Phosphoric Acid Aqueous Solution Research Articles

Determination of antibiotics of the tetracycline group in water by high-performance liquid chromatography on a diode matrix detector with preliminary concentration by solid-phase extraction

Introduction. Antibiotic contamination of the environment is a serious environmental threat that poses a hazard to human health. To monitor the content of tetracycline antibiotics in environmental objects and control technological processes aimed at their disposal, accessible analytical methods are needed. 
 Purpose of the study. Development of a method for determining antibiotics of the tetracycline group in water using a diode array detector with preliminary solid-phase concentration.
 Material and methods. The objects of the study were model solutions of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline in deionized, tap, natural, and treated wastewater. For solid-phase extraction, Diapak P and Diapak PG cartridges were used. SPE was performed using a VacMaster-10 manifold (Biotage). Chromatographic separation was carried out on Diasphere C10CN and Kromasil Eternity 250 × 4.6 mm 5 µm columns on an Agilent 1100 liquid chromatograph (Agilent Technology).
 Results. Optimal conditions for the chromatographic separation of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline were selected: isocratic mode, wavelength of 350 nm, mobile phase – acetonitrile: aqueous solution of phosphoric acid (pH = 3.0). The analysis time on Diasphere C10CN and Kromasil Eternity columns was 12 and 14 minutes, respectively. The reliability of the linear approximation in both cases was more than 0.99, however, the slopes on the Kromasil Eternity column were 1.35 –1.65 times higher than on Diasphere C10CN. The degree of extraction of tetracyclines from deionized water on Diapak P and Diapak PG cartridges was 90–95%, from tap water 61–89%, from purified waste water: 51–87%.
 Limitations. The method is not suitable for water bodies with tetracycline contents less than 2 µg/dm3.
 Conclusion. An HPLC method has been developed for the determination of minocycline, tetracycline, oxytetracycline, demeclocycline, metacycline, and doxycycline in water with preliminary SPE concentration on Diapak P and Diapak PG cartridges. The lower limit of determination for the sorption of target compounds from 0,1 dm3 of sample was 2 μg/dm3.

The method of determination for 2, 3-Butanedione in the air of workplace by high performance liquid chromatography with derivatization

Objective: To establish a method for the determination of 2, 3-Butanedione (BUT) in the air of workplace, which including the process of collection by absorption in phosphoric acid aqueous solution and the process of analysis and detection by high performance liquid chromatography with derivatization. Methods: In October 2022, a porous glass plate absorption tube containing 10 ml of 0.01% phosphoric acid solution was used to collect BUT in the air of the workplace at a flow rate of 0.2 L/min. The absorption solution was derived by 2, 4-dinitrophenylhydrazine for 75 min and separated on a SB-C18 column (250 mm×4.6 mm, 5 μm) . At the column temperature of 30 ℃, the mixture of acetonitrile-water (V∶V, 1∶1) was eluted at the flow rate of 1.0 ml/min. It was detected by UV detector (λ=365 nm) , qualitatived by retention time and quantitatived by external standard. Results: It showed that BUT in phosphoric acid aqueous solution could be stored for at least 7 d at 4 ℃. There was a linear relationship within the determination range of 0.05-6.00 μg/ml, the linear regression equation was y=89.610x+0.133, r=0.9999. The sampling absorption efficiencies were 98.33%-100.00%, the detection limit of the method was 0.005 μg/ml, the minimum detection concentration was 0.016 mg/m(3) (based on V(0)=3.0 L) . The recovery rates were 95.96%-102.44%, the intra batch precision were 4.36%-7.78%, and the inter batch precision were 4.96%-6.06%. Conclusion: The method has the advantages of simple operation, high sensitivity and good accuracy. It can prevent the loss and degradation of BUT. It can be used for the determination of BUT in the air of workplace.

