Gas chromatography-mass spectrometry and Raman imaging measurement of squalene content and distribution in human hair.

A sensitive and specific gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the measurement of the squalene content from root to tip, in both Chinese black virgin and bleached hair. Deuterated squalene was used as the internal standard. For quantification, selective ion monitoring (SIM) at m/z 410.0 and 347.0 were monitored for squalene and deuterated squalene, respectively. Different methods for the extraction of squalene from ex vivo human hair were compared including organic solvent extraction and acid/alkali hydrolysis. The best extraction efficiency was obtained by using a mixed solvent consisting of chloroform:methanol = 2:1 (v:v). The linear range of squalene ran from 1.0 to 50.0 µg mL(-1). The limit of detection (LOD) was 0.10 µg mL(-1) (corresponding to 0.005 mg g(-1) in human hair), which enabled quantification of squalene in human hair at very low level. The recovery of squalene was 96.4 ± 1.46% (n = 3). Using the above-mentioned mixed solvent extraction, squalene content in human hair was successfully quantified from root to tip. Meanwhile, a Raman imaging method was developed to visualize the squalene distribution in Chinese white virgin hair from cuticle to medulla.

Instant tooth whitening from a silica toothpaste containing blue covarine.

OBJECTIVE: To measure the instant whitening effect delivered immediately after brushing with a novel silica whitening toothpaste containing blue covarine. METHODS: A controlled, single blind, cross-over study was performed to compare the tooth colour measured in a group of subjects at baseline and immediately after brushing with a silica whitening toothpaste containing blue covarine versus a clear gel negative control toothpaste. Measurements of tooth colour were made using a mobile non-contact camera-based digital imaging system and expressed as CIELAB and WIO whiteness index. RESULTS: Analysis of covariance (ANCOVA) showed that the silica whitening toothpaste containing blue covarine was significantly more effective than the negative control toothpaste (p < 0.05), and made teeth measurably less yellow, less red and overall whiter immediately after brushing. CONCLUSION: A statistically significant reduction in tooth yellowness and improvement in tooth whiteness was measured immediately after brushing with a novel whitening toothpaste containing blue covarine.

The in vitro and in vivo validation of a mobile non-contact camera-based digital imaging system for tooth colour measurement.

OBJECTIVE: To assess the reproducibility of a mobile non-contact camera-based digital imaging system (DIS) for measuring tooth colour under in vitro and in vivo conditions. METHODS: One in vitro and two in vivo studies were performed using a mobile non-contact camera-based digital imaging system. In vitro study: two operators used the DIS to image 10 dry tooth specimens in a randomised order on three occasions. In vivo study 1:25 subjects with two natural, normally aligned, upper central incisors had their teeth imaged using the DIS on four consecutive days by one operator to measure day-to-day variability. On one of the four test days, duplicate images were collected by three different operators to measure inter- and intra-operator variability. In vivo study 2:11 subjects with two natural, normally aligned, upper central incisors had their teeth imaged using the DIS twice daily over three days within the same week to assess day-to-day variability. Three operators collected images from subjects in a randomised order to measure inter- and intra-operator variability. RESULTS: Subject-to-subject variability was the largest source of variation within the data. Pairwise correlations and concordance coefficients were > 0.7 for each operator, demonstrating good precision and excellent operator agreement in each of the studies. Intraclass correlation coefficients (ICCs) for each operator indicate that day-to-day reliability was good to excellent, where all ICC's where > 0.75 for each operator. CONCLUSION: The mobile non-contact camera-based digital imaging system was shown to be a reproducible means of measuring tooth colour in both in vitro and in vivo experiments.

Ex-vivo measurement of scalp follicular infundibulum delivery of zinc pyrithione and climbazole from an anti-dandruff shampoo.

Efficient delivery of anti-dandruff (AD) actives into the scalp follicular infundibulum as well as onto the scalp surface is critical for the efficacy of AD shampoos. A method involving scalp cyanoacrylate (CA) biopsy sampling, a tailor made cutting device, ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis, scanning electron microscopy (SEM) measurement and Raman imaging has been developed for the measurement of delivery of zinc pyrithione (ZPT) and climbazole (CBZ) from an AD shampoo into the scalp follicular infundibulum. Scalp CA biopsy enables the sampling of ZPT and CBZ delivered into the scalp follicular infundibula as well as onto the scalp surface. Raman imaging of scalp CA biopsy samples allows the visualization of the spatial distribution of ZPT and CBZ deposited on the scalp. A tailor made cutting device enables the separation of the scalp follicular infundibulum sample (20µm below the scalp surface) from the scalp surface samples (including top 20µm of infundibula). UHPLC-MS/MS was used as a sensitive and specific methodology enabling the quantification of ZPT and CBZ without interference. Using this method, both ZPT and CBZ were successfully quantified and spacially visualized within the scalp follicular infundibulum, after scalp was washed with an AD shampoo.

Sensitive and simultaneous quantification of zinc pyrithione and climbazole deposition from anti-dandruff shampoos onto human scalp.

A sensitive ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method has been developed and validated for simultaneous quantification of zinc pyrithione (ZPT) and climbazole (CBZ) deposited onto human scalp from anti-dandruff (AD) shampoos. Scrubbing with a buffer solution was used as the sampling method for the extraction of ZPT and CBZ from scalp. Derivatization of ZPT was carried out prior to UHPLC-MS/MS analysis. The identification of ZPT and CBZ was performed by examining ratios of selected multiple reaction monitoring (MRM) transitions in combination with UHPLC retention times. The limit of detection for ZPT and CBZ was established to be 1 and 2ng/mL, respectively. This sensitivity enables the quantification of ZPT and CBZ at deposition levels in the low ng/cm(2) range. The method was successfully applied for the analysis of scalp buffer scrub samples from an in vivo study. The levels of ZPT and CBZ deposited on the scalp at different time points after application of the AD shampoo were measured. The results revealed that dual-active AD shampoo delivered more ZPT onto the scalp in a single wash than single active shampoo did. The amount of ZPT and CBZ retained on the scalp after AD shampoo application declined over 72h.