An improved microwave plasma torch for atomic spectrometry

The analytical performance of a microwave plasma torch was improved through mechanical alterations. Several problems reported in earlier designs were addressed: the ignition and stabilization of a helium plasma in the MPT was difficult; high powers were required to both ignite and operate the plasma; otherwise, the plasma would erratically change from an annular to a filament type discharge. In the new torch, the helium discharge was stabilized by replacing the copper central tube with one made of quartz. In addition, air entrainment was alleviated through use of a sheathing gas. This modification simplified the background mass spectrum and raised the effective ionization temperature of the discharge. A detailed schematic diagram of the new microwave plasma torch is presented.     

Determination of precious metals in geological samples by continuous powder introduction microwave induced plasma atomic emission spectrometry after preconcentration on activated carbon

A novel method was developed for analysing geological materials for Au, Ag, Pd and Pt by continuous powder introduction microwave induced plasma atomic emission spectrometry (CPI-MIP-AES). The preconcentration of the trace metals on activated carbon (AC) was performed before conducting MIP-AES measurements in order to obtain accurate and precise analytical results. The method proposed is based on the selective sorption of precious metals that are subsequently introduced to the plasma as a dry particulate aerosol consisted of analytes collected on the sorbent. The technical design and operating conditions of the novel sample introduction system based on the fluidized-bed concept has been optimized. The microwave excitation source with integrated rectangular cavity TE₁₀₁ and vertically positioned plasma torch has been used. The signal stability proved to be adequate for sequential mode of measurements due to the vertical plasma configuration as well as the MIP-AES system compatibility with the CPI technique. Calibration was done using home-made standards obtained by sorption of metals of interest from standard solutions on activated carbon. Precision is typically 1-4% relative standard deviation at the 1 μg g⁻¹ level. Under measurement conditions the detection limits for Ag, Au, Pd and Pt were 24, 43, 57 and 550 ng per 1 g of AC, respectively. The proposed procedure was used for Au, Ag, Pd and Pt determination in the platinum ore SARM-7 as well as Au and Ag in the Chinese soil GBW-07405 certified reference materials. The standard addition technique was used and recoveries revealed that the proposed method shows good accuracy and precision.     

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。     

Determination of major and trace elements in biological materials by microwave induced plasma optical emission spectrometry (MIP-OES) following tetramethylammonium hydroxide (TMAH) solubilization

A simple, alternative method to acid digestion is presented for the preparation of biological materials for major and trace elements by microwave induced plasma optical emission spectrometry (MIP-OES). Standard reference materials were solubilized using a methanolic solution of tetramethylammonium hydroxide (TMAH) by the application of ultrasonic agitation. Following dilution with water suspensions were pumped to a V-groove Babington-type nebulizer then into argon plasma. Limits of detection and precision are reported for major (Na, K, Ca, Mg) and trace (Cu, Fe, Sr, Zn) elements. Standard addition procedures were used to minimize possible matrix interferences. The method offers relatively good precision (R.S.D. ranged from 6 to 12%). Measured concentrations are in satisfactory agreement with certified values for the biological reference materials: TORT-1 (Lobster hepatopancreas), IAEA-153 (Milk powder) and NIST 1577 (Bovine liver). The simple procedure could be useful as a routine analysis of biological materials.     

微波消解-原子吸收光谱法测定蚕蛹中的微量元素

分别采用FAAS和GFAAS方法,测定蚕蛹样品中的常见微量元素及有害重金属元素。对微波消解条件和测定方法进行了探讨和优化,并用标准物质贻贝验证,获得较满意的准确度和精密度。方法可用于蚕蛹样品及同类产品的微量元素元素测定。     

Simultaneous determination of hydride forming elements (As, Sb, Se, Sn) and Hg in sonicate slurries of biological and environmental reference materials by hydride generation microwave induced plasma optical emission spectrometry (SS-HG-MIP-OES)

A slurry sampling hydride generation (SS-HG) method for the simultaneous determination of hydride forming elements (As, Sb, Se, Sn) and Hg, without total sample digestion, has been developed using batch mode generation system coupled with microwave induced plasma optical emission spectrometry (MIP-OES) from certified biological and environmental reference materials. Slurry concentration up to 3.6% m/v (particles < 80 μm) prepared in 10% HCl containing 100 μl of decanol, by the application of ultrasonic agitation, was used with calibration by the standard addition technique. Harsh conditions were used in the slurry preparation in order to reduce the hydride forming elements to their lower oxidation states, As(III), Sb(III), Se(IV) and Sn(II) and Hg, being reduced to mercury vapor, before reacting with sodium tetrahydroborate. An ultrasonic probe was used to homogenize the slurry in the quartz cup just before its introduction into the reaction vessel. For 10 ml of slurry sample, detection limits (LOD, 3σ_blank, peak area) of 0.06, 0.08, 0.15, 0.12 and 0.10 μg g^− 1 were obtained for As, Sb, Se, Sn and Hg, respectively. The method offers relatively good precision (RSD ranged from 9 to 12%) for slurry analysis. To test the accuracy, three certified reference materials were analyzed with the analyte concentrations mostly in the μg g^− 1 level. Measured concentrations are in satisfactory agreement with certified values for the biological reference materials: NRCC LUTS-1 (lobster hepatopancreas), NRCC DOLT-2 (Dogfish Liver) and environmental reference material: NRCC PACS-1 (Marine Sediment), all adequate for slurry sampling. The method requires small amounts of reagents and reduces contamination and losses.     