Quality evaluation of salt-fired Eucommiae Cortex based on HPLC fingerprint, multi-component content determination, and chemometrics

This study established an HPLC fingerprint and multi-component content determination method for salt-fired Eucommiae Cortex, and evaluated the quality of salt-fired Eucommiae Cortex from different sources using fingerprint similarity evaluation, cluster analysis(CA), principal component analysis(PCA), and orthogonal partial least square discriminate analysis(OPLS-DA). HPLC was launched on a Cosmosil 5C_(18)-MS-Ⅱ column(4.6 mm×250 mm, 5 μm) by gradient elution with a mobile phase of methanol-0.2% phosphoric acid aqueous solution at a flow rate of 1.0 mL·min~(-1), detection wavelength of 238 nm, column temperature of 30 ℃, and an injection volume of 10 μL. The results of fingerprint similarity evaluation for 20 batches of salt-fired Eucommiae Cortex indicated that, except for batch S3 with a similarity of 0.893, the similarity of the other 19 batches was of ≥ 0.919, suggesting good similarity. Fourteen common peaks were calibrated and seven common peaks were identified including geniposidic acid. The mass fractions of geniposidic acid, chlorogenic acid, geniposide, genipin, pinoresinol diglucoside, liriodendrin, and pinoresinol-4-O-β-D-glucopyranoside were 0.062 0%-0.426 9%, 0.024 9%-0.116 5%, 0.009 5%-0.052 9%, 0.005 5%-0.034 8%, 0.115 9%-0.317 8%, 0.016 4%-0.108 8%, and 0.026 4%-0.039 8%, respectively. Using CA, PCA, and OPLS-DA, the 20 batches of salt-fired Eucommiae Cortex were classified into three categories. Additionally, through the analysis of variable importance in projection(VIP) under OPLS-DA, two differential quality markers, geniposidic acid and chlorogenic acid, were identified. The established HPLC fingerprint and multi-component content determination method is stable and reliable, providing a reference for quality control of salt-fired Eucommiae Cortex.

Development of a dispersive liquid-liquid microextraction method for the determination of plastic additives in seawater.

A method using dispersive liquid-liquid microextraction (DLLME) prior to high performance liquid chromatography-diode array detection (HPLC-DAD) was developed to determine seven additives from the plastics industry (butylated hydroxytoluene, diisodecyl phthalate, irgafos 168, lawsone, quercetin, triclosan and vitamin E) in seawater samples. These compounds can reach seawater due to direct discharge from wastewater treatment plants and leaching from plastics and microplastics. The extraction was performed using 25 mL of seawater, 500 μL of 1-octanol (extraction solvent) and a stirring step instead of dispersive solvent. Additive concentrations were determined by LC-DAD on a C18 column with a mobile phase of acetonitrile and phosphoric acid aqueous solution (pH 3.5) by gradient elution. The analytical recoveries ranged from 82 to 93% for all compounds, except for lawsone (60%). Repeatability and intermediate precision were adequate with RSD < calculated values following the Horwitz equation at the concentration levels evaluated (0.06 and 0.24 mg L-1). All additives exhibited linear matrix calibration curves (R2 > 0.99). Detection limits ranged from 0.009 to 0.028 mg L-1 and quantification limits ranged from 0.027 to 0.084 mg L-1. Finally, the application of the method to real samples verified the method as accurate and applicable to seawater.

Formulating an altered dentin substrate to improve dentin bonding

Statement of problemSecondary caries is a major factor in the failure of dental restorations. However, studies on the fabrication of acid-resistant and antibacterial dentin to improve dentin bonding are sparse. PurposeThe purpose of this in vitro study was to compare the effects of 2 types of fluoride-containing etchants on dentin bonding and explore the feasibility of formulating an altered dentin substrate to improve dentin bonding. Material and methodsNaF-containing and SnF2-containing etchants were developed by adding sodium fluoride and stannous fluoride to a 35% phosphoric acid aqueous solution. Two groups (N1 and N2) containing NaF, 10 and 30 mg/mL respectively, and 2 groups (S1 and S2) containing SnF2, 18.6 and 55.8 mg/mL respectively, were formulated. The etchant of the control group (C) was 35% phosphoric acid gel. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), microhardness, antierosion, and antibacterial tests were performed on the treated dentin. Moreover, the microtensile bond strength (µTBS) of each group was tested, and the fracture mode was determined after testing. Statistical analysis was performed with the 2-way ANOVA test (α=.05). ResultsThe exposed collagen fiber was observed in group C, and minerals were formed on the dentin in the experimental groups. SEM, FTIR, and the microhardness test indicated more remineralization in the SnF2-containing etchant groups. The µTBS of S1 (77.5 ±10.36 MPa) was the highest in all groups, and group C (38.5 ±9.01 MPa) was the lowest. Moreover, the antierosion and antibacterial properties of the S2 group were the best among all groups (P<.05). ConclusionsCompared with NaF-containing etchant, SnF2-containing etchant could improve the dentin substrate, increase remineralization, improve bonding strength, and enhance antibacterial ability, especially by increasing resistance to acid erosion.

