Determination of α-hydroxy acids in cosmetics by UHPLC-MS/MS / 上海预防医学

ObjectiveTo establish a UHPLC-MS/MS quantitative method for the determination of glucuronic acid， tartaric acid， glycolic acid， malic acid， lactic acid， citric acid， DL-2-hydroxybutyric acid sodium， mandelic acid， benzilic acid， hydroxycaprylic acid， lactobionic acid， gluconic acid and N-acetylneuraminic acid in cosmetics. MethodsSamples were prepared by ultrasonic extraction， cleansed by precipitating reagent and followed by high-speed centrifugation of the extraction solution. The supernatant was filtered by 0.22 μm Millipore filter. The continued filtrate was taken for analysis. A reversed phase column， Poroshell 120 EC-C18 （2.7 μm， 4.6 mm×1 000 mm） was used with 0.1% formic acid buffer and acetonitrile as the mobile phase under the condition of gradient elution. The analytes were detected with electrospray ionization source in negative ion mode （ESI-） and multiple reactions monitoring （MRM）， and quantified by external standard curve. ResultsThe method showed a good linearity of glucuronic acid， tartaric acid， malic acid， DL-2-hydroxybutyric acid sodium， benzilic acid， hydroxycaprylic acid and N-acetylneuraminic acid within the concentration range of 50.0‒2 000.0 μg·L-1 （r>0.995）. The method showed a good linearity of glycolic acid， lactic acid， citric acid and mandelic acid within the concentration range of 100.0‒5 000.0 μg·L-1 （r>0.995）. The method showed a good linearity of lactobionic acid and gluconic acid within the concentration range of 50.0‒5 000.0 μg·L-1 （r>0.995）. The recoveries were in the range of 92.3%‒114.1%； the relative standard deviations （RSD） were in the range of 0.9%‒6.0% （n=3）. The detection limits of glucuronic acid， tartaric acid， malic acid， citric acid， DL-2-hydroxybutyric acid sodium， mandelic acid， benzilic acid， hydroxycaprylic acid， lactobionic acid， gluconic acid and N-acetylneuraminic acid were 0.003% while the detection limits of glycolic acid， lactic acid and mandelic acid were 0.006%. In 10 batches of commercially available cosmetics， eight batches showed positive result. ConclusionThe UHPLC-MS/MS method is efficient， sensitive and accurate and is applicable to the determination of 13 α-hydroxy acidic components in cosmetics.

Determination of azelaic acid and potassium azeloycinate diglycinate in cosmetics by HPLC / 上海预防医学

ObjectiveAn HPLC method was established for the determination of azelaic acid and potassium azeloycinate diglycinate in cosmetics. MethodsThe samples were extracted with 60 mmol·L-1 sodium hydroxide water solution-methyl alcohol. After centrifugation and filtration， the analysis of azelaic acid and potassium azeloycinate diglycinate was performed with a SVEA C8（250 mm×4.6 mm， 5 μm） column， using 15 mmol‧L-1 potassium dihydrogen phosphate solution （pH=3.0） and acetonitrile for gradient elution at a flow rate of 1.0 mL·min-1.The analytes were detected with UV detector， and quantified by external standard curve. ResultsThe results showed a good linearity in the range of 5‒1 000 μg‧mL-1 with correlation coefficients （r） larger than 0.999. The detection limit of azelaic acid and potassium azeloycinate diglycinate （LOD） was 0.020% and 0.015%， respectively. The spiked recoveries were 87.66% to 108.96% with the relative standard deviation （RSD） of 0.6% to 3.3%. ConclusionThe method is simple， rapid and highly sensitive. It is suitable for the determination of azelaic acid and potassium azeloycinate diglycinate in cosmetics.

Determination of five prostaglandin analogs in eyelash enhancing cosmetics by LC-MS/MS / 上海预防医学

Objective To determine bimatoprost， tafluprost ethyl amide， latanoprost， travoprost and tafluprost in eyelash enhancing cosmetics by establishing a LC-MS/MS method. Methods The samples were extracted with a 50% acetonitrile water solution. A salt mixture（4 g NaCl， 1 g MgSO4） was added to the solution to induce phase separation. After centrifugation and filtration， the analysis of five prostaglandin analogs was performed with an Agilent Poroshell 120 PFP-C18 （2.7 μm， 2.1 mm×100 mm） column， using 0.02% formic acid containing 5 mmol·L-1 Acetic acid amine and acetonitrile by gradient elution at a flow rate of 0.5 mL·min-1. The analytes were detected with electrospray ionization source in positive ion mode （ESI+） and multiple reaction monitoring （MRM）， and quantified by external standard curve. Results The results showed that it had a good linearity in the range of locatable ambit of concentration with correlation coefficients （r） larger than 0.999. The detection limit of five prostaglandin analogs （LOD） was 0.000 2‒1.5 μg·g-1. The spiked recoveries were 93.2% to 103.5% with a relative standard deviation （RSD） of 1.2% to 3.4%. Conclusion The method is simple， rapid and highly sensitive. It is suitable for the determination of five prostaglandin analogs in eyelash enhancing cosmetics.

Determination of catechins in cosmetics by high⁃performance liquid chromatography / 上海预防医学

ObjectiveTo establish a high⁃performance liquid chromatography （HPLC） quantitative method for the determination of epicatechin （EC）， （-）⁃epicatechin gallate （ECG）， （-）⁃epigallocatechin （EGC）， （-）⁃epigallocatechin gallate （EGCG）， （-）⁃gallocatechin （GC）， （-）⁃gallocatechin gallate （GCG）， （-）⁃catechin gallate （CG）， cianidanol （CD） and gallic acid （GA） in cosmetics. MethodsSamples were prepared by ultrasonic extraction and followed by high-speed centrifugation of the extraction solution. The supernatant was filtered by 0.45 μm Millipore filter. The continued filtrate was taken for analysis. A reversed phase column， Kromasil 100-5 C18 （5 μm， 4.6 mm×250 mm） was used with 0.05% trifluoroacetic acid buffer and methanol as mobile phase under the condition of gradient elution. Diode array detection （DAD） method was used for the determination. Qualitative and quantitative determination was conducted in 10 batches of commercially available cosmetics. ResultsThe relative standard deviations （RSD） were in the range of 0.11%-6.30% （n=3）； the recoveries were in the range of 84.4%-114.7%. The method showed a good linearity within the concentration range of 0.49-105.39 mg·L-1 （r>0.995）. The detection limit was 5 μg·g-1. In 10 batches of commercially available cosmetics， three batches showed positive result， which was consistent with the UV spectrum of the standard. ConclusionThis method is efficient， sensitive and accurate. It is applicable to the determination of EC， ECG， EGC， EGCG， GC， GCG， CG， CD and GA in cosmetics.