Photochemical reaction of glucocorticoids in aqueous solution: Influencing factors and photolysis products.

Glucocorticoids (GCs), as endocrine disruptors, have attracted widespread attention due to their impacts on organisms' growth, development, and reproduction. In the current study, the photodegradation of budesonide (BD) and clobetasol propionate (CP), as targeted GCs, was investigated including the effects of initial concentrations and typical environmental factors (Cl-, NO2-, Fe3+, and fulvic acid (FA)). The results showed that the degradation rate constants (k) were 0.0060 and 0.0039 min-1 for BD and CP at concentration of 50 µg·L-1, and increased with the initial concentrations. Under the addition of Cl-, NO2-, and Fe3+ to the GCs/water system, the photodegradation rate was decreased with increasing Cl-, NO2-, and Fe3+ concentrations, which were in contrast to the addition of FA. Electron resonance spectroscopy (EPR) analysis and the radical quenching experiments verified that GCs could transition to the triplet excited states of GCs (3GCs*) for direct photolysis under irradiation to undergo, while NO2-, Fe3+, and FA could generate ·OH to induce indirect photolysis. According to HPLC-Q-TOF MS analysis, the structures of the three photodegradation products of BD and CP were elucidated, respectively, and the phototransformation pathways were inferred based on the product structures. These findings help to grasp the fate of synthetic GCs in the environment and contribute to the understanding of their ecological risks.

Root exudation of prometryn and its metabolites from Chinese celery (Apium graveolens).

Root exudates from Chinese celery (Apium graveolens) and Chinese cabbage (pak choi, Brassica chinensis) plants treated by prometryn, an herbicide, were qualitatively and quantitatively investigated and compared under hydroponic cultivation. Prometryn and its metabolites released into the nutrient solution were analyzed by ultra-performance liquid chromatograph coupled with orbitrap mass spectrometer to investigate whether this xylem-mobile herbicide is exuded from the roots. The results showed that celery and pak choi had different root exudation profiles. Celery metabolized prometryn to prometryn sulfoxide and released both compounds from the roots. In contrast, pak choi barely metabolized or actively released prometryn from the roots. The concentration of prometryn sulfoxide released from celery after 96 hr was 21 µg/L, which was nearly one-third that of released prometryn. Our results indicate that the root exudation and translocation of xylem-mobile herbicides could be significant in plants and are highly species dependent compared with phloem-mobile herbicides.

Effect of Third-Stage Heat Treatments on Microstructure and Properties of Dual-Phase Titanium Alloy.

Two-phase TC21 titanium alloy samples were solution-treated at 990 °C (ß phase zone) and cooled by furnace cooling (FC), air cooling (AC), and water quenching (WQ), respectively. The second solution stage treatment was carried out at 900 °C (α + ß phase zone), then aging treatment was performed at 590 °C. The influence of the size and quantity of the α phase on the properties of the sample were studied. The experimental results showed as the cooling rate increased after the first solution stage treatment, wherein the thickness of primary layer α gradually decreased, and the tensile strength and yield strength gradually increased. After the second solution stage treatment, the tensile properties of samples increased due to the quantity of layers α increased. The aging treatment promoted the precipitation of the dispersed α phase and further improved the tensile strength. After the third solution stage treatments, the FC samples with more ß-phase had the best comprehensive mechanical properties.

Simultaneous determination of vanillin, ethyl vanillin and methyl vanillin in Chinese infant food and other dairy products by LC-MS/MS.

An efficient and simple method for determining vanillin, methyl vanillin and ethyl vanillin in milk and dairy products was developed using a liquid-liquid extraction (LLE) procedure coupled to high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Different extraction procedures were tested and optimised by spiking three vanillin compounds into a blank matrix in which none of any food additives were detected, and the extraction with acetonitrile solution and n-hexane as cleaning sorbent allowed an efficient recovery of 87.6-101.7% with RSDs less than 5%. The limit of detection (LOD) ranged from 6.2 to 20.1 µg/kg. High sensitivity, accuracy and selectivity were found for the in-house validated method, which can eliminate the interferences from complicated matrices effectively, and fulfil the quality criteria for routine laboratory application for real samples. The developed method was then finally applied to screen the three analytes in 65 milk and dairy products including infant formula milk powders from local markets to check for compliance with Chinese Regulation. Concentrations of the total vanillin and ethyl vanillin ranged from 0.0323 to 246.3 mg/kg, which is within the limits of Chinese regulations.

