Determination of manganese in feedstuffs by flow injection spectrophotometry based on rapid formation of permanganate at room temperature

A simple and rapid flow injection spectrophotometric procedure was developed for determination of manganese. In the presence of pyrophosphate and acetate, manganese was immediately oxidized to permanganate by periodate at room temperature in slightly alkaline medium. Under optimized conditions, the determination was made with a sampling rate of 120/h, a linear range of 0-30 mg/L Mn(II), a detection limit (S/N = 3) of 0.08 mg/L, and a relative standard deviation of 0.6% (n = 11) at 10 mg/L Mn(II). The proposed method was used to determine manganese in trace mineral premixes and feedstuffs. Results agreed well with those obtained by the standard atomic absorption spectroscopy method.     

嵌段分子筛聚合材料P123-SH萃取分离-石墨炉原子吸收光谱法分析痕量铬的形态

研究了嵌段分子筛聚合材料P123-SH萃取分离-石墨炉原子吸收光谱法对尿中痕量铬的形态分析方法,探讨了嵌段分子筛聚合材料P123-SH吸附铬的原理和最佳条件。在pH 7.0、常温下,Cr3+和Cr(Ⅵ)被很好的分离,且Cr3+可被该材料定量吸附,其吸附容量为6.15 mg/g。吸附的Cr3+可用2 mol/L的HCl洗脱,用石墨炉原子吸收法测定洗脱下来的Cr3+,往溶液中加入0.1%抗坏血酸将Cr(Ⅵ)还原为Cr3+测总铬,Cr(Ⅵ)含量为总铬减去Cr3+,方法测定Cr3+的检出限为0.011μg/L(3σ,n=11),线性范围为0.1～10μg/L,加标回收率在94%～106%之间,对0.50μg/L的Cr3+溶液平行测定7次,RSD为3.6%。方法可应用于生物样品和环境样品中痕量铬的形态分析。     

On-line precipitation/dissolution system for the preconcentration and determination of manganese traces by atomic absorption spectrometry

Flame atomic absorption spectrometry was used for the determination of Mn in biological material following preconcentration by precipitation. The proposed preconcentration method is based on the continuous precipitation of Mn(II) as hydrated Mn(IV) oxide in ammonia buffer and dissolution of the precipitate with hydrogen oxalate or dilute nitric acid. The sensitivity of the Mn determination is increased by the presence of hydrogen peroxide, which raises the rate of oxidation of Mn(II) to Mn(IV). By using a time-based technique (at a sample loading rate of 4 ml min⁻¹) a concentration factor of up to 55 was obtained using 24 ml of sample. The effect of concurrent cations was investigated; the most adverse effect was exerted by Fe(III), which interfered at concentrations 50 times higher than that of Mn(II).     

Speciation analysis of chromium in natural water samples by electrothermal atomic absorbance spectrometry after separation/preconcentration with nanometer zirconium phosphate

A sensitive and simple method for the electrothermal atomic absorption spectrometry (ETAAS) determination of Cr(III) after separation/preconcentration on a micro-column packed with nanometer sized zirconium phosphate has been developed. Total chromium was determined after the reduction of Cr(VI) to Cr(III) by 10% (m/v) of aqueous ascorbic acid. The limit of detection for Cr(III) was 1.5 ng/L with an enrichment factor of 300. The static adsorption capacity of the sorbent for Cr(III) was 9.34 mg/g. The relative standard deviation was 3.2% (n = 7, c = 10 ng/mL). The method was applied successfully to the determination of Cr(III) and Cr(VI) in natural water samples.     

Flow Injection Semi-online Preconcentration Graphite Furnace Atomic Absorption Spectrometry for Determination of Cadmium, Copper and Manganese

IntroductionGraphite furnace atomic absorption spectrome-try (GFAAS) is one of the most sensitive tech-niques for the determination of various elementswith detection limits in the range ofμg/ L to ng/ L.Despite the impressive detection power of the tech-nique,GFAAS can tbe routinely used to make di-rect analysis of some real samples with complexcomposition[1] . This is due to the matrix interfer-ence and/ or insufficient detection power. Conse-quently,separation and preconcentration proc…     

