Formic Acid Aqueous Solution Research Articles

Content change of main components in processed Ligustrum lucidum fruits of different processing time and their characteristic quality standard based on UPLC technology

To investigate the dynamic change law of the main components in Ligustri Lucidi Fructus during the wine-steaming process and attempt to establish the characteristic quality standard of wine-steamed Ligustri Lucidi Fructus by determining the content of salidroside and specnuezhenide using Ultra Performance Liquid Chromatography (UPLC) technology at different processing time points (12, 15, 18, 21, 24 h). The chromatographic separation was performed on Waters Acquity UPLC®BEH C₁₈ column (2.1 mm×50 mm, 1.7 μm) with acetonitrile and 0.2% formic acid aqueous solution as the mobile phase for gradient elution; and the detection wavelength was set at 280 nm; the flow rate was 0.5 mL·min⁻¹, and the column temperature was set at 40 °C. The results showed that the two components were well separated in the above conditions. The salidroside and specnuezhenide showed a good linear relationship within the range of 10.19-326 ng and 49.53-1 585 ng, respectively. Their average recovery was 103.4% and 101.7% with RSD of 0.81% and 0.79%, respectively. With the extension of processing time, the content of specnuezhenide was decreased, while salidroside was gradually increased. For the 27 batches of Ligustri Lucidi Fructus, the content of salidroside was between 0.042 5% and 0.192 4%, and that of specnuezhenide was between 0.829 7% and 5.218 0%. While for the 25 batches of wine-steamed Ligustri Lucidi Fructus, the content of the first one was between 0.229 2% and 1.045 8%, and the latter one was between 0.743 8% and 3.645 4%. As compared with Ligustri Lucidi Fructus, the ratio of specnuezhenide to salidroside was significantly decreased in the wine-steamed Ligustri Lucidi Fructus. According to the experimental results, the quality standard of Ligustri Lucidi Fructus is tentatively fixed as follows: the content of specnuezhenide shall not be less than 0.80%, and the ratio of specnuezhenide content/salidroside content (Sp/Sa) should not be smaller than 15. As for the wine-steamed ones, the content of salidroside should not be less than 0.20%, and specnuezhenide content should not be less than 0.70%; Sp/Sa should not be greater than 8. The method established in this study is simple and reliable, which could be used for the content detection of salidroside and specnuezhenide in Ligustri Lucidi Fructus samples. The characteristic quality standard established in this study could be used to distinguish the Ligustri Lucidi Fructus and wine-steamed Ligustri Lucidi Fructus.

Pharmacokinetic characteristics of fourteen main components of Gegen Qinlian Decoction in rats

A specific and selective UPLC-MS/MS method was developed and validated for the simultaneous determination of isoflavonoids(3'-hydroxy puerarin, puerarin, daidzin, daidzein, genistin, genistein), flavonoids (baicalin, baicalein, wogonoside, wogonin, liquiritin)and alkaloids(berberine, jatrorrhizine, palmatine)(14 bioactive compounds) of Gegen Qinlian Decoction(GQD) in plasma. The pharmacokinetics characteristics of 14 bioactive compounds were study after oral administration of GQD at a single dose to rats. Prednisolone was used as the internal standard of liquiritin, and naringin was used as the internal standard of the other thirteen analytes. After the plasma samples were processed by precipitation protein method, the constituents and internal standards were gradient eluted by using a Zorbax SB-18 column with a mobile phase of acetonitrile(A) and 0.1% formic acid aqueous solution(B) using a gradient elution of 0-2.5 min, 15%-30% A; 2.5-3.5 min, 30%-35% A; 3.5-5.0 min, 35%-40% A; 5.0-9.0 min, 40%-60% A; 9.0-11.0 min, 60%-15% A, and the flow rate was 0.4 mL·min⁻¹. The auto sampler was conditioned at 25 °C and the sample injection volume was 5 μL. A mass spectrometry was applied with electrospray ionization (ESI) ion source in the positive and negative ion multiple reaction monitoring(MRM) mode. All pharmacokinetic parameters were processed by non-compartmental analysis with DAS 3.2.2 software. The results showed that the linear correlation coefficient of the 14 components were all greater than 0.99, indicating that the method had good linearity in their respective concentration ranges. Post-preparative stability (25 °C, 24 h), short-term stability(25 °C, 12 h), long-term stability (-20 °C, 7 d), and freeze and thaw stability (3-cycles) of the fourteen constituents were examined to evaluate the stability of methodology. The results of the inner and inter-day relative standard deviations were both less than 10%, indicating legitimate precise and accuracy to the requirement of biological sample analysis. The assay method is proved to be sensitive, accurate and convenient. It can be applied to the pharmacokinetic study of the fourteen analytes. The kinetic parameters of the related drugs were calculated according to the blood concentration of the 14 components. The results showed that the MRT0-t of the isoflavones and flavonoids was 7.5-11.8 h, T1/2z were mainly in 11.0-29.7 h, and the AUC0-t flavonoids were larger than the isoflavones. The MRT0-t of alkaloids were between 4.3-7.2 h, T1/2z were 1.0-5.0 h, AUC0-t were less than flavonoids and isoflavones. The results suggest that flavonoids and isoflavones have a high concentration of blood and long time of action, which are beneficial to the anti-inflammatory and antipyretic effects. The concentration of alkaloids in the body is low and the time of action is short, and it may play its bacteriostasis in the intestinal tract.

