Multi-element determination in raft mussels by fast microwave-assisted acid leaching and inductively coupled plasma-optical emission spectrometry

Studies on the application of a short microwave irradiation cycle and the use of diluted acids to extract trace elements from raft mussel samples were developed. Multi-element determinations (Al, Ba, Cd, Cr, Cu, Fe, Mn, Pb, Sn, V and Zn) were carried out by inductively coupled plasma-optical emission spectrometry (ICP-OES). Parameters such as acid/oxidizing reagents (diluted nitric acid, hydrochloric acid and hydrogen peroxide) concentrations, acid/oxidizing solution volume, temperature, ramp time and hold time for the microwave heating were simultaneously studied by using an experimental design approach. The optimum conditions have showed the sample pre-treatment of 10 mussel samples to less than 3.0 min when a microwave power of 600 W and a controlled temperature of 65 °C were used. This time (hold time plus ramp time) is quite shorter than those reported for conventional microwave-assisted acid digestion procedures. Since temperature inside the reactor is not high, the venting time can be shorted to 15 min. In addition, the concentration of acid/oxidizing reagents needed to complete the acid leaching (2.5 M, 3.0 M and 0.5 % (m/v) for nitric acid, hydrochloric acid and hydrogen peroxide, respectively) is lower than the required concentration for a conventional microwave-assisted acid digestion (concentrated acids). The proposed method has showed a good repeatability of the overall method, and relative standard deviations between 11 and 2% were reached for 12 replicate microwave-assisted acid leaching and ICP-OES measurements. The method was finally validated by analyzing TORT-1 and GBW-08571 certified reference materials and it was successfully applied to fast multi-element determinations in several raft mussel samples.     

Use of enzymatic hydrolysis for the multi-element determination in mussel soft tissue by inductively coupled plasma-atomic emission spectrometry

A systematic evaluation of different variables affecting the enzymatic hydrolysis of mussel soft tissue by five enzymes, three proteases (pepsin, pancreatin and trypsin), lipase and amylase, has been carried out for the determination of trace elements (As, Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Enzymatic hydrolysis methods offers advantages such as a less species alteration, safer laboratory conditions and a less contaminant wastes. The enzymatic hydrolysis was performed in an incubation camera Boxcult with orbital and horizontal shaker. Variables affecting the enzymatic hydrolysis process were simultaneously studied by applying a Plackett-Burman design (PBD). For a confidence interval of 95%, the significant factors for all enzymes and for most of the elements were the pH, the incubation temperature and the ionic strength. These significant factors were optimized later by using a central composite design (CCD), which gave optimum conditions at pH of 1, incubation temperature of 37 °C and ionic strength fixed by sodium chloride at 0.2 M when using pepsin. For pancreatin, trypsin, lipase and amylase there were found two different optimum condition sets. The first one involves the use of a 0.5 M phosphate buffer (ionic strength), at a pH of 6 and at an incubation temperature of 37 °C, which allows the quantitative extraction of Al, Cr, Mn, Pb and Zn. The second conditions set employees a 0.1 M phosphate buffer (ionic strength), a pH of 9 and an incubation temperature at 37 °C, and it results adequate to extract As, Cd, Cu, Fe and Ni. Analytical performances, repeatability of the over-all procedure and accuracy, by analyzing DORM-1, DORM-2 and TORT-1 certified reference materials, were finally assessed for each enzyme. Good agreement with certified values has been assessed for most of the elements (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn) when using trypsin, pepsin and/or pancreatin, except for Cd and Pb in DORM-1 and DORM-2 because of the certified contents in such certified reference materials are lower than the limit of detection (0.10 and 0.16 μg g⁻¹ for Cd and Pb, respectively, for the use of trypsin).     

On-line preconcentration and simultaneous determination of heavy metal ions by inductively coupled plasma-atomic emission spectrometry

