An optimization strategy for charged aerosol detection to linearize the detector response in the multicomponent quantitative analysis of Qishen Yiqi dripping pills.

Charged aerosol detection, increasingly recognized for quantifying pharmaceutical compounds with weak ultraviolet absorption, is a universal detection technique for high-performance liquid chromatography (HPLC). Charged aerosol detection shows a non-linear response with increasing analyte concentration over a wide range, limiting its versatility in various analytical applications. In this work, a co-optimization strategy for power function value (PFV) and power laws was proposed and applied to broaden the linear range of the standard curve of saccharides in Qishen Yiqi dripping pills using the HPLC-charged aerosol detection (HPLC-CAD) method. Power function values for all analytes were optimized based on empirical models. Subsequently, the optimum power laws were investigated based on a preferred PFV. Additionally, various regression equations were evaluated to ensure the accuracy and precision of the results. With the optimized PFV and power law, the ordinary least squares model demonstrated a satisfactory fit. The optimal PFVs and power laws expanded the standard curve's linear range by 2.7 times compared to default settings, reducing model uncertainty. This paper presents a vital method for developing a multi-component quantitative HPLC-CAD approach without external data transformation outside the provided software, especially suitable for analytical applications of traditional Chinese medicine with significant quality differences.

Identification and quantification of biosurfactants produced by the marine bacterium Alcanivorax borkumensis by hyphenated techniques.

A novel biosurfactant was discovered to be synthesized by the marine bacterium Alcanivorax borkumensis in 1992. This bacterium is abundant in marine environments affected by oil spills, where it helps to degrade alkanes and, under such conditions, produces a glycine-glucolipid biosurfactant. The biosurfactant enhances the bacterium's attachment to oil droplets and facilitates the uptake of hydrocarbons. Due to its useful properties expected, there is interest in the biotechnological production of this biosurfactant. To support this effort analytically, a method combining reversed-phase high-performance liquid chromatography (HPLC) with high-resolution mass spectrometry (HRMS) was developed, allowing the separation and identification of glycine-glucolipid congeners. Accurate mass, retention time, and characteristic fragmentation pattern were utilized for species assignment. In addition, charged-aerosol detection (CAD) was employed to enable absolute quantification without authentic standards. The methodology was used to investigate the glycine-glucolipid production by A. borkumensis SK2 using different carbon sources. Mass spectrometry allowed us to identify congeners with varying chain lengths (C6-C12) and degrees of unsaturation (0-1 double bonds) in the incorporated 3-hydroxy-alkanoic acids, some previously unknown. Quantification using CAD revealed that the titer was approximately twice as high when grown with hexadecane as with pyruvate (49 mg/L versus 22 mg/L). The main congener for both carbon sources was glc-40:0-gly, accounting for 64% with pyruvate and 85% with hexadecane as sole carbon source. With the here presented analytical suit, complex and varying glycolipids can be identified, characterized, and quantified, as here exemplarily shown for the interesting glycine-glucolipid of A. borkumensis.

Differentiating root and rhizome of panax notoginseng based on precursor ion scanning and multi heart-cutting two-dimensional liquid chromatography.

Owing to increasing demand for Panax notoginseng-based medicines and health products, establishing a fast, simple, and reliable assay to analyze the chemical differences between its root and rhizome is important. Although previous studies showed that the chemical and biological differences between the root and rhizome of P. notoginseng seem to be small, efforts should be taken to investigate such differences to ensure the safety and efficacy of the products. This work describes a holistic approach that combines characteristic fingerprinting using ultra-high performance liquid chromatography-tandem mass spectrometry parent ion scanning with charged aerosol detection and targeted separation by online heart-cutting two-dimensional liquid chromatography, to identify and evaluate characteristic markers allowing differentiation of the root and rhizome. A total of five potential markers chikusetsusaponin L5 , ginsenoside Rb2 , stipuleanoside R2, malonyl-ginsenoside Rb1 , and malonyl-ginsenoside Rd, were identified and confirmed by comparing chromatographic retention time, the accurate mass of molecular weight, and the fragments of secondary MS with the available reference materials. The results showed that all five markers were 2.8-7 times higher in content in the rhizome than in the root.

Determination of lipid content and stability in lipid nanoparticles using ultra high-performance liquid chromatography in combination with a Corona Charged Aerosol Detector.