[Simultaneous determination of 38 limited colorants in cosmetics by high performance liquid chromatography].

A method has been established for the simultaneous determination of 38 limited colorants in cosmetics by high performance liquid chromatography (HPLC). The samples were extracted by ultrasonic with tetrahydrofuran, methanol, ammonium acetate solution as extraction solvents. After centrifugation, nitrogen blow and redissolved in turn, the extracts were separated on an Agilent zorbax SB-Aq column (150 mm x 3.0 mm, 3.5 µm) using a gradient elution program with acetonitrile and 30 mmol/L ammonium acetate containing 0.075% (v/v) formic acid as mobile phases. The detection wavelengths were set at 254, 416, 484, 514, 590 and 620 nm. The linear ranges of the 38 target compounds were all in the range of 1 to 10 mg/L with correlation coefficients more than 0.999. The limits of quantification (LOQs) for the 38 colorants were in the range of 5-50 µg/g. The average recoveries at two spiked levels ranged from 93.2% to 107.6% with the relative standard deviations (RSDs) less than 10% (n = 6). This method is accurate, simple, sensitive and reliable, and can be used for the analysis of the 38 limited colorants in cosmetics.

[Measurement of 11 benzophenone ultraviolet-filters in cosmetics by high performance liquid chromatography].

A sample preparation and analytical method with liquid-liquid extraction (LLE) and high performance liquid chromatography (HPLC) was developed to detect 11 benzophenone ultraviolet-filters in cosmetics. The target compounds were extracted by the mixed solutions of tetrahydrofuran (TH)/methanol/water or dichloromethane/water at proper ratios. The extracts were centrifuged and filtered to remove matrix compounds, and then analyzed by HPLC. The separation of analytes was carried out on a Diamonsil-C18 column (150 mm x 4.6 mm, 5 µm) with 0.1% (v/v) formic acid aqueous solution (containing 10 mmol/L ammonium acetate) as mobile phase A and methanol containing 0.1% (v/v) formic acid as mobile phase B. The spiked recoveries of the method (n = 7) were 93.4%-103.8% with the relative standard deviations of 0.1%-4.2%. The limits of detection (LODs) were in the range of 4.0-30 µg/g and the limits of quantitation (LOQs) ranged from 15 to 100 µg/g. The method was applied to the determination of 42 cosmetic samples randomly purchased from the supermarket in Dalian. Five benzophenone series were always detected, in which the content of benzophenone-3 in sunscreen cream and the content of benzophenone-2 in perfume were very high and reached 2 785 µg/g and 2 106 µg/g, respectively. The results showed that the developed method is efficient, reliable and sensitive, which can be applied to the determination of benzophenones in cosmetics.

[Determination of 17 ultraviolet-filters in cosmetics by high performance liquid chromatography].

An optimum HPLC method was developed for the simultaneous determination of 17 ultraviolet (UV)-filters in cosmetics, in which two UV-filters were included more than the 15 UV-filters specified in the Hygenic Standard for Cosmetics (HSC). Our research focused on the optimization of sample processing, chromatographic column, and mobile phase, in order to avoid the use of highly corrosive solvents as tetrahydrofuran (THF) and perchloric acid, which are used in the HSC method. The cosmetic sample was extracted by the mixed solution of THF/methanol/water. The target chemicals were separated on a Phenomenex PFP column (250 mm x 4.6 mm, 5 microm) in gradient elution mode using water solution (containing 0.1% formic acid) and 20% methanol solution of isopropyl alcohol (containing 0.1% formic acid) as mobile phases. The detection wavelengths were set at 311 nm and 280 nm. The results of recovery tests and samples analysis indicated that the developed method can be used to simultaneously determine the 17 UV-filters in cosmetics, accurately and reliably. It is a more universal analytical method than the HSC method because common HPLC pump without improvement to adapt to corrosive THF, can be used. At the same time, the quantitative accuracy can be improved because baseline separation of all target chemicals was achieved