A flow injection analysis system for on-line preconcentration and simultaneous determination of Bi³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺ and Zn²⁺ in aqueous samples by inductively coupled plasma (ICP)-atomic emission spectrometry with a charge coupled detector is described. The preconcentration of analytes is accomplished by retention of their chelates with sodium diethyldithiocarbamate in aqueous solution on a solid phase containing octadecyl silica in a minicolumn. Methanol, as eluent, is introduced into the conventional nebulizer of the ICP instrument. The effects of different parameters, including preconcentration flow rate (equal to sample flow rate (SR)), eluent flow rate (ER), weight of solid phase (W) and eluent loop volume (EV), were optimized by the super-modified simplex method. The optimum conditions were evaluated to be SR 7.2 ml min⁻¹, ER 3.5 ml min⁻¹, W of 100 mg and EV of 0.8 ml. An enrichment factor of 312.5 for each analyte was obtained. The detection limits of the proposed method for Bi³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺ and Zn²⁺ were evaluated as 1.3, 1.0, 0.8, 0.3, 14.7, 0.5, 5.5 and 0.1 ng l⁻¹, respectively. The effect of several metal ions on percent recovery was also studied. The method was applied to the recovery of these heavy metals from real matrices and to the simultaneous determination of these cations in different water samples.     

In-situ determination of cross-over point for overcoming plasma-related matrix effects in inductively coupled plasma-atomic emission spectrometry

A novel method is described for overcoming plasma-related matrix effects in inductively coupled plasma-atomic emission spectrometry (ICP-AES). The method is based on measurement of the vertically resolved atomic emission of analyte within the plasma and therefore requires the addition of no reagents to the sample solution or to the plasma. Plasma-related matrix effects enhance analyte emission intensity low in the plasma but depress the same emission signal at higher positions. Such bipolar behavior is true for all emission lines and matrices that induce plasma-related interferences. The transition where the enhancement is balanced by the depression (the so-called cross-over point) results in a spatial region with no apparent matrix effects. Although it would be desirable always to perform determinations at this cross-over point, its location varies between analytes and from matrix to matrix, so it would have to be found separately for every analyte and for every sample. Here, a novel approach is developed for the in-situ determination of the location of this cross-over point. It was found that the location of the cross-over point is practically invariant for a particular analyte emission line when the concentration of the matrix was varied. As a result, it is possible to determine in-situ the location of the cross-over point for all analyte emission lines in a sample by means of a simple one-step sample dilution. When the original sample is diluted by a factor of 2 and the diluted sample is analyzed again, the extent of the matrix effect is identical (zero) between the original sample and the diluted sample at one and only one location — the cross-over point. This novel method was verified with several single-element matrices (0.05 M Na, Ca, Ba and La) and some mixed-element matrices (mixtures of Na–Ca, Ca–Ba, and a plant-sample digest). The inaccuracy in emission intensity due to the matrix effect could be as large as − 30% for conventional measurements in the normal analytical zone, but is reduced to within 5% with this new method. The major currently known limitation is that the accuracy of the method is highly sensitive to fluctuations and noise in the vertical emission-intensity profile, so the stability of the ICP system must be controlled to preferably within 1%.     

Comparative determination of Ba, Cu, Fe, Pb and Zn in tea leaves by slurry sampling electrothermal atomic absorption and liquid sampling inductively coupled plasma atomic emission spectrometry

The comparative determination of barium, copper, iron, lead and zinc in tea leaf samples by two atomic spectrometric techniques is reported. At first, slurry sampling electrothermal atomization atomic absorption spectrometry (ETAAS) was applied. The results of Ba and Pb determination were calculated using the method of standard additions, and results of Cu, Fe and Zn from the calibration graphs based on aqueous standards. These results were compared with the results obtained after microwave-assisted wet (nitric+hydrochloric+hydrofluoric acids) digestion in closed vessels followed by inductively coupled plasma-atomic emission spectrometric (ICP-AES) determination with the calibration by means of aqueous standards. The exception was lead determined after a wet digestion procedure by ETAAS. The accuracy of the studied methods was checked by the use of the certified reference material Tea GBW-07605. The recoveries of the analytes varied in the range from 91 to 99% for slurry sampling ETAAS, and from 92.5 to 102% for liquid sampling ICP-AES. The advantages of slurry sampling ETAAS method are simplicity of sample preparation and very good sensitivity. Slurry sampling ETAAS method is relatively fast but if several elements must be determined in one sample, the time of the whole microwave-assisted digestion procedure and ICP-AES determination will be shorter. However, worse detection limits of ICP-AES must also be taken into the consideration in a case of some analytes.     

