Chromotrope 2B Research Articles

NEW METHODS FOR DETERMINATION OF AMBROXOL HYDROCHLORIDE IN PURE FORM AND FARMACEUTICAL FORMULATIONS BASED ON SPECTROPHOTOMETRY

The proposed methods are simple, rapid, and accurate, used for the determination of Ambroxol Hydrochloride (AMB.HCl). There were two methods, the First method included chromotrope 2R, chromotrope 2B, arsenazo I, ASPANDS, and chromotrope 2C for the determination of AMB.HCl in its pure and pharmaceutical forms. The first method is based on the drug oxidation with Potassium permanganate in excess. The unreacted potassium permanganate was determined by measuring the absorbance of colored chromotropic acid azo dyes namely chromotrope 2R, chromotrope 2B, arsenazo I, SPADNS, and chromotrope 2C. The suitable ƛmax were 500, 510, 500, 510, and 520 nm, respectively. Under optimized conditions, Beer’s Law showed good correlation and obeyed in the concentration range 1.51-7.46, 0.82-4.97, 1.65-6.63, 0.82-6.63, and 1.73-8.29 µg mL-1 for chromotrope 2R, chromotrope 2B, arsenazo I , SPADNS, and chromotrope 2C. The apparent molar absorptivity, Sandell sensitivity, LOD, and LOQ were calculated. Pure and pharmaceutical forms containing AMB.HCl were analyzed and tested for the validity of the proposed methods. The Second method spectrophotometric titration is based on the determination of unreacted potassium permanganate using spectrophotometric titration against ferrous ammonium sulfate, where the end-point was detected spectrophotometrically using ferrion indicator at 510 nm, the Relative standard deviation where 0.23-2.04 with average recovery 100.35-103%.

Sulfasalazine and Chromotrope 2B reduce oxidative stress in murine bone marrow-derived mesenchymal stem cells

With advancing age of stem cells, dysregulation of various processes at the cellular level occurs, thereby decreasing their regeneration potential. One of the changes that occurs during the aging process is the accumulation of reactive oxygen species (ROS), which accelerates the processes of cellular senescence and cell death. The aim of this study is to evaluate two antioxidant compounds; Chromotrope 2B and Sulfasalazine, for their antioxidant effects on young and old rat bone marrow mesenchymal stem cells (MSCs). Oxidative stress was induced in MSCs by 5 µM dexamethasone for 96h and the cells were treated with Chromotrope 2B or Sulfasalazine, 50 µM each. The effects of antioxidant treatment following oxidative stress induction was evaluated by transcriptional profiling of genes involved in the oxidative stress and telomere maintenance. Expression levels of Cat, Gpx7, Sod1, Dhcr24, Idh1, and Txnrd2 were found to be increased in young MSCs (yMSCs) as a result of oxidative stress, while Duox2, Parp1, and Tert1 expression were found to be decreased as compared to the control. In old MSCs (oMSCs), the expressions of Dhcr24, Txnrd2, and Parp1 increased, while that of Duox2, Gpx7, Idh1, and Sod1 decreased following oxidative stress. In both MSC groups, Chromotrope 2B prompted decrease in the ROS generation before and after the induction of oxidative stress. In oMSCs, ROS content was significantly reduced in the Sulfasalazine treated group. Our findings suggest that both Chromotrope 2B and Sulfasalazine possess the potential to reduce the ROS content in both age groups, though the latter was found to be more potent. These compounds can be used to precondition MSCs to enhance their regenerative potential for future cell-based therapeutics.

Optimization of Preparation Conditions of Poly(m-phenylene isophthalamide) PMIA Hollow Fiber Nanofiltration Membranes for Dye/Salt Wastewater Treatment.

Externally selective thin film composite (TFC) hollow fiber (HF) nanofiltration membranes (NFMs) hold great industrial application prospects because of their high surface area module. However, the complicated preparation process of the membrane has hindered its mass manufacture and application. In this work, PMIA TFC HF NFMs were successfully prepared by the interfacial polymerization (IP) of piperazine (PIP) with 1,3,5-benzenetricarbonyl trichloride (TMC). The effect of the membrane preparation conditions on their separation performance was systematically investigated. The characterized results showed the successful formation of a polyamide (PA) separation layer on PMIA HF substrates by the IP process. The as-prepared HF NFMs' performance under optimized conditions achieved the highest pure water permeability (18.20 L·m-2·h-1, 0.35 MPa) and superior salt rejection in the order: RNa2SO4 (98.30%) > RMgSO4 (94.60%) > RMgCl2 (61.48%) > RNaCl (19.24%). In addition, the as-prepared PMIA HF TFC NFMs exhibited desirable pressure resistance at various operating bars and Na2SO4 feed concentrations. Excellent separation performance of chromotrope 2B dye was also achieved. The as-prepared PMIA HF NFMs thus show great promise for printing and dyeing wastewater treatment.

