A Novel Molecularly Imprinted Photoelectrochemical Sensor Based on g‐C3N4‐AuNPs for the Highly Sensitive and Selective Detection of Triclosan

A novel molecularly imprinted polymer (MIP) photoelectrochemical sensor was fabricated for the highly sensitive and selective detection of triclosan. The MIP photoelectrochemical sensor was fabricated using graphite‐like carbon nitride (g‐C₃N₄) and gold nanoparticles (AuNPs) as photoelectric materials. The MIP/g‐C₃N₄‐AuNPs sensor used photocurrent as the detection signal and was triggered by ultraviolet light (UV‐Light 365 nm). g‐C₃N₄‐AuNPs was immobilized on indium tin oxide electrodes to produce the photoelectrochemically responsive electrode of the MIP/g‐C₃N₄‐AuNPs sensor. A MIP layer of poly‐o‐phenylenediamine was electropolymerized on the g‐C₃N₄‐AuNPs‐modified electrode to act as the recognition element of the MIP/g‐C₃N₄‐AuNPs sensor and to enable the selective adsorption of triclosan to the sensor through specific binding. Under optimal experimental conditions, the designed MIP/g‐C₃N₄‐AuNPs sensor presented high sensitivity for triclosan with a linear range of 2×10⁻¹² to 8×10⁻¹⁰ M and a limit of detection of 6.01×10⁻¹³ M. Moreover, the MIP/g‐C₃N₄‐AuNPs sensor showed excellent selectivity. The sensor had been successfully applied in the analysis of toothpaste samples.     

A molecularly imprinted polymer for solid phase extraction of allantoin

We describe a molecularly imprinted polymer (MIP) for the solid-phase extraction of the skin protectant allantoin. The MIP was deposited on the surface of monodisperse silica microspheres possessing acroyl groups on the surface (MH-SiO₂). The resulting MIP microspheres (MH-SiO₂@MIP) showed a 3.4-fold higher adsorption capacity and a 1.9-fold better selectivity for allantoin than the respective non-imprinted polymer (MH-SiO₂@NIP). The monolayer adsorption capacities of the MH-SiO₂@MIP and the MH-SiO₂@NIP were calculated with the help of the Langmuir model and found to be 6.8 and 1.9 mg•g⁻¹, respectively. Adsorption kinetics fit a pseudo-second order rate mechanism, with an initial adsorption rate of 1.44 for the MH-SiO₂@MIP, and of 0.07 mg•g⁻¹•min⁻¹ for the MH-SiO₂@NIP. The material can be regenerated, and its adsorption capacity for allantoin remains stable for at least five regeneration cycles. It was successfully used as a sorbent for the selective solid-phase extraction of allantoin from Rhizoma dioscoreae.

A molecularly imprinted polymer for the selective separation of allantoin was developed. It was successfully used as a sorbent for the selective solid-phase extraction of allantoin from Rhizoma dioscoreae.

     

Solid‐phase Extraction of β‐Sitosterol from Oldenlandia diffusa Using Molecular Imprinting Polymer

The β‐sitosterol imprinted polymer was prepared for selective extraction and analysis of β‐sitosterol from Oldenlandia diffusa (O. diffusa) followed by HPLC with UV detection. The imprinted polymers show high affinity and selectivity to β‐sitosterol. Using this molecularly imprinted polymer (MIP) cartridge as solid‐phase extraction (SPE) material, the interferences could be quickly washed out and β‐sitosterol was selectively retained and enriched. HPLC analysis method was used to evaluate the characteristics of this MIP material. At the condition of mobile phase composed of MeOH/H₂O/H₃PO₄ (99/1/0.1, V/V/V, pH=6.0) and the flow rate of 1.0 mL·min^?1, a good linear relationship was demonstrated when the concentrations of β‐sitosterol were in the range of 0.50–100.0 µg·mL^?1. The recoveries ranged from 75.3% to 86.5% and the inter‐day and intra‐day relative standard deviations were less than 5%. This developed HPLC method was proved to be acceptable for extraction of β‐sitosterol from O. diffusa.     

