Compound optimization, also referred to as tuning, is the process in which mass spectrometry parameters such as the precursor\/product ions, collision energies, and other voltages are optimized for each analyte. Compound optimization can often be overlooked. It might seem easier to find an article or application note and just use the compound settings for a specific analyte, but this shortcut might have consequences for the analyte performance. All mass spectrometers differ from one another; even ones of the same make and model. Because of this variability, transition parameters that work for one instrument may not be optimal for another instrument. This can result in a loss of sensitivity and may impact the detection limits for a particular compound.<\/p>\n\n\n\n
In the example below, three compounds were assessed to see how using optimized compound settings impacted analyte response. Settings for cocaine, morphine, and \u03949-THC were optimized on a Shimadzu LCMS-8045. Another set of settings for these analytes were obtained from an LC-MS\/MS method featured in a journal article1<\/sup>. The optimized and literature settings are listed below.<\/p>\n\n\n\n Table 1.<\/strong> Analyte settings optimized in-lab on Shimadzu LCMS-8045.<\/p>\n\n\n\n Table 2.<\/strong> Analyte settings obtained from journal article (not optimized in-lab)1<\/sup>.<\/p>\n\n\n\n A sample containing the analytes at a concentration of 100 ng\/mL was run on two methods, one using the optimized and one using the literature settings. All other method parameters were the same for both methods. The peak heights and areas were compared for each analyte using the optimized versus literature settings.<\/p>\n\n\nAnalyte<\/strong><\/td> Ion Mode<\/strong><\/td> Parent<\/strong><\/td> Product<\/strong><\/td> Q1 Pre Bias (V)<\/strong><\/td> CE<\/strong><\/td> Q3 Pre Bias (V)<\/strong><\/td><\/tr> Cocaine<\/td> ESI+<\/td> 303.90<\/td> 182.10<\/td> -16<\/td> -20<\/td> -19<\/td><\/tr> 82.15<\/td> -16<\/td> -30<\/td> -16<\/td><\/tr> Morphine<\/td> ESI+<\/td> 285.90<\/td> 201.05<\/td> -15<\/td> -27<\/td> -21<\/td><\/tr> 152.15<\/td> -11<\/td> -55<\/td> -28<\/td><\/tr> \u03949-THC<\/td> ESI+<\/td> 315.10<\/td> 193.05<\/td> -23<\/td> -24<\/td> -20<\/td><\/tr> 123.25<\/td> -16<\/td> -35<\/td> -23<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n Analyte<\/strong><\/td> Ion Mode<\/strong><\/td> Parent<\/strong><\/td> Product<\/strong><\/td> Q1 Pre Bias (V)<\/strong><\/td> CE<\/strong><\/td> Q3 Pre Bias (V)<\/strong><\/td><\/tr> Cocaine<\/td> ESI+<\/td> 304.00<\/td> 182.00<\/td> -20<\/td> -18<\/td> -18<\/td><\/tr> 82.00<\/td> -20<\/td> -31<\/td> -14<\/td><\/tr> Morphine<\/td> ESI+<\/td> 286.20<\/td> 152.20<\/td> -20<\/td> -55<\/td> -30<\/td><\/tr> 201.20<\/td> -20<\/td> -25<\/td> -12<\/td><\/tr> \u03949-THC<\/td> ESI+<\/td> 315.00<\/td> 193.30<\/td> -16<\/td> -23<\/td> -19<\/td><\/tr> 123.10<\/td> -16<\/td> -34<\/td> -12<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n