Separation and determination of polyethylene glycol fatty acid esters in cosmetics by a reversed-phase HPLC/ELSD

Controlling the positive ion electrospray ionization of poly(ethylene glycols) when using ultra-high-performance supercritical fluid chromatography-mass spectrometry

Poly(ethylene glycols) are complex polymers often added to pharmaceutical formulations to improve drug solubility and delivery. One of the main challenges when using chromatographic techniques coupled to mass spectrometry is the unselective ionization of poly(ethylene glycols) oligomers. Additionally, when the chain length is large enough, multiple charged species are formed, further complicating the mass spectra and processing. This study uses the advanced oligomer separation provided by supercritical fluid chromatography with a mass spectrometry approach that selectively ionizes poly(ethylene glycols) as ammoniated molecules to simplify data analysis and facilitate batch-to-batch comparisons. Several visual representations of the response of the ionization events based on the polymer molecular weight and the repeating unit were used to elucidate trends in ionization. Evaluation of the influence of the oligomer length and end-group on the electrospray ionization of the polymer allowed the development of a process to enable selective ionization for these complex polymers.

Development and validation of a novel UPLC-ELSD method for the assessment of lipid composition of nanomedicine formulation

Lipid nanocarriers incorporating glycerides, polyethylene glycol (PEG)-stearates and phospholipids have attracted great attention for in vivo diagnostic, in vivo imaging, activated or non-activated targeted drug delivery. For quality control purposes, the development of appropriate methods for the quantification of their lipid components is needed. In the present study, we developed an analytical method for lipid quantification in formulated nanoparticles. PEG-stearates and glycerides were analyzed in a single run by RP-UPLC-ELSD using a two-step gradient elution program, while the analysis of phospholipids was accomplished by HILIC-UPLC-ELSD after isolation using an SPE silica column. Using both isolated compounds and commercial lipid standards, calibration curves were produced using second-order polynomials to attain the quantitative evaluation of each lipid excipient. Relative standard deviation of all analytes was between 0.9% and 5.3% for intra-day precision and recovery ranged from 83.5% to 112.2%. The presented method was successfully implemented to study the manufacturing process and stability of the formulated lipid excipients during long-term storage and accelerated conditions. The formulation lipid yield was determined and found equal to 82.5%.

An efficient PEGylated liposomal nanocarrier containing cell-penetrating peptide and pH-sensitive hydrazone bond for enhancing tumor-targeted drug delivery

Cell-penetrating peptides (CPPs) as small molecular transporters with abilities of cell penetrating, internalization, and endosomal escape have potential prospect in drug delivery systems. However, a bottleneck hampering their application is the poor specificity for cells. By utilizing the function of hydration shell of polyethylene glycol (PEG) and acid sensitivity of hydrazone bond, we constructed a kind of CPP-modified pH-sensitive PEGylated liposomes (CPPL) to improve the selectivity of these peptides for tumor targeting. In CPPL, CPP was directly attached to liposome surfaces via coupling with stearate (STR) to avoid the hindrance of PEG as a linker on the penetrating efficiency of CPP. A PEG derivative by conjugating PEG with STR via acid-degradable hydrazone bond (PEG2000-Hz-STR, PHS) was synthesized. High-performance liquid chromatography and flow cytometry demonstrated that PHS was stable at normal neutral conditions and PEG could be completely cleaved from liposome surface to expose CPP under acidic environments in tumor. An optimal CPP density on liposomes was screened to guaranty a maximum targeting efficiency on tumor cells as well as not being captured by normal cells that consequently lead to a long circulation in blood. In vitro and in vivo studies indicated, in 4 mol% CPP of lipid modified system, that CPP exerted higher efficiency on internalizing the liposomes into targeted subcellular compartments while remaining inactive and free from opsonins at a maximum extent in systemic circulation. The 4% CPPL as a drug delivery system will have great potential in the clinical application of anticancer drugs in future.

Evaporative light scattering detector: toward a general molecular weight cutoff characterization of nanofiltration membranes

An evaporative light scattering detector (ELSD) coupled with HPLC was used for the first time to characterize membranes. Polydispersed PEG-200, 600, and 1000 were selected as probe molecules to study the dependence of membrane retention on molecular weight via a gradient eluted HPLC separation coupled to ELSD detection. The results show that HPLC/ELSD is a really general and powerful technique to study the nanofiltration (NF) process since it does not require any special properties for the solutes (chromospheres or fluorophores) and possesses the required sensitivity. Especially in solvent resistant NF (SRNF), where a wide range of organic solvents is used, the ELSD detector was not affected by the interaction between solvent and solutes, which is a critical issue compared to other more common detectors.

Simultaneous determination of jujuboside A, B and betulinic acid in semen Ziziphi spinosae by high performance liquid chromatography-evaporative light scattering detection

A reverse phase high performance liquid chromatographic (HPLC) method with evaporative light scattering detection (ELSD) was developed for simultaneous determination of jujuboside A, B and betulinic acid in semen Ziziphi spinosae. The analysis was performed by gradient elution, using an aqueous mobile phase (containing 0.1% acetic acid) modified by acetonitrile. The evaporator tube temperature of ELSD was set at 45 degrees C, and with the nebulizing gas flow-rate of 1.8l/min. The method was validated for accuracy, reproducibility, precision and limits of detection and quantification. Quantification of the three active compounds in semen Ziziphi spinosae from different locations was performed by this method, which provides a new tool for quality assessment of semen Ziziphi spinosae.