For many years, lipid nanoparticles (LNPs) have been used as delivery vehicles for various payloads (especially various oligonucleotides and mRNA), finding numerous applications in drug and vaccine development. LNP stability and bilayer fluidity are determined by the identities and the amounts of the various lipids employed in the formulation and LNP efficacy is determined in large part by the lipid composition which usually contains a cationic lipid, a PEG-lipid conjugate, cholesterol, and a zwitterionic helper phospholipid. Analytical methods developed for LNP characterization must be able to determine not only the identity and content of each individual lipid component (i.e., the parent lipids), but also the associated impurities and degradants. In this work, we describe an efficient and sensitive reversed-phase chromatographic method with charged aerosol detection (CAD) suitable for this purpose. Sample preparation diluent and mobile phase pH conditions are critical and have been optimized for the lipids of interest. This method was validated for its linearity, accuracy, precision, and specificity for lipid analysis to support process and formulation development for new drugs and vaccines.

Establishing a chromatographic fingerprint using tandem UV/charged aerosol detection and similarity analysis for Shengmai capsule: A novel method for natural product quality control.

INTRODUCTION: Shengmai San, a well-known traditional Chinese medicine formula, is used to treat coronary heart diseases and myocardial infarction. The complex composition and complicated mechanism of the Shengmai preparations bring a significant challenge in the development of a suitable quality control method. OBJECTIVES: This work aims to establish a chromatographic fingerprinting method and propose a weighting algorithm for application in fingerprint similarity analysis to ensure consistent quality of the Shengmai capsule. METHODOLOGY: A chromatographic fingerprint method was established using tandem UV/charged aerosol detection (CAD) for Shengmai capsule quality control. After method verification, the developed method was applied to analyze 15 batches of the samples. Then a weighting algorithm of the fingerprint peak was proposed and used for the fingerprint similarity analysis. RESULTS: An HPLC-UV/CAD fingerprint method was successfully developed for the Shengmai capsules. Chromatographic conditions of the HPLC-UV/CAD method were optimized with a definitive screening design, and the optimized ranges of operating parameters were obtained with a Monte Carlo simulation method. The combined use of the proposed weighting algorithm and similarity analysis on fingerprint data improves the sensitivity of distinguishing batch-to-batch quality differences. CONCLUSION: The developed HPLC-UV/CAD fingerprint method is robust, reliable, and efficient. The proposed weighting algorithm combined with similarity analysis is promising and meaningful for the quality consistency assessment of HPLC-UV/CAD fingerprints.

Establishment and validation of the quantitative analysis of multi-components by single marker for the quality control of Qishen Yiqi dripping pills by high-performance liquid chromatography with charged aerosol detection.

INTRODUCTION: Charged aerosol detection (CAD) has the merits of high sensitivity, high universality and response uniformity. The strategy that combines the quantitative analysis of multi-components by single marker (QAMS) with CAD has certain advantages for the quantification of multi-components. However, relevant research was limited. OBJECTIVES: To comprehensively investigate the crucial factors that affect the performance of the HPLC-CAD-QAMS approach and validate the credibility and feasibility of the method. METHODOLOGY: Multiple components of Qishen Yiqi dripping pills (QSYQ) were assayed using the high-performance liquid chromatography (HPLC)-CAD-QAMS approach. Some factors that affect the sensitivity and accuracy of the approach were sufficiently studied. After the method verification, principal component analysis (PCA) was applied to evaluate the quality consistency of three types of samples: normal samples, expired samples and negative samples. RESULTS: A HPLC-CAD-QAMS method was successfully developed for the multi-component determination of QSYQ. First, chromatographic conditions were optimised by a definitive screening design, and the optimised ranges of operating parameters were obtained with a Monte Carlo simulation method. Next, a new method to select the internal reference standards was successfully introduced based on the heatmap of Pearson correlation coefficients of the response factors. Then, the multi-point method was selected to calculate the relative correction factors, and a robustness test was conducted with Plackett-Burman design. Finally, the PCA was proved to be effective for the quality consistency evaluation of different samples. CONCLUSION: The developed HPLC-CAD-QAMS method can be a reliable and superior means for the multi-component quantitative analysis of QSYQ.

Benefits and Pitfalls of HPLC Coupled to Diode-Array, Charged Aerosol, and Coulometric Detections: Effect of Detection on Screening of Bioactive Compounds in Apples.