2,6‐Dimethoxy‐7,9‐dimethylpurinium iodide hemihydrate

In the title compound, C₉H₁₃N₄O₂⁺·I⁻·0.5H₂O, the non‐H atoms of the ionic components lie on a mirror plane in Cmca, with the O atom of the partial water molecule lying on a twofold rotation axis. Whereas one of the methoxy methyl groups is directed away from the adjacent N‐methyl group, the other methoxy methyl group is directed towards its adjacent N‐methyl group. The conformation of the methoxy methyl groups provides an explanation for the outcomes of intramolecular thermal rearrangements of 2,6‐dialkoxy‐7,9‐dimethylpurinium salts.     

1‐Carboxymethyl‐3‐methyl‐1H‐imidazol‐3‐ium chloride 2‐(3‐methyl‐1H‐imidazol‐3‐ium‐1‐yl)acetate monohydrate: a crystal stabilized by imidazolium zwitterions

The title compound, C₆H₉N₂O₂⁺·Cl⁻·C₆H₈N₂O₂·H₂O, contains one 2‐(3‐methyl‐1H‐imidazol‐3‐ium‐1‐yl)acetate inner salt molecule, one 1‐carboxymethyl‐3‐methyl‐1H‐imidazol‐3‐ium cation, one chloride ion and one water molecule. In the extended structure, chloride anions and water molecules are linked via O—H...Cl hydrogen bonds, forming an infinite one‐dimensional chain. The chloride anions are also linked by two weak C—H...Cl interactions to neighbouring methylene groups and imidazole rings. Two imidazolium moieties form a homoconjugated cation through a strong and asymmetric O—H...O hydrogen bond of 2.472 (2) Å. The IR spectrum shows a continuous D‐type absorption in the region below 1300 cm⁻¹ and is different to that of 1‐carboxymethyl‐3‐methylimidazolium chloride [Xuan, Wang & Xue (2012). Spectrochim. Acta Part A, 96 , 436–443].     

A Novel Electrochemical Sensor for β2‐Agonists with High Sensitivity and Selectivity Based on Surface Molecularly Imprinted Sol‐gel Doped with Antimony‐Doped Tin Oxide

A novel strategy to improve the sensitivity of molecularly imprinted polymer (MIP) sensors was proposed for the determination of β₂‐agonists. The imprinted sol‐gel film was prepared by mixing silica sol with a functional monomer of antimony‐doped tin oxide (ATO) and a template of β₂‐agonists. ATO, which was embedded in the surface of the molecularly imprinted sol‐gel film, not only provides the excellent conductivity for biosensor but also increases the stability and the surface area of the MIP film. The imprinted sensor was characterised by field emission scanning electron microscope, fourier transform infrared spectroscopy and electrochemical methods. Under the optimal experimental conditions, the peak current was linear with the logarithm of the concentration of clenbuterol (CLB) in the range of 5.5 nM–6.3 µM, and a detection limit of 1.7 nM was obtained. Meanwhile, the electrochemical sensor showed excellent specific recognition of the template molecule among structurally similar coexisting substances. Furthermore, the proposed sensor was satisfactorily applied to determine β₂‐agonists in human serum samples. The good results indicated that highly effective molecularly imprinted sol‐gel films doped with ATO can be employed for other analytes.     

Kinetics and Mechanism of Radical‐Chain Oxidation of 1,2‐Substituted Ethylene and 1,4‐Substituted Butadiene‐1,3

A combination of microvolumetry, the rotating sector method, ESR, ¹H NMR, and IR allowed to establish a detailed mechanism of liquid‐phase oxidation of vinyl compounds X₁CH=CHX₂ and X₁CH=CH–CH=CHX₂ (X₁ and X₂—a polar substitute: С₆Н₅–, CO–, СOO–) initiated by azobisisobutyronitrile. A distinctive feature of the mechanism is the fact that the oxidation chain is carried out by a low‐molecular hydroperoxide radical joining the π‐bond. For nine compounds in the temperature range of 303–353 K, relative chain propagation and termination rate constants were measured (k ₂•k ₃^−0.5). Absolute values of k ₂ were obtained for diphenylethylene (110 L·mol⁻¹·s⁻¹), ethyl ether of trans‐phenyl‐pentadiene acid (13 L·mol⁻¹·s⁻¹), and methyl ether of trans‐phenyl‐pentadiene acid (14.2 L·mol⁻¹·s⁻¹) at T = 323 K. For the same conditions, 10⁻⁸k ₃ were calculated for diphenylethylene (0.87 L·mol⁻¹·s⁻¹) and methyl ether of trans‐phenyl‐pentadiene acid (1.21 L·mol⁻¹·s⁻¹). A cyclic mechanism of the oxidation chain termination on introduced antioxidants (stable nitroxyl radicals of the piperidine series ( > NO^●) and the transition metal compounds (Meⁿ )) was established. The inhibition factor (f ) showing how many reaction chains are terminated by the one particle of the antioxidant is equal to 10². The cyclic chain termination is caused by the following reactions: HO₂^● + > NO^● → NOH + O₂, HO₂● + NOH → >NO^● + H₂O₂ (for >NO^●) and HO₂^● + Meⁿ → Me^{n +1} + HO₂^●−, HO₂^● + Me^{n +1} → Meⁿ + H⁺ + O₂ (for Meⁿ ).     