[Simultaneous determination of 7 rhodamine dyes in hot chili products by high performance liquid chromatography-tandem mass spectrometry].

A credible method was developed for the simultaneous determination of 7 rhodamine dyes in hot chili products based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The samples were extracted with hexane or methanol-water (1:1, v/v) and then cleaned up by a solid phase extraction cartridge. The target analytes were separated on an SB-C18 column with gradient elution using acetonitrile and water (containing 0.1% (v/v) formic acid for both) as mobile phases. The identification and quantification were achieved by using ESI-MS/MS in positive ion mode and with multiple reaction monitoring (MRM). The linear ranges were from 0.0005 to 1.0 mg/L with the correlation coefficients (r2) above 0.997 for all the 7 rhodamine dyes. The limits of detection (LOD) in chili powder and chili oil were from 0.21 to 51 microg/kg and 0.19 to 25 microg/kg, respectively. The relative standard deviations of intra-day and inter-day were both less than 20%. The recoveries of the method were between 85.0% and 106%. The method is simple, rapid, highly sensitive and suitable for the simultaneous determination of 7 rhodamine dyes in foods.

[Simultaneous determination of pantothenic acid and D-panthenol in cosmetics by high performance liquid chromatography].

A high performance liquid chromatographic method (HPLC) and sample pretreatment method were developed for the simultaneous determination of pantothenic acid (vitamin B5) and D-panthenol (provitamin B5) in cosmetics with different matrices (including of creams, lotions, aqueous cosmetics, oily cosmetics, wax-based cosmetics, nail polish etc). A liquid-liquid extraction system composed of water and water-immiscible solvent was used to preliminarily separate the target components from other oil-soluble components and surfactants in cosmetics, then macromolecular water-soluble matrices in cosmetics were removed by coprecipitation with potassium ferrocyanide-zinc acetate precipitating agent, and then under acid condition, pantothenic acid and D-panthenol were enriched on a C18 solid-phase extraction sorbent. After the removal of other water-soluble impurities, target components were eluted by 40% methanol and then separated and quantitatively analyzed by high performance liquid chromatography with external standard method. Good linear relationship was achieved in the concentration range of 0.1-10 microg/g for pantothenic acid and D-panthenol. The linear correlation coefficients were separately 0.998 9 and 0.999 6. The average recoveries of the target components in cosmetics were more than 90%. Limit of detection of the method was 30 microg/g and the limit of quantification was 100 microg/g. This method can be used to simultaneously determine pantothenic acid and D-panthenol in cosmetics. The results are accurate and reliable.

Separation of compounds interacting with liposome membrane in combined prescription of traditional Chinese medicines with immobilized liposome chromatography.

Immobilized liposome chromatography (ILC), the stationary phase of which has been regarded as a mimic biomembranes system was used to separate and analyze compounds interacting with liposome membrane in Danggui Buxue decoction, a combined prescription of traditional Chinese medicines (CPTCMs), and its compositions Radix Astragli and Radix Angelica Sinensis. More than 10 main peaks in the extract of Danggui Buxue decoction were resolved on the ILC column, suggesting that more than 10 components in the prescription have significant retention on ILC column. Ligustilide, astragaloside IV and formononetin, three main bioactive ingredients in Danggui Buxue decoction, were found to have relatively significant, while ferulic acid, another bioactive ingredient in the prescription, relatively weak retention on ILC column. Effects of the eluent pH and amount of immobilized phosphatidylcholine (PC) on separation of interactional compounds in the extract of Danggui Buxue decoction were also investigated. It was found that these two factors strongly affected the retention of some interactional compounds. In addition, the fractions partitioned with different solvents from water extract of this combined prescription were evaluated with this ILC column system.

