DETERMINATION OF N-NITROSODIETHANOLAMINE AS NITRITE IN ETHANOLAMINE DERIVATIVE RAW-MATERIALS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITHFLUORESCENCE DETECTION AFTER ALKALINE DENITROSATION

A precise and sensitive method is described for the determination of N -nitrosodiethanolamine (NDELA) at the 1 mu g l(-1) level. NDELA was fo und to be extracted from aqueous solution by ethyl acetate at pH 1.0. The technique is based on the alkaline denitrosation of NDELA and reac tion of the nitrite liberated with Coumarin 120 (4-methyl-7-aminocouma rin) in sulphuric acid medium to give the corresponding 7-diazo compou nd. After hydrolysis at 100 degrees C, the corresponding 7-hydroxycoum arin (4-methylumbelliferone) is detected fluorimetrically at 380 nm af ter excitation at 325 nn. HPLC is essential to separate excess Coumari n 120 from 4-methylumbelliferone. Linearity was obtained from 1 to 30 mu g l(-1) (r = 0.997). The limit of detection was 0.8 mu g l(-1) for a signal-to-noise ratio of 3. The repeatability expressed as R.S.D. wa s 6.8% at 1 mu g l(-1) and 5.5% at 30 mu g l(-1). The reproducibility, established by two operators on three consecutive days at 5 mu g l(-1 ) (n = 6), was 9.2% (R.S.D.). Under the conditions adopted, detection of trace levels of NDELA in ethanolamine derivatives is possible.