A molecularly imprinted polymer for solid phase extraction of allantoin

We describe a molecularly imprinted polymer (MIP) for the solid-phase extraction of the skin protectant allantoin. The MIP was deposited on the surface of monodisperse silica microspheres possessing acroyl groups on the surface (MH-SiO₂). The resulting MIP microspheres (MH-SiO₂@MIP) showed a 3.4-fold higher adsorption capacity and a 1.9-fold better selectivity for allantoin than the respective non-imprinted polymer (MH-SiO₂@NIP). The monolayer adsorption capacities of the MH-SiO₂@MIP and the MH-SiO₂@NIP were calculated with the help of the Langmuir model and found to be 6.8 and 1.9 mg?g^?1, respectively. Adsorption kinetics fit a pseudo-second order rate mechanism, with an initial adsorption rate of 1.44 for the MH-SiO₂@MIP, and of 0.07 mg?g^?1?min^?1 for the MH-SiO₂@NIP. The material can be regenerated, and its adsorption capacity for allantoin remains stable for at least five regeneration cycles. It was successfully used as a sorbent for the selective solid-phase extraction of allantoin from Rhizoma dioscoreae.

Quantitative Analysis of Holmium Ion by a Ho3+ Ion‐Selective Sensor Based on a Symmetric Thio‐Schiff's Base

A poly(vinyl chloride) (PVC) membrane sensor for holmium ions was fabricated based on N‐[(Z)‐1‐(2‐thienyl)‐ methylidene]‐N‐[4‐(4‐{[(Z)‐1‐(2‐thienyl)methylidene]amino} phenoxy)phenyl] amine (TPA) as a new ion carrier, acetophenon (AP) as plasticizing solvent mediator and sodium tetraphenyl borate (NaTPB) as an anion excluder. The electrode shows a good selectivity towards Ho³⁺ ions respect to other inorganic cations, including alkali, alkaline earth, transition and heavy metal ions. The constructed sensor displays a Nernstian behavior (19.5±0.3 mV/decade) over the concentration range of 1.0×10⁻⁶ to 1.0×10⁻² mol·L⁻¹ with the detection limit of the electrode being 4.6×10⁻⁷ mol·L⁻¹ and very short response time (ca. 5 s). It has a useful working pH range of 3.2–9.8 for at least 8 weeks. The electrode was successfully applied as an indicator electrode for the potentiometric titration of a Ho³⁺ solution with EDTA and holmium determination in some alloys. The proposed sensor accuracy was studied by the determination of Ho³⁺ in mixtures of three different ions.     

2,4‐Diamino‐6‐methyl‐1,3,5‐triazin‐1‐ium trifluoroacetate

Crystals of the title compound, C₄H₈N₅⁺·C₂F₃O₂⁻, are built up of singly protonated 2,4‐diamino‐6‐methyl‐1,3,5‐triazin‐1‐ium cations and trifluoroacetate anions. The CF₃ group of the anion is disordered. The oppositely charged ions interact via almost linear N—H...O hydrogen bonds, forming a CF₃COO⁻...C₄H₈N₅⁺ unit. Two units related by an inversion centre interact through a pair of N—H...N hydrogen bonds, forming planar (CF₃COO⁻...C₄H₈N₅⁺...C₄H₈N₅⁺·CF₃COO⁻) aggregates that are linked by a pair of N—H...O hydrogen bonds into chains running along the c axis.     