Heterogeneous catalytic oxidation of chromotrope 2B with H2O2 and metal complexes supported on aluminum oxide hydroxide as catalyst

AbstractThe heterogeneous catalytic oxidation of Chromotrope 2B (C2B) dye with H2O2 and the aluminum oxide hydroxide (AlOOH) modified with ammonia complexes of CuII, CoII, NiII, and CrIII (AlOOH/[Mn+(amm)m]) as catalysts were studied. The AlOOH/[CuII(amm)4] is the most efficient catalyst and therefore it was chosen as the potential catalyst for the oxidative degradation of C2B in an aqueous solution. The AlOOH/[CuII(amm)4] was characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray (EDX), and transmission electron microscopy (TEM), techniques. The rate of reaction was dependent on the type of the metal complex supported on the AlOOH, initial concentration of the dye and H2O2, catalyst dose, pH, the concentration of NaCl, and temperature. The catalytic activity of the AlOOH/[Mn+(amm)m] according to the kind of metal ion decreased in the order: CuII > CoII > CrIII > NiII. Other catalysts consisting of the AlOOH supported with CuII complexed with ethylenediamine, ethanolamine, 1,3 propanediamine, and 1,4 butanediamine, (AlOOH/[CuII(amine)m]), were also investigated. The activity of the (AlOOH/[CuII(amine)m]) as catalyst according to the type of ligand followed the order: 1,4 butanediamine > 1,3 propanediamine > ethanolamine > ethylenediamine > ammonia. The reaction rate increased with increasing the catalyst dose, concentration of H2O2, C2B, and NaCl, pH, and temperature. Since the reusability results for the AlOOH/[CuII(amm)4] revealed good stability over seven cycles, it can thus be considered a promising and cost‐effective catalyst for the removal of harmful dyes from wastewater.

Determination of Naphthol Yellow S and Chromotrope 2B at trace levels by spectrophotometry after mixed micellar cloud point extraction using TX-114 and TBAB

A method for the determination of two anionic dyes, Naphthol Yellow S (NYS) and Chromotrope 2B (CTB) in the presence of TBAB (Tetra butyl ammonium bromide) and Triton X-114 (Polyethylene glycol tert-octylphenyl ether) mixed micelles was developed by cloud point extraction pre-concentration technique. Good extraction efficiency was achieved for both NYS and CTB(85-92)% from their aqueous solutions by the optimization of pH of the solution, concentration of surfactants and salting out agent. Linearity was found to be in the range 1.5 – 30.0 μg mL-1for NYS and 1.86 – 27.2 μg mL-1 for CTB. The limit of detection was found to be in ngmL-1 range. Langmuir adsorption model was successfully applied to the phase separation process. The enthalpy, entropy and free energy change for solubilization of these dyes in surfactant phase were also determined. This method was then used to determine the dye concentration in the tap and sea water samples.

Chelate Formation between Thorium(IV) and p-Nitrobeazeneazochromotropic Acid (Chromotrope 2B) : Spectrophotometric and Electrical Conductance Studies

Chelate Formation between Thorium(IV) and p-Nitrobeazeneazochromotropic Acid (Chromotrope 2B) : Spectrophotometric and Electrical Conductance Studies

Polydopamine-Assisted Two-Dimensional Molybdenum Disulfide (MoS2)-Modified PES Tight Ultrafiltration Mixed-Matrix Membranes: Enhanced Dye Separation Performance.