Size Exclusion Coupled to Reversed Phase Liquid Chromatography for the Characterization of Cranberry Products

A combination of solvent extraction, size exclusion purification, and reversed-phase liquid chromatography with UV absorption and fluorescence detection was here used for the determination of flavan-3-ols and related oligomeric compounds in cranberry products. The method relied on robust, simple, and inexpensive instrumental equipment present in most of routine analytical laboratories. Sample extracts in methanol/water/hydrochloric acid solution (60:39:1, v/v/v) were subjected to size-exclusion chromatography (SEC) using Sephadex LH-20 as the sorbent to separate simple phenolic and oligomeric components. As a novel aspect of this work, the implementation of the SEC process in a reusable packed column was practically and economically highly advantageous. Fractions were analyzed by reversed-phase chromatography using a C18 core-shell analytical column and 0.1% formic acid aqueous solution and methanol as the components of the mobile phase. Chromatograms were recorded by UV absorption spectroscopy at 280 nm and by fluorescence spectroscopy at λex 280 nm/λem 347 nm. The method was applied to the determination of flavan-3-ols in various cranberry samples. Catechin, epicatechin, and procyanidins A2 and B2 were found in different amounts depending on the cranberry varieties.

Pharmacokinetics of eight constituents in rat plasma after oral administration of Modified Xiaochaihu Granules for gastric ulcer based on UPLC-MS/MS

An ultra-performance liquid chromatography-tandem mass spectrometric method (UPLC-MS/MS) was developed in this study to simultaneously determine the contents of eight effective constituents in rat plasma, including baicalin, wogonoside, baicalein, liquiritin, glycyrrhizic acid, berberine hydrochloride, saikosaponin a and saikosaponin d in plasma of gastric ulcer rats, and investigate the pharmacokinetics of Modified Xiaochaihu Granules. Chromatographic separation was conducted on Zorbax SB-C₁₈ column (2.1 mm×100 mm, 1.8 μm) with acetonitrile -0.1% formic acid aqueous solution as the mobile phase for gradient elution, at a flow rate of 0.4 mL·min⁻¹ and column temperature of 40 °C. Detection was performed in the multiple reaction monitoring (MRM) mode with ESI ion source. All calibration curves showed good linearity (r>0.996) over a wide concentration range for all constituents. RSDs of intra-day and inter-day precision were all within 15% and the extraction recoveries of all the constituents were in the range of 81.92% to 104.8%. The time to peak (tmax) of these eight constituents was (2.69±2.02), (5.17±2.04), (0.25±0), (0.83±0.26), (0.92±0.20), (0.92±0.20), (0.58±0.20), and (0.083±0) h, respectively; the half-life (t1/2) of them was (7.85±0.34), (10.16±2.21), (6.79±0.21), (8.32±0.48), (11.05±1.78), (11.56±3.46), (15.30±1.84), and (5.54±1.91) h, respectively; the peak concentration (Cmax) of them was (55.02±1.67), (213.66±4.62), (62.61±0.69), (68.43±1.42), (62.22±0.39), (30.17±1.89), (61.79±4.81), and (38.02±1.75) μg·L⁻¹, respectively. This established method is simple and accurate with good repeatability and strong specificity, which could provide modern experimental basis for modified Xiaochaihu granules in clinical treatment of gastric ulcer.