Development of an Electrochemical Sensor Based on Covalent Molecular Imprinting for Selective Determination of Bisphenol‐A

In this study, an electrochemical sensor was developed and used for selective determination of bisfenol‐A (BPA) by integrating sol‐gel technique and multi‐walled carbon nanotubes (MWCNTs) modified paste electrode. BPA bounded by covalently to isocyanatopropyl‐triethoxy silane (ICPTS) was synthesized as a new precursor (BPA‐ICPTS) and then BPA‐imprinted polymer (BPA‐IP) sol‐gel was prepared by using tetramethoxysilane (TMOS) and BPA‐ICPTS. Non‐imprinted polymer (NIP) sol‐gel was obtained by using TMOS and (3‐Aminopropyl) triethoxysilane. Both BPA‐IP and NIP sol‐gels were characterized by nitrogen adsorption‐desorption analysis, FTIR, SEM, particle size analyzer and optical microscope. Carbon paste sensor electrode was fabricated by mixing the newly synthesized BPA‐IP with MWCNTs, graphite powder and paraffin oil. The electrochemical characterization of the sensor electrode was achieved with cyclic and differential pulse voltammetric techniques. The response of the developed sensor under the most proper conditions was linear in BPA concentration range from 4.0×10⁻⁹ to 1.0×10⁻⁷ mol L⁻¹ and 5.0×10⁻⁷ to 5.0×10⁻⁵ mol L⁻¹ and the detection limit was 4.4×10⁻⁹ mol L⁻¹. The results unclosed that the proposed sensor displayed high sensitivity and selectivity, superior electrochemical performance and rapid response to BPA.     

A sensitive and selective sensor‐coated molecularly imprinted sol–gel film incorporating β‐cyclodextrin‐multi‐walled carbon nanotubes and cobalt nanoparticles‐chitosan for oxacillin determination

A sensitive and selective imprinted electrochemical sensor for the determination of oxacillin was developed based on indium tin oxide electrode. The proposed sensor was decorated with imprinted sol–gel film and cobalt nanoparticles‐chitosan/β‐cyclodextrin‐multiwalled carbon nanotubes nanocomposites. The surface morphologies of the modified electrodes were characterized by scanning electron microscopy and transmission electron microscope. The stepwise assembly process and electrochemical behavior of the novel sensor were characterized by differential pulse voltammetry, cyclic voltammetry and Amperometric i‐t response. The imprinted sensor displayed excellent selectivity toward oxacillin. Meanwhile, the introduced cobalt nanoparticles‐chitosan and β‐cyclodextrin‐multi‐walled carbon nanotubes exhibited noticeable amplified electrochemical response signal. The differential voltammetric anodic peak current was linear to oxacillin concentration in the range from 2.0 × 10^?7 to 1.0 × 10^?4 mol·l^?1, and the detection limit was 6.9 × 10^?9 mol·l^?1. The proposed imprinted sensor was applied to the determination of oxacillin in human blood serum samples successfully. Copyright © 2011 John Wiley & Sons, Ltd.     

Nimustine hydrochloride: the first crystal structure determination of a 2‐chloroethyl‐N‐nitrosourea hydrochloride derivative by X‐ray powder diffraction and solid‐state NMR

Nimustine hydrochloride [systematic name: 4‐amino‐5‐({[N‐(2‐chloroethyl)‐N‐nitrosocarbamoyl]amino}methyl)‐2‐methylpyrimidin‐1‐ium chloride], C₉H₁₄ClN₆O₂⁺·Cl⁻, is a prodrug of CENU (chloroethylnitrosourea) and is used as a cytostatic agent in cancer therapy. Its crystal structure was determined from laboratory X‐ray powder diffraction data. The protonation at an N atom of the pyrimidine ring was established by solid‐state NMR spectroscopy.     