Interference-free determination of trace levels of gold and palladium in geological and metallurgical samples by flame atomic absorption spectrometry coupled with a flow injection on-line microcolumn preconcentration and separation system

A simple and highly selective method was developed for the routine determination of trace or ultratrace amounts of gold and palladium in geological and metallurgical samples. The method uses flow injection on-line preconcentration and separation with determination by flame atomic absorption spectrometry. Au and Pd in the sample are adsorbed on a 2-mercaptopyrimidine chemically modified silica gel (MPMSG) packed microcolumn in a 0.50M HCl medium and then eluted with 0.5 or 1.0% thiourea solution. The eluates are introduced into the flame atomic absorption spectrometer directly. With the use of a 0.85 mL microcolumn (about 0.14 g MPMSG packed), the present system tolerated concentrations of common base metal ions up to 25.0 mg/mL and concentrations of anions up to 100.0 mg/mL when Au(III) at 0.100 microg/mL and Pd(II) at 0.200 microg/mL were preconcentrated for 60 s with a sample flow rate of 5.0 mL/min. The limits of detection were 3.1 ng/mL for Au(III) and 6.1 ng/mL for Pd(II) with relative standard deviations of < or = 2.5%. The analytical results obtained by the proposed method for geological and metallurgical samples were in good agreement with the certified values.     

Atomic absorption spectrometric determination of Cd(II), Mn(II), Ni(II), Pb(II) and Zn(II) ions in water,fertilizer and tea samples after preconcentration on Amberlite XAD-1180 resin loaded with l-(2-pyridylazo)-2-naphthol

A new chelating resin, 1-(2-pyridylazo)-2-naphthol (PAN) coated Amberlite XAD-1180 (AXAD-1180), was prepared and used for the preconcentration of Cd(II), Mn(II), Ni(II), Pb(II) and Zn(II) ions prior to their determination by flame atomic absorption spectrometry (FAAS). The optimum pH for simultaneous retention of the elements and the best elution means for their simultaneous elution were pH 9.5 and 3 M HNO₃, respectively. The sorption capacity of the resin was found to be 5.3 mg/g for Cd and 3.7 mg/g for Ni. The detection limits for Cd(II), Mn(II), Ni(II), Pb(II) and Zn(II) were 0.7, 10, 3.1, 29 and 0.8 μg/L, respectively. The effects of interfering ions for quantitative sorption of the metal ions were investigated. The preconcentration factors of the method were in the range of 10–30. The recoveries obtained were quantitative (≥95%). The standard reference material (GBW07605 Tea sample) was analysed for accuracy of the described method. The proposed method was successfully applied to the analysis of various water, urea fertilizer and tea samples. The article is published in the original.     

Optimization and use of composite coatings based on silicon oxide and polyvinylsulfonic acid for the adsorption-spectrophotometric determination of iron(II) and zinc(II) phenanthrolinates

Conditions are optimized for preparing sol-gel modified composite films based on silicon oxide and polyvinylsulfonic acid in the presence of the Tween 20 nonionic surfactant as a template for the adsorption of Fe(II) and Zn(II) phenanthrolinates. The adsorption of Zn(II), Cu(II), Mn(II), Co(II), and Ni(II) phenanthrolinates followed by their development on the surface with Rose Bengal oxyxanthene dye was studied by spectrophotometry. The variation of the pH of the solution pH and the addition of 0.01 M of EDTA enhanced the selectivity of determining Zn(II) using a film obtained under optimum conditions. The applicability of the proposed thin-film coatings to the adsorption-spectrophotometric determination of Fe(II) and Zn(II) in the ranges of 0.2–5.6 and 0.3–5.0 mg/L, respectively, was shown. The procedure was used to determine zinc in vitamin preparations, a food supplement, and an insulin preparation. The accuracy of determination was checked by atomic absorption spectrometry. The detection limit for zinc was 0.06 mg/L at a liquid phase volume of 25 mL and absorption layer thickness of 0.015 ± 0.003 mm.     