A validated LC-MS/MS method for the determination of specnuezhenide and salidroside in rat plasma and its application to a pharmacokinetic study.

The aim of this study was to establish and validate a rapid and sensitive LC-MS/MS method for the simultaneous determination of specnuezhenide and its bioactive metabolite salidroside in rat plasma. Protein precipitation was carried out and the analytes were separated on a Waters Acquity UPLC HSS T3 column (2.1 × 100 mm, 1.8μm). A mobile phase consisting of acetonitrile and 0.1% formic acid aqueous solution was used for elution under gradient conditions at a flow rate of 0.4 mL/min. Quantification was performed in the negative multiple reaction monitoring mode with precursor-to-product transitions at m/z 685.2 → 453.1 for specnuezhenide, m/z 229.3 → 119.0 for salidroside and 493.2 → 147.1 for the internal standard. The method showed good linearity, accuracy, precision and stability in the range 0.5-500.0 ng/mL for specnuezhenide and salidroside. The values of the matrix effect were within the range of 100.02-111.87% for both analytes, while the mean extraction recovery was within the range 64.19-78.26%. The intra- and inter-day precisions (RSD) were <13.49% and the accuracy (RR) ranged from 93.59 to 102.24%. This study was successfully utilized for the pharmacokinetic study of specnuezhenide in rats after oral and intravenous administration. The oral bioavailability of specnuezhenide was 1.93%.

Multiresidue determination of 21 pharmaceuticals in crayfish (Procambarus clarkii) using enzymatic microwave-assisted liquid extraction and ultrahigh-performance liquid chromatography-triple quadrupole mass spectrometry analysis

In this paper, a multiresidue enzymatic-microwave assisted extraction prior to ultrahigh performance liquid chromatography and triple quadrupole mass spectrometry analysis has been developed for the determination of 21 pharmaceuticals in crayfish (Procambarus Clarkii) samples. The analysed compounds corresponding to 6 therapeutic families were: fluoroquinolones (ciprofloxacin, danofloxacin, enrofloxacin, flumequine, gatifloxacin, grepafloxacin, marbofloxacin and norfloxacin); tetracyclines (chlortetracycline and oxytetracycline); sulphonamides (sulfamethoxazole, sulfadiazine, sulfamethazine, sulfamerazine); penicillins (amoxicillin); anfenicols (chloramphenicol, thiamphenicol and florfenicol); non-steroidal anti-inflammatory drugs (ibuprofen and salicylic acid) and trimethoprim an antibiotic that is frequently co-administered with sulfamethoxazole. The main factors affecting the extraction efficiency were optimized for 0.5 g of lyophilized tissue. The enzymatic microwave extraction was carried out using an extraction time of 5 min with 5 mL of an acetonitrile: water (1:1, v/v) mixture, 50 μL of Proteinase-K solution and 5 μL of formic acid at 50 W. After centrifugation, the liquid extract was evaporated and the residue was reconstituted with 1 mL of 0.1% (v/v) formic acid.Chromatographic and MS parameters, in both positive and negative ionization modes, were also optimized. The mobile phase used consisted on a mixture of 0.1% (v/v) formic acid aqueous solution and acetonitrile in gradient elution mode at a 0.4 mL min−1 flow rate. The proposed method was validated and recoveries over 70% were obtained for all the analytes with detection limits in the 0.6-12 ng g−1 range. The proposed method was successfully applied to crayfish specimens from Doñana National Park, Spain.

Quality control of Dandeng Tongnao Ruanjiaonang based on UPLC fingerprint combined with chemical pattern recognition

To establish the ultra performance liquid chromatography (UPLC) fingerprint of Dandeng Tongnao Ruanjiaonang and conduct a systemic, comprehensive quality evaluation of the drug by combining with a chemical pattern recognition method. In this study, Waters UPLC ultra-high performance liquid chromatography instrument and ACQUITY UPLCHSS T3 chromatographic colum n were employed to perform the separation with acetonitrile-0.1% formic acid aqueous solution as the mobile phase for gradient elution; and the detection wavelength was set at 256 nm to establish the UPLC fingerprint of 10 batches of Dandeng Tongnao Ruanjiaonang. Then, the further quality assessment of the drug was carried out by similarity evaluation, Cluster Analysis(CA), Principal Component Analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA). Finally, 77 peaks were recognised as common peaks in the fingerprint, and 15 peaks of them were identified using standard references. The similarity value of these 10 batches of drugs was all above 0.960, indicating a relatively stable quality. But minor differences were still discovered between the batches of the drug by CA and PCA. Finally, 6 common peaks were recognised as the quality makers using OPLS-DA method. The analysis method established in this study was scientific, accurate, reliable and simple; fingerprint combined with chemical pattern recognition technique can be used to systematically and comprehensively evaluate the drug quality of Dandeng Tongnao Ruanjiaonang; what's more, it could also provide a reference for the quality control of traditional Chinese medicine and its preparations at the same time.

