Proteomic approaches are extremely valuable in many fields of research, where mass spectrometry methods have gained an increasing interest especially due to the ability to perform quantitative analysis. Nonetheless, sample preparation prior to mass spectrometry analysis is of the utmost importance. In this work two protein precipitation approaches, widely used for cleaning and concentrating protein samples, were tested and compared in a case of very diluted samples solubilized in a strong buffer (containing SDS). The amount of protein recovered after acetone and TCA/acetone precipitation was assessed, as well as the protein identification and relative quantification by SWATH-MS yields which were compared with the results from the same sample without precipitation. With this study it was possible to conclude that, in the case of diluted samples in denaturing buffers, the use of cold acetone as precipitation protocol is more favourable than the use of TCA/acetone in terms of reproducibility in protein recovery, number of identified and quantified proteins. Furthermore, the reproducibility in relative quantification of the proteins is even higher in samples precipitated with acetone when comparing to the original sample.