Determination of Pb(II) and Cu(II) by Electrothermal Atomic Absorption Spectrometry after Preconcentration by a Schiff Base Adsorbed on Surfactant Coated Alumina

1,2-Bis（salicylidenamino）ethane loaded onto sodium dodecyl sulfate-coated alumina was used as a new chelating sorbent for the preconcentration of traces of Pb（Ⅱ） and Cu（Ⅱ） prior to atomic absorption spectrometric determination. The influence of pH, flow rates of sample and eluent solutions, and foreign ions on the recovery of Pb（Ⅱ） and Cu（Ⅱ） by this sorbent has been studied. The retained ions were eluted with 4 mol·L nitric acid and determined by electrothermal atomic absorption spectrometry （ETAAS）. The data of limit of detection （3σ） for Pb（Ⅱ） and Cu（Ⅱ） were found to be 8.57 and 2.69 ng·L^-1 respectively, while the enrichment factor for both ions was 100. The proposed method was successfully applied to determination of lead and copper in different water samples.     

Solid sampling coupled to flame furnace atomic absorption spectrometry for Mn and Ni determination in petroleum coke

A solid sampling flame furnace atomic absorption spectrometry (SS-FF-AAS) system was developed for Mn and Ni determination in petroleum coke. The proposed system for solid sampling was a quartz cell with two perpendicular tubes (T-shaped tubes), positioned above the burner. Manganese and Ni determination was made using an atomic absorption spectrometer with deuterium background corrector, air-acetylene flame and a single slit burner. Powdered samples of coke were introduced as pellets (up to 62 mg) into the quartz cell with a movable hollow quartz piston. When the sample pellet reached the end of quartz cell (T-connection), in the presence of a constant oxygen flow, it quickly burned and the combustion products were transferred to the upper slit tube where the atomic absorption process occurs. Calibration was possible using aqueous reference solutions applied directly on high purity graphite pellets. Results obtained for Mn and Ni using the proposed SS-FF-AAS system were compared to those obtained by inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) after sample decomposition by high pressure microwave assisted acid digestion and also by microwave induced combustion. Agreement better than 96% was obtained for both methods employing a previous step of sample digestion (ICP OES and ICP-MS) and by SS-FF-AAS. Accuracy was evaluated using certified reference materials and also recovery tests. The relative standard deviation was lower than 9% for both analytes. The characteristic mass was 18.3 and 14.7 ng and the limit of detection was 0.6 and 0.8 µg g^− 1 for Mn and Ni, respectively. The proposed SS-FF-AAS system can be applied for Mn and Ni determination in petroleum coke, combining a relatively high sample throughput (9 determinations per h), and a suitable precision and accuracy.     

微量进样火焰原子吸收光谱法对牛奶中钙的直接测定

采用微量进样火焰原子吸收光谱法（FAAS）直接测定牛奶中的钙,无需样品预处理。该法与消化后常规FAAS法的测定结果一致。钙质量浓度在0～20 mg/L范围内与吸光度呈线性关系,检出限（S/N=3）为0.013 mg/L,加标回收率为98%～101%,相对标准偏差（n=6）小于2%。方法应用于实际样品的测定,结果令人满意。     

微波消解石墨炉原子吸收法测定环境空气中痕量锡

建立石墨炉原子吸收法测定环境空气中痕量锡的方法。采用混合纤维素微孔滤膜采集环境空气样品,用硝酸–氢氟酸微波消解样品,以5%硝酸镧–10%酒石酸混合液作基体改进剂,石墨炉原子吸收法进行测定。当采样体积为4 800 L,定容体积50 m L时,方法检出限为0.024μg/m~3,样品加标回收率为96.0%~106.0%,测定结果的相对标准偏差为2.74%~5.81%(n=7)。该方法样品处理操作过程简单,酸用量少,可用于环境空气中痕量锡的测定。     

The electrothermal atomic absorption spectrometric determination of lead,manganese, vanadium and molybdenum in sea water with ascorbic acid to reduce matrix effects

The effect of ascorbic acid on the response of several metals in sea water obtained by graphite-furnace atomic absorption spectrometry was evaluated from the variation of peak time and the sensitivity. Matrix interferences from sea water in the determination of lead, manganese, vanadium and molybdenum were suppressed by addition of 10% (w/v) ascorbic acid solution to the sample in the furnace. Matrix effects on the determination of cobalt and copper could not be removed in this way. A direct method for the determination of lead, manganese, vanadium and molybdenum in sea water is proposed.     