Releasing Hydrogen at High Pressures from Liquid Carriers: Aspects for the H2Delivery to Fueling Stations

Hydrogen fueling stations require multiple stages of compression to achieve the pressure needed to refuel hydrogen fuel cell electric vehicles at 700 bar. The physical compression equipment constitutes a large share of the total investment cost of hydrogen fueling stations. Hydrogen carriers, i.e., materials that carry either physisorbed or chemisorbed H2, provide an alternate approach to transport and deliver higher densities of hydrogen to the fueling station at lower pressures. Additionally, some liquid phase hydrogen carriers (LPHCs) are defined by thermodynamic properties that allow H2 release at elevated pressure, thus providing an opportunity to reduce the number of compressors at the fueling station. This study compares a series of LPHCs and evaluates the approach of using aqueous solutions of formic acid (FA) to deliver high volumetric densities of H2 to fueling stations and provide a first step of compression. While hydrogen release from most liquid carriers will provide hydrogen slightly above ...

Identification and characterization of major constituents in Juglans mandshurica using ultra performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-ESI-Q-TOF/MS)

The present study was designed to identify and characterize the major constituents in Juglans mandshurica Maxim. A simple, efficient and sensitive ultra performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-ESI-Q-TOF/MS) method was established and validated under positive and negative ion modes. The separation was performed on a Waters ACQUITY UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 μm) by gradient elution with a mobile phase (Phase A: 0.1% aqueous formic acid solution, Phase B: 0.1% formic acid acetonitrile solution). A total of 165 compounds were rapidly selected by Targeted and Non-Targeted Peak Finding approaches, and then tentatively identifled by comparing with reference substances or inferred through mass spectrometry fragment ion analysis and literature data. These compounds included 68 naphthalenequinones, 20 diarylheptanoids, 29 flavonoids, 20 triterpenes, and 28 phenolic acids. In conclusion, the present study provided an effective approach to identifying components in complex matrices of herbal medicines such as Juglans mandshurica Maxim.

Simultaneous Determination of Paracetamol and Chlorzoxazone in Their Combined Pharmaceutical Formulations by Reversed-phase Capillary Liquid Chromatography Using a Polymethacrylate Monolithic Column.

Recently, analytical separation techniques have the potential toward green approaches to reduce the environmental impact. This study focuses on the development of an analytical method for the determination of paracetamol and chlorzoxazone in their pharmaceutical combination. The separation was achieved using a home-made capillary column (0.10 mm i.d. × 200 mm length) filled with porous cross-linked hexyl polymethacrylate as monolithic stationary phase. The method proved to be simple, fast, sensitive, efficient, cost-effective and green approach due to the combination of the amazing properties of a monolithic material and a miniaturized liquid chromatography, which would be considered as a step toward reducing the analytical costs and the environmental impact of chromatographic applications. Both components were detected using a 3-nL nano-UV cell fixed at 270 nm wavelength. The optimized mobile phase was composed of 1% aqueous formic acid solution and acetonitrile at 40:60 ratio, 1.0 μL/min flow rate, 4.0 nL injection volume and 50°C column temperature. Under the optimized conditions, paracetamol and chlorzoxazone have been separated in about 6.5 min with chromatographic resolution of 2.37. The prepared column and the analysis method was fully validated and compared with other reported works. All findings allow to conclude that the prepared column and proposed method are applicable for quality control and routine analysis of the two drugs.

