ANALYSIS OF NITROSAMINES 307 A B z 4 ATT.64 • ATT.32---• LU • ATT.64 • -ATT.32 0 3 6 9 0 3 6 9 TIME (minutes) TIME (minutes) Figure 12. HPLC-TEA chromatograms of N-nitrosodiethanolamine (NDELA) and N-nitrosodiisopro- pylamine (NDIPA) on IxPorasil with 35:65 (v/v) acetone-isooctane. Flow rate: 1.5 ml/min. A: in a shampoo product. B: standard NDELA (32.5 ppb) and NDIPA (45 ppb). (Reprinted with permission from reference 57. Copyright 1981 Pergamon Press.)

308 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS A B C O N Of! N N INJ 10 Off , i , i INJ 10 INJ 10 rNJ 10 Figure 13. HPLC-TEA chromatograms of N-nitrosodiethanolamine (NDELA) in triethanolamine on Spherisorb-Silica with 4:96 (v/v) methanol-methylene chloride. Flow rate: 2 ml/min (N indicates NDELA peak). A: 200 ng NDELA. B: Triethanolamine specimen A. C: Triethanolamine specimen B. D: Trietha- nolamine + 100 ng NDELA. (Reprinted with permission from reference 48, Cosmetic, Toiletry and Fragrance Association.) to form the diazonium salt. The reaction then proceeds with the addition of the cou- pling reagent, N-l-naphthylethylenediamine dihydrochloride. Complete color forma- tion occurs within ca. 25 minutes and is measured at 540 nm on a spectrophotometer. The reactions are summarized below: SO2NH 2 SO2NH 2 q- NO 2 q- 2H + -• NH 2 N2 + + 2H20 (17) SO2NH 2 NHCH2CH2NH 2 N2 + SO2NH 2 N N NHCH2CH2NH 2