流动注射在线萃取色谱分离原子吸收光谱法测定痕量铂

研究了流动注射在线分离富集原子吸收光谱法测定痕量铂的方法。以自制的GDX501-TBP萃取树脂为微型分离柱，在优化后的分离富集条件下，进样时间为60s，洗脱时间为45s。在线分离测定时间为3min，方法检出限为0．25μg/L，线性范围10—600μg/L，加标回收率为97．8％-103．6％，相对标准偏差3．49％-4．25％。方法已用于矿物管理样中铂的测定。     

流动注射在线萃取—石墨炉原子吸收光谱法测定地质样品痕量钯

应用流动注射在线萃取技术将ＰｄＣｌ＾２－６萃入２－巯基苯并噻唑－甲基异丁基酮直接进行石墨炉原子吸收测定。研究了流动注射在线萃取－石墨炉原子吸收光谱法测定地质样品中钯的实验条件、流路参数等。采样速率为２０样／ｈ,ＲＳＤ（ｎ＝１０）为４．８％,测定Ｐｄ的特征质量为２．６＊１０＾－１１。     

流动注射在线分离富集-火焰原子吸收光谱法测定钯

将聚氯乙烯-丁二酮肟复膜树脂作为固定相填充到自制的微型柱中,将流动注射在线分离富集与火焰原子吸收光度法联用,组成同时富集、顺序反向洗脱的环内双柱复线流路及检测系统,对废催化剂中微量钯进行测定.废催化剂样品经盐酸(5+95)溶液溶解后,过滤所得残渣溶于王水中.分析时将pH 2的试液以7.5 mL·min-1速率采样90 s,用乙二胺-20 g·L-1氢氧化钠(1+9)混合溶液作为洗脱液,从柱上将钯(Ⅱ)洗脱并引入原子吸收光谱仪的雾化器中进行测定,线性范围为1.25 mg·L-1以内,检出限(3S/N)为15μg·L-1,应用此方法分析了地质标样及铂矿样等已知样品,测得结果与标准值或已知值相符,其相对标准偏差(n=7)均小于2.5%.     

流动注射在线分离富集火焰原子吸收法测定环境样品中的铅和镉

使用PT-C18色谱预处理柱,以二乙基二硫代氨基甲酸钠（DDTC）和吡咯啶二硫代氨基甲酸铵（APDC）混合物为螯合剂,甲醇为洗脱剂,采用流动注射在线分离富集与原子吸收联且技术,对铅和镉的测定进行了研究。1min（4.2mL),检出限：Pb为6.90μg/L;Cd为0.45μg/L,相对标准偏差：Pb为2.80%;Cd为2.47%。     

流动注射在线分离富集-石墨炉原子吸收光谱法测定氧化铅中痕量金

采用流动流射在线分离富集－石墨炉原子吸收光谱法测定了氧化铅中痕量金。使用本文研究的取样杯,实现了流动注射装置与石墨炉原子吸收联机测定。通过在线分离富集,提高了分析速度,消除了基体干扰,使金的测定灵敏度提高３０倍,金特征量为０．０６ｐｇ,检出限为０．０３８ｐｇ。分析了含金量为０．２＊１０＾－６％的试样,相对标准偏差。为２．６％。     

流动注射在线萃取色谱预浓集火焰原子吸收法测定钯

以三异辛胺萃淋树脂为微型柱固定相，采用流动注射在线预浓集与火焰原子吸收法联用技术，对微量钯的测定进行了研究。在0.5mol/L的HCl介质中以7.8mL/min的速率采样90s再用0.1mol/L硫脲－0.5mol/L HCl洗脱；在27h^-1的采样频率下，浓集系数为50倍，浓集效率为22.5min，消耗指数0.23mL。线性范围为0－1000μg/L，检出限为0.34μg/L。钯含量水平50μg/L时，连续11次测定的相对标准偏差为2.6%，并对加氢催化剂中的钯进行了加标回收率实验，回收率为99.3%-101.2%。     

流动注射在线液-液萃取火焰原子吸收法测定水中痕量铅

提出了一种流动注射在线液－液萃取火焰原子吸收直接测定水中痕量铅的分析方法。实验以APDC为螯合剂,用MIBK为萃取剂,研究了在线萃取中各种实验参数、酸度条件的影响,考察了共存元素的干扰。方法的RSD（n=12)为2．7％,测定检出限为3．1μg/L,回收率为96％－106％。     

流动注射化学发光法测定痕量钯

在NaOH介质中,H_2O_2能氧化鲁米诺(Luminol)产生化学发光,在OP乳化剂存在下,金属钯能催化该反应,据此建立了Luminol-NaOH-H_2O_2-OP-Pd(Ⅱ)化学发光体系,用流动注射化学发光法测定钯,检出限为4.1ng/mL,Pd(Ⅱ)浓度在1.0×10~(-8)～1.0×10~(-6)g/mL范围内与发光强度呈良好的线性关系,相对标准偏差(n=10)为3.8％。     