Optimization of a chemical modifier in the determination of selenium by graphite furnace atomic absorption spectrometry and its application to wheat and wheat flour analysis.

A method for the determination of total selenium in wheat and wheat flour using graphite furnace atomic absorption spectrometry (GFAAS) with palladium/ascorbic acid as a chemical modifier was studied. The effects of nickel nitrate, palladium/ascorbic acid, and palladium/magnesium nitrate as chemical modifiers on the sensitivity in the determination of selenite, selenate and selenomethionine by GFAAS were compared. The palladium/ascorbic acid modifier was used for the determination of total selenium in wheat and wheat flour, because the oxidation states of the selenium ion are not important in the determination. The detection limit was estimated to be 1 microg L(-1) (calculated as 3sigma of the blank); the calibration curve was linear for the concentration range 5 - 50 microg L(-1) and the recovery range was 96.66 - 101.80%. The optimal ashing and atomizing temperatures were 1300 degrees C and 2250 degrees C, respectively. The proposed method was successfully applied to the determination of total selenium in wheat and wheat flour.     

Indirect flow-injection determination of ascorbic acid by flame atomic absorption spectrometry

A continuous-flow procedure is proposed for the indirect determination of ascorbic acid, based on its reducing properties because of the oxidation of its 1,2-enediol group. Iron(III) was injected into a 1,10-phenanthroline stream, which was mixed with a sample carrier and then with a sodium picrate solution stream. In these conditions the iron(III) was reduced to iron(II) by the ascorbic acid. Thus, the iron(II) formed reacts with 1,10-phenanthroline to form a charged red complex, which with picrate ion forms a stable red-orange uncharged ion-association complex that is adsorbed on-line on a non-ionic polymeric adsorbent (Amberlite XAD-4), proportionally to the ascorbic acid in the sample. The unadsorbed iron was determined by flame atomic absorption spectrometry. The proposed method allows the determination of ascorbic acid in the range 0.5–25 g ml^–1 with a relative standard deviation of 2.9% at a rate of ca. 90 samples h^–1. This method has been applied to the determination of ascorbic acid in pharmaceutical preparations, fruit juices and sweets. The results obtained in the analysis are compared with those provided by the 2,6-dichloroindophenol method.     

Application of a metal ion-imprinted polymer based on salen-Cu complex to flow injection preconcentration and FAAS determination of copper

A new Cu(II)-imprinted polymer (Cu-IIP) for preconcentration of copper by liquid-solid extraction via flow injection technique has been proposed. Cu-IIP was obtained by copolymerization of salen-Cu(II) complex with styrene and divinylbenzene using suspension polymerization technique. Granules fraction of 60-80 microm in diameter was used as a microcolumn packing. Cu(II) sorption was proved to be the most effective from solutions of pH 7, whereas similar elution effectiveness was observed when applying as eluents hydrochloric or nitric acid in the concentration range of 0.5-10% (v/v). The system exhibited good long-term stability and acid resistance. Batch sorbent capacity was found to be 0.11 mmol g(-1) of a dry polymer. Enrichment factor (EF) for 30 s loading time was 16. Preconcentration of Cu(II) and potentially interfering metal ions is strongly pH dependent. Examination of Cu(II) sorption in the presence of Pb(II), Cd(II), Zn(II) and Ag(I) showed significant influence of cadmium and zinc ions only and that was for the interferent concentrations above 0.5 mg L(-1) (Cu-IIP mass of ca. 35 mg). The interference effect was reduced with the sorbent mass increase. Fe(III) and Mn(II) ions, present in treated tap water in relatively high concentrations, did not interfere. Effective pH adjusting of the loaded solution in on-line mode, when applying diluted Clark-Lubs buffering solution, allowed accurate copper determination in tap water (compared to graphite furnace atomic absorption spectrometry, GFAAS) using standard addition or combination calibration method.     