Nucleation & growth of α-Ti(HPO4)2·H2O single-crystal and its structure determination from X-ray single–crystal data

α-titanium phosphate phase [α-Ti(HPO4)2·H2O; abbreviated as α-TiP] is a nanolayered metal phosphate with several industrial and recent biotechnological applications related to their nanolayered morphology and ion exchange capabilities. Structural wise, α-TiP is a tetravalent metal phosphate that tends to crystallize into microcrystalline powder. Here we report that the crystallization of single α-TiP crystals with suitable dimensions (>50 μm) for single-crystal X-ray diffraction could be effectuated using a prolonged hydrothermal treatment of a metallic titanium alloy (Ti–6Al–4V) in a highly concentrated phosphoric acid aqueous solution. Accordingly, the single-crystal X-ray diffraction analysis revealed the crystalline structure in a monoclinic space group, P21/c, with a = 8.6288(5) Å, b = 5.00546(17) Å, c = 19.1468(11) Å, and β = 127.555(9)°. Although the space group is the same crystallographic space group that was previously reported from the microcrystalline powder relying on powder X-ray diffraction (PXRD) and neutron powder diffraction, the obtained unit cell volume is slightly larger. Bulk of the obtained crystals were also subjected to detailed analyses using polarization optical microscopy (POM), scanning electron microscopy combined with energy dispersive X-ray microanalysis (SEM-EDX), Fourier transform Infrared Spectroscopy (FTIR) and thermal analysis (TG/SDTA). The single crystals are hexagonally shaped and exhibit the exact titanium to phosphorus ratio expected for α-TiP. The bulk sample PXRD pattern resembles perfectly that reported for the α-TiP polycrystalline powder with clearly sharper peaks. TGA-SDTA analysis revealed the expected thermal behaviour for α-TiP phase and demonstrated their higher thermal stability when compared to the polycrystalline powder.

Determination of 4 Nucleosides via One Reference Compound in Chinese Cordyceps by HPLC-UV at Equal Absorption Wavelength

A high-performance liquid chromatography (HPLC) method for the determination of 4 nucleosides by one reference compound in Chinese cordyceps was developed. The sample of Chinese cordyceps was prepared by ultrasonic extraction with a 0.5% phosphoric acid aqueous solution. The separation of the sample was performed on a CORTECS T3 column (100 mm × 4.6 mm, 2.7 μm) by gradient elution with acetonitrile and water at a flow rate of 1.0 mL/min. The wavelengths were set as 258 nm (0-5 min), 252 nm (5-9.1 min), 258 nm (9.1-10.5 min), 249 nm (10.5-20 min) at which 4 nucleosides exhibited identical ultraviolet absorption. The accuracy, precision, reproducibility, and stability tests of the HPLC method were carried out, and the results indicated that the established HPLC method was suitable for the quantitative analysis of 4 nucleosides in Chinese cordyceps. This approach was compared to the traditional external standard method with 4 nucleoside reference compounds and the relative standard errors of the content determination results by the 2 methods were less than 3.5%. The HPLC method developed for quantitative measurement of 4 nucleosides in Chinese cordyceps is simple, lower cost, and time-saving, which provides a methodology alternative for quality control of Chinese cordyceps.

Effect of L-Glutamic Acid on the Composition and Morphology of Nanostructured Calcium Phosphate as Biomaterial.