Tight ultrafiltration (TUF) membranes with high performance have attracted more and more attention in the separation of organic molecules. To improve membrane performance, some methods such as interface polymerization have been applied. However, these approaches have complex operation procedures. In this study, a polydopamine (PDA) modified MoS2 (MoS2@PDA) blending polyethersulfone (PES) membrane with smaller pore size and excellent selectivity was fabricated by a simple phase inversion method. The molecular weight cut-off (MWCO) of as-prepared MoS2@PDA mixed matrix membranes (MMMs) changes, and the effective separation of dye molecules in MoS2@PDA MMMs with different concentrations were obtained. The addition amount of MoS2@PDA increased from 0 to 4.5 wt %, resulting in a series of membranes with the MWCO values of 7402.29, 7007.89, 5803.58, 5589.50, 6632.77, and 6664.55 Da. The MWCO of the membrane M3 (3.0 wt %) was the lowest, the pore size was defined as 2.62 nm, and the pure water flux was 42.0 L m−2 h−1 bar−1. The rejection of Chromotrope 2B (C2B), Reactive Blue 4 (RB4), and Janus Green B (JGB) in aqueous solution with different concentrations of dyes was better than that of unmodified membrane. The separation effect of M3 and M0 on JGB at different pH values was also investigated. The rejection rate of M3 to JGB was higher than M0 at different pH ranges from 3 to 11. The rejection of M3 was 98.17–99.88%. When pH was 11, the rejection of membranes decreased with the extension of separation time. Specifically, at 180 min, the rejection of M0 and M3 dropped to 77.59% and 88.61%, respectively. In addition, the membrane had a very low retention of salt ions, Nacl 1.58%, Na2SO4 10.52%, MgSO4 4.64%, and MgCl2 1.55%, reflecting the potential for separating salts and dyes of MoS2@PDA/PES MMMs.

Spectrophotometric Determination of Benzethonium Chloride Using Some Chromotropic Acid Azo Dyes

Five simple, sensitive, rapid and accurate spectrophotometric methods were developed for the determination of benzethonium chloride in its pharmaceutical formulation. The proposed methods are based on ion-pairs formation of the drug with some chromotropic acid azo dyes such as arsenazo (I) (ARZO (I)), arsenazo (III) (ARZO (III)), SPADNS, chromotrope 2R (C2R) and chromotrope 2B (C2B) and subsequent extraction into methylene chloride. The extracts have maximum absorbance at 520, 540, 520, 530, and 520 nm respectively. The method of solvent extraction showed good sensitivity and wide linearity over a concentration range of 8.96-89.62, 4.48-44.81, 4.48-44.81, 4.48-44.81 and 8.96-89.62 µg/mL. Limits of detection 0.52, 1.07, 0.14, 0.62, and 0.77 µg/mL for ARZO (I), ARZO (III), SPADNS, C2R, and C2B, respectively. They were also used for the analysis of the antibacterial spray Dermoplast® with excellent recovery (95.88-102.45%) and relative standard deviation values (0.49-2.68%). The statistical analysis of the obtaine data was performed.

Homogeneous and heterogeneous catalytic oxidation of some azo dyes using copper(II) ions.

The kinetics of the homogeneous and heterogeneous catalytic oxidation processes of three azo dyes in presence of copper (II) - ions, copper (II) - ions - supported on alumina and on zinc oxide as well as copper ammonia complex supported on alumina were investigated in aqueous solutions. The dyes are Chromotrope 2B (C2B), Chromotrope 2R (C2R) and Chrysophenen (CRY). The reaction progress was followed by monitoring the decrease in absorbance at ℷmax 512, 511 and 401 nm, respectively. The rate of reaction increased with increasing either the concentration of the dye or the catalyst, giving a plateau at high concentrations of the catalyst. On the other hand, the rate of reaction increased gradually with increasing hydrogen peroxide concentration attaining a maximum then decreased thereafter. The reaction rate was also increased with increasing pH and temperature and was found to be entropy controlled. This work could be applied for dye baths water reuse to reduce costs in textile and dyeing factories as will as for environmental purposes.

