Occurrence and Dietary Exposure to Acrylamide from Foods Consumed within and outside Main Meals in Singapore.

This study investigated the influence of 'snackification' in Singaporean diets, leading to increased dietary acrylamide exposure. Acrylamide concentrations in commonly consumed foods within and outside the main meals were measured using liquid chromatography with tandem mass spectrometry (LC-MS/MS). High acrylamide concentrations were detected in vegetables cooked at high temperatures (ranging from 0.5 to 478.4 µg/kg) and potato-based crackers and chips (ranging from 81.8 to 2095.8 µg/kg). The estimated total dietary exposure for the Singapore population was 0.165 µg/kg bw/day for general consumers and 0.392 µg/kg bw/day for high consumers (95th percentile). The acrylamide exposure from outside main meals was nearly equivalent to that from within the main meals. The calculated margins of exposure (MOE) were below 10,000, indicating potential human health concern. These findings highlight the need for industry practices and consumer advisories to reduce acrylamide exposure from foods consumed both within and outside main meals.

Occurrence and Dietary Exposure of 3-MCPD Esters and Glycidyl Esters in Domestically and Commercially Prepared Food in Singapore.

This study investigated the prevalence and occurrence of 3-monochloropropanediol esters (3-MCPDEs) and glycidyl esters (GEs) in domestically and commercially prepared food in Singapore and assessed the total dietary exposure for the Singaporean population. Minimal impact on the formation of 3-MCPDEs and GEs was observed from the domestic cooking methods commonly practiced in Singapore such as deep frying and stir frying. The estimated total dietary exposure to 3-MCPDEs for the Singaporean population (aged 15 to 92) was 0.982 µg/kg bw/day for general consumers and 2.212 µg/kg bw/day for high consumers (95th percentile), which accounted for 49.1% and 110.6% of the tolerable dietary intake (TDI) at 2 µg/kg bw/day by the European Food Safety Authority (EFSA). The calculated margins of exposure (MOE) for GEs based on the dietary exposure for general consumers at 0.882 µg/kg bw/day and 2.209 µg/kg bw/day for high consumers were below 10,000, indicating a potential health concern. Our study showed that the occurrence of 3-MCPDEs and GEs varied among vegetable oils, and domestic cooking methods did not significantly impact the levels of 3-MCPDEs and GEs in prepared food. The critical factor influencing the prevalence and occurrence of 3-MCPDEs and GEs was the choice of oil used for cooking, which absorbed into the cooked food. It is essential to encourage the food industry to continue its innovation on mitigation measures to control and reduce 3-MCPDEs and GEs in vegetable oil production. Consumers are advised to make informed choices on food consumption and cooking oil for food preparation to reduce their exposure to 3-MCPDEs and GEs.

Improving the accuracy of chloride measurements through participation in regular external quality assessment programme.

BACKGROUND: A chloride test is an integral part of a basic metabolic panel that is essential for the assessment of a patient's acid-base and electrolyte status. While many methods are available commercially for the routine measurement of chloride, there is a need to address the accuracy and variability among the measurement results, especially with the prevalence of patients seeking treatment across different healthcare providers for alternative opinions. METHOD: A method based on sector field inductively coupled plasma isotope dilution mass spectrometry (SF-ICP-IDMS) was developed for the measurement of chloride in human serum. The SF-ICP-IDMS method was then used to assign the target values in the Health Sciences Authority (HSA) External Quality Assessment (EQA) Programme to evaluate the results of chloride test from participating clinical laboratories. RESULTS: The accuracy of the measurements was evaluated by comparing the results with the certified values of Electrolytes in Frozen Human Serum Certified Reference Materials (SRM 956c and SRM 956d) from the National Institute of Standards and Technology (NIST) at different chloride concentration levels. Over a five-year period from 2014-2018, the number of clinical laboratories which participated in the EQA Programme increased from 23 to 33. Comparison of robust means from the laboratories' results with our assigned target values revealed a reduction in relative deviation over time. The relationship between the deviation of each brand of clinical analysers and the chloride levels was established, where a larger deviation was uncovered at low chloride concentration. The SF-ICP-IDMS method was further demonstrated to be comparable with methods used by other metrology institutes in an international comparison organised by HSA under the auspice of the Consultative Committee for Amount of Substance - Metrology in Chemistry and Biology (CCQM). CONCLUSION: The use of metrologically traceable assigned target values enabled the study of method biasness from a small pool of dataset in each of the four brands of clinical analysers in HSA EQA Programme. This work underscores the need to improve the accuracy of chloride measurements by regular participation in an accuracy-based EQA Programme.

An unexpected Bromolactamization of Olefinic Amides Using a Three-Component Co-catalyst System.

Reaction between (N,N-dimethylamino)pyridine and isocyanate unexpectedly produced a three-component mixture. By using this mixture as an unprecedented three-component catalyst system, a facile and selective bromolactamization of olefinic amides has been developed. The protocol confers enhanced selectivity of N- over O-cyclization, leading to the formation of a structurally diverse range of lactams including both small and medium ring sizes.

Carbamate-catalyzed enantioselective bromolactamization.

A highly facile, efficient, and enantioselective bromolactamization of olefinic amides was effected by a carbamate catalyst and ethanol additive. The amide substrates underwent N-cyclization predominantly to give a diverse range of enantioenriched bromolactam products containing up to two stereogenic centers.

Catalyst-free and metal-free electrophilic bromoamidation of unactivated olefins using the N-bromosuccinimide/sulfonamide protocol.

An efficient, catalyst-free, and metal-free bromoamidation of unactivated olefins has been developed. 4-(Trifluoromethyl)benzenesulfonamide and N-bromosuccinimide were used as the nitrogen and halogen sources, respectively. The methodology is applicable to both cyclic and aliphatic olefins.

Recent advances in asymmetric intra- and intermolecular halofunctionalizations of alkenes.

This review seeks to provide coverage on recent advances in catalytic enantioselective halofunctionalization of alkenes. The aim is to give an overview of various reports, highlighting the new reaction types and strategies developed during the past two years. The scope and challenges of intra- and intermolecular reaction variants are discussed as well.

Stereoselective bromofunctionalization of alkenes.

The stereoselective bromofunctionalization of alkenes, particularly the enantioselective format, has been a subject of intense research in recent years. The ground-breaking works are documented in recent reviews. On the other hand, this account will provide an insight into our group's approach in tackling the challenges in enantioselective bromocyclization of alkenes as well as the development of diastereoselective N-bromosuccinimide-initiated multicomponent reactions.