Dependence of Protein Recognition of Temperature‐Sensitive Imprinted Hydrogels on Preparation Temperature

Temperature‐sensitive imprinted and non‐imprinted hydrogels composed of N‐isopropylacrylamide (NIPA) and 2‐acrylamido‐2‐methyl‐propanosulfonic acid (AMPS) have been prepared by free‐radical crosslinking copolymerization in aqueous solution at three different temperatures: 10 °C (below the lower critical solution temperature, LCST), 33 °C (at the LCST), and 40 °C (above the LCST). Myoglobin (Mb, MW 17 kDa) is used as the template biomolecule. The effects of the initial concentration and adsorption time over the Mb adsorption capacity of the hydrogels have been analyzed and found to be strongly dependent on the preparation temperature (T_prep). The maximum Mb adsorption for the imprinted hydrogel prepared at 10 °C is 97.40 ± 2.35 mg Mb · g⁻¹ dry gel in 0.32 mg · mL⁻¹ Mb solution at 22 °C. Moreover, batch adsorption equilibrium and selectivity studies have been performed using a reference molecule, hemoglobin (Hb, MW 65 kDa). The imprinted hydrogels have a 2.8–3.3 times higher adsorption capacity for Mb than the non‐imprinted hydrogels prepared at the same T_preps, and also have a 1.8–2.7 times higher selectivity for the imprinted molecule.

     

Development of a Creatinine Sensor Based on a Molecularly Imprinted Polymer‐Modified Sol‐Gel Film on Graphite Electrode

An electrochemical creatinine sensor based on a molecularly imprinted polymer (MIP)‐modified sol‐gel film on graphite electrode was developed. The surface coating of MIP over sol‐gel was advantageous to obtain a porous film with outwardly exposed MIP cavities for unhindered selective rebinding of creatinine from aqueous and biological samples. A fast differential pulse, cathodic stripping voltammetric response of creatinine can be obtained after being preanodized the sensor in neutral medium containing appropriate amount of creatinine at +1.8 V versus SCE for 120 s. A linear response over creatinine concentration in the range of 1.23 to 100 μg mL^?1 was exhibited with a detection limit of 0.37 μg mL^?1 (S/N=3).     

Synthesis and Nonlinear Optical Properties of a New A-π-A Two-Photon Compound Utilizing Dibenzothiophene as Center

A new two‐photon material, 3E,6E‐bis(2‐pyrid‐4′‐ylvinyl)dibenzothiophene (BPVDBT), has been firstly synthesized by an efficient Pd‐catalyzed Heck coupling route. The single‐ and two‐photon fluorescence, quantum yields, lifetimes, solvent effects of the chromophore were studied in detail and the compound exhibited solvent‐sensitivity. The fluorescence intensity (I_out) and input excitation intensity (I_in) can fit in well with the quadratic parabolas, which indicates that the up‐converted fluorescence was induced by the two‐photon absorption (TPA). TPA cross‐section of BPVDBT has been measured using the two‐photon‐induced fluorescence method, whose value is 14.24×10^?50 cm⁴·s·photon^?1·molecule^?1 at 750 nm. The experimental results confirm that BPVDBT is a good two‐photon absorbing chromophore with an A‐π‐A type.     

Cadmium‐1,3,6,8‐tetrakis(4‐carboxylphenyl)pyrene Framework as a Thermometer for Fluorescence Sensing of Temperature

Compounds exhibiting tunable fluorescence emission upon adjusting the temperature are considered smart materials. Herein a three‐dimensional structure of {[Cd(TBAPy)(H₂O)₂] · 4(H₂O)}_n ( 1 ) constructed from Cd^II and 1,3,6,8‐tetrakis(4‐carboxylphenyl)pyrene (TBAPy^4–) ligand was synthesized and characterized. Temperature‐dependent fluorescence studies showed the emission intensities for compound 1 decrease as temperature increasing. The emission intensity is linearly related to temperature in the range of 100 to 300 K. This findings demonstrate that compound 1 is a good candidate for temperature sensitive sensor over a wide temperature range. Such a fluorescence behavior is closely related to the highly conjugated organic ligand with a pyrene core.     