Highly Sensitive and Selective Detection of Dopamine at Poly(chromotrope 2B)-Modified Glassy Carbon Electrode in the Presence of Uric Acid and Ascorbic Acid

A highly sensitive and selective electrochemical method based on a poly(chromotrope 2B)-modified anodized glassy carbon electrode (PCHAGCE) was developed for the determination of dopamine (DA) in the presence of uric acid (UA) and ascorbic acid (AA). The PCHAGCE sensor exhibited excellent electron-mediating behavior towards the oxidation of DA in 0.1M phosphate buffer solution (PBS) (pH7.0). It was found that the electrocatalytic activity was significantly dependent on the charge status and molecular structure of the target molecules. Differential pulse voltammetry (DPV) measurements revealed oxidation signals for DA, UA, and AA that were well-resolved into three distinct peaks with AA–DA, DA–UA, and AA–UA peak potential separations (ΔEp) of 172, 132, and 304mV, respectively. A detection limit of 0.04±0.001μM (S/N=3) and a quantification limit (S/N=10) of 0.149±0.03μM were obtained for DA sensing in a linear range of 1 to 40μM in PBS (pH7.0) with a very high sensitivity of 1.522±0.032μA·μM−1. The DA concentrations in human urine samples were also successfully determined with recoveries of 94.0–98.0%. This approach provides a simple, easy, sensitive, and selective method to detect DA in the presence of AA and UA.

Simultaneous determination of ranitidine and metronidazole in pharmaceutical formulations at poly(chromotrope 2B) modified activated glassy carbon electrodes

A simple and sensitive electrochemical method for the simultaneous and quantitative detection of ranitidine (RT) and metronidazole (MT) was developed, based on a poly(chromotrope 2B) modified activated glassy carbon electrode (PCHAGCE). The PCHAGCE showed excellent electrocatalytic activity toward the reduction of both RT and MT in 0.1 mol/L phosphate buffer solution (pH 6.0). The peak-to-peak separations for the simultaneous detection of RT and MT between the two reduction waves in cyclic voltammetry were increased significantly from ∼0.1 V at activated GCE, to ∼0.55 V at PCHAGCE. By differential pulse voltammetry techniques, the reduction peak currents of RT and MT were both linear over the range of 1.0 × 10−5–4.0×10−4 mol/L. The detection limits (S/N = 3) were 5.4 × 10−7 mol/L and 3.3 × 10−7 mol/L for RT and MT, respectively. The modified electrode was successfully applied to the determination of RT and MT in pharmaceutical preparations and human serum as real samples with stable and reliable recovery data.

Additions and Corrections - Coprecipitative Preconcentration of Cr(III), Pb(II), Zn(II), Cd(II) and Mn(II) Ions with Al(III) and Fe(III) Carriers and Chromotrope 2B Reagent and their FAAS Determination in Various Water and Food Samples

Coprecipitation methods using Al(III) and Fe(III) as carrier elements and chromotrope 2B as coprecipitative reagent were described for the preconcentration of Cr(III), Pb(II), Zn(II), Cd(II) and Mn(II) ions. The surface morphology of coprecipitants was examined by scanning electron microscopy (SEM). The optimum conditions for both coprecipitation methods, such as pH of the solution, amounts of carriers and reagent, sample volume and effect of interfering ions were investigated. Similar results were obtained for both carriers. The optimal pH was found at 9.0. The limits of detection (LOD) found were: 0.54 for Cr(III), 1.16 for Pb(II) and 0.08 µg L-1 for Zn(II) when Al(III) carrier was used and 0.08, 0.17, 0.08 and 1.16 µg L-1 for Cd(II), Mn(II), Zn(II) and Pb(II), respectively, when Fe(III) was the carrier. For the accuracy of the methods, the analysis of certified reference materials (TMDA 54.4 and TMDA 70 fortified lake waters and SRM 1578a rice flour) and recovery studies were performed. The method was applied for the determination of analytes in water (tap water, dam water and river water) and food (apricot, mint and macaroni) samples.

Coprecipitative preconcentration of Cr(III), Pb(II), Zn(II), Cd(II) and Mn(II) Ions with Al(III) and Fe(III) carriers and chromotrope 2B reagent and their FAAS determination in various water and food samples

Coprecipitative preconcentration of Cr(III), Pb(II), Zn(II), Cd(II) and Mn(II) Ions with Al(III) and Fe(III) carriers and chromotrope 2B reagent and their FAAS determination in various water and food samples

A new fading spectrophotometric assay of chitosan with chromotrope 2B

Taking advantage of the reaction between chitosan and chromotrope 2B in Clark-Lubs buffer medium which shows a decrease in absorbance at the maximum absorption peak of 516 nm, a fairly new, simple and sensitive fading spectrophotometric method for the determination of chitosan was developed. Optimum reaction conditions and other important analytical parameters for the reaction system were investigated. A concentration range of 1.0–9.0 mg L−1 for chitosan was used in accordance with Beer’s Law. The proposed method was applied for the determination of chitosan in different chitosan capsule samples with satisfactory results that agreed with those of the bromophenol blue spectrophotometric method.

