336 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS (a) o 50 mobile phase 80% methanol O n-butyl p-hydroxybenzoate A Isopropyl methyl phenol [] 2-Hydroxy-4-methoxybenzophenone I I I 6O 7O 8O Methanol concentration at ion source I I • I 0 50 80•100 Methanol content in matrix solution added post-column 9O (%) (%) (b) z 4O 3O 2O 10 O n-butyl p-hydroxybenzoate /• Isopropyl methyl phenol [] 2-Hydroxy-4-methoxybenzophenone I I I 50 60 70 80 90 (%) Methanol concentration at ion source 50 80 --100 (%) Methanol content in matrix solution added post-column Figure 4. Effect of methanol content at ion source on (a) relative intensity (80% methanol = 1) and (b) S/N ratio.

ANALYSIS OF COSMETIC INGREDIENTS 337 2.0 0.0 O Creatinine A Nicotinamide [] Pyridoxine-HCI + Pantothenylethylether x Methyl p-hydroxybenzoate ß n-butyl p-hydroxybenzoate ß _me_th heno one ] i i i 0 20 40 60 80 1 )0 (%) Methanol content at ion source Figure 5. Effect of methanol content at ion source on relative intensity. Data from Figures 2-4 were normalized on the basis of values at around 50% methanol content at the ion source taken as 1.0. 5.0 4.0 Z 3.0 • 2.0 O Creatinine A Nicotinamide [] Pyridoxine-HCI + Pantothenylethylether x Methyl p-hydroxybenzoate ß n-butyl p-hydroxybenzoate ß Isopropyl methyl phenol ß 2-Hydroxy-4-methoxybenzophenone 1.0 0.0 , , , 0 20 40 60 80 100 Methanol content at ion source (%) Figure 6. Effect of methanol content at ion source on SIN ratio. Data from Figures 2-4 were normalized on the basis of values at around 50% methanol content at the ion source taken as 1.0.