This study aims to propose a new method for derivatizing fatty acids (FAs) from human milk (HM), eliminating the lipid extraction step, and simplifying the preparation for gas chromatography with a flame ionization detection (GC-FID) analysis to quantify the FAs. The Design Expert software optimized the reaction times, concentrations, and sample amount. The proposed method (PM) was validated for lyophilized HM and results for the figures of merit for precision in relative standard deviation (RSD) (RSDintra-day 1.34-4.03% and RSDinter day 2.08 5.16%), accuracy (99.87-102.16%), and robustness are within a linear range of 3 to 38% lipids in HM samples. The atmospheric solids analysis probe tandem mass spectrometry (ASAP-MS/MS) technique confirmed the efficiency of PM by expressing the molecular composition of triacylglycerol formed by FAs from the GC-FID technique. The PM requires a small sample size and conducts derivatization directly in the sample matrix, minimizing extraction errors. (FAs HM, , (HM) step GCFID GC FID (GC-FID times concentrations amount (PM RSD (RSD RSDintraday RSDintra 1.344.03% 134403 1.34 4.03% 1 34 4 03 1.34-4.03 208 2 08 2.0 5.16%, 516 5.16% 5 16 5.16%) 99.87102.16%, 998710216 99.87 102.16% 99 87 102 (99.87-102.16%) 38 samples ASAPMS/MS ASAPMSMS ASAP MS/MS MS (ASAP-MS/MS matrix errors (HM 344 1.344.03 13440 134 1.3 403 4.03 0 1.34-4.0 20 2. 51 5.16 87102 99.87102.16% 99871021 9987 99.8 10216 102.16 9 8 10 (99.87-102.16% ASAPMS MSMS 1.344.0 1344 13 1. 40 4.0 1.34-4. 5.1 8710 99.87102.16 9987102 998 99. 1021 102.1 (99.87-102.16 1.344. 4. 1.34-4 5. 871 99.87102.1 998710 102. (99.87-102.1 1.344 1.34- 99.87102. 99871 (99.87-102. 99.87102 (99.87-102 99.8710 (99.87-10 99.871 (99.87-1 (99.87- (99.87 (99.8 (99. (99 (9 (

RESUMEN El agrietamiento en uniones de aluminio constituye un problema frecuente cuya solución requiere un enfoque científico dada su esencia fenomenológica. En el presente trabajo se determinan las causas del agrietamiento en uniones de aluminio 3003 por soldadura GMAW (gas metal arc welding). El estudio se realizó en uniones reales de un contenedor de productos alimenticios. La muestra se extrajo con disco refrigerado, cuidando no alterar el material para mantener las evidencias de las posibles causas de falla. A la muestra de la unión le fueron realizados los análisis siguientes: inspección visual, análisis químico por espectrometría de emisión óptica, ensayo de tensión del material base y macrografía de las uniones soldadas. Se concluye que la causa del agrietamiento tiene su origen en la falta de fusión y penetración, que actúan como concentraciones de tensión y que fueron originadas por deficiencias en la ejecución de la soldadura.

ABSTRACT A frequent problem, whose solution requires a scientific approach due to its phenomenological essence, is cracking in aluminum joints. The causes of cracking in 3003 aluminum joints by Gas Metal Arc Welding (GMAW) are defined in this research. The study was carried out on actual joints in a food product container. A refrigerated disk was used for extracting the sample, trying not to alter the material to maintain evidence of possible causes of failure. Macrograph of the welded joints, and visual inspection, chemical analysis by optical emission spectrometry, stress testing of base material analyzes were performed to the joint sample. It is conclude that the lack of fusion and penetration is the cause of cracking, which act as stress concentrations and they were originated by deficiencies when carrying out welding.