Unilamellar liposomes covalently coupled on silica gel for liquid chromatography.

Silica gel was used as a support for the covalent coupling of liposomes, which could overcome drawbacks of soft gel beads in column efficiency and separation speed. The influences of the concentration of added dimethylaminopyridine and reaction time on the chloroformate activation reaction of silica gel were investigated. Temperature and pH for covalent coupling of liposomes on the activated silica gel were also optimized. Experimental results indicated that the stability of the covalently coupled liposome columns was obviously superior to that of the noncovalently coated liposome columns but the selectivity of both columns was basically identical. Separation and analysis of a crude extract of a traditional Chinese medicine Ligusticum Wallichii and a mixture of small peptides on both columns further support this conclusion.

Screening and analysis of permeable compounds in Radix Angelica Sinensis with immobilized liposome chromatography.

Immobilized liposome chromatography (ILC) was used to screen and analyze permeable compounds in traditional Chinese medicines (TCMs), testing extracts from Radix Angelica Sinensis. More than 10 peaks were resolved based on their interactions with the ILC stationary phase, a system which mimics biomembranes; this means that more than 10 components in Radix Angelica Sinensis extract have significant retention on an ILC column. Two of them, ligustilide and ferulic acid, were identified from their MS spectrum and with standard samples. A possible molecular structure of another component retained on ILC was also preliminarily identified as 3-butylidene-4,5-dihydro-2(1,3H)-1-isobenzofuranol according to its MS spectrum, hydrophobicity and 1H NMR spectrum. Of all detected components, ligustilide had the best penetration ability through the biomembrane. The effects of pH, column temperature, and ionic strength on the chromatography of methanolic extracts of Radix Angelica Sinensis were also investigated. It was found that the separation selectivity on ILC is strongly affected by the eluent pH, but only slightly by the column temperature and ionic strength.

High-performance affinity chromatography for characterization of human immunoglobulin G digestion with papain.

Reactive continuous rods of macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) were prepared within the confines of a stainless steel column. Then papain was immobilized on these monoliths either directly or linked by a spacer arm. In a further step, a protein A affinity column was used for the characterization of the digestion products of human immunoglobulin G (IgG) by papain. The results showed that papain immobilized on the monolithic rod through a spacer arm exhibits higher activity for the digestion of human IgG than that without a spacer arm. The apparent Michaelis-Menten kinetic constants of free and immobilized papain, K(m) and V(max), were determined. The digestion conditions of human IgG with free and immobilized papain were optimized. Comparison of the thermal stability of free and immobilized papain showed that the immobilized papain exhibited higher thermal stability than the free enzyme. The half-time of immobilized papain reaches about a week under optimum pH and temperature conditions.

[Preparation of molecularly imprinted chiral monolithic column and its applications for separation of diastereomers].

A cinchonine imprinted chiral monolithic column was prepared for the separation of the diastereomers of cinchonine and cinchonidine by in-situ molecular imprinting technique. This type of molecularly imprinted column can be prepared only by a single-step procedure. In order to improve the selectivity and efficiency, a new in-situ molecular imprinting polymerization system was introduced by adopting porogenic solvents of toluene and 1-dodecanol with relatively low polarity and appropriate ratios of polymerization mixture. Diastereomers of cinchonine and cinchonidine were fully separated both under isocratic and gradient elutions on the chiral monolithic column. The broad peak shown in isocratic elution could be improved in gradient elution. Effects of mobile phase composition, flow rate and temperature on retention and separation factor were investigated. Due to the large throughput pores in the chiral monolithic column, low backpressure was observed during the separation process and a separation factor of 3.18 was obtained at 1.0 mL/min. The increase of temperature could improve the separation factor and a maximum separation factor of 5.40 was obtained at 60 degrees C.