacetic acid, which went entirely into the aqueous layer. No BSTFA or its byproduct N-trimethylsilyltrifluoroacetamide or trifluroacetamide was found in the organic layer where the derivatized alcohols existed, which in turn completely eliminated their interference, enabling accurate and precise determination of parts per billion of the short-chain alcohols in the food additive. Contrary to the conventional wisdom that a trimethylsilyl derivative is susceptible to hydrolysis, the derivatized short-chain alcohols were found stable even in the presence of 0.17N aqueous sodium hydroxide as the improved GC/MS method was validated successfully, with a satisfactory linearity response in the concentration range of 10-400ng/g (regression coefficient greater than 0.999), good method precision (<4%), good recovery (90-98%), and excellent limit of detection (3ng/g) and limit of quantitation (10ng/g).
authors.affiliation: The Dow Chemical Company, Analytical Sciences, Midland, MI, 48667, USA. Electronic address: kzhu@dow.com.
authors.forename: Koudi
authors.initials: K
authors.lastname: Zhu
authors.affiliation: The Dow Chemical Company, Analytical Sciences, Midland, MI, 48667, USA.
authors.forename: Binghe
authors.initials: B
authors.lastname: Gu
authors.affiliation: The Dow Chemical Company, Analytical Sciences, Midland, MI, 48667, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Kerry
authors.affiliation: The Dow Chemical Company, Dow Wolff Cellulosics Gmbh & Ohg, Bomlitz, ND, 29699, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Mintert
authors.affiliation: The Dow Chemical Company, Analytical Sciences, Fort Saskatchewan, AB, T8L 2P4, Canada.
authors.forename: Jim
authors.initials: J
authors.lastname: Luong
authors.affiliation: The Dow Chemical Company, Analytical Sciences, Stade BN, 21677, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Pursch
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D002728:Chlorohydrins / Q000032:analysis*; D005503:Food Additives / Q000737:chemistry / Q000302:isolation & purification*; D008401:Gas Chromatography-Mass Spectrometry; D059625:Liquid-Liquid Extraction / Q000379:methods*; D014297:Trimethylsilyl Compounds / Q000737:chemistry*
chemical_list: D000081:Acetamides; D002728:Chlorohydrins; D005503:Food Additives; C103255:N,O-bis(trimethylsilyl)trifluoroacetamide; D014297:Trimethylsilyl Compounds; C053204:2-chloro-1-propanol; C015750:1-chloro-2-propanol
keywords: BSTFA interference elimination; Base treatment; Food additive; GC/MS; Shortchain alcohol