The new screening method for rapid evaluation of major phenolic compounds in apples has been developed. Suitability of coupling HPLC/UHPLC separation with the diode-array detection and universal charged aerosol detection with respect to the presence of interfering substances was tested. Characteristics of both detection techniques were compared and method linearity, limits of detection and quantitation, and selectivity of them determined. Student t-test based on slopes of calibration plots was applied for the detailed comparison. The diode-array detection provided the best results regarding sensitivity and selectivity of the developed method in terms of evaluation of phenolics profiles. The response of the charged aerosol detector was negatively affected by co-eluting substances during rapid-screening analyses. Coulometric detection was used for advanced characterization of extracts in terms of antioxidant content and strength to obtain more complex information concerning sample composition. This detection also allowed evaluation of unidentified compounds with antioxidant activity. HPLC/UHPLC separation using a combination of diode-array and coulometric detectors thus represented the best approach enabling quick, yet complex characterization of bioactive compounds in apples.

Development of an ultra-high-performance liquid chromatography-charged aerosol detection/UV method for the quantitation of linear polyethylenimines in oligonucleotide polyplexes.

Linear polyethylenimines are polycationic excipients that have found many pharmaceutical applications, including as a delivery vehicle for gene therapy through formation of polyplexes with oligonucleotides. Accurate quantitation of linear polyethylenimines in both starting solution and formulation containing oligonucleotide/polyethylenimine polyplexes is critical. Existing methods using spectroscopy, matrix-assisted laser desorption/ionization mass spectrometry time-of-flight, or nuclear magnetic resonance are either complex or suffer from low selectivity. Here, the development and performance of a simple analytical method is described whereby linear polyethylenimines are resolved by ultra-high-performance liquid chromatography and quantified using either a charged aerosol detector or an ultraviolet detector. For formulated oligonucleotide/polyethylenimine polyplexes, sample preparation through decomplexation/digestion by trifluoroacetic acid was necessary to eliminate separation interference. The method can be used not only to support formulation development but also to monitor the synthesis/purification and characterization of linear polyethylenimines.

[Fingerprinting analysis of non-saponins from water-soluble part and determination of dencichine from Panax notoginseng, P. ginseng and P. quinquefolium based on liquid chromatography coupled with charged aerosol detection].

This work describes the holistic fingerprinting method based on liquid chromatography coupled with charged aerosol detection(CAD) to profile non-saponin from water-soluble parts and determination of dencichine in Panax ginseng(PG), P. quinquefolium(PQ) and P. notoginseng(PNG). Sample extraction was carried out by water with ultra sonication for 30 min, which was eluted by Retain PEP for further analysis. The analysis was performed on a Hypercarb of porous graphitized carbon(3.0 mm×150 mm, 3 µm) column with acetonitrile and 0.1% perfluoropentanoic acid as mobile phase at a flow rate of 0.8 mL·min~(-1). Temperature of evaporator and nitrogen pressure for CAD were set at 50 ℃and 60.1 psi(1 psi≈6.895 kPa), respectively. As a result, dencichine and other polar components had a good performance on resolution and retention. The correlation coefficient(R~2) of dencichine was 0.998 2 in the concentration from 0.019 2 to 0.48 µg·mL~(-1). Limit of quantitation calculated by signal to noise of 10 was 7.4 ng·mL~(-1), and the recovery ranged from 95.52% to 102.7%. Chemical profile of the water-soluble part from PG, PQ and PNG was similar holistically, while the relative content for dencichine and other partial components varied significantly. The proposed method was used for characteristic of chemical profiling for non-saponin from water-soluble part, and determination of dencichine in PG, PQ and PNG.

Hydrophilic Interaction Chromatography Coupled with Charged Aerosol Detection for Simultaneous Quantitation of Carbohydrates, Polyols and Ions in Food and Beverages.

Here, we report an accurate and versatile method for the simultaneous determination of 17 sugars (arabinose, erythrose, fructose, galactose, glucose, isomaltulose, lactose, lyxose, maltose, maltotriose, mannose, raffinose, rhamnose, ribose, sucrose, sorbose and xylose), seven polyols (erythritol, inositol, lactitol, maltitol, mannitol, sorbitol and xylitol), five ions (K+, Br-, Cl-, NO3- and SO42-) and the pseudosaccharide acarbose. For compound separation, hydrophilic interaction chromatography (HILIC) coupled to a corona charged aerosol detector (CAD) was used. The method was validated for linearity, precision, reproducibility, retention factor and optimal injection volume. Standards were measured in the range of 1-1000 mg L-1 and showed good intraday and interday repeatability, as well as precision (relative standard deviation (RSD) < 5%). The LODs and LOQs for the 30 analytes were in the range of 0.032-2.675 mg L-1 and 0.107-8.918 mg L-1, respectively. This method exhibited correlation coefficients of at least R2 > 0.97 for all analytes. The method was tested in 24 food and beverage samples to validate the separation efficiency and sensitivity in natural food matrices and to show the practicability of its use for routine food analysis.