火焰原子吸收光谱法测定天然气转化催化剂中的氧化钾

建立火焰原子吸收光谱法测定天然气转化催化剂中氧化钾的分析方法。该方法将催化剂样品和助溶剂四硼酸锂熔融后再用盐酸溶解定容,采用火焰原子吸收光谱仪对样品溶液进行测定。在优化的实验条件下,钾离子的质量浓度在0.05~0.50 mg/L范围内与吸光度呈良好线性关系,相关系数为0.9995。钾的方法检出限为0.001 mg/L,定量限为0.01 mg/L,测定结果的相对标准偏差为2.6%~4.3%(n=6),样品加标回收率为97.8%~102.3%。与HG/T 3543-2014中的酸溶制样法相比,该方法能够将催化剂样品中的难溶钾盐溶出,分析结果准确度更高,可用于天然气转化催化剂中氧化钾含量的测定。     

On-line pre-concentration of Cr(III) and Mn(II) in FI-FAAS: A critical study involving interference effects and analytical use of an immobilized 8-hydroxyquinoline minicolumn

A flow injection system with a pre-concentration minicolumn based on a chelating resin was coupled to a flame atomic absorption spectrometer. The focus of this work was the investigation of interference effects and the analytical applicability of the azo-immobilized 8-hydroxyquinoline on controlled-pore glass for the determination of Cr and Mn in mussel and non-fat milk powder. All studied concomitants affected the retention of Cr(III). These effects are probably related to the formation of hydroxo-complexes at the optimum pH range 9.0-10. The positive effect caused by Ca(II) was exploited to increase the retention of Cr(III) species and to improve the slope by 70%. The interferences on Mn(II) retention were less severe. The quantification of Cr and Mn was performed by standard additions. The proposed methodology was validated by analysis of three certified reference materials of mussels (Cr and Mn) and non-fat milk powder (Mn) with a mean relative percent error of <6.5% and mean relative standard deviation of <13%. Chromium and Mn were determined in typical Chilean mussels samples, and Mn was determined in non-fat milk powder samples. Results agreed at the 95% confidence level with those obtained by electrothermal atomic absorption spectrometry (ETAAS) using graphite furnace atomization. The method detection limits for a 30 s pre-concentration time were 0.9 and 1.1 micro g L(-1) for Mn, and 2.2 and 2.5 micro g L(-1) for Cr in acid digested solutions of mussel and non-fat milk, respectively. The methodology is simple, fast (sampling frequency 60-72 h(-1)), reliable, of low cost, and can be applied to the determination of traces of Cr (> or =0.18 micro g g(-1)) and Mn (> or =0.6 micro g g(-1)) in mussel samples, and Mn (> or =0.37 micro g g(-1)) in non-fat milk powder.     

Determination of total arsenic by batch hydride generation atomic absorption spectrometry in injectable drugs containing high levels of Sb(V) as N-methylglucamine antimonate

A procedure for the determination of arsenic by batch hydride generation atomic absorption spectrometry (HG AAS) in commercial samples of injectable drugs, containing high concentrations of Sb(V), is described. The procedure is based on the complexing effect for Sb of citric, oxalic and acetic acids as reaction media. Aqua regia was used for sample digestion prior to As determination by HG AAS. The following experimental conditions for the determination of total As, as As(V), were evaluated: the acid medium and its concentration, sodium tetrahydroborate concentration, purge time, and influence of the different oxidation states of As. The effect of the delay time after mixing of sample and acid solution was also studied. Optimized conditions were: 10% (m/v) citric acid, 1.5% (m/v) sodium tetrahydroborate solution and 30 s for purge time. A delay time of 1 h was required after the digested sample had been mixed with citric acid, before As determination could be carried out. No interference on As(III) and As(V) signals was observed in the presence of up to 1 mg Sb(V). The tolerance limits for Ni(II), Cu(II) and Pb(II) were 1 mg, 100 μg and 100 μg, respectively. Recovery tests for As(III) and As(V) resulted in values between 97 and 101%. Characteristic mass and detection limit (3σ), using the recommended conditions, were 0.52 and 0.8 ng, respectively, for total As.     

流动注射在线富集-FAAS测定合金钢中微量镍

提出了流动注射在线离子交换富集-火焰原子吸收光谱法测定合金钢中微量镍的分析方法.在线离子交换采用双柱正向富集和反向洗脱流路方式,使用80目732强酸型阳离子交换树脂在酸度为0.10mol/L HCl中富集样品中的Ni2+,并用2.0mol/L HCl洗脱.设计了流动注射在线离子交换富集双柱流路的操作程序,优化了各项仪器...