Determination of arsenic and antimony by microwave plasma atomic emission spectrometry coupled with hydride generation and a PTFE membrane separator

The performance of a microwave plasma torch (MPT) discharge atomic emission spectrometry (AES) system directly coupled with hydride generation (HG) for the determination of As and Sb has been studied. The argon MPT system can sustain a stable plasma over a wide range of carrier and support gas flow rates with optimum performance at 250 and 1450 ml min⁻¹, respectively. The presence of trace amount of water in the MPT discharge is found to affect the detection limits and the signal to noise ratio. A PTFE membrane separator is applied for hydride introduction and water rejection. In addition, the membrane cell separator also improves the signal to noise ratio by serving as a pressure buffer to minimize noise due to pressure fluctuation. Detection limits (3σ) of 8.1 and 3.2 ng ml⁻¹ are obtained with the analytical lines As I 228.812 nm and Sb I 259.809 nm, respectively at an MPT power of 135 W. The detection limits are improved when a concentrated sulfuric acid cell is placed after the membrane cell to further remove water. This double cell system yields detection limits of 5.3 and 2.1 ng ml⁻¹ for As and Sb, respectively under the same operating conditions. Linear dynamic ranges of three orders of magnitude could be obtained.     

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.     

High-pressure microwave dissolution of ceramics prior to trace metal determinations by microwave induced plasma atomic emission spectrometry

A commercial laboratory microwave acid digestion system was evaluated for the acid dissolution of ceramic powders (Al₂O₃, AlN, BN and Si₃N₄) prior to the determination of their trace element content by microwave induced plasma atomic emission spectrometry. Newly designed vessels, capable of withstanding internal pressures of over 110 bar, provide rapid and satisfactory results for sample dissolution. Sample preparation time was approximately 30 min (including the subsequent cooling time and preparation of the final solution). Results from conventional stainless-steel acid digestion vessel (Teflon bomb) dissolution are compared with the microwave bomb results of microwave plasma atomic emission spectrometry.     

微波消解-微波等离子体炬原子发射光谱法测定合金钢中的铜、锰、钼

用微波等离子体炬 (MPT)为激发光源 ,氩气为等离子体工作气体 ,用气动雾化进样 ,研究了微波消解 微波等离子体炬原子发射光谱法 (MPT AES)测定合金钢中铜、锰、钼的方法。考察了微波功率、载气流量、工作气流量、氧屏蔽气流量等实验参数对测定铜、锰、钼的影响。对微波消解合金钢样品的消解条件进行了考察 ,建立了最佳消解程序。测定铜、锰、钼的检出限分别为 3.3、3.7和 42ng mL ,RSD(n =6)分别为 1 7%、2 .4%、3.8% ,并且测得它们的线性范围分别为0 .0 2～ 5 0 μg mL、0 .0 4～ 5 0 μg mL和 0 .2 0～ 5 0 μg mL。     

有机溶液进样大功率微波诱导空气等离子体发射光谱法测定金属离子的研究

研究了由Okamoto腔产生的大功率微波诱导空气等离子体的分析性能以及用该等离子体直接有机溶液进样测定有机溶剂或含有大量有机溶剂的废水中的金属污染物的可行性。用本方法测定了几种工业废水中的金属污染物,并与原子吸收光谱法的测定结果进行了比较。     

电感耦合等离子体原子发射光谱法（ICP-AES）测定RoHS指令聚合物中的铅和镉

本文引入微波技术消解聚合物塑料样品,使用电感耦合等离子体原子发射光谱仪（ICP-AES）测定聚合物中的铅（Pb）和镉（Cd）含量,并建立了优化的样品消解程序和测定方法,得到满意的测定结果。[摘要应包括目的、方法、结果、结论,请修改,同时修改英文]该方法具有效率高、污染小的优点。检测结果具有良好的精密度。     

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.     

Carbon-related matrix effects in inductively coupled plasma atomic emission spectrometry

In Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), it has been observed that the emission intensity of some atomic lines is enhanced or depressed by the presence of carbon in the matrix. The goal of this work was to investigate the origin and magnitude of the carbon-related matrix effects in ICP-AES. To this end, the influence of the carbon concentration and source (i.e. glycerol, citric acid and potassium hydrogen phthalate), the experimental conditions and sample introduction system on the aerosol characteristics and transport, plasma excitation conditions and the emission intensity of several atomic and ionic lines of a total of 15 elements has been studied. Results indicate that carbon related matrix effects do not depend on the carbon source and they become more severe when the amount of carbon loaded into the plasma increases, i.e., when using: (i) carbon concentrations higher than 5 g L^− 1; (ii) high sample uptake rates; and (iii) efficient sample introduction systems. Thus, when introducing carbon into the plasma, the emission intensity of atomic lines with excitation energies below 6 eV is depressed (up to 15%) whereas the emission intensity of atomic lines of higher excitation energies (i.e. As and Se) are enhanced (up to 30%). The emission intensity of the ionic lines is not affected by the presence of carbon. The origin of the carbon-related interferences on the emission intensity of atomic lines is related to changes in the line excitation mechanism since the carbon containing solutions show the same aerosol characteristics and transport efficiencies as the corresponding aqueous solutions. Based on the previous findings, a calibration approach for the accurate determination of Se in a Se-enriched yeast certified material (SELM-1) has been proposed.     