Calcium phosphate (CaP) with several chemical compositions and morphologies was prepared by precipitation using aqueous solutions of L-Glutamic acid (H2G) and calcium hydroxide, both mixed together with an aqueous solution (0.15 M) of phosphoric acid. Plate-shaped dicalcium phosphate dihydrate (brushite) particles were obtained and identified at a lower concentration of the solution of the reactants. The Ca/P ratio deduced by EDS was ~1, as expected. The nanoscale dimension of carbonate apatite and amorphous calcium phosphate, with variable Ca/P ratios, were revealed by X-ray diffraction (XRD) and scanning electron microscopy and energy dispersive X-ray spectroscopy analysis (SEM-EDS). They were characterized in medium and high concentrations of calcium hydroxide (0.15 M and 0.20 M). The equilibria involved in all the reactions in aqueous solution were determined. The thermodynamic calculations showed a decrease in the amount of chelate complexes with an increase in pH, being the opposite of [CaPO4-] and [CaHG+]. This fluctuation showed an evident influence on the morphology and polymorphism of CaP particles obtained under the present experimental conditions, with potential use as a biomaterial.

Cellulose hydrogenolysis to alcohol and ketone products using Co@C catalysts in the phosphoric acid aqueous solution

Combining encapsulated Co@C catalyst and H3PO4 aqueous solution, high value-added chemicals that are widely used in various fields can be obtained from renewable biomass materials.

Optimized HPLC extraction method of quercetin and berberine based on response surface analysis.

In order to establish a method for simultaneous determination and extraction of quercetin and berberine in soil, HPLC-PDA multi-wavelength method was used to detect the content of berberine and quercetin in soil solution. The detection wavelength was 210 nm and 347 nm. The column temperature was 30 °C, the mobile phase A was acetonitrile, the mobile phase B was 0.1% phosphoric acid aqueous solution, and the flow rate was 1.0 mL min-1. Under the condition of isocratic elution, quercetin and berberine were completely separated within 20 min. The detection limit concentration of quercetin was 0.078 mg L-1, and the detection limit of berberine was 0.019 mg L-1. Both of them reached the trace level, and the recovery rate was between 97.2% and 107.4%. The response surface method was used to optimize the ultrasonic extraction method. The three main factors of extraction concentration, extraction temperature and solid-liquid ratio were optimized to obtain the highest extraction efficiency. The optimum extraction efficiency was as follows: 1 g soil sample was extracted with 80% ethanol aqueous solution, ultrasonic time was 10 min, ultrasonic temperature was 44 °C, and solid-liquid ratio was 1 : 17 g mL-1. The extracted quercetin and berberine concentrations were close to the predicted values of response surface optimization. The method of extracting and determining berberine and quercetin from soil established in this experiment is simple, fast, low cost and high safety. The feedback of the results also further verifies the feasibility in practical production and application, and provides reference value for further research and analysis of different allelochemicals in soil.

Fenugreek seed and cape gooseberry leaf extracts as green corrosion inhibitors for steel in the phosphoric acid industry

Phosphoric acid is the core material for the fertilizer industry; however, it is incredibly corrosive to manufacturing plants’ structures, mainly steel. Corrosion is one of the most severe problems encountered during phosphate fertilizer manufacturing. Recently, plant extracts have been commonly used as corrosion inhibitors because they are cheap and environmentally friendly. Steel corrosion in a 20% aqueous phosphoric acid solution in the absence and presence of fenugreek seed (Fen) or cape gooseberry leaf (CgL) extracts was investigated using the electrochemical impedance spectroscopy technique, potentiodynamic polarization measurement, scanning electron microscope, and quantum chemical calculations. Fourier Transform Infrared, FTIR, was used to identify the functional groups in Fen and CgL extracts. The inhibition efficiency for steel in 20% aqueous phosphoric acid was roughly equal to 80% for 0.4 g/L CgL and 1.2 g/L Fen extracts. A scanning electron microscope showed that the chemical constituents of extracts block the surface roughness of steel, decreasing the corrosion rate. The activation parameters indicated the effectiveness of the extracts at a higher temperature. Measurements of the potential of zero charges showed that the steel surface is positively charged in the phosphoric acid solution. Quantum chemical computations were also employed to examine the corrosion inhibition mechanisms of the natural extracts.

