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

ANALYSIS OF NITROSAMINES 309 A B C D I,I E N O F 13 F O F 13 F O F ,'o o ,'o ,'o,,o Figure 14. HPLC-TEA chromatograms of N-nitrosodiethanolamine (NDELA) in alkanolamides on Spher- isorb-CN with 2:98 (v/v) methanol-methylene chloride. Flow rate: 2 ml/min (N indicates NDELA peak). A: 200 mg NDELA. B: Lauramide DEA. C: Lauramide DEA + 300 ng NDELA. D: Cocamide DEA. E: Cocamide DEA + 200 ng NDELA. (Reprinted with permission from reference 49, Cosmetic, Toiletry and Fragrance Association.) While the Griess reaction has been widely used to quantitate nitrosamines at part per million and higher levels, its utility at the part per billion level has been limited primarily because of matrix interferences. These interferences generally occur in the form of species present in the matrix that consume the released nitrosating agent faster than the desired aromatic amine or matrix components that react with the various Griess reactants. Thus, it is clear that when employing a nonspecific method of analysis for the determination of nitrosamines, a very thorough investigation and understanding A B N ol o F 10 10 10 1 10 Figure 15. HPLC-TEA chromatograms of N-nitrosodiethanolamine (NDELA) in monoethanolamine salt matrix on Spherisorb-CN with 2:98 (v/v) methanol-methylene chloride. Flow rate: 2 ml/min (N indicates NDELA peak). A: 200 ng NDELA. B: Cocamide MEA. C: Cocamide MEA + 200 ng NDELA. D: Lauramide MEA. E: Lauramide MEA q- 200 ng NDELA. (Reprinted with permission from reference 50, Cosmetic, Toiletry and Fragrance Association.)