Simultaneous determination of six bioactive saponins from Rhizoma Panacis Japonici in rat plasma by UHPLC-MS/MS: Application to a pharmacokinetic study

A specific, sensitive and rapid ultra high performance liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) method was developed and validated for simultaneous determination of six major bioactive constituents in Rhizoma Panacis Japonici (RPJ), including oleanolic acid-type chikusetsusaponin V, IV, hemsgiganoside B, damarane-type ginsenoside Rb1, Rg1 and Re in rat plasma, using estazolam as the internal standard (IS). Plasma samples were pretreated with methanol/acetonitrile (1:1, V/V) for protein precipitation. Chromatographic separation was performed on an Agilent Eclipse Plus C18 column, using a gradient mobile phase consisting of methanol and 0.1% formic acid aqueous solution. A tandem mass spectrometric detection with an electrospray ionization (ESI) interface was conducted via multiple reaction monitoring (MRM) under positive ionization mode. For all the six analytes of interest, the calibration curves were linear in the concentration range of 2.00–500 ng/mL with r ≥ 0.9956. The intra- and inter-day precisions (in terms of relative standard deviation, RSD) were all below 10.2% and the accuracies (in terms of relative error, RE) were within −5.0% to 6.3% for all six analytes. Extraction recovery, matrix effect and stability data all met the acceptance criteria of FDA guideline for bioanalytical method validation. The developed method was applied to the pharmacokinetic study in rat. After oral administration of the total saponins from RPJ, six analytes were quickly absorbed into the blood and presented the phenomenon of double peaks. Among the six analytes, ginsenoside Rb1 showed slowest elimination from plasma with a t1/2z of 16.00 h, while that of the others were between 1.72 and 5.62 h. In conclusion, the developed method was successfully used to simultaneously analyze major oleanolic acid-type and damarane-type saponins of RPJ in rat plasma after oral administration.

A liquid chromatography-mass spectrometry study on the spirocyclization of ninhydrin with the aminothiols

Ninhydrin reacts with some aminothiols to form spiranes adducts whose optical and chromatographic properties have proved to be useful for chiral recognition. Liquid chromatography-mass spectrometry data along with spectroscopic analysis reveal that under certain conditions, in addition to the known single-spirane configuration, the spirothiazolidinic complexes can exist also as double- and mixed double-spiranes. The reaction was exploited to check the enantiomeric purity of two commercially available dosage form of D-penicillamine and to measure the aminothiol concentration in the urine sample from a subject under treatment with the drug. Separation of diastereoisomers was achieved on a C18 column in isocratic mode by using a mixture of an aqueous solution of formic acid (30 mmol/L)/acetonitrile (90:10, v/v) as a mobile phase. Diastereoisomers were detected by a fluorescence detector and mass spectrometer in short times and with a good resolution. Intra- and inter-assay reproducibility were under 4% with an average recovery of 98%. At a LOD of 0.01%, no evidence of the toxic distomer (l-enantiomer) was found in the biological sample and drugs.

Determination of 15 functional components in sweet potato leaves by ultra high performance liquid chromatography-tandem mass spectrometry

A method for the rapid determination of 15 functional components in sweet potato leaves by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was established. The samples were extracted with 80% (v/v) methanol aqueous solution, and then separated on a C18 column (100 mm×2.1 mm, 1.8 μm) with gradient elution. The mobile phases were acetonitrile and 0.15% (v/v) formic acid aqueous solution. The multiple reaction monitoring (MRM) mode was used to detect the molecular ion peak of each component in electrospray ionization (ESI) source and negative ion scan mode. The results showed that the good linear relationships for the 15 components were obtained with correlation coefficients (r) ranging from 0.9995 to 0.9998. The recoveries of all the components ranged from 82.2% to 131.4% with relative standard deviations of 3.6%-8.3%. The method is simple, sensitive, and is suitable for the rapid analysis of the functional components in sweet potato leaves.

LC-MS Identification of Proanthocyanidins in Bark and Fruit of six Terminalia species

Proanthocyanidins (PAs) are the most important and valuable polyphenolic compounds of Terminalia species (family Combretaceae) used for the treatment of several diseases. This study aims to seek identification and characterization of PAs in the ethanolic extracts of bark and fruit of six Terminalia species viz T. arjuna, T. bellerica, T. catappa, T. chebula, T. elliptica and T. paniculata. A high performance liquid chromatography with quadrupole time-of-flight tandem mass spectrometry (HPLC/ESI-QTOF-MS/MS) method was developed for the simultaneous identification and characterization of PAs. The chromatographic separation was carried on a Thermo Betasil C8 column (250 mmx4.5 mm, 5μm) operated with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase. The MS/MS fragmentation study of [M-H]- ions obtained from these PAs showed distinguishable fragment ions with high mass accuracy. Heterocyclic ring fission (HRF), retro-Diels-Alder (RDA) fragmentation, quinone methide (QM) fragmentation and benzofuran formation (BFF) have been identified as the characteristic fragments. Total of 51 PAs were tentatively identified which include 28 dimers, 15 trimers and 8 other flavan-3-ols.

