Development of a selective fluorimetric technique for rapid trace determination of zinc using 3-hydroxyflavone

AbstractA sensitive and a selective spectrofluorimetric method have been developed for the rapid determination of trace levels of zinc. The method is based on complex formation between zinc and 3-hydroxyflavone (3HF), which displays an intense emission signal around 478nm. The analytical performance of the method was examined by considering the factors that affect the complex formation such as pH, mole ratio of the metal and solvent type. The optimum conditions for the complex formation were metal to ligand stoichiometric ratio of 1:1 at pH 7.5 with 0.1M Tris buffer. Under these conditions the detection limit attained was 1.5ppb. The method was appropriately validated and yielded relative standard deviations of less than 2% (n=5), which was considered acceptable. It was successfully applied to the trace determination of zinc in drinking water, hair shampoo and pharmaceutical samples

Laser ablation of hard and soft materials – prospects and problems

Ablative laser technology (LA-ICP-MS) of solid samples is gaining popularity as a contemporary analytical technique. However, irradiation of soft samples presents a problem as they tend to splash and splatter, making analysis impractical. An original method has been developed in our research laboratory to ablate and analyze soft samples like pastes, gels and waxes. Samples were pre-treated with liquid nitrogen, petrified, and quickly analyzed before thawing set in. The technique has the potential to analyze soft samples, rapidly, without undergoing the tedious process of sample digestion. The technique functions by depth-profiling (petrified) soft samples to determine the elemental distribution within the matrix. An Nd:YAG deep UV (213-nm) laser ablation system was attached to a high-precision ICP-MS instrument. Irradiations were conducted with a flat-beam profile of 60% total energy and 50 µm beam diameter. The laser dwell time was 4 s; and repetition rate was 10 Hz. The laser ablated a total depth of 50 µm at 5 µm-intervals. Our hyphenated laser facility is capable of recording three-dimensional elemental profiles of soft samples (solidified), with minimal or no splashing effects. Elemental profiling is qualitative for heterogeneous solid targets due to the fact that matrix matched standards are generally not available for such variable matrices. However, quantitation is possible with homogeneous soft targets. The method is highly viable and makes a useful contribution to analytical science and to instrumental analysis, in general

Radioactivity in Oily Sludge and Produced Waste Water from Oil: Environmental Concerns and Potential Remedial Measures

Produced water separated from oil is usually returned to the environment and could permeate through the water table. If such water is contaminated with radioactive substances, it could create a definite threat to the water supply, especially in arid regions where ground water and overhead streams are sources of potable water. Low-level radioactive contamination of oily sludge is equally hazardous and also leads to detrimental pollution of water resources. We investigated the distribution of 226 Ra, 40 K and 228 Ac in produced waste water and oily sludge and found abnormal levels of radioactivity. A total of 90 ground wastewater samples were collected from different sites for a period of one year. The presence of these radionuclides was identified by their characteristic gamma rays. The detection system consisted of a high-purity germanium detector. Our results show that about 20% of the samples exhibited 20–60 Bq/L radioactivity and ~6% of the samples exceeded 60 Bq/L. Roughly 70% of the experimental samples fell in the range of 2–20 Bq/L, which still exceeded the maximum admissible drinking-water limit 0.2 Bq/L.radioactivity; oil sludge; waste water; gamma rays

Depth Profiling (ICP-MS) Study of Toxic Metal Buildup in Concrete Matrices: Potential Environmental Impact

This paper explores the potential of concrete material to accumulate toxic trace elements using ablative laser technology (ICP-MS). Concrete existing in offshore structures submerged in seawater acts as a sink for hazardous metals, which could be gradually released into the ocean creating pollution and anoxic conditions for marine life. Ablative laser technology is a valuable tool for depth profiling concrete to evaluate the distribution of toxic metals and locate internal areas where such metals accumulate. Upon rapid degradation of concrete these “hotspots” could be suddenly released, thus posing a distinct threat to aquatic life. Our work simulated offshore drilling conditions by immersing concrete blocks in seawater and investigating accumulated toxic trace metals (As, Be, Cd, Hg, Os, Pb) in cored samples by laser ablation. The experimental results showed distinct inhomogeneity in metal distribution. The data suggest that conditions within the concrete structure are favorable for random metal accumulation at certain points. The exact mechanism for this behavior is not clear at this stage and has considerable scope for extended research including modeling and remedial studies

Sustainability Study on Heavy Metal Uptake in Neem Biodiesel Using Selective Catalytic Preparation and Hyphenated Mass Spectrometry

It is common knowledge that the presence of trace metals in biofuels can be detrimental to the environment and long-term sustainable development. This study provides an insight into selective catalytic preparation of biofuel to compare uptake of trace metals in the biodiesel fraction with preferential base catalysts. The role of specific metal hydroxides in controlling trace metal content in biofuel production is relatively unexplored, and the effect of different homogeneous catalysts (NaOH, KOH) on metal retention in biodiesel from commercial neem oil was examined. A detailed study of this nature of catalyst vs. metal uptake is in the interest of sustainable living and could make a significant contribution to biofuels research. Both catalysts displayed variable uptake for certain toxic elements, which was attributed to the behavior of the catalyst in the reaction mixture. A general comparison reflected specific trends in metal retention (ICP-MS) with the use of different base catalysts. Challenges encountered by extending the study and using a heterogeneous catalyst (CaO) are presented. Our work could play a significant role in influencing catalyzed transesterfication processes to control elemental and toxic metal uptake in biofuels. The impact of our work on sustainable living is presented

Depth Profiling (ICP-MS) Study of Toxic Metal Buildup in Concrete Matrices: Potential Environmental Impact

This paper explores the potential of concrete material to accumulate toxic trace elements using ablative laser technology (ICP-MS). Concrete existing in offshore structures submerged in seawater acts as a sink for hazardous metals, which could be gradually released into the ocean creating pollution and anoxic conditions for marine life. Ablative laser technology is a valuable tool for depth profiling concrete to evaluate the distribution of toxic metals and locate internal areas where such metals accumulate. Upon rapid degradation of concrete these “hotspots” could be suddenly released, thus posing a distinct threat to aquatic life. Our work simulated offshore drilling conditions by immersing concrete blocks in seawater and investigating accumulated toxic trace metals (As, Be, Cd, Hg, Os, Pb) in cored samples by laser ablation. The experimental results showed distinct inhomogeneity in metal distribution. The data suggest that conditions within the concrete structure are favorable for random metal accumulation at certain points. The exact mechanism for this behavior is not clear at this stage and has considerable scope for extended research including modeling and remedial studies.concrete; seawater; toxic trace elements; laser ablation; environment; ICP-MS