流动注射在线共沉淀预富集火焰原子吸收法测定痕量铜

研究了以Ｎｉ＾２＋－ＤＤＴＣ为共沉淀载体，流动注射在线共沉淀预富集－火焰原子吸收光谱法测定痕量铜的体系，在０．３ｍｏｌ．Ｌ＾－１的硝酸介质中，铜离子在编织反应器中与Ｎｉ＾２＋－ＤＤＴＣ（产生共沉淀，并被收集在编织器内壁上，用甲基异丁基酮（ＭＩＢＫ）在线洗脱沉积物并引入火争原子化器中测定。当富集时间为４０ｓ时，４０μｇ．Ｌ＾－１的铜１０次测定的相对标准偏差为３．０％，灵敏度提高６０倍，检出限（３σ）     

An ion-exchange method for speciation of antimony by flow injection electrothermal atomic absorption spectrometry

In this work, a simple preconcentration system, achieved by replacing the sample tip of the autosampler arm by a micro-column packed with Amberlite IRA-910 or silica gel chelating resin functionalised with 1,5-bis(di-2-pyridyl)methylene tbiocarbohydrazide (DPTH-gel), is developed for the determination of Sb(V) and total antimony, respectively. Different factors including pH of sample solution, ionic strength, concentration and volume of eluent, sample flow rate, sample loading time and matrix effects for preconcentration were investigated. The method has been applied to the determination of antimony species in different samples.     

On-line flow injection solvent extraction for electrothermal atomic absorption spectrometry: Determination of nickel in biological samples

A flow injection (FI) on-line solvent extraction system for electrothermal atomic absorption spectrometry (ETAAS) was developed with nickel as a model trace element. The nickel pyrrolidine-dithiocarbamate chelate was extracted on line into isobutyl methyl ketone, which was delivered into the FI system by a peristaltic pump equipped with poly(tetrafluoroethylene) tubing. The organic phase was separated from the aqueous phase by a novel gravity phase separator with a small conical cavity, and stored in a collector tube, from which 50 μl organic concentrate was introduced into the graphite tube by an air flow. ETAAS determination of the analyte was performed in parallel with the extraction process. An enrichment factor of 25 was obtained in comparison with 50 μl direct introduction while achieving a detection limit of 4 ng l⁻¹ (3σ), and a precision of 1.5% relative standard deviation for 1.0 μg l⁻¹ nickel (n = 11). The proposed method was successfully applied to the determination of nickel in body fluids and other biological samples.     

Utilization of electrodeposition for electrothermal atomic absorption spectrometry determination of gold

Gold was determined by electrothermal atomic absorption spectrometry after electrochemical preconcentration on the graphite ridge probe used as a working electrode and sample support. The probe surface was electrochemically modified with Pd, Re and the mixture of both. The electrolysis of gold was performed under galvanostatic control at 0.5 mA. Maximum pyrolysis temperature for the probe surface modified with Pd was 1200 °C, with Re 1300 °C. The relative standard deviation for the determination of 2 μg l^− 1 Au was not higher than 5.6% (n = 8) for 2 min electrodeposition. The sensitivity of gold determination was reproducible for 300 electrodeposition and atomization cycles. When the probe surface was modified with a mixture of Pd and Re the detection limit was 31 ng l^− 1 for 2 min electrodeposition, 3.7 ng l^− 1 for 30 min, 1.5 ng l^− 1 for 1 h and 0.4 ng l^− 1 for 4 h electrodeposition, respectively. The procedure was applied to the determination of gold in river water samples. The relative standard deviation for the determination of 2.5 ng l^− 1 Au at 4 h electrodeposition time at 0.5 mA was 7.5%.     

Automated determination of tin and nickel in brass by on-line anodic electrodissolution and electrothermal atomic absorption spectrometry

The application of an on-line metallic alloy dissolution system using anodic electrodissolution in a flow injection system for the determination of tin and nickel in copper alloys is described. After the electrolyzed material was collected in the autosampler cup, determination was carried out using electrothermal atomic absorption spectrometry (ETAAS). Using specific software developed in Turbo Pascal 7.0, it is possible to control electrolysis time, intensity of the applied current, and triggering of the three-way solenoid valves that push the fluids. Through manipulation of these variables, it is possible to adjust the analytical signal to within the working range of the spectrometer. Calibration of the spectrometer was accomplished by processing reference material. For tin, relative standard deviations for a series of measurements (n=5) performed on the same point and on different points of the sample was smaller than 2 and 4%, respectively; for nickel, 2 and 5%, respectively. The results for tin and nickel were in good agreement with those obtained through application of the classical methodology, as well as with data obtained by optical emission spectrometry. The detection limit for tin was 0.001% (w/w), whereas for nickel it was 0.003% (w/w). The analytical throughput is 30 samples h⁻¹.     

