Detector supports: application to aliphatic amines in wastewater

Solid support assisted derivatization coupled to diffuse reflectance spectroscopy (DRS) was proposed and proved useful for the detection and quantification of aliphatic amines in water as an example. Dabsyl chloride (DBS), ninhydrin and sodium 1,2-naphtoquinone 4-sulphonate (NQS) were assayed as derivatization reagents. C18 and SDB-XC disks and C18 cartridges were tested for amine retention and after that derivatization. The decrease of the orange colour of dabsyl chloride on SBD-XC disks produced by the formation of its derivative with methylamine in the support (10 min at 100 °C) allowed the selective determination of the amine at concentration level equal or higher than 0.5 mg L−1. Ninhydrin can be used for methylamine, ethylamine, propylamine, butylamine and pentylamine (between 5 and 15 mg L−1) by measuring the diffuse reflectance produced by the brown derivative formed in C18 extraction disks after 15 min at 100 °C. NQS and C18 SPE columns can be also employed to estimate amines, but the detection limits were higher than those provided by DBS and Ninhydrin, around 10 mg L−1. As an example, found concentration of methylamine or total amines (expressed as –NH2–N mg L−1) in a wastewater sample is given employing dabsyl chloride or ninhydrin reagents, respectively with satisfactory results.