Measurement of pharmacokinetics and tissue distribution of three bioactive constituents from Zanthoxylum armatum DC in rat plasma and tissues through UFLC-MS/MS

The compounds of N-Methylanhydrotetrahydroberberrubine A, dictamnine and eudesmin were the primary bioactive components in the roots of Zanthoxylum armatum DC (Z. armatum). To clarify the pharmacokinetics and distribution of these three compounds, an ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) was employed to determine the contents of these three compounds in rat plasma and seven tissues. The separation was achieved on a Kinetex XB–C18 100A column (2.1 × 50 mm, 2.6 μm, Phenomenex). The optimized mobile phase system was set with 0.1‰ formic acid aqueous solution (A) and acetonitrile (containing 0.1‰ formic acid) (B) with a programmed elution of 0.00 to 0.50 min, 2% B; 0.51–4.00 min, 30%–60% B; and 4.01–5.00 min, 2% B. All analytes were measured with optimized multiple reaction monitoring (MRM) in the positive ion ESI mode. Berberine hydrochloride was selected as the internal standard (IS). The MS/MS transitions of N-Methylanhydrotetrahydroberberrubine A, dictamnine, eudesmin and IS were 339.9135.1, 200.1 → 129.1, 387.4 → 369.0 and 337.1 → 321.1, respectively. The lower limits quantification (LLOQ) of the three analytes was 0.5–20 ng/ml. The linear ranges were 0.5–400 ng/ml for N-Methylanhydrotetrahydroberberrubine A and dictamnine and 20–4000 ng/ml for eudesmin. The present analysis showed that the two alkaloids were quickly absorbed, with Tmax in 0.167–0.292 h, and eudesmin was absorbed in 2.5 h. Moreover, all compounds were found at high concentrations in the gastrointestinal track. These results are helpful for further investigation of the clinical application of Z. armatum.

Synthesis, Growth, and Characterization of a New Thiourea and Bismuth Chloride Complex with Excellent Nonlinear Optical Properties

Crystals of a new organometallic nonlinear optical (NLO) compound, di-μ-chloro-bis[chlorotri(thiourea)bismuth(III)]-pentachloro(thiourea)bismuth-ate(III) (DCBPB), have been successfully grown from formic acid aqueous solutions of thiourea and bismuth chloride by a slow evaporation technique. The crystal structure and atomic composition of DCBPB have been confirmed by single crystal X-ray diffraction (SCXRD), Fourier transform infrared spectra, and elemental analysis. The SCXRD results proved that DCBPB crystallizes in triclinic space group P1 with unit cell dimensions of a = 7.0606(2) Å, b = 8.8106(4) Å, c = 16.3247(8) Å, α = 99.242(4)°, β = 95.309(3)°, γ = 105.856(3)°, and Z = 2. DCBPB crystal exhibits excellent transmittance from 500 to 2500 nm and green fluorescence with maximum emission at 508 nm. The thermogravimetric-differential scanning calorimetry (TG-DSC) analysis indicates that a solid-phase reaction took place at 170.1 °C, whereas the decomposition temperature of the crystal material was 189 °C. The NLO property obtained by the Kurtz powder test showed that the second harmonic generation efficiency of DCBPB crystal is two-seventh of KDP crystal.

Determination of 42 glucocorticoids in infant eczema products by auto-solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of 42 glucocorticoids in infant eczema products by auto-solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (ASPE-UHPLC-MS/MS).The analytes were extracted by acetonitrile after dispersing in saturated sodium chloride solution.Macromolecules matrix were precipitated by adding potassium and zinc acetate, and then purified by HLB SPE column.The chromatographic separations were performed on a DIKMA EndeavorsilTM C18 column (100 mm×2.1 mm, 1.7 μm).Acetonitrile and 0.1%(v/v) formic acid aqueous solution were used as the mobile phases.Electrospray ionization (ESI) source was operated in the positive mode using multiple reaction monitoring (MRM) scanning mode.The results were quantified by external standard method.The correlation coefficients of linear calibration curves were greater than 0.998 in the corresponding mass concentration ranges.The average recoveries at three spiked levels ranged from 78.7% to 101.5%, and the relative standard deviations (RSDs) were 2.0%-8.8%(n=6).The LODs (S/N ≥ 3) and LOQs were 0.002-0.031 mg/kg and 0.0007-0.103 mg/kg, respectively.The method is simple, rapid, sensitive, and reliable, and can be used for the detection of glucocorticoids in infant eczema products.