Flow field-flow fractionation with off-line electrothermal atomic absorption spectrometry for size characterization of silver nanoparticles

Flow field-flow fractionation (Fl-FFF) with off-line electrothermal atomic absorption spectrometry (ETAAS) detection was developed and employed for particle size characterization of Ag NPs stabilized by citrate, pectin, and alginate. Citrate stabilized-Ag NPs were prepared from sodium borohydride reduction of silver nitrate. Sodium citrate was used as the capping agent to stabilize Ag NPs and prevent the aggregation process. Pectin stabilized- and alginate stabilized-Ag NPs were prepared from ascorbic acid reduction of silver nitrate. Pectin and alginate were used as the capping agent for pectin stabilized- and alginate stabilized-Ag NPs, respectively. Three types of Ag NPs were characterized by using FlFFF, zeta potentiometer, and TEM technique. The mean particle sizes of Ag NPs as characterized by FlFFF were 9 nm, 19 nm, and 45 nm for citrate stabilized-, pectin stabilized-, and alginate stabilized-Ag NPs, respectively, in deionized water. Further, FlFFF with ETAAS detection was employed to observe the aggregation of Ag NPs of various types in environmental water in the absence and presence of humic acid. Citrate stabilized-Ag NPs underwent aggregation more rapid than the pectin stabilized- and alginate stabilized-Ag NPs as the latter two types were sterically stabilized. Further, humic acid could prolong the stability of Ag NPs in the environment.     

Separation and preconcentration by flow injection coupled to tungsten coil electrothermal atomic absorption spectrometry

A flow injection system coupled to a tungsten coil electrothermal atomizer has been developed for on-line separation and preconcentration, using lead as a model element. The system utilizes three-way solenoid valves for sampling, buffering, washing and reconditioning solution management, and the resin column is inserted in the tip of the autosampler arm of a Varian GTA-96. The solenoid valves and tungsten coil power supply were controlled by a computer program written in Visual Basic, interfaced with the built-in Varian software. The system performance was tested by loading the resin column with the sample flowing at 3 ml min⁻¹ for 60 s. Elution was performed automatically by sampling 20 μl of the eluent from a sample cup of the autosampler, and this aliquot was delivered into a 150 W tungsten coil. With Chelex-100 resin, the separation of concomitants was tested with lead in the presence of as much as 1000 mg l⁻¹ of Ca, Mg, Na or K. The model system presented an enrichment factor of 64 at a sampling rate of 30 samples per hour.     

Investigation of on-line coupling electrothermal atomic absorption spectrometry with flow injection sorption preconcentration using a knotted reactor for totally automatic determination of lead in water samples

A flow injection on-line sorption preconcentration electrothermal atomic absorption spectrometric system for fully automatic determination of lead in water was investigated. The discrete non-flow-through nature of ETAAS, the limited capacity of the graphite tube and the relatively large volume of the knotted reactor (KR) are obstacles to overcome for the on-line coupling of the KR sorption preconcentration system with ETAAS. A new FI manifold has been developed with the aim of reducing the eluate volume and minimizing dispersion. The lead diethyldithiocarbamate complex was adsorbed on the inner walls of a knotted reactor made of PTFE tubing (100 cm long, 0.5 mm i.d.). After that, an air flow was introduced to remove the residual solution from the KR and the eluate delivery tube, then the adsorbed analyte chelate was quantitatively eluted into a delivery tube with 50 μl of ethanol. An air flow was used to propel the eluent from the eluent loop through the reactor and to introduce all the ethanolic eluate onto the platform of the transversely heated graphite tube atomizer, which was preheated to 80°C. With the use of the new FI manifold, the consumption of eluent was greatly reduced and dispersion was minimized. The adsorption efficiency was 58%, and the enhancement factor was 142 in the concentration range 0.01–0.05 μg l⁻¹ Pb at a sample loading rate of 6.8 ml min⁻¹ with 60 s preconcentration time. For the range 0.1–2.0 μg l⁻¹ of Pb a loading rate of 3.0 ml min⁻¹ and 30 s preconcentration time were chosen, resulting in an adsorption efficiency of 42% and an enhancement factor of 21, respectively. A detection limit (3σ) of 2.2 ng l⁻¹ of lead was obtained using a sample loading rate of 6.8 ml min⁻¹ and 60 s preconcentration. The relative standard deviation of the entire procedure was 4.9% at the 0.01 μg l⁻¹ Pb level with a loading rate of 6.8 ml min⁻¹ and 60 s preconcentration, and 2.9% at the 0.5 μg l⁻¹ Pb level with a 3.0 ml min⁻¹ loading rate and 30 s preconcentration. Efficient washing of the matrix from the reactor was critical, requiring the use of the standard addition method for seawater samples. The analytical results obtained for seawater and river water standard reference materials were in good agreement with the certified values.     