Determination of trace impurities in high-purity zirconium dioxide by inductively coupled plasma atomic emission spectrometry using microwave-assisted digestion and wavelet transform-based correction procedure

This paper describes a rapid, accurate and precise method for the determination of trace Fe, Hf, Mn, Na, Si and Ti in high-purity zirconium dioxide (ZrO₂) powders by inductively coupled plasma atomic emission spectrometry (ICP-AES). The samples were dissolved by a microwave-assisted digestion system. Four different digestion programs with various reagents were tested. It was found that using a mixture of sulfuric acid (H₂SO₄) and ammonium sulfate ((NH₄)₂SO₄), the total sample dissolution time was 30 min, much shorter than that required for conventional digestion in an opening system. The determination of almost all of the target analytes suffered from spectral interferences, since Zr shows a line-rich atomic emission spectrometry. The wavelet transform (WT), a recently developed mathematical technique was applied to the correction of spectral interference, and more accurate and precise results were obtained, compared with traditional off-peak background correction procedure. Experimental work revealed that a high Zr concentration would result in a significant decrease in peak height of the analyte lines, which was corrected by standard addition method. The performance of the developed method was evaluated by using synthetic samples. The recoveries were in the range of 87-112% and relative standard deviation was within 1.1-3.4%. The detection limits (3σ) for Fe, Hf, Mn, Na, Si and Ti were found to be 1.2, 13.3, 1.0, 4.5, 5.8 and 2.0 μg g⁻¹, respectively. The results showed that with the microwave-assisted digestion and the WT correction, the detection limits have improved by a factor of about 5 for Fe, 4 for Mn and Ti, 3 for Si, and 2 for Hf and Na, respectively, in comparison with conventional open-system digestion and off-peak correction. The proposed technique was applied to the analysis of trace elements above-mentioned in three types of ZrO₂ powders.     

Preconcentration and determination of trace elements with 2-aminoacetylthiophenol functionalized Amberlite XAD-2 by inductively coupled plasma-atomic emission spectrometry

2-Aminoacetylthiophenol (AATP)-modified Amberlite XAD-2 has been synthesized by coupling it through NNNH group. The resulting chelating resin, characterized by elemental analysis, thermogravimetric analysis (TGA) and infrared (IR) spectra, was used to preconcentrate Cd, Hg, Ag, Ni, Co, Cu and Zn ions. Several parameters, such as distribution coefficient and sorption capacity of the chelating resin, pH and flow rates of uptake and striping, volume of sample and eluent, were evaluated. The effects of electrolytes and cations on the preconcentration were also investigated. The recoveries were >96%. The procedure was validated by standard addition and analysis of a standard reference sediment material (GBW 07309 China). The developed method was utilized for preconcentration and determination of Cd, Hg, Ag, Ni, Co, Cu and Zn in tap water, river water and sediment samples by inductively coupled plasma-atomic emission spectrometry (ICP-AES) with satisfactory results. The 3σ detection limits for Cd, Hg, Ag, Ni, Co, Cu and Zn were found to be 0.10, 0.23, 0.41, 0.13, 0.25, 0.39 and 0.58 μg l⁻¹, respectively. The relative standard deviation of the determination was <10%.     

微波消解-电感耦合等离子体原子发射光谱(ICP-AES)法测定含铜污泥中多种重金属

为了填补现有方法的技术空白,本方法采用微波消解和电感耦合等离子体原子发射光谱法（ ICP-AES）相结合,实现对含铜污泥中铅、锌、铬、镉、砷、镁、铝、锑量的同时测定。首先采用盐酸-硝酸-氢氟酸微波消解进行样品的前处理,消解后加入高氯酸置于电热板进行除碳并赶酸,溶样效果理想,且有效避免了高温溶样对易挥发元素砷、锑的损失,整个过程安全、高效、无损。溶样后以电感耦合等离子体发射光谱法（ ICP-AES）进行测定。对含铜污泥的分解方法进行了合理选择,并对测定时的元素分析谱线及各测定元素间干扰情况等进行了讨论。该方法的加标回收率在95.31%~107.28%%,相对标准偏差（RSD）在0.31%~2.05%之间（n=7),结果表明,该方法准确度高,操作简单快捷,可同时测定多种元素,能满足批量的测定含铜污泥中铅、锌、镍、铁、镉、铬、砷、锑含量的测定要求。     

Application of Metalfix Chelamine prior to the determination of noble metals by the inductively coupled plasma atomic emission spectrometry

