JOURNAL OF COSMETIC SCIENCE 328 Table II Recovery and Reproducibility of the Analysis of Commercial Permanent Hair Dyes by HPLC (n = 6) Compound Added (mg/kg) Hair dye Aa Hair dye Bb Found (mg/kg) Recovery (%) C.V. (%) Found (mg/kg) Recovery (%) C.V. (%) Hydroquinone 25 20.4 81.7 0.74 20.6 82.5 1.04 50 41.5 83.1 0.83 42.8 85.4 3.01 250 211.5 84.6 1.02 218.0 87.2 1.45 2500 2095 83.8 1.47 2128 85.1 1.52 Resorcinol 25 – – – 21.2 84.8 1.51 50 – – – 45.0 90.2 3.18 250 807.5 97.8 2.15 222.8 89.1 1.39 2500 3000 97.6 2.05 2318 92.7 1.12 o-Phenylenediamine 25 20.9 83.5 1.44 21.1 84.3 1.50 50 43.8 87.6 0.94 44.0 88.0 3.69 250 248.0 99.2 2.78 215.8 86.3 1.89 2500 2470 98.8 2.60 2365 94.6 1.66 1,5-Naphthalenediol 25 20.7 82.6 1.18 20.8 83.2 1.02 50 42.8 85.6 1.45 43.3 86.3 3.61 250 217.0 86.8 0.89 219.0 87.6 1.68 2500 2158 86.3 1.09 2188 87.5 1.87 2,6-Diaminopyridine 25 20.8 83.0 1.04 21.0 83.8 1.88 50 43.8 87.7 1.85 44.5 88.8 3.51 250 230.8 92.3 1.02 218.8 87.5 1.43 2500 2495 99.8 1.65 2515 100.6 1.27 p-Aminophenol 125 106.5 85.3 2.48 – – – 250 217.3 86.9 1.53 – – – 1250 1168 93.3 2.41 – – – 2500 2315 92.6 1.23 – – – Phenol 125 118.0 94.4 2.56 121.3 97.0 1.54 250 246.5 98.6 1.89 235.3 94.1 1.82 1250 1213 97.0 1.88 1193 95.4 2.35 2500 2430 97.2 1.58 2423 96.9 1.57 m-Aminophenol 125 106.3 85.0 1.92 – – – 250 212.5 85.0 1.14 – – – 1250 1178 94.1 1.83 – – – 2500 2463 98.5 3.33 – – – 4-Methylaminophenol 125 108.3 86.6 3.09 107.5 85.9 3.09 250 217.3 86.9 1.10 215.0 86.0 0.96 1250 1093 87.3 2.43 1103 88.1 2.83 2500 2158 86.3 1.84 2180 87.2 1.53 p-Phenylenediamine 125 107.8 86.3 3.05 – – – 250 220.3 88.1 2.15 – – – 1250 1175 93.9 1.90 – – – 2500 2520 100.8 1.80 – – – (Continued)

DETERMINATION OF 13 COMPONENTS IN OXIDATIVE HAIR DYES 329 2,5-Diaminotoluene 125 105.3 84.2 2.22 112.5 90.1 2.32 250 217.3 86.9 1.08 218.5 87.4 1.53 1250 1185 94.8 2.04 1198 95.7 2.66 2500 2540 101.6 1.42 2533 101.3 1.04 3,4-Diaminetoluene 125 117.5 93.9 1.87 117.8 94.2 1.77 250 244.0 97.6 2.64 245.0 98.0 2.17 1250 1153 92.3 2.40 1248 99.9 2.23 2500 2290 91.6 1.63 2525 101.0 0.80 N,N-diethyl-p- phenylenediamine 250 238.0 95.2 1.98 247.5 99.0 1.91 500 477.5 95.6 2.54 490.0 97.8 2.32 2500 2550 102.0 0.90 2253 90.1 1.26 a Hair dye A contained 536.6 mg/kg resorcinol. b Hair dye B contained 3528 mg/kg m-aminophenol, 6618 mg/kg p-aminophenol, and 8727 mg/kg p-phenylenediamine. Table II Continued Compound Added (mg/kg) Hair dye Aa Hair dye Bb Found (mg/kg) Recovery (%) C.V. (%) Found (mg/kg) Recovery (%) C.V. (%) ACCURACY AND RECOVERY The results of the standard recovery test (Table II) showed that the average recoveries were in the range of 81.7–102.0% with four addition levels of two original commercial samples, and the RSDs (relative standard deviation) were about 0.9–3.5%. The precision data obtained from the evaluation of the results of a collaborative trial involving fi ve laborato- ries and three replicates with hair dye A (containing 536.6 mg/kg resorcinol) and hair dye B (containing 3528 mg/kg m-aminophenol, 6618 mg/kg p-aminophenol, and 8727 mg/kg p-phenylenediamine) were shown in Table III. CONCLUSIONS A sensitive and accurate analytical method for the determination of 13 dye intermediates in commercial hair dyes was developed. The introduction of sodium dithionite as a reductant Table III The Repeatability (r) and Reproducibility (R) of This Method (mg/kg) (20) Sample Compound ma Srb SRc rd Re Hair dye A Resorcinol 553 10 12 29 34 Hair dye B m-Aminophenol 3525 66 68 183 189 p-Aminophenol 6631 60 90 167 252 p-Phenylenediamine 8636 78 78 217 217 a m is the general average. b Sr is the repeatability standard deviation. c SR is the reproducibility standard deviation. d r is calculated according to ISO 5725-2:1994. e R is calculated according to ISO 5725-2:1994.