Algorithm for in vitro Sun Protection Factor based on transmission spectrum measurement with concomitant evaluation of photostability

In the in vitro evaluation of Sun Protection Factor (SPF), the photostability of the ultraviolet (UV) filters can have a major impact, especially for high-SPF formulations, but is generally not taken into consideration. In this study, we present a UV transmission spectrum measurement system utilizing a high-sensitivity UV photomultiplier tube with concomitant evaluation of photostability. We have developed an algorithm to estimate SPF in vitro by converting the amount of UV light transmission through the sunscreen layer into cumulative relative erythema effectiveness to obtain one minimal erythema dose. Thus, the algorithm uses the same endpoint as in vivo SPF methods, but with a photomultiplier tube as the detector instead of skin. The values obtained showed an excellent correlation with in vivo SPF values, even for high-SPF sunscreens exceeding SPF 50. This method should be suitable as an in vitro SPF testing method for regulatory purposes.     

Improved determination of milk oligosaccharides using a single derivatization with anthranilic acid and separation by reversed-phase high-performance liquid chromatography

An improved analytical scheme for human milk neutral oligosaccharides determination was developed, in which, the oligosaccharides were pooled in two fractions (pools 1 and 2) after gel filtration, and then were quantitatively derivatized with a single fluorescent reagent, 2-anthranilic acid. Separation was by reversed-phase HPLC on an ODS-100Z column with a mobile phase of 50 mM ammonium acetate pH 4.0 and 150 mM citrate buffer pH 4.5 and monitored by a fluorescence detector at 360 nm excitation and 425 nm emission wavelengths. The method improved on the separation of neutral tetra- and hexa-saccharide isomers, namely, lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT) as well as of lacto-N-difucohexaose I (LNDFH I) and lacto-N-difucohexaose II (LNDFH II). The separation of trisacccharide isomers, 3-fucosyllactose (3-FL) and 2′-fucosyllactose (2′-FL) was also successful. Limits of detection and quantification were in the range of 1–10 ng/l and 2–30 ng/l, respectively. The methods’ accuracy was good with its precision at <20% RSD and <1% RSD, respectively, for oligosaccharide concentration and retention time. The recoveries were in the range of 80–100%. This method was successfully applied to the separation and determination of representative neutral oligosaccharide contents in Samoa women milk.     

Nanoprecipitation for ultrafiltration membranes

Polymer nanoparticles are readily obtainable by rapidly mixing a dilute polymer solution and a poor solvent. The nanoparticles of poly(vinylphenol), poly(vinylidene fluoride), and emeraldine base polyaniline prepared by nanoprecipitation become sticky when their diameters decrease down to a few tens of nanometers, and such polymer nanoparticles spontaneously assemble into rigid fractal networks of the nanoparticles. By filtering these fibrous nanoparticle networks on a microfiltration membrane, ultrafiltration membranes with a thin free‐standing filter cake layer made of nanoparticles are obtainable. The nanoparticle membranes are robust at least up to the applied pressure of 2 MPa and can separate 99% of 10 nm Au nanoparticles from the aqueous dispersion at the flux of more than 1835 L m^?2 h^?1 even at very low pressure difference of 0.08 MPa. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 615–620     

New solvent for polyrotaxane. II. Dissolution behavior of polyrotaxane in ionic liquids and preparation of ionic liquid‐containing slide‐ring gels

The dissolution behavior of polyrotaxanes, consisting of α‐cyclodextrin and poly(ethylene glycol), with different molecular weights (2000 and 35,000) was investigated. Halogen‐containing ionic liquids, such as chlorides or bromides, were found to be good solvents for polyrotaxanes, regardless of their cations. Dissolution required a high temperature (above 90 °C), while intensive heating over 105 °C seemed to cause decomposition of the polyrotaxane. The discovery of new solvents for polyrotaxane was applied in the preparation of ionic liquid‐containing slide‐ring gels (SR gels), that is supramolecular networks of polyrotaxane swollen with ionic liquids, using a devised “non‐drying” technique accompanied by solvent exchange. Significant swelling of the SR gels with the ionic liquids was confirmed by dynamic mechanical measurements. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1985–1994, 2006     

A Rapid Sample Preparation Procedure Using MonoSpin CBA and Amide Columns for Tetrodotoxin Detection in Serum and Urine Using LC–MS/MS Analysis

Clinical diagnosis of tetrodotoxin (TTX) poisoning can be difficult because of the lack of characteristic morphological findings and a screening test, such as an immunoassay. Here, we present a fully validated method for the analysis of TTX in serum and urine. In this method, serum and urine samples were extracted using MonoSpin CBA or amide columns, followed by LC–MS/MS analysis. The TTX was eluted from the column by 0.1 mL of 10 % acetic acid solution, and was directly injected into LC–MS/MS. An Agilent 1200 HPLC system equipped with a HILIC separation column (Zorbax HILIC Plus 2.1 × 100 mm, 3.5 μm) was used for isocratic elution, with a mobile phase of 10 mM ammonium formate with formic acid (95:5, v/v), along with 5 mM trifluoroacetic acid and 2 % acetonitrile. TTX was detected with an Agilent 6410 mass spectrometer utilizing positive electrospray ionization and multiple reaction monitoring. Limits of quantification for serum and urine were established to be 1 and 0.5 ng mL^?1, respectively. Limits of detection for serum and urine were 0.5 and 0.25 ng mL^?1, respectively. Intra-day and inter-day precision varied from 1.5 to 8.5 %. The recovery was >86.5 % for both matrices. In this method, the sample preparation process prior to injection into the LC–MS/MS takes approximately 10–15 min, which reduces the extraction time to one-tenth of that of previous methods. The application of this method was further verified by analysis of biological materials from a patient suffering from puffer fish poisoning.     