Metalfix Chelamine chelating resins of two different bead sizes (150-300 and 40-80 μm) were examined and compared regarding their application for sorption of Au, Ir, Pd, Pt, Rh and Ru ions from medium of HCl, HNO₃ and mixtures of HCl and HNO₃. The quantitative enrichment of Au, Ir, Pd and Pt was established for the resin of 150-300 μm particle size and for solutions acidified with HCl and HNO₃ (3:1) up to the concentration of 0.50 mol l⁻¹. In the case of Rh and Ru, the uptake of these metals by the resin was lower than 50%. For the elution, solutions of different reagents, i.e. HCl, HNO₃, KCN, KI, KSCN and (NH₂)₂CS, were studied with respect to the complete release of the analytes retained by the resin. In addition, influence of various base metals, i.e. Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, on the retention of the noble metals was investigated. Under the selected conditions for the retention and elution of Au, Ir, Pd and Pt, the analytical performance of the proposed pre-concentration procedure was evaluated and it was applied to the determination of these noble metals in anodic sludge sample.     

ICP-AES 法测定硅铁中痕量元素

采用电感耦合等离子原子发射光谱法测定硅铁中的痕量元素,研究了 Fe 基体对被测元素的影响,并选择了最佳工作条件.被测元素的检测限为 0 .60～76.2 ng/mL,样品加标回收率为 92%～108%,RSD(n=8)<3%.     

Direct determination of toxic trace metals in honey and sugars using inductively coupled plasma atomic emission spectrometry

A rapid method for the determination of Pb, Cd, Cu, Cr, Co, Ni, Mn and Zn in honey and sugars without prior digestion or ashing of the sample was developed, using inductively coupled plasma atomic emission spectrometry (ICP-AES). The critical instrumental parameters such as sample flow rate and radio frequency incident power were thoroughly optimized. The effect of matrix type and its concentration was also examined for glucose/fructose, sucrose and honey matrices. The sensitivity was investigated using calibration curves obtained in presence of the above matrices. The obtained recoveries for Cd, Cu, Cr, Co, Ni and Mn at the μg l⁻¹ level were satisfactory and practically independent of the matrix used for the calibration standards. The recoveries of Pb and Zn were less sufficient. Various commercial samples of honey, sugar, glucose and fructose were analyzed with respect to their toxic metal content. The method can be applied for routine analysis, quality and environmental pollution control purposes at the μg l⁻¹ level of concentration, after suitable dilution of the samples.     

A clean up step of fat content previous to trace metal characterization in mussel tissues by inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry analysis of trace and major elements of mussel tissues can be quickly and accurately analyzed after cleaning up the interfering fat content before the sample is digested in a microwave oven. Making use of experimental designs, the clean up procedure was achieved by the extraction of 1 g of freeze-dried tissue sample stirred with 5 ml of dichloromethane during five minutes. The microwave assisted digestion of the fat free samples was carried out with 0.2 g of tissue sample, 15 ml of 7.0% nitric acid with a power of 980 W during 18 min. The analytical method efficiency (accuracy and precision) was evaluated with a CRM: (NIST 2977, mussel tissue) and real mussel samples analyzed previously. The results confirmed the accuracy of the analysis by agreement with the previous results but the precision was significantly improved. The developed method allows operating routinely permitting to large numbers of samples to be quickly screened for trace metals.     

Separation and preconcentration of ultra trace amounts of beryllium in water samples using mixed micelle-mediated extraction and determination by inductively coupled plasma-atomic emission spectrometry

In the present study a cloud point extraction process using mixed micelle of the cationic surfactant cetyl-pyridinium chloride (CPC) and non-ionic surfactant Triton X-114 for extraction of beryllium from aqueous solutions is developed. The extraction of analyte from aqueous samples was performed in the presence of 1,8-dihydroxyanthrone as chelating agent in buffer media of pH 9.5. After phase separation, the surfactant-rich phase was diluted with 0.4 mL of a 60:40 methanol-water mixture containing 0.03 mL HNO₃. Then, the enriched analyte in the surfactant-rich phase was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The different variables affecting the complexation and extraction conditions were optimized. Under the optimum conditions (i.e. 1.6 × 10⁻⁴ mol L⁻¹ 1,8-dihydroxyanthrone, 1.2 × 10⁻⁴ mol L⁻¹ CPC, 0.15% (v/v) Triton X-114, 50 °C equilibrium temperature) the calibration graph was linear in the range of 0.006-80 ng mL⁻¹ with detection limit of 0.001 ng mL⁻¹ and the precision (R.S.D.%) for five replicate determinations at 18 ng mL⁻¹ of Be(II) was better than 2.9%. In this manner the preconcentration and enrichment factors were 16.7 and 24.8, respectively. Under the presence of foreign ions no significant interference was observed. Finally, the proposed method was successfully utilized for the determination of this cation in water samples.     