Electrochemical Sensor for Sensitive Determination of Ga(III) Ion Based on β‐Cyclodextrin Incorporated Multi‐walled Carbon Nanotubes and Imprinted Sol‐gel Composite Film

A novel sensor for detection of trace gallium ion [Ga(III)] was created by stepwise modification of a gold electrode with β‐cyclodextrin (β‐CD)/multi‐walled carbon nanotubes (MWCNTs) and an ion imprinted polymer (IIP). The sensor surface morphology was characterized by scanning electron microscopy. The electrochemical performance of the imprinted sensor was investigated by cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The sensor displayed excellent selectivity towards the target Ga(III) ion. Meanwhile, the introduced MWCNTs displayed noticeable catalytic activity, and β‐CD demonstrated significant enrichment capacity. A linear calibration curve was obtained covering the concentration range from 5.0×10^?8 to 1.0×10^?4 mol·L^?1, with a detection limit of 7.6×10^?9 mol·L^?1. The proposed sensor was successfully applied to detect Ga(III) in real urine samples.     

A self‐penetrated three‐dimensional zinc(II) coordination framework based on 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoic acid and 1,3‐bis[(imidazol‐1‐yl)methyl]benzene ligands: synthesis,structure and properties

With the rapid development of metal–organic frameworks (MOFs), a variety of MOFs and their derivatives have been synthesized and reported in recent years. Commonly, multifunctional aromatic polycarboxylic acids and nitrogen‐containing ligands are employed to construct MOFs with fascinating structures. 4,4′,4′′‐(1,3,5‐Triazine‐2,4,6‐triyl)tribenzoic acid (H₃TATB) and the bidentate nitrogen‐containing ligand 1,3‐bis[(imidazol‐1‐yl)methyl]benzene (bib) were selected to prepare a novel Zn^II‐MOF under solvothermal conditions, namely poly[[tris{μ‐1,3‐bis[(imidazol‐1‐yl)methyl]benzene}bis[μ₃‐4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoato]trizinc(II)] dimethylformamide disolvate trihydrate], {[Zn₃(C₂₄H₁₂N₃O₆)₂(C₁₄H₁₄N₄)₃]·2C₃H₇NO·3H₂O}_n ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction, IR spectroscopy and powder X‐ray diffraction. The properties of 1 were investigated by thermogravimetric and fluorescence analysis. Single‐crystal X‐ray diffraction shows that 1 belongs to the monoclinic space group Pc. The asymmetric unit contains three crystallographically independent Zn^II centres, two 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoate (TATB^3?) anions, three complete bib ligands, one and a half free dimethylformamide molecules and three guest water molecules. Each Zn^II centre is four‐coordinated and displays a distorted tetrahedral coordination geometry. The Zn^II centres are connected by TATB^3? anions to form an angled ladder chain with large windows. Simultaneously, the bib ligands link Zn^II centres to give a helical Zn–bib–Zn chain. Furthermore, adjacent ladders are bridged by Zn–bib–Zn chains to form a fascinating three‐dimensional self‐penetrated framework with the short Schläfli symbol 6⁵·7·8¹³·9·10. In addition, the luminescence properties of 1 in the solid state and the fluorescence sensing of metal ions in suspension were studied. Significantly, compound 1 shows potential application as a fluorescent sensor with sensing properties for Zr⁴⁺ and Cu²⁺ ions.     

Determination of Three Tanshinones from Radix Salvia Miltiorrhiza by Molecularly Imprinted Solid-phase Extraction

A selective molecularly imprinted solid‐phase extraction procedure was developed for the selective separation of tanshinone I, tanshinone IIA, and cryptotanshinone from Radix Salvia Miltiorrhiza samples. Tanshinone IIA imprinted polymers (MIP) synthesized in ethanol‐dodecanol system show high affinity to tanshinone IIA and its structure analogs in aqueous environment and the affinity can be controlled by adjusting the intensity of the eluents. By using 60% water‐40% methanol (volume ratio) and 99.5% methanol‐0.5% trifluoroacetic acid (volume ratio) as washing and eluting solvents, most interferences originating from the salvia matrix were eliminated. The extracts were sufficiently clean enough to be directly injected into HPLC for further chromatographic analysis. Good linearity was obtained from 0.4 to 500.0 mg·L^?1 (r²=0.999) with the relative standard deviations less than 4.2%. The mean recoveries of tanshinone IIA in Radix Salvia Miltiorrhiza were more than 85.6% at three different concentrations and the limits of detection were 0.06–0.09 mg·L^?1. This method is a viable alternative tool to the existing HPLC methods for analyzing the content of the three tanshinones in Radix Salvia Miltiorrhiza samples.