Silicon determination by inductively coupled plasma atomic emission spectrometry after generation of volatile silicon tetrafluoride

A method for the determination of silicon by inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. The procedure is based on a discontinuous generation of volatile silicon tetrafluoride in concentrated sulphuric acid medium after injecting 125 μl of 0.1%, w/v sodium fluoride solution into 100 μl of the sample. The gaseous silicon tetrafluoride is fed directly into the ICP torch by a flow of 250 ml min⁻¹ Ar carrier gas. The calibration curve was linear up to at least 100 μg ml⁻¹ of Si(IV) and the absolute detection limit was 9.8 ng working with a solution volume of 100 μl. The relative standard deviation for six measurements of 10 μg ml⁻¹ of Si(IV) was 2.32%. The method was applied to the determination of silicon in water and iron ores.     

Coupling on-line preconcentration by ion-exchange with microwave plasma torch-atomic emission spectrometry for the determination of cobalt and nickel

In the present work, a simple and sensitive preconcentration-microwave plasma torch-atomic emission spectrometric procedure was carried out for the determination of cobalt and nickel. The method was based upon a flow-injection system with on-line preconcentration of the metal ions on a minicolumn of a strong acid cation-exchange resin. The operation parameters including sample acidity, flow rate, loading time, and eluent concentration, flow rate were studied and optimized. Under the optimal experimental conditions the enrichment factors were calculated as 13.58 and 17.65 for cobalt and nickel, respectively. The relative standard deviations, 3.73% for cobalt and 4.23% for nickel (n = 7), and a sample throughput of 40 h^− 1 were obtained. Furthermore, the limits of detection were shown to be 1.28 and 1.80 μg·L^− 1 for cobalt and nickel, respectively. The method was applied to the determination of cobalt and nickel in tea samples and the accuracy was assessed through recovery experiments.     

Flow injection on-line preconcentration with an ion-exchange resin coupled with microwave plasma torch-atomic emission spectrometry for the determination of trace rare earth elements

A sensitive and rapid on-line method has been developed for the determination of trace amounts rare earth elements (REEs), lanthanum, cerium, neodymium and yttrium, by microwave plasma torch-atomic emission spectrometry (MPT-AES) combined with micro-column separation/preconcentration. A strong basic cinnamene anion exchange resin is used for matrix elimination and enrichment of the analytes. The adsorbed metal ions are subsequently eluted from the column and transferred into the detector with nitric acid solution for simultaneous multi-element determination. Various factors influencing the separation/preconcentration, sample flow rate, loading time, acidity and eluent flow rate, concentration, have been studied in detail. Under the optimized conditions, the detection limits for lanthanum, cerium, neodymium and yttrium based on three times of standard deviations of blank by 7 replicates are 0.89, 2.02, 1.56 and 0.78 μg·L^− 1, and the relative standard deviations are determined as 1.54, 4.29, 4.95 and 3.90%, respectively. The proposed method has been applied to the analysis of the four REEs in high purity Sm₂O₃, Eu₂O₃, Gd₂O₃, Tb₂O₃, Dy₂O₃, Yb₂O₃, and Lu₂O₃ samples with a recovery range of 95.1-104.8%.     

MPT-AES法同时测定航空润滑油中铁、银和镍

用微波等离子体炬原子发射光谱法(MPT-AES)同时测定未使用过的航空润滑油中铁、银和镍的方法。详细考察了微波功率、载气流量、工作气流量、氧屏蔽气压力等实验参数对铁、银和镍发射强度的影响,并进行了系统优化。测得铁、银和镍的检出限分别为21.94ng/mL0、.36ng/mL9、.82ng/mL,线性范围分别为0.1~100μg/mL、0.001~8μg/mL、0.05~8μg/mL,各元素测定结果的相对标准偏差均小于3.95%,回收率在93.1%~107.4%之间。     

微波消解-GFAAS测定浅水湖泊底泥中重金属元素

探讨了采用微波消解作为底泥样品的前处理方法,运用石墨炉原子吸收法测定浅水湖泊底泥中Cu,Pb,Zn,Cd,Cr含量的实验条件.方法的RSD为2.0％～4.1％,平均回收率为97.4％～101.5％,Cu,Pb,Zn,Cd,Cr的检出限分别为0.4,5,2.8,0.25,2.5ng.该法适合于浅水湖泊底泥中重金属含量的测定.     

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.