Determining High-Intensity Sweeteners in White Spirits Using an Ultrahigh Performance Liquid Chromatograph with a Photo-Diode Array Detector and Charged Aerosol Detector.

In China, white spirit is not only an alcoholic drink but also a cultural symbol. A novel and accurate method for simultaneously determining nine sweeteners (most authorized for use in China) in white spirits by ultrahigh performance liquid chromatography (UHPLC) with a photo-diode array detector (PDA) and charged aerosol detector (CAD) was developed. The sweeteners were acesulfame, alitame, aspartame, dulcin, neotame, neohesperidine dihydrochalcone, saccharin, sodium cyclamate, and sucralose. The sweeteners were separated within 16 min using a BEH C18 column and linear gradient-elution program. The optimized method allowed low concentrations (micrograms per gram) of sweeteners to be simultaneously detected. The CAD gave good linearities (correlation coefficients > 0.9936) for all analytes at concentrations of 0.5 to 50.0 µg/g. The limits of detection were 0.16 to 0.77 µg/g. Acesulfame, dulcin, neohesperidine dihydrochalcone, and saccharin were determined using the PDA detector, which gave correlation coefficients > 0.9994 and limits of detection of 0.16 to 0.22 µg/g. The recoveries were 95.1% to 104.9% and the relative standard deviations were 1.6% to 3.8%. The UHPLC-PDA-CAD method is more convenient and cheaper than LC-MS/MS methods. The method was successfully used in a major project called "Special Action against Counterfeit and Shoddy white spirits" and to monitor risks posed by white spirits in China.

A multi-detector chromatographic approach for characterization and quantitation of botanical constituents to enable in silico safety assessments.

An approach has been developed to characterize the individual chemical constituents of botanicals. The challenge was to identify and quantitate the significant analytes in these complex mixtures, largely in the absence of authentic standards. The data-rich information content generated by this three-detector configuration was specifically intended to be used to conduct safety and/or quality evaluations for complex botanical mixtures, on a chemical constituent basis. The approach utilized a broad gradient UHPLC chromatographic separation. Following the chromatographic separation and UV detection, the eluent was split and sent into a charged aerosol detector (CAD), for quantitation, and a quadrupole/time-of-flight high-resolution mass spectrometer for component identification. The known bias of the otherwise universal CAD response, for organic solvent composition of the mobile phase, was compensated by the addition of an inverse gradient make-up stream. This approach and the orthogonal information content from the chromatography and three different detectors was specifically designed to enable in-silico safety assessments. These guide, minimize, or even eliminate the need for in vivo and in vitro safety assessments. The methodology was developed and demonstrated using standardized extracts of Ginkgo biloba. Results from the development of this novel approach and the characterization example reported here demonstrate the suitability of this instrumental configuration for enabling in-silico safety assessments and proving general quality assessments of botanicals.

An HPLC-CAD/fluorescence lipidomics platform using fluorescent fatty acids as metabolic tracers.

Fluorescent lipids are important tools for live imaging in cell culture and animal models, yet their metabolism has not been well-characterized. Here we describe a novel combined HPLC and LC-MS/MS method developed to characterize both total lipid profiles and the products of fluorescently labeled lipids. Using this approach, we found that lipids labeled with the fluorescent tags, 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY FL), 4,4-difluoro-5-(2-thienyl)-4-bora-3a,4a-diaza-s-indacene [BODIPY(558/568)], and dipyrrometheneboron difluoride undecanoic acid (TopFluor) are all metabolized into varying arrays of polar and nonpolar fluorescent lipid products when they are fed to larval zebrafish. Quantitative metabolic labeling experiments performed in this system revealed significant effects of total dietary lipid composition on fluorescent lipid partitioning. We provide evidence that cholesterol metabolism in the intestine is important in determining the metabolic fates of dietary FAs. Using this method, we found that inhibitors of dietary cholesterol absorption and esterification both decreased incorporation of dietary fluorescent FAs into cholesterol esters (CEs), suggesting that CE synthesis in enterocytes is primarily responsive to the availability of dietary cholesterol. These results are the first to comprehensively characterize fluorescent FA metabolism and to demonstrate their utility as metabolic labeling reagents, effectively coupling quantitative biochemistry with live imaging studies.