Etch-mineralizing treatment to improve dentin bonding

Objectives This study aimed to investigate the effect of etch-mineralizing solution as a dentin treatment agent on dentin bonding.Methods This study designed four kinds of etch-mineralizing solutions (EMs) by adding sodium fluoride in 35% phosphoric acid aqueous solution with four different concentrations (5, 10, 20, and 30 mg/ml), and named F1, F2, F3 and F4, respectively. 35% phosphoric acid gel treatment was the control group. SEM, EDS, FTIR and microhardness tests were performed on the treated dentin. Shear bond strength was measured before and after aging. Nanoleakage was also evaluated. Fracture mode was researched after SBS testing. The antibacterial properties of treated dentin were also investigated through live/dead staining of biofilms.Results The smear layer was removed and mineralization substances were observed on the dentin surface and tubule, and no obvious collagen fibers were observed compared with the control group. FTIR spectrums showed that the ratios of phosphate/collagen on EMs treated dentin surfaces were significantly increased (P < 0.05). F2 group had the highest bonding strength (32.14 ± 7.33 MPa) and microhardness (66.08 ± 10.58), while the control group had the lowest bonding strength (21.81 ± 4.03 MPa) and microhardness (42.34 ± 7.08) (p < 0.05), and excellent bonding strength caused more cohesive fracture. Experimental groups showed less nanoleakage than group C (P < 0.05). Moreover, experimental groups had better antiaging performance and antibacterial properties than the control group (p < 0.05).Conclusion EMs treatment not only improved dentin bonding and antibacterial ability, but also remineralized dentin with autologous mineral elements.Clinical significance The treatment provides a novel therapeutic strategy for obtaining ideal dentin bonding strength and prolonging the longevity of the restoration.

A simple and green liquid chromatography method for the determination of ibuprofen in milk-containing simulated gastrointestinal media for monitoring the dissolution studies of three-dimensional-printed formulations.

A fast and green ultra-high-performance liquid chromatographic method was developed for the determination of ibuprofen in milk-containing simulated gastrointestinal media to monitor the dissolution of three-dimensional printed formulations. To remove interfering compounds, protein precipitation using methanol as a precipitation reagent was performed. The separation of the target analyte was performed on a C18 column using a mobile phase consisting of 0.05% v/v aqueous phosphoric acid solution: methanol, 25:75% v/v. Method validation was conducted using the total error concept. The β-expectation tolerance intervals did not exceed the acceptance criteria of±15%, meaning that 95% of future results will be included in the defined bias limits. The relative bias ranged between ─1.1 and +3.2% for all analytes, while the relative standard deviation values for repeatability and intermediate precision were less than 2.8% and 3.9%, respectively. The achieved limit of detection was 0.01μg/ml and the lower limit of quantitation was established as 2μg/ml. The proposed method was simple, and it required reduced organic solvent consumption following the requirements of Green Analytical Chemistry. The method was successfully employed for the determination of ibuprofen in real biorelevant media obtained from dissolution studies.

Anodic Composite Nanostructure: Formation, Morphology, Optical and Photoluminescent Properties

Two-layer Al/Nb (1000/200 nm) was deposited by sputtering using a DC magnetron method on Si wafers. The anodizing was in 0.2 M oxalic solution at 53 V, re-anodized in the 0.5 M boric acid in potentiodynamic mode at increase of potential until 400 V. For forming anodic composite nanostructure, the porous anodic aluminum oxide was partially removed in 50 % aqueous solution of phosphoric acid at 50°C for 1200 s. The morphology, photoluminescence, and optical reflection of an anodic composite nanostructure were investigated. The anodic composite nanostructure showed effective optical reflection in the wavelength range from 540 to 1000 nm, and the maximum reflective efficiency was observed at a wavelength of 850 nm, 52 % reflectance occurs. The photoluminescence maximum was observed at a wavelength of 453 nm.