PdSn/NiO/NaTaO3:La for photocatalytic ammonia synthesis by reduction of NO3− with formic acid in aqueous solution

Photocatalytic ammonia synthesis is of great importance but remains very challenging in photocatalysis. Here, we fabricated a photocatalytic reaction system for the efficiently photocatalytic nitrate reduction to ammonia under UV irradiation using PdSn/NiO/NaTaO3:La as a photocatalyst in the presence of formic acid. Several important factors of the photocatalytic performance were investigated, including initial concentration of the nitrate solution, initial pH value and cocatalyst loadings. Nitrate conversion reaches 100% and ammonia selectivity is 72% over the optimum photocatalyst with 5% bimetallic PdSn alloy and 0.2% NiO loadings. The outstanding performance of photocatalyst can be ascribed to both the strong adsorption of nitrite on NiO and the efficient separation of electron-hole pairs by PdSn bimetallic alloy. Besides as the hole scavenger, formic acid also provides not only carboxyl anion radicals for nitrate reduction but also the in-situ buffer effect on ammonia formation. These results give inspiration for designing the reactive system with efficient photocatalytic ammonia synthesis.

Concentration determination of urinary metabolites of N,N-dimethylacetamide by high-performance liquid chromatography-tandem mass spectrometry.

Objectives: N,N-Dimethylacetamide (DMAC) is widely used in industry as a solvent. It can be absorbed through human skin. Therefore, it is necessary to determine exposure to DMAC via biological monitoring. However, the precision of traditional gas chromatography (GC) is low due to the thermal decomposition of metabolites in the high-temperature GC injection port. To overcome this problem, we have developed a new method for the simultaneous separation and quantification of urinary DMAC metabolites using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methods: Urine samples were diluted 10-fold in formic acid, and 1-μl aliquots were injected into the LC-MS/MS equipment. A C18 reverse-phase Octa Decyl Silyl (ODS) column was used as the analytical column, and the mobile phase consisted of a mixture of methanol and aqueous formic acid solution. Results: Urinary concentrations of DMAC and its known metabolites (N-hydroxymethyl-N-methylacetamide (DMAC-OH), N-methylacetamide (NMAC), and S- (acetamidomethyl) mercapturic acid (AMMA) ) were determined in a single run. The dynamic ranges of the calibration curves were 0.05-5 mg/l (r≥0.999) for all four compounds. The limits of detection for DMAC, DMAC-OH, NMAC, and AMMA in urine were 0.04, 0.02, 0.05, and 0.02 mg/l, respectively. Within-run accuracies were 96.5%-109.6% with relative standard deviations of precision being 3.43%-10.31%. Conclusions: The results demonstrated that the proposed method could successfully quantify low concentrations of DMAC and its metabolites with high precision. Hence, this method is useful for evaluating DMAC exposure. In addition, this method can be used to examine metabolite behaviors in human bodies after exposure and to select appropriate biomarkers.

Authentication and Quantitation of Fraud in Extra Virgin Olive Oils Based on HPLC-UV Fingerprinting and Multivariate Calibration.

High performance liquid chromatography method with ultra-violet detection (HPLC-UV) fingerprinting was applied for the analysis and characterization of olive oils, and was performed using a Zorbax Eclipse XDB-C8 reversed-phase column under gradient elution, employing 0.1% formic acid aqueous solution and methanol as mobile phase. More than 130 edible oils, including monovarietal extra-virgin olive oils (EVOOs) and other vegetable oils, were analyzed. Principal component analysis results showed a noticeable discrimination between olive oils and other vegetable oils using raw HPLC-UV chromatographic profiles as data descriptors. However, selected HPLC-UV chromatographic time-window segments were necessary to achieve discrimination among monovarietal EVOOs. Partial least square (PLS) regression was employed to tackle olive oil authentication of Arbequina EVOO adulterated with Picual EVOO, a refined olive oil, and sunflower oil. Highly satisfactory results were obtained after PLS analysis, with overall errors in the quantitation of adulteration in the Arbequina EVOO (minimum 2.5% adulterant) below 2.9%.