Food products containing simultaneously benzoate salts and ascorbic acid have a risk of benzene formation. This study has developed gas chromatography-mass spectrometry method GC-MS to determine the benzene content in foods containing benzoate salts and ascorbic acid simultaneously. The analyte sample was distilled to recover benzene and analyzed on GC-MS using a purge and trap injector, the analysis was controlled by benzened6 internal standard. The method has been validated for the parameters specified by AOAC. The method detection limit was 0.05 µg/kg, the method quantification limit was 0.15 µg/kg, the recovery ranged from 86.6 to 110.9%, Repeatability, RSDr in the range of 4.0 - 7.2%. The method has been applied to analyze the benzene content in 120 food samples including: soft drinks, fruit nectar, chili sauce and jam. Results of detecting benzene in 33 samples out of 120 surveyed samples, benzene content ranged from 0 to 109.7 µg/kg.  

A sensitive GC-MS/MS method has been developed and validated for determining ester forms of 3-MCPD and 2-MCPD in infant formula, using 3-MCPD-d5 and 2-MCPD-d5 as internal standards, respectively. The esters of MCPDs were extracted from infant formula powder with mixture of ethanol/n-hexane/diethyl ether (1/1/1, v/v/v), then treated with sulfuric acid to release free MCPDs. Free MCPDs and internal standards were derivatized with phenylboronic acid and the corresponding derivatives were used for GC-MS/MS analysis. The chromatographic separation was performed in a DB-5MS capillary column using helium as mobile phase at flow rate of 1 mL/min. Tandem mass spectroscopic detection of each analyte was done in MRM mode by monitoring one precursor ion and two product ions. Validation results confirmed the suitability of the developed method for intended application. Application of the method in samples collected from different provinces in Vietnam detected esterified 3-MCPD in 38.9% of samples, esterified 2-MCPD in 34.7% of samples.

Nghiên cứu đã phát triển và thẩm định phương pháp xác định đồng thời các dạng ester của 3-MCPD và 2-MCPD trong sữa công thức bằng GC-MS/MS. Các ester của MCPD được chiết từ mẫu sữa công thức bằng hỗn hợp ethanol/n-hexane/diethyl ether (1/1/1, v/v/v), sau đó được xử lý với acid sulfuric để giải phóng dạng tự do. Các chất 3-MCPD và 2-MCPD dạng tự do và nội chuẩn đồng vị 3-MCPD-d5 and 2-MCPD-d5 được dẫn xuất với acid phenylboronic và sau đó dẫn xuất được phân tích bằng GC-MS/MS ở chế độ MRM. Cột tách được sử dụng là cột mao quản DB-5MS, khí mang là Heli ở tốc độ 1 mL/phút. Chế độ MRM đã được sử dụng để lựa chọn 1 ion mẹ và 2 ion con cho mỗi chất phân tích. Kết quả thẩm định cho thấy phương pháp đáp ứng các yêu cầu theo AOAC SMPR. Phương pháp đã được ứng dụng để xác định các ester của 3-MCPD và 2-MCPD trong các mẫu sữa công thức lấy ở một số tỉnh, thành phố của Việt Nam. Có 38,9% số mẫu phát hiện 3-MCPD ester và 34,7% số mẫu phát hiện 2-MCPD ester.

Oxygen radical absorbance capacity (ORAC) assay has been applied to determine the Hydrophilic – ORAC index in food. The method measures antioxidant scavenging activity against peroxyl radical induced by 2,2′-azobis(2-amidino-propane) dihydrochloride (AAPH) at 37ºC, used fluororescein as the fluorescent probe. The antioxidant capacity is measured by assemssing the fluorescence decay curve (AUC) of the sample as compared to that of the blank in which no antioxidant is present. Results expressed in ORAC units, equivalent to micromole Trolox per 100 grams sample (Trolox equivalent). The method was shown with high selectivity, a wide linear range, from 5 to 50µM Trolox with linear coefficient R2 = 0.9987. The recovery from 93.2% to 104.4% and repeatability (RSD) was less than 6.60%. The limits of detection and quantitation were 5 and 10µM Trolox, respectively. The method has been applied to determine of H-ORAC index in 65 samples including vegetables, fruits, vegetable products and health supplements with content ranging from 720 µM TE/100g to 310878 µM TE/100g.