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Introduction: Internal standards correct for measurement variation due to sample loss. Isotope labeled analytes are ideal internal standards for the measurement of fatty acids in human plasma but are not always readily available. For this reason, quantification of multiple analytes at once is most often done using only a single or few internal standards. The magnitude of the impact this has on method accuracy and precision is not well studied for gas chromatography-mass spectrometry systems. Objective: This study aims to estimate bias and changes in uncertainty associated with using alternative fatty acid isotopologue internal standards for the estimation of similar or dissimilar long chain fatty acids. Method: Using a previously reported method for the quantification of 27 fatty acids in human plasma using 18 internal standards we obtained estimates of bias and uncertainty at up to three levels of fatty acid concentration. Results: With some notable exceptions, method accuracy remained relatively stable when using an alternative internal standard (Median Relative Absolute Percent Bias: 1.76%, Median Spike-Recovery Absolute Percent Bias: 8.82%), with larger changes in method precision (Median Increase in Variance: 141%). Additionally, the degree of difference between analyte and internal standard structure was related to the magnitude of bias and uncertainty of the measurement. Conclusion: The data presented here show that the choice of internal standard used to estimate fatty acid concentration can affect the accuracy and reliability of measurement results and, therefore, needs to be assessed carefully when developing analytical methods for the measurement of fatty acid profiles.Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention/the Agency for Toxic Substances and Disease Registry. Use of trade names is for identification only and does not imply endorsement by the Centers for Disease Control and Prevention, the Public Health Service, and the US Department of Health and Human Services.

Objectives: Intake of trans fatty acids (TFA) increases the risk of cardiovascular disease. Assessment of TFA exposure in the population is key for determining TFA burden and monitoring change over time. One approach for TFA monitoring is measurement of TFA levels in plasma. Understanding costs associated with this approach can facilitate program planning, implementation and scale-up. This report provides an assessment of costs associated with a pilot program to measure plasma TFA levels in Thailand. Study design: Cost analysis in a laboratory facility in Thailand. Methods: We defined three broad cost modules: laboratory, personnel, and facility costs, which were further classified into sub-components and into fixed and variable categories. Costs were estimated based on the number of processed plasma samples (100–2700 in increments of 50) per year over a certain number of years (1–5), in both USD and Thai Baht. Total cost and average costs per sample were estimated across a range of samples processed. Results: The average cost per sample of analyzing 900 samples annually over 5 years was estimated at USD186. Laboratory, personnel, and facility costs constitute 67%, 23%, and 10% of costs, respectively. The breakdown across fixed costs, such as laboratory instruments and personnel, and variable costs, such as chemical supplies, was 60% and 40%, respectively. Average costs decline as more samples are processed: the cost per sample for analyzing 100, 500, 1500, and 2500 samples per year over 5 years is USD1351, USD301, USD195; and USD177, respectively. Conclusions: Laboratory analysis of plasma TFA levels has high potential for economies of scale, encouraging a long-term approach to TFA monitoring initiatives, particularly in countries that already maintain national biometric repositories.

Objectives: To estimate the impact of the 2006 policy restricting use of trans fatty acids (TFAs) in New York City restaurants on change in serum TFA concentrations in New York City adults., Methods: Two cross-sectional population-based New York City Health and Nutrition Examination Surveys conducted in 2004 (n = 212) and 2013-2014 (n = 247) provided estimates of serum TFA exposure and average frequency of weekly restaurant meals. We estimated the geometric mean of the sum of serum TFAs by year and restaurant meal frequency by using linear regression., Results: Among those who ate less than 1 restaurant meal per week, geometric mean of the sum of serum TFAs declined 51.1% (95% confidence interval [CI] = 42.7, 58.3)-from 44.6 (95% CI = 39.7, 50.1) to 21.8 (95% CI = 19.3, 24.5) micromoles per liter. The decline in the geometric mean was greater (P for interaction = .04) among those who ate 4 or more restaurant meals per week: 61.6% (95% CI = 55.8, 66.7) or from 54.6 (95% CI = 49.3, 60.5) to 21.0 (95% CI = 18.9, 23.3) micromoles per liter., Conclusions: New York City adult serum TFA concentrations declined between 2004 and 2014. The indication of greater decline in serum TFAs among those eating restaurant meals more frequently suggests that the municipal restriction on TFA use was effective in reducing TFA exposure. Public Health Implications. Local policies focused on restaurants can promote nutritional improvements.