Determination of boron in water and pharmaceuticals by sequential-injection analysis and fluorimetric detection

Decay-Associated Fluorescence for Boron Determination in Uranium-Based Nuclear Fuels

Herein is reported a novel as well as simple, sensitive, and cost-effective method for determination of boron by time-resolved fluorescence spectrometry in uranium-based nuclear fuels. Boron is complexed with fluorescent ligand chromotropic acid, and the complex formed is a measure of boron. Since the steady-state fluorescence spectra of excess ligand and complex are overlapping, the developed method emphasizes the power of time resolution. The signatory fluorescence decay times of ligand and complex are employed to derive their decay-associated spectra (DAS) and, thereby, spectroscopically eliminate the high background of ligand fluorescence. The calibration plot has a wide linear dynamic range of 5-100 ppb with r2 better than 0.998. Precision is better than 5% at the 10 ppb level and 4% at the 50 ppb level (n = 9). The detection limit is 1.5 ppb, and recovery of spiked boron (25 ppb) from the uranium samples was better than 94%. The developed method was validated by analyzing U3O8-based ILCE Standards and applied to enriched uranium fuel samples. The main advantage of the developed method is a reduction in sample size requirement due to better sensitivity and selectivity. This in turn reduces the load of uranium recovery from analytical waste, especially in the case of enriched uranium samples. Additionally, it eliminates the need of organic solvents/medium.

Curcumin nanoparticle doped starch thin film as a green colorimetric sensor for detection of boron

A tapioca starch film doped with curcumin nanoparticles was successfully fabricated and applied as a novel green colorimetric sensor for detection of boron in wastewater. Curcumin nanoparticles (curn, 30-90 nm) extracted from turmeric powder were used as a green probe, while tapioca starch was used as a natural support substrate. A yellow thin film (51 μm thick) fabricated on a used plastic spoon turned red-brown after immersion in boron solution (pH 9) for 15 min with excellent selectivity. The film costs only 0.0007 USD, while the cost of the sensor (curn-film on new plastic spoon) was 0.004 USD. After use the film could be completely washed from the plastic, it being biodegradable, while the used plastic spoon could be re-used to fabricate a new sensor at least 10 times. The good 1.52%RSD precision was obtained across three lots fabricated. When the curn-film was used in conjunction with digital image colorimetry (DIC), a simple and rapid quantification of boron was achieved. The green color layer in reflected light image of the red-brown product (I_G) provided the highest sensitivity (64 ± 1 a.u. L mg^-1) and the lowest detection limit of 0.052 ± 0.001 mg L^-1. The intra-day testing (9 films) had 2.41 to 4.34%RSD, while the inter-day testing had 2.29 to 5.66%RSD (15 films, 5 days). Accuracy in terms of relative error for control samples (0.40 mg L^-1) was +3.63%. Wastewater samples from Para-rubber wood processing plant were quantified by curn-film and DIC, giving 4248 ± 391 mg L^-1 boron concentration with no significant difference to ICP determination at 95% confidence level. The sensors after storage in a desiccator for a year gave readings changed by only +3.5% and -2.1% relative to freshly prepared sensors.

Determination of boron with molecular emission using laser-induced breakdown spectroscopy combined with laser-induced radical fluorescence

Boron is an essential element for industry, but it is hard to accurately and rapidly determine high boron content with conventional laser-induced breakdown spectroscopy (LIBS), due to the matrix and self-absorption effect. Using molecular emission is an alternative method for boron content analysis, but its weak spectra are major challenges. Here, boron monoxide (BO) radicals were used to establish calibration assisted by LIBS and laser-induced radical fluorescence (LIBS-LIRF). Two types of BO radical excitations, vibrational ground state excitation (LIRFG) and vibrational excited state excitation (LIRFE), were compared. The results showed that LIRFG achieved better sensitivity with a limit of detection of 0.0993 wt.%, while the LIRFE was more accurate with a root mean square error of cross validation of 0.2514 wt.%. In conclusion, this work provided a potential approach for molecular emission analysis with LIBS-LIRF.

Determination of boron in water samples by dispersive liquid–liquid microextraction based on the solidification of a floating organic drop coupled with a fluorimetric method

Dispersive liquid–liquid microextraction based on the solidification of a floating organic drop (DLLME-SFO) prior to fluorescence spectra analysis.

Fluorimetric detection of boron by azomethine-H in micellar solution and sol-gel

Mixtures of boron and azomethine-H in solution result in slow complexation. Addition of sodium dodecyl sulfate (SDS), polyethylene glycol dodecyl ether (Brij-35), 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (TritonX-100), and cetyltrimethyl ammonium bromide (CTAB) result in considerable decrease in complexation time and enhancement in signal of peak in solution and also sol-gel. The fluorescence of the complex is monitored at an emission wavelength of 486 nm with excitation at 416 nm. The presence of 1x10(-3) mol L(-1) SDS decreased the complexation time up to 10 min in solution and 20 min in sol-gel for above 0.25 microg B mL(-1) and 30 min in solution and 35 min in sol-gel for below 0.25 microg B mL(-1). However, the photostability did not change by adding micelle in both media. The proposed method shows a linear response toward boron in the concentration range of 0.05-10 microg mL(-1) and is selective for boron over a large number of electrolytes and cations. The detection limit was 7 microg L(-1). This method has been used for the detection of boron in environmental water samples and fruit juices with satisfactory results.

Voltammetric determination of boron by using Alizarin Red S

A novel voltammetric method for boron determination in ppb level is described. Boron complexes with Alizarin Red S (ARS) and the complex, as well as the free ligand, both adsorbs on a hanging mercury drop electrode. The method is based on the monitoring the anodic peak of the complex at -0.47 V in ammonium acetate-phosphate buffer (pH 7). The maximum peak current was obtained by scanning the potential from -700 mV versus Ag/AgCl to more positive potentials without accumulation in the presence of 1 x 10(-6) mol L(-1) of ARS. The instrumental parameters were mainly differential pulse mode with a pulse duration of 0.02 s and a scan rate of 5 mV s(-1). The limit of detection based on signal to ratio of 3 was calculated as 15 microgL(-1). The calibration plot for boron was linear in the range of 0-500 microg L(-1). The interference of various ions was examined and serious interference was observed from antimony(III). The relative standard deviation was found to be 5.1% for the 100 microg L(-1) boron level (n=10). The method was applied to the determination of boron in water and seawater samples with high boron content. The results obtained from the developed method were compared with Azomethine-H-method and no statistically significant difference was found.

Application of sequential injection analysis to pharmaceutical analysis

Sequential injection analysis is a well established tool for automation of pharmaceutical analysis. A short historical background of this technique is given as well as a brief discussion on the basic principles and potentials. The current applications of SIA in the pharmaceutical analysis are also described and discussed. The manifolds developed offer good analytical characteristics and are suitable for analysis of drug formulations, process analysis, drug-dissolution, drug-release testing and functional assays for screening potential drugs. The results obtained are in good agreement with those furnished by the application of the reference methods presented in the pharmacopoeias.