Optimization of dispersive liquid-liquid microextraction coupled with inductively coupled plasma-optical emission spectrometry with the aid of experimental design for simultaneous determination of heavy metals in natural waters

In this study, dispersive liquid-liquid microextraction (DLLME) combined with inductively coupled plasma optical emission spectrometry (ICP-OES) was developed for simultaneous preconcentration and trace determination of chromium, copper, nickel and zinc in water samples. Sodium diethyldithiocarbamate (Na-DDTC), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. The effective parameters of DLLME such as volume of extraction and disperser solvents, pH, concentration of salt and concentration of the chelating agent were studied by a (2^f−1) fractional factorial design to identify the most important parameters and their interactions. The results showed that concentration of salt and volume of disperser solvent had no effect on the extraction efficiency. In the next step, central composite design was used to obtain optimum levels of effective parameters. The optimal conditions were: volume of extraction solvent, 113 μL; concentration of the chelating agent, 540 mg L⁻¹; and pH, 6.70. The linear dynamic range for Cu, Ni and Zn was 1-1000 μg L⁻¹ and for Cr was 1-750 μg L⁻¹. The correlation coefficient (R²) was higher than 0.993. The limits of detection were 0.23-0.55 μg L⁻¹. The relative standard deviations (RSDs, C = 200 μg L⁻¹, n = 7) were in the range of 2.1-3.8%. The method was successfully applied to determination of Cr, Cu, Ni and Zn in the real water samples and satisfactory relative recoveries (90-99%) were achieved.     

An off-line automated preconcentration system with ethylenediaminetriacetate chelating resin for the determination of trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry

A novel automated off-line preconcentration system for trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in seawater was developed by improving a commercially available solid-phase extraction system SPE-100 (Hiranuma Sangyo). The utilized chelating resin was NOBIAS Chelate-PA1 (Hitachi High-Technologies) with ethylenediaminetriacetic acid and iminodiacetic acid functional groups. Parts of the 8-way valve made of alumina and zirconia in the original SPE-100 system were replaced with parts made of polychlorotrifluoroethylene in order to reduce contamination of trace metals. The eluent pass was altered for the back flush elution of trace metals. We optimized the cleaning procedures for the chelating resin column and flow lines of the preconcentration system, and developed a preconcentration procedure, which required less labor and led to a superior performance compared to manual preconcentration (Sohrin et al. [5]). The nine trace metals were simultaneously and quantitatively preconcentrated from ∼120 g of seawater, eluted with ∼15 g of 1 M HNO₃, and determined by HR-ICP-MS using the calibration curve method. The single-step preconcentration removed more than 99.998% of Na, K, Mg, Ca, and Sr from seawater. The procedural blanks and detection limits were lower than the lowest concentrations in seawater for Mn, Ni, Cu, and Pb, while they were as low as the lowest concentrations in seawater for Al, Fe, Co, Zn, and Cd. The accuracy and precision of this method were confirmed by the analysis of reference seawater samples (CASS-5, NASS-5, GEOTRACES GS, and GD) and seawater samples for vertical distribution in the western North Pacific Ocean.     

电感耦合等离子体质谱法测定固体生物质燃料中重金属

为开展重金属监测及环境保护,本文建立了电感耦合等离子体质谱法测定固体生物质燃料中重金属方法。对样品全消解酸溶法进行了实验研究,确定了微波消解酸体系和微波消解程序。采用Ge和In作为内标元素消除仪器干扰,方法线性关系良好,线性系数>0.999,检出限为0.001～0.089mg/kg。采用标准物质对方法准确性和稳定性进行验证,各元素测定值均在标准证书值范围内,相对标准偏差在0.36%～3.96%,Hg的加标平均回收率为104.7%。通过3家实验室协同实验验证了方法准确性,并给出了方法精密度。     

Multiple small volume microwave-assisted digestions using conventional equipment for multielemental analysis of human breast biopsies by inductively coupled plasma optical emission spectrometry

