Linear correlation of aliphatic diamines to response factors by number of carbons in GC–MS

Diamines are widely used as building blocks for the chemical synthesis of bio-based polymers such as polyamides, polyimides, and polyurea. However, the detection and quantification of diamines are still being as difficult tasks due to their high toxicity and polarity and other hazardous standards are needed to obtain the calibration curve for the diamine quantification. Hence, we have established a simple method for the analysis of aliphatic diamines using GC–MS based on the linear correlations between carbon number, retention time and response factors of diamines. The aliphatic diamines were derivatized with ethylchloroformate (ECF) by applying total ion current (TIC) and single ion monitoring (SIM) at the m/z of 102. The linear correlation of the aliphatic diamines to the retention time (RT) (R2 = 0.9949) and response factor (RF) (R2 = 0.9538) was determined by using carbon numbers from C3 to C12, via experimentation. The finding of linear correlations between aliphatic diamines are more advantageous and requires less authentic samples of using or calibrating of each diamine sample of the quantification and identification. The established method was successfully employed on a bacterium Shewanella oneidensis which is known to produce potential precursors of the biopolymer synthesis and assessed by, based on the predicted retention time and response factor of 1,4-diaminobutane for the quantification of secreted putrescine and cadaverine. By applying one or two diamines, the retention time, peak area and response factors can easily be expected depending on the concentration and this approach could be applied for the quantification of aliphatic diamines in various industrial sectors.