Fabrication of boehmite nanofiber aerogels by a phosphate gelation process for optical applications

A transparent wet gel was obtained in a few minutes at room temperature by adding an aqueous phosphoric acid solution of appropriate concentration to boehmite nanofiber sol. After room temperature aging and supercritical carbon dioxide drying, low bulk density aerogels with visible light transmittance of over 90% at 10 mm thickness were obtained. These aerogels exhibited high Young’s modulus and visible light transmittance, while having the same bulk density as the samples obtained by a conventional gelation process using a base. The high optical transmittance of the aerogel were hardly lost even at high humidity because the phosphorylation of the skeletal surface reduced the percentage of hydroxyl groups. The three-dimensional imaging inspection of the exterior and interior of the aerogel was carried out. The various developments reported in this paper make aerogels with ultralow bulk density (<0.01 g cm−3) and high visible light transmission even more promising for applications in the physical field. Graphical abstract

Microwave-assisted synthesis and formation mechanism of fluorescent carbon dots from starch

We report the synthesis of fluorescent carbon dots (CDs) via the microwave (MW)-assisted hydrothermal treatment of starch in an aqueous phosphoric acid solution. CDs emitting blue, orange, and green fluorescence in different solvents were obtained. The fluorescence quantum yield of the CDs emitting blue fluorescence is 30%, which is comparable to those of semiconductor quantum dots. The formation of the CDs under MW irradiation was monitored using a spectroscopic approach. The formation of blue-fluorescent CDs began at an early stage of the reaction. Subsequently, the CDs underwent aggregation. The aggregations were effectively extracted to the toluene layer by liquid−liquid extraction, and they emitted orange fluorescence in toluene and green fluorescence in water. The formation of the aggregates was followed by a steep increase in the yield of the CDs that emit blue fluorescence. MW heating for a certain duration was required to increase the yield of the blue-fluorescent CDs.

Rapid separation of High-viscosity phosphorous Acid/Tributyl phosphate extraction system by a stable anticorrosive Super-PA-phobic mesh

Inefficient, slow separation resulting from the high viscosity of phosphoric acid (PA) is a crucial problem that limits the process economy of industrial PA extraction. In this work, a super-PA-phobic stainless-steel mesh (SPPSSM) with excellent anticorrosion properties and stability is prepared and used for rapid separation in various PA/tributyl phosphate (TBP) extraction systems. The separation efficiency in batch operation of a PA-enriched raffinate (PER) and TBP-enriched phase (TEP) mixture formed from pure PA and TBP exceeds 97.59%, and the maximum TEP flux is 19.2593 L·m−2·h−1 at 60 °C. The maximum TEP flux of 886.1571 L·m−2·h−1 is obtained for a 20 wt% TBP kerosene solution and 20 wt% PA aqueous solution. A continuous separation device using the SPPSSM as the core component maintains a recovery rate of more than 95.57% in long-term operation, confirming its performance stability and robustness. The stable selective penetration of the SPPSSM originates from its super-PA-phobicity, which results from its rough surface with low surface energy; the SPPSSM repels PA but allows TBP to pass through. The separation ability of the SPPSSM is determined by the viscosity, density, and surface tension of the two liquid phases after extraction. It can be predicted using an equation based on the filtration mode after correction by a coefficient representing the Reynolds and Weber numbers. This work proposes a material for the rapid separation of PA/TBP in extraction systems and broadens the application field of superwetted materials under harsh conditions.

Effect of bioactivation through acid/alkali process on the flexure strength of zirconia-based ceramics and composites

Zirconia-based ceramics such as tetragonal zirconia polycrystals (TZP) and alumina toughened zirconia (ATZ) are attractive as biomaterials because of their high strength, high fracture toughness, and excellent biocompatibility. However, their application has been limited by their bio-inertness, which prevents them from directly bonding to the living bone. Therefore, the bioactivation of zirconia materials through the acid/alkali process has been studied. Currently, there is little information on the low-temperature degradation (LTD) behavior associated with this treatment. In this study, we investigated the degradation behavior of TZP or ATZ by examining the monoclinic fraction and biaxial flexure strength after immersion in sodium hydroxide or phosphoric acid aqueous solutions. The results showed that the monoclinic fraction increased significantly, indicating LTD at the surface, whereas the strength was not affected. In addition, more apatite formation was observed on TZP than on ATZ after immersion in SBF for 7 days. In particular, under the phosphoric acid treatment condition, almost the entire surface was covered with apatite. The contact angle measurement showed the possibility of predicting the apatite formation ability during immersion in SBF.