A multiple microwave-assisted digestion procedure using small PTFE closed vials (6 mL capacity) inserted into conventional microwave digestion vessels has been developed as a fast, efficient and clean methodology for multielemental analysis of human breast biopsies by inductively coupled plasma optical emission spectrometry. This small volume strategy allows drastically diminishing the volume of acid needed for digestion, and in turn, a decrease in sample dilution and an increase in sample throughput is achieved. A 2_IV^4-1 fractional factorial design was used for screening optimization of four variables that can influence the digestion efficiency: (A) nitric acid volume, (B) pre-digestion step, (C) microwave power, and (D) digestion time. A validation study included linearity, precision, detection and quantification limits. Validation against different biological certified reference materials (CRMs) was also performed.The digestion method is suitable for the determination of Al, Ca, Cu, Fe, K, Mg, Mn, P, S and Zn in small size biological samples such as breast biopsies (<30 mg dry mass). Forty-seven biopsies from 39 women were analyzed: 20 samples from healthy women corresponding to mammoplasties and 27 samples from patients suffering from cancer pathology (19 corresponded to tumour and 8 to adjacent normal tissue). A significant accumulation of Al, Ca, Cu, K, Mg, Mn, P and Zn was found in tumour as compared to healthy tissues. When this comparison is made for tumour and adjacent tissues, a significant accumulation of Al, Mg, P and Zn in tumour tissues was observed. Finally, only Ca significantly accumulates in the adjacent tissues as compared to healthy tissues.     

Determination of trace elements in human serum by inductively coupled plasma atomic emission spectrometry with flow injection

An analytical method for the simultaneous determination of some trace elements (Au, Fe, Mg, Li, Sr, Zn) in human serum by inductively coupled plasma atomic emission spectrometry (ICP-AES) with flow injection is described. Physical interference caused by the change of sample viscosity is discussed. When 100 μl of serum was injected, the relevant recoveries of > 99% for Li, > 98% for Cu and Mg, > 95% for Fe were obtained for an NIST SRM with R.S.D. > 1.3% using optimized flow injection parameters. The prepared lyophilized control serum for routine analysis in clinical laboratories was analyzed and verified for the validity of the technique employed in this experiment using NIST SRM 909 as a primary reference material.     

Single-step microwave digestion with HNO(3) alone for determination of trace elements in coal by ICP spectrometry

A microwave digestion method with HNO₃ alone was conducted at a temperature as high as 250 °C for determination of 19 trace elements (Li, Be, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Cd, Cs, Ba, Hg, and Pb) in coal jointly by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and flow injection ICP-MS (FI-ICP-MS). The validity of determination was assessed by using three standard coals, SRM 1632c, BCR 180, and SARM 19. It was found that the high-temperature digestion led to an extensive decomposition of the organic matrix and clay in coal, and no dissolved and solid carbon remained in the final solution after evaporation. Good recoveries were observed for all trace elements in three coals, with the exception of V, Rb, and Cs in high-ash SARM 19. Additionally, FI-ICP-MS combined with the present digestion without evaporation pretreatment was proved to be a rapid and efficient approach for determination of ultra-trace elements such as Se, Cd, and Hg in coal.     

On-line metals preconcentration and simultaneous determination using cloud point extraction and inductively coupled plasma optical emission spectrometry in water samples

A new on-line cloud point extraction (CPE) system coupled to ICP-OES was designed for simultaneous extraction, preconcentration and determination of Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺ and Mn²⁺ ions in water samples. This is based on the complexation of the metal ions with 1-(2-thenoyl)-3,3,3-trifluoraceton reagent (TTA) at pH 6.0 in the presence of non-ionic surfactant of Triton X-114. The micellar solution was heated above 60 °C and loaded through a column packed with cotton, which acts as a filter for retaining the analyte-entrapped surfactant-rich phase. Then the surfactant-rich phase was eluted using propanol:0.5 mol L⁻¹ nitric acid solution (75:25, v/v) at a flow rate of 3.0 mL min⁻¹ and directly introduced into the nebulizer of the ICP-OES. Several factors influencing the instrumental conditions and extraction were evaluated and optimized. Under the optimum conditions, the enhancement factors of the proposed method for target ions were between 42 and 97, the detection limits (DLs) were in the range of 0.1-2.2 μg L⁻¹. The relative standard deviations (R.S.D.s) at 100 μg L⁻¹ concentration levels of each ion were found to be less than 4.6%. Also, the calibration graphs were linear in the range of 0.5-100 μg L⁻¹ with the correlation coefficients within the range of 0.9948-0.9994.Finally, the developed method was successfully applied to the extraction and determination of the mentioned metal ions in the tap, well, sea and mineral water samples and satisfactory results were obtained.