sodium-dodecyl-sulfate and phthalic-acid

In vitro safety tests may be used as replacements for animal tests owing to their accuracy and high-throughput performance. However, several in vitro skin sensitization tests produce false-negative results such as acid anhydride. Here, we investigated the relationship between false-negative results of acid anhydride and its hydrolysis by aqueous vehicle. Differences in the pattern of hydrolysis for phthalic anhydride (PAH) due to addition of 1 drop of stock solution of PAH in liquid paraffin (LP) dispersion medium and PAH in DMSO were analyzed in a cell-free system. The results showed that use of LP dispersion medium stabilized the concentration of PAH in water over 5min by sustained-release, although almost all PAH converted to phthalic acid in water within 5min using DMSO. Additionally, treatment of THP-1 cells with PAH and phthalic acid using LP dispersion medium for 5min resulted in a 32-fold increase in IL-8 release for PAH as compared with that in the vehicle control. In contrast, for PAH using aqueous vehicle and phthalic acid using LP dispersion medium, there were no significant increases in IL-8 release. Similarly, using LP dispersion medium, trimellitic anhydride significantly increased IL-8 release was observed.

Topics: Allergens; Anhydrides; Cell Line, Tumor; Cell Survival; Humans; Hydrolysis; Interleukin-8; Mineral Oil; Nickel; Phthalic Acids; Skin Tests; Sodium Dodecyl Sulfate

Micellar liquid chromatography (MLC) has been used primarily for the separation of neutral analytes of varying polarities, most commonly phenols and polyaromatic hydrocarbons, but does not seem to have been used to study aromatic hydroxy acids in detail. We have studied the separation of hydroxybenzoic acid mixtures, including monohydroxybenzoic and dihydroxybenzoic acid positional isomers by MLC. Sodium dodecylsulfate (SDS) is investigated as the modifying surfactant on a C18 ultra-high performance liquid chromatography (UHPLC) column (100 × 2.1mm, 1.8 μm). The addition of only SDS (no organic solvent) to the mobile phase reduced the influence of hydrophobic interactions while improving the retention times, resolution, and peak shapes, even at concentrations below the critical micellization concentration (CMC). The UHPLC separation of 7 hydroxybenzoic acids, including 6 dihydroxybenzoic acid positional isomers and one trihydroxybenzoic acid, is achieved with high efficiency using 0.1% SDS in 1.84 mM sulfuric acid (pH 2.43) mobile phase, in less than 6 min with a flow rate of 0.3 mL min(-1), and in less than four min with a flow rate of 0.7 mL min(-1). Six monohydroxybenzoic acid isomers are also effectively separated by MLC, using a 0.5% SDS mobile phase modifier, in less than 20 min with a flow rate of 0.3 mL min(-1), and in less than 14 min with a flow rate of 0.7 mL min(-1). The 3 phthalic acid isomers could be separated using a similar mobile phase and flow rates in less than 6 and 4 min. Solute-micelle equilibrium constants and partition coefficients are calculated for 6 monohydroxybenzoic acids based on a plot of MLC retention factor vs. mobile phase micelle concentration. All aromatic acid isomers studied can be classified as binding solutes in the MLC retention mechanism. Less effective separations are observed with shorter chain surfactants, leading to higher retention times and poor peak shapes. It is concluded that increasing chain length led to more efficient MLC separations, and SDS is the preferred modifying surfactant for the examined separation.

Topics: Chromatography, High Pressure Liquid; Hydrophobic and Hydrophilic Interactions; Hydroxybenzoates; Ions; Isomerism; Micelles; Phenols; Phthalic Acids; Sodium Dodecyl Sulfate; Solvents; Surface-Active Agents

Phthalate plasticizers are widely used in the plastics industry, but they have been detected in soft drinks, pharmaceuticals and food products. This study developed a method that uses water plug-assisted analyte focusing by micelle collapse and microemulsion electrokinetic chromatography (WPA-AFMC-MEEKC) for quantifying benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), diethylhexyl phthalate (DEHP), and diisodecyl phthalate (DIDP) in pediatric pharmaceuticals. The AFMC strategy was applied to improve the detection sensitivity, and a short water plug was introduced to assist micelle collapse in the micelle dilution zone for sample stacking. To carry neutral phthalates into the capillary through electrokinetic injection, sodium dodecyl sulfate (SDS) was added to the sample solution, and 8mM SDS was selected as the optimal concentration. The optimized background solution (BGS) contained 16.13mM phosphate buffer (pH=2.5), 150mM SDS, 0.75% n-octane (v/v), 5% 1-butanol (BuOH), 22.5% acetonitrile (ACN), and 15% isopropanol (IPA). Under the optimal separation conditions, four phthalates could be quantified within 20min with enhancement factors of 58, 200, 86 and 90 for DIDP, DEHP, BBP, and DBP, respectively, compared to the conventional MEEKC mode. The limits of detection were within the range of 0.047-0.010μgmL(-1). The accuracy of the method was within the range of 96-117%. The WPA-AFMC-MEEKC method was applied for the analysis of six pediatric pharmaceuticals, and the results demonstrated that the developed method is sensitive and accurate, allowing it to be used for quality control of pediatric pharmaceuticals.

Topics: 1-Butanol; Chemistry Techniques, Analytical; Chromatography, Micellar Electrokinetic Capillary; Environmental Pollutants; Esters; Limit of Detection; Micelles; Octanes; Pharmaceutical Preparations; Phthalic Acids; Plasticizers; Reproducibility of Results; Sodium Dodecyl Sulfate; Water