Quality evaluation of Dalbergiae Odoriferae Lignum by HPLC fingerprint and multi-component quantitative analysis

The present study detected the component content in Dalbergiae Odoriferae Lignum by HPLC fingerprint and the multi-component determination method. HPLC analysis was performed on the Agilent ZORBAX SB-C_(18) column(4.6 mm×250 mm, 5 μm). Acetonitrile-0.5% phosphoric acid aqueous solution with gradient elution was employed as the mobile phase. The flow rate was 1.0 mL·min~(-1) and the column temperature was maintained at 30 ℃. The detection wavelength was 210 nm and the sample volume was 10 μL. The similarity of 18 batches of Dalbergiae Odoriferae Lignum was 0.343-0.779, indicating that there were great differences between different batches of Dalbergiae Odoriferae Lignum. Eighteen common peaks were identified, including eight flavonoids such as liquiritigenin and latifolin. The mass fractions of liquiritigenin, luteolin, naringenin, isoliquiritigenin, formononetin, dalbergin, latifolin, and pinocembrin were in the ranges of 0.134 1%-0.495 2%, 0.028 2%-0.167 0%, 0.016 3%-0.591 3%, 0.053 5%-0.188 0%, 0.142 4%-0.640 1%, 0.068 0%-0.590 7%, 0.003 2%-1.980 7%, and 0.009 6%-0.740 2%, respectively. Eighteen batches of Dalbergiae Odoriferae Lignum were divided into three categories by cluster analysis and eight differential components in Dalbergiae Odoriferae Lignum were marked by partial least-squares discriminant analysis(PLS-DA). The cumulative variance contribution rate was 90.5%. The HPLC fingerprint combined with the multi-component determination method for Dalbergiae Odoriferae Lignum is easy in operation and accurate in results, with good repeatability and reliability. The quality of Dalbergiae Odoriferae Lignum can be evaluated and analyzed by the PLS-DA model. This study is expected to provide a reference for the quality control and clinical application of Dalbergiae Odoriferae Lignum.

Cr(VI) removal from the aqueous solutions by the samples of polyanyline doped with phosphoric acid

Samples of polyaniline (PAn) were synthesized by oxidative polycondensation of aniline in the presence ammonium peroxydisulfate in the aqueous solutions of phosphoric acid (PA) of different concentrations (0.16–3.30 M). Produced polyaniline was in the form of the emeraldine salt of phosphoric acid (PAn–PA). The prepared samples were used to study in the static conditions of their adsorption properties with regard to Cr(VI) from the aqueous solutions of different concentrations, namely 50, 100, 150, 200 and 300 mg/L, accordingly to the following technique: the 10 ml of the K 2 Cr 2 O 7 solution with appropriate concentration has been added to the portion of adsorbent sample, recorded time and at certain intervals took samples with a volume of 500 μl. These selected samples have been placed into the quartz cuvette with 2 mm thick and has been photometered. The amount of adsorpted substance was determined by the calibration plot. The adsorption experiments were carried out under the temperature 20±1°С. It is shown that the percentage of Cr(VI) removal by PAn samples reaches 94–99 %. It was found that the sorption capacity of all PAn–PA samples increases with increasing phosphoric acid concentration in the reaction mixture during synthesis. Analysis of the IR-FT spectra of PAn–PA samples shown that the partial oxidation of the emeraldine salt to pernigraniline takes place in the result of Cr(VI) adsorption. It was demonstrated that this process can be described sufficiently good by Langmuir or Freundlich adsorption isotherms, while the kinetics of process is in good agreement with model of pseudo second order. As a result of research, the possibility of the using of PAn samples, where polymer is doped with phosphoric acid during synthesis, for sorption of Cr(VI) from aqueous solutions without their additional acidification, has been determined. Keywords : polyaniline, Cr(VI) sorption, kinetics.