SYNTHESIS AND STRUCTURAL STUDY OF THE ION-ASSOCIATES OF SILDENAFIL CITRATE WITH CHROMOTROPIC ACID AZO DYES

Five ion-associates of the drug sildenafil citrate (SC) with mono-chromotropic acid azo dyes, chromotrope 2B (I) and chromotrope 2R (II), and chromotropic acid bi-azo dyes, bis-3,6-(o-hydroxyphenylazo)-chromotropic acid (III), bis-3,6-(p-N,N-dimethylphenylazo)-chromotropic acid (IV) and 3-phenylazo-6-o-hydroxyphenylazo-chromotorpic acid (V) have been synthesized. Structural characterization of these novel sildenafil citrate ion-associates was carried out using elemental analysis and spectral techniques (Vis and IR). IR absorption spectra of the investigated ion-associates are studied and compared with those of the pure azo dyes and the drug. The spectral characteristics, oscillator strengths, transition dipole moments and resonance energy of the ion-associates in the ground state have been calculated.

Simultaneous removal of chromotrope 2B and radionuclides from mixed radioactive process wastewater using organo-bentonite

The simultaneous removal of cationic radionuclides, 137 Cs(I), 60 Co(II) and 152+154 Eu(III), and a chemically toxic anionic pollutant, the analytical reagent chromotrope 2B (C2B), from simulated mixed radioactive process wastewater (MRPWW) has been investigated using bentonite modified with cetyltrimethylammonium bromide. Modification was confirmed by elemental analysis, X-ray diffraction and infrared spectroscopy. Bentonite partially modified to 78% of the cation exchange capacity (PMB) was found capable to adsorb adequately both C2B and the radionuclides from aqueous solutions. Detailed batch kinetics and isotherm studies for removal of C2B singly and the radionuclides simultaneously were performed. The C2B and radionuclides kinetics conform to pseudo-first-order rate equation and the adsorption isotherms are treated with Freundlich and Langmuir models. Thermodynamic parameters were evaluated. Results suggest physisorption and ion-exchange as the principal uptake mechanism for C2B and the radionuclides, respectively. High simultaneous removal was obtained for C2B (≈ 100%) and each of the test radionuclides (>99%) from the simulated MRPWW.

Spectrophotometric determination of sildenafil citrate in pure form and in pharmaceutical formulation using some chromotropic acid azo dyes

Two simple and highly sensitive spectrophotometric methods were developed for the quantitative determination of the drug sildenafil citrate (SC), Viagra, in pure form and in pharmaceutical formulations, through ion-associate formation reactions (method A) with mono-chromotropic acid azo dyes, chromotrope 2B (I) and chromotrope 2R (II) and ion-pair reactions (method B) with bi-chromotropic acid azo dyes, 3-phenylazo-6-o-carboxyphenylazo-chromotropic acid (III), bis-3,6-(o-hydroxyphenylazo)-chromotropic acid (IV), bis-3,6-(p-N,N-dimethylphenylazo)-chromotropic acid (V) and 3-phenylazo-6-o-hydroxyphenylazo-chromotorpic acid (VI). The reaction products, extractable in methylene chloride, were quantitatively measured at 540, 520, 540, 570, 600 and 575 nm using reagents, I–VI, respectively. The reaction conditions were studied and optimized. Beer's plots were linear in the concentration ranges 3.3–87.0, 3.3–96.0, 5.0–115.0, 2.5–125.0, 8.3–166.7 and 0.8–15.0 μg mL −1 with corresponding molar absorptivities 1.02 × 10 4, 8.34 × 10 3, 6.86 × 10 3, 5.42 × 10 3, 3.35 × 10 3 and 2.32 × 10 4 L mol −1 cm −1 using reagents I–VI, respectively. The limits of detection and Sandell's sensitivities were calculated. The methods were successfully applied to the analysis of commercial tablets (Vigoran) and the recovery study reveals that there is no interference from the common excipients that are present in tablets. Statistical comparison of the results was performed with regard to accuracy and precision using Student's t- and F-tests at 95% confidence level. There is no significant difference between the reported and proposed methods with regard to accuracy and precision.