Identification and Quantification of Aconitines and Colchicine in Serum,Urine, and Plants using MonoSpin C18 and LC-MSMS

Chromatographia - Aconitum and Colchicum are known to be highly toxic plants based on their respective toxins, namely aconite and colchicine. Aconite and colchicine poisoning generally occurs...     

Rapid Determination of Polar and Non-Polar Pesticides in Human Serum, Using Mixed-Mode C-C18 Monolithic Spin Column Extraction and LC–MS/MS

Organophosphates and carbamates are pesticides whose acute toxicities are caused by inhibition of acetylcholinesterase. A liquid chromatography–mass spectrometry/mass spectrometry method was developed and validated for the quantification of 16 organophosphate and carbamate insecticides in human serum. Nonpolar and polar pesticides were simultaneously extracted from serum samples using a simple and fast monolithic spin column procedure using mixed-mode C-C₁₈ cartridges. Recovery was achieved in the range 11.9–99.2 %. Chromatography was carried out on an InertSustain^® C₁₈ HP 3 μm analytical column with gradient elution. Mass spectrometric analysis was performed using an Agilent 6410 Triple Quad Tandem mass spectrometer coupled with an electrospray ionization source in the positive ion mode. The assay was validated over a large concentration range and the limits of detection for all compounds ranged from 0.1 to 50 ng mL^?1. The precision for both intra- and inter-day determination of all analytes was found to be acceptable (< 12.9 %) and no significant matrix effect was observed. The developed method was effectively applied to clinical samples from patients presenting at hospital with symptoms of acute intentional organophosphate or carbamate poisoning, demonstrating its applicability to diagnostic applications.     

Rapid Determination of Polar and Non-Polar Pesticides in Human Serum,Using Mixed-Mode C-C18 Monolithic Spin Column Extraction and LC–MS/MS

Organophosphates and carbamates are pesticides whose acute toxicities are caused by inhibition of acetylcholinesterase. A liquid chromatography–mass spectrometry/mass spectrometry method was developed and validated for the quantification of 16 organophosphate and carbamate insecticides in human serum. Nonpolar and polar pesticides were simultaneously extracted from serum samples using a simple and fast monolithic spin column procedure using mixed-mode C-C₁₈ cartridges. Recovery was achieved in the range 11.9–99.2 %. Chromatography was carried out on an InertSustain^® C₁₈ HP 3 μm analytical column with gradient elution. Mass spectrometric analysis was performed using an Agilent 6410 Triple Quad Tandem mass spectrometer coupled with an electrospray ionization source in the positive ion mode. The assay was validated over a large concentration range and the limits of detection for all compounds ranged from 0.1 to 50 ng mL⁻¹. The precision for both intra- and inter-day determination of all analytes was found to be acceptable (< 12.9 %) and no significant matrix effect was observed. The developed method was effectively applied to clinical samples from patients presenting at hospital with symptoms of acute intentional organophosphate or carbamate poisoning, demonstrating its applicability to diagnostic applications.

     

Monolithic Spin Column Extraction and GC-MS for Simultaneously Detecting Nine Cold Medication Compounds and the Drug Bromoisovaleryl Urea in Human Serum

We describe and validate a gas chromatography-mass spectrometry (GC-MS) method for the simultaneous quantitative detection of nine cold medication compounds and bromoisovaleryl urea an over-the-counter cold medication, in human serum; the nine compounds are acetaminophen (APAP), codeine, dihydrocodeine, three ephedrines, ethenzamide, ibuprofen, and salicylic acid. After adding the internal standard, acetaminophen-d ₄ (APAP-d ₄), compounds were extracted from the serum samples in the monolithic spin column. The extracted samples were evaporated to dryness. The residues were derivatized with acetonitrile and N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide + 1% tert-butyldimethylchlorosilane, which were subjected to GC-MS analysis. The limit of quantification (LOQ) was 0.005–0.1 μg mL^?1. The calibration curves were linear (r ² > 0.995) in the concentration range from the LOQ to 10 μg mL^?1. The intra- and inter-day variations, determined by the measurement of quality control samples at three tested concentrations, showed acceptable values. The lower limit of detection was between 0.005 and 0.05 μg mL^?1. Mean recoveries from the serum samples were between 2.5 and 73.8%. This procedure was applied in the toxicological analysis of an intoxicated patient who was responsible for a traffic accident.