Abstract
Fourteen types of corona discharge needles made of different materials were used for high performance liquid chromatography/atmospheric pressure chemical ionizationquadrupole mass spectrometer (LC/APCI-QMS), and after a lapse of one hour and five hours from the start of the equipment, selected-ion monitoring determination of 3,5-di-tert-butyl-4-hydroxytoluene (BHT) was made seven times repeatedly. Suitability as a discharge needle was judged by the total (n=14) relative standard deviation (T-RSD) of the quantitative determination value. T-RSD's of the iron needle, tin-plated iron needle, silver alloy needle, platinum alloy needle and stainless steel needle were 1-3%.
It could be elucidated from the scanning electron micrograph of the needle surface that suitability as a discharge needle was related to the stability of needle surface material against the corona discharge. The iron needle, having a small T-RSD was judged to be the most suitable as a corona discharge needle for quantitative analysis.