Voltammetric Studies on Chromotrope 2B‐Protein Interaction and Its Analytical Application

AbstractIn this paper the interaction of chromotrope 2B (Ch2B) with proteins was studied by the electrochemical method. Ch2B is an azo dye and shows irreversible electrochemical responses on the mercury electrode in a pH 3.0 Britton‐Robinson (B‐R) buffer solution. After the addition of human serum albumin (HSA) into the Ch2B solution, an interaction took place, and a supramolecular complex was formed in the mixed solution. The electrochemical parameters of the Ch2B‐HSA interaction system were calculated and compared. The results showed that in the absence and presence of HSA in Ch2B solution, the electrochemical parameters such as the formal potential E0, the electrode reaction standard rate constant ks, etc. showed no significant changes, which indicated that an electro‐inactive supramolecular biocomplex was formed. The free concentration of Ch2B in reaction solution was decreased, and this resulted in the decrease of the peak current. The binding constant and the binding ratio were calculated as 7.85 × 109 and 1:2, respectively, and the interaction mechanism was discussed. Based on the decrease of the peak current, this new electrochemical method was proposed for the determination of HSA in the concentration range of 2.0˜25.0 mg/L with the linear regression equation as ΔIp′ (nA) = 50.56C (mg/L) — 6.72 (γ = 0.995). This method was further used to determine other different kinds of proteins, such as bovine serum albumin (BSA), oval albumin, etc‥ The new method was successfully applied to detect the content of albumin in healthy human serum samples with the results in good agreement with the traditional Coomassie Brilliant Blue G‐250 spectrophotometric method.

Spectrophotometric determination of pipazethate HCl, dextromethorphan HBr and drotaverine HCl in their pharmaceutical preparations

A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of pipazethate hydrochloride, dextromethorphan hydrobromide and drotaverine hydrochloride using chromotrope 2B (C2B) and chromotrope 2R (C2R). The method consists of extracting the formed ion-associates into chloroform in the case of pipazethate HCl and dextromethorphan HBr or into methylene chloride in the case of drotaverine HCl. The ion-associates exhibit absorption maxima at 528, 540 and 532 nm with C2B and at 526, 517 and 522 nm with C2R for pipazethate HCl, dextromethorphan HBr and drotaverine HCl, respectively. The calibration curves resulting from the measurements of absorbance–concentration relations (at the optimum reaction conditions) of the extracted ion-pairs are linear over the concentration range 4.36–52.32 μg mL −1 for pipazethate, 3.7–48.15 μg mL −1 for dextromethorphan and 4.34–60.76 μg mL −1 for drotaverine, respectively. The effect of acidity, reagent concentration, time, solvent and stoichiometric ratio of the ion-associates were estimated. The molar absorptivity and Sandell sensitivity of the reaction products were calculated. Statistical treatment of the results reflects that the procedure is precise, accurate and easily applied for the determination of the drugs under investigation in pure form and in their pharmaceutical preparations.

Laser-induced breakdown spectroscopy in analysis of Al 3+ liquid droplets: On-line preconcentration by use of flow-injection manifold

Laser-induced breakdown spectroscopy (LIBS), combined with a flow-injection system, is demonstrated to analyze liquid droplets of aluminum salt, as generated with an electrospray ionization device. The spray needle also serves as the anode, through which the analyte solution is spread toward the other metal base as the cathode. Along the passage of the FI manifold, the Al-sample loading speed is controlled at 0.15 mL min −1, restricted to the small diameter of the spray needle, and the loading volume amounts to 0.1 mL. The metal ion is retained in a cation-exchange resin microcolumn immobilized with Chromotrope 2B chelating agent, followed by elution with a 0.5 M HCl solution into LIBS. Upon laser irradiation at the preconcentrated liquid droplets, the time-resolved laser-induced breakdown (LIB) emission and plasma-induced current signals are acquired concurrently on a single-shot basis. The area under the LIB/current distribution increases in linear proportion as the concentration of the sample solution increases. The detection limit thus obtained can reach 1.5 mg L −1, about an order of magnitude lower than those achieved previously using single-laser ablation without involvement of preconcentration. The linear dynamic range is more than two orders of magnitude.