Introduction
Phenoxyethanol is a kind of colorless, slightly sticky, liquid and organic compound. It smells fragrant and tastes astringent. It can be fully mixed with acetone, ethanol and glycerin and slightly dissolve in water. Phenoxyethanol is a common and relatively safe preservative in cosmetics and the maximum concentration in cosmetics is limited to 1%.
Nipagin esters, also called paraben, is a better preservative than benzoic and its salts due to the higher antibacterial property and lower toxicity. Nipagin esters’ bacteriostasis is little impacted by pH, so it is often added in food, medicine and cosmetics as preservative.
In this paper, an efficient analytical method was introduced in determination of those two kinds of preservatives using Bonshell Polar Phenyl.
Table 1 Information of analytes
Analytes | Structure | Formula | Molecular Weigh | CAS |
Phenoxyethanol |
| C8H10O2 | 138.16 | 122-99-6 |
Methylparaben |
| C8H8O3 | 152.25 | 99-76-3 |
Ethylparaben |
| C9H10O3 | 166.17 | 118-61-6 |
Isopropylparaben |
| C10H12O3 | 180.2 | 4191-73-5 |
Propylparaben |
| C10H12O3 | 180.2 | 94-13-3 |
Isobutylparaben |
| C11H14O3 | 194.23 | 4247-02-3 |
Butylparaben |
| C11H14O3 | 194.23 | 94-26-8 |
Experimental
Material and Reagents
Watsons water; HPLC purity of methanol and potassium dihydrogen phosphate;
Standard solution of 7 preservatives mix: provided by customer;
Instrumentation
Column: Bonshell Polar Phenyl; 2.7 μm, 100 Å, 4.6 × 100 mm;
Mobile phase: 10 mmol/L of potassium dihydrogen phosphate : methanol = 60:40 (V/V);
Detection: 257 nm;
Flow rate: 1.0 mL/min;
Column temperature: 40 °C;
Injection: 5 mL.
Results and Discussion
We developed a robust analytical method for quantifying 7 kinds of preservatives in cosmetics. Excellent chromatographic separation was obtained using Bonshell Polar Phenyl for each analyte.
Table 2 Performance of Bonshell Polar Phenyl in analysis of standard solution of 7 preservatives mixed
Analytes | Retention Time | Number of Theoretical Plates | Tailing Factor | Resolution | Notes | |
Component1 | 2.091 | 10902 | 1.039 | - | Figure 1 | |
Component2 | 2.374 | 9339 | 1.042 | 3.14 | ||
Component3 | 3.738 | 10736 | 1.022 | 11.13 | ||
Component4 | 5.742 | 11767 | 1.015 | 11.16 | ||
Component5 | 6.648 | 13076 | 1.043 | 4.02 | ||
Component6 | 11.515 | 13452 | 1.016 | 15.15 | ||
Component7 | 12.823 | 13515 | 1.001 | 3.10 |
Figure 1 Chromatography of 7 preservatives standard solution mixed
Conclusion
We developed a robust analytical method for quantifying 7 kinds of preservatives in cosmetics. Excellent chromatographic separation was obtained using Bonshell Polar Phenyl for each analyte. Bonshell Polar Phenyl delivered robustness performance and thoroughly meet the demand of safety and regulatory testing.
Ordering Information
Products | Specification | Cat.No |
Bonshell® Polar Phenyl | 2.7 μm,100 Å, 4.6×100 mm | SXP621005-0 |
1.5 mL vials | Screw neck vials, 12 × 32 mm | AV1001-6 |
Caps and Septa | Screw neck cap, center hole; red silicone/ white PTEE septa, slitted | AV2200-0 |
Syringe Filter (Nylon) | Monofilm, 13 mm, 0.45 μm | AS021345-T |
Disposable Needle-Free injection systems | 2 mL, 100/pk | LZSQ-2ML |