Determination of morpholine in air by derivatisation with 1-naphthylisothiocyanate and HPLC analysis

Abstract

A method for the determination of morpholine in air was developed. Samples were collected with adsorbent tubes containing XAD-2 resin coated with 1-naphthylisothiocyanate (NIT). The thiourea derivative formed was subsequently desorbed with acetonitrile and analysed by HPLC with UV detection. The recovery after gas phase spiking with morpholine (2.2–1570 μg) was 91% (86–100%) with a relative standard deviation of 5.5%. No effect on recovery from relative humidity or amount of morpholine was seen. The lowest level tested corresponded to 7 mg m⁻³ (1/10 threshold limit value) for a 15 min sampling period with a sampling rate of 20 ml min⁻¹. Exposed NIT-coated XAD-2 tubes were stable at room temperature for at least 2 weeks.