Quantitative determination of 15 bioactive triterpenoid saponins in different parts of Acanthopanax henryi by HPLC with charged aerosol detection and confirmation by LC-ESI-TOF-MS.

Triterpenoid saponins are difficult to analyze using high-performance liquid chromatography coupled to UV/vis spectrophotometry due to their lack of chromophores. This study describes the first analytical method for the determination of 15 triterpenoid saponins from the leaves, stems, root bark, and fruits of Acanthopanax henryi, using a high-performance liquid chromatography with charged aerosol detection coupled with electrospray ionization mass spectrometry method. The separation was carried out on a Kinetex XB-C18 column with an acetonitrile/water gradient as the mobile phase, followed by charged aerosol detection. The operating conditions of charged aerosol detection were set at 24 kPa for nitrogen pressure and 100 pA for the detection range. Liquid chromatography with electrospray ionization mass spectrometry is described for the identification of compounds in plant samples. The electrospray ionization mass spectrometry method involved the use of the [M + Na](+) and [M + NH4 ](+) ions for compounds 1-15 in the positive ion mode with an extracted ion chromatogram. The developed method was fully validated in terms of linearity, sensitivity, precision, repeatability, and recovery, then subsequently applied to evaluate the quality of A. henryi.

Chromatographic methods for characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers.

The objective of this study was to develop chromatographic methods for the determination of the modification degree and the characterization of poly(ethylene glycol)-modified polyamidoamine dendrimers (PEG-PAMAMs). The PEG-PAMAMs were prepared by reacting PAMAM generation 4 with monomethoxy PEG-nitrophenyl carbonate (mPEG-NPC). The modification degrees of PEG-PAMAMs were determined by quantifying 4-nitrophenol released from mPEG-NPC after PEGylation reaction using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The PEG-PAMAMs, which have poor UV absorbances, were characterized by HPLC with charged aerosol detection. This study demonstrates that the combination of these two detectors is a powerful tool for the preparation and characterization of PEG-PAMAMs.

Combination of a sub-3 µm superficially porous particle packed column with charged aerosol detection for the simple and sensitive measurement of nine macrolides in human urine.

Due to the lack of chromophores in many macrolides, analytical methods based on mass spectrometry and electrochemical detection coupled to liquid chromatography have been suggested to be suitable for the quantification of macrolides in complex matrices. In this study, a simple and sensitive analytical method was established for the simultaneous measurement of nine macrolides in human urine by combining a sub-3 µm superficially porous particle packed column with charged aerosol detection. After thorough investigation of various sample preparation methods, including two liquid-liquid extraction methods and four solid-phase extraction methods, HLB solid-phase extraction was selected and further optimized. Absolute recovery of the optimized sample preparation method ranged from 99.5-110.2%, indicating its very high extraction/clean-up efficiency. For chromatography, parameters influencing macrolide separation were systematically optimized, and the resulting conditions allowed baseline separation of nine macrolides within 24 min using a very simple mobile phase. The established method was validated for linearity, limit of detection, limit of quantification, absolute recovery, and precision. Based on its limit of detection (0.025-0.100 µg/mL), the method had similar or greater sensitivity than most methods based on electrochemical detection. It was found that the current method was appropriate for application to real human urine samples after drug administration.

Characterizing interregional differences in the rheological properties and composition of rat small intestinal mucus.

The mucus layer in the small intestine is generally regarded as a barrier to drug absorption. However, the mucus layer is a complex system, and presently, only a few studies have been conducted to elucidate its physicochemical properties. The current study hypothesizes that the mucus layer contains solubility-enhancing surfactants and thus might aid the oral absorption of poorly water-soluble drugs. Mucus was sampled from sections of the small intestine of fasted rats to analyze the rheological properties and determine the mucus pH and concentrations of proteins and endogenous surfactants, i.e., bile salts, polar lipids, and neutral lipids. The mucus layer in the two proximal sections of the small intestine exhibited different rheological properties such as higher zero-shear viscosity and lower loss tangent and higher protein concentrations compared to all subsequent sections of the small intestine. The pH of the mucus layer was stable at ~ 6.5 throughout most of the small intestine, but increased to 7.5 in the ileum. The bile salt concentrations increased from the duodenum (16.0 ± 2.2 mM) until the mid jejunum (55.1 ± 9.5 mM), whereas the concentrations of polar lipids and neutral lipids decreased from the duodenum (17.4 ± 2.2 mM and 37.8 ± 1.6 mM, respectively) until the ileum (4.8 ± 0.4 mM and 10.7 ± 1.1 mM, respectively). In conclusion, the mucus layer of the rat small intestine contains endogenous surfactants at levels that might benefit solubilization and absorption of orally administered poorly water-soluble drugs.

High throughput multidimensional liquid chromatography approach for online protein removal and characterization of polysorbates and poloxamer in monoclonal antibody formulations.

The majority of commercially available monoclonal antibody (mAb) formulations are stabilized with one of three non-ionic surfactants: polysorbate 20 (PS20), polysorbate 80 (PS80), or poloxamer 188 (P188). All three surfactants are susceptible to degradation, which can result in functionality loss and subsequent protein aggregation or free fatty acid particle formation. Consequently, quantitative, and qualitative analysis of surfactants is an integral part of formulation development, stability, and batch release testing. Due to the heterogeneous nature of both polysorbates and poloxamer, online isolation of all the compounds from the protein and other excipients that may disturb the subsequent liquid chromatography with charged aerosol detection (LC-CAD) analysis poses a challenge. Herein, we present an analytical method employing LC-CAD, utilizing a combination of anion and cation exchange columns to completely remove proteins online before infusing the isolated surfactant onto a reversed-phase column. The method allows high throughput analysis of polysorbates within 8 minutes and poloxamer 188 within 12 minutes, providing a separation of the surfactant species of polysorbates (unesterified species, lower esters, and higher esters) and poloxamer 188 (early eluters and main species). Accuracy and precision assessed according to the International Council for harmonisation (ICH) guideline were 96 - 109 % and ≤1 % relative standard deviation respectively for all three surfactants in samples containing up to 110 mg/mL mAb. Subsequently, the method was effectively applied to quantify polysorbate 20 and polysorbate 80 in nine commercial drug products with mAb concentration of up to 180 mg/mL.

Solubility of Poorly Soluble Drugs in Phosphatidylcholine-Based Drug Delivery Systems: Comparison of the Loading Capacity in the Bulk Formulation and Its Dispersed State.

The aim of this study was to determine the drug loading capacity of phosphatidylcholine-based formulations for four poorly water-soluble drug substances (clofazimine, fenofibrate, artemether, cannabidiol). Two self-dispersing lipid formulations were investigated, which consisted of soybean phospholipids, medium-chain triglycerides and ethanol with a different phospholipid-oil ratio. The direct loading of the bulk formulation was conducted with dual centrifugation, which proved to be a suitable method for screening experiments with the highly viscous formulations. To estimate possible precipitation after dispersion in the gastrointestinal fluids, the solubility of the drugs was investigated in the dispersed formulations. For this purpose, nanodispersions were prepared from the bulk formulations via high pressure homogenization and subsequently subjected to passive loading. A newly developed HPLC method with Charged Aerosol Detection allowed a simultaneous evaluation of the content of soybean lecithin and medium-chain triglycerides in the nanodispersions. When comparing the two phosphatidylcholine-based formulations, a high content of oil was advantageous with regard to a high loading capacity. Drug substances with melting points below 150 °C exhibited a high solubility in the phospholipid-based formulations. A surprisingly high solubility was observed for artemether and cannabidiol with up to 13.0% and 33.3% drug loaded to the formulations, respectively. In the dispersions, a similar solubility as in the bulk formulations was obtained for fenofibrate and cannabidiol. Clofazimine yielded a higher loading result in the nanodispersions than in the bulk formulation.

Analysis of pharmaceutical impurities using multi-heartcutting 2D LC coupled with UV-charged aerosol MS detection.

To overcome challenges in HPLC impurity analysis of pharmaceuticals, we developed an automated online multi-heartcutting 2D HPLC system with hyphenated UV-charged aerosol MS detection. The first dimension has a primary column and the second dimension has six orthogonal columns to enhance flexibility and selectivity. The two dimensions were interfaced by a pair of switching valves equipped with six trapping loops that allow multi-heartcutting of peaks of interest in the first dimension and also allow "peak parking." The hyphenated UV-charged aerosol MS detection provides comprehensive detection for compounds with and without UV chromophores, organics, and inorganics. It also provides structural information for impurity identification. A hidden degradation product that co-eluted with the drug main peak was revealed by RP × RP separation and thus enabled the stability-indicating method development. A poorly retained polar component with no UV chromophores was analyzed by RP × hydrophilic interaction liquid chromatography separation with charged aerosol detection. Furthermore, using this system, the structures of low-level impurities separated by a method using nonvolatile phosphate buffer were identified and tracked by MS in the second dimension.