Automated on-line separation preconcentration system for palladium determination by graphite furnace atomic absorption spectrometry and its application to palladium determination in environmental and food samples

A flow injection (FI) system was used to develop an efficient on-line sorbent extraction preconcentration system for palladium by graphite furnace atomic absorption spectrometry (GFAAS). The investigated metal was preconcentrated on a microcolumn packed with 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide immobilized on silica gel (DPTH-gel). The palladium is eluted with 40 μl of HCl 4 M and directly introduced into the graphite furnace. The detection limit for palladium under the optimum conditions was 0.4 ng ml⁻¹. This procedure was employed to determine palladium in different samples.     

Evaluation of different permanent modifiers for the determination of arsenic in environmental samples by electrothermal atomic absorption spectrometry

Single noble metal permanent modifiers such as, Rh, Ir, and Ru, as well as mixed tungsten plus noble metal (W-Rh, W-Ru, W-Ir) permanent modifiers thermally deposited on the integrated platform of transversally heated graphite atomizer were employed for the determination of arsenic in sludges, soils, sediments, coals, ashes and waters by electrothermal atomic absorption spectrometry. Microwave digests of solid samples and water samples were employed for obtaining the analytical characteristics of the methods with different permanent modifiers. The performance of the modifiers for arsenic determination in the real samples depended strongly on the type of permanent modifier chosen. The single noble metal (Rh, Ir and Ru) permanent modifiers were suitable for the analyte determinations in simpler matrices such as waters (recoveries of certified values 95-105%), but the analyte recoveries of certified values in sludges, soils, sediments, coals, and ashes were always lower than 90%. On the other hand, for the determination of arsenic, using W-Rh, W-Ru, and W-Ir permanent modifiers presented recoveries of certified values within 95-105% for all the samples. Long-term stability curves obtained for the determination of arsenic in environmental samples with different permanent modifiers (Rh, Ir, Ru, W-Rh, W-Ir, W-Ru) showed that the improvement in the tube lifetime depends on the tungsten deposit onto the platform. The tungsten plus noble metal permanent modifier presents a tube lifetime of at least 35% longer when compared with single permanent modifier. The results for the determination of As employing different permanent modifiers in the samples were in agreement with the certified reference materials, since no statistical differences were found after applying the paired t-test at the 95% confidence level.     

Flow injection on-line dilution for zinc determination in human saliva with electrothermal atomic absorption spectrometry detection

An automated method is described for the determination of zinc in human saliva by electrothermal atomic absorption spectrometry (ET AAS) after on-line dilution of samples with a significant reduction of sample consumption per analysis (<0.4 mL including the dead volume of the system). In order to fulfill this aim without changing the sample transport conduits during the experiments, a flow injection (FI) dilution system was constructed. Its principal parts are: one propulsion device (peristaltic pump, PP) for either samples, standards or washing solution all located in an autosampler tray and for the surfactant solution (Triton X-100) used as diluent, and a two-position time based solenoid injector (TBSI₁) which allowed the introduction of 10 μL of either solution in the diluent stream. To avoid unnecessary waste of samples, the TBSI₁ also permitted the recirculation of the solutions to their respective autosampler cups. The downstream diluted solution fills a home made sampling arm assembly. The sequential deposition of 20 μL aliquots of samples or standards on the graphite tube platform was carried out by air displacement with a similar time based solenoid injector (TBSI₂). The dilution procedure and the injection of solutions into the atomizer are computer controlled and synchronized with the operation of the temperature program. Samples or standards solutions were submitted to two drying steps (at 90 and 130 °C), followed by pyrolysis and atomization at 700 and 1700 °C, respectively. The aqueous calibration was linear up to 120.0 μg L⁻¹ for diluted standard solutions/samples and its slope was similar (p > 0.05) to the standard addition curve, indicating lack of matrix effect. The precision tested by repeated analysis of real saliva samples was less than 3% and the detection limit (3σ) was of 0.35 μg L⁻¹. To test the accuracy of the proposed procedure, recovery tests were performed, obtaining mean recovery of added zinc of 97.8 ± 1.3%. Furthermore, Zn values estimated by the procedure developed in this work were compared with those obtained by a standard addition flame-AAS method applied to 20 randomly selected saliva samples. No significant differences (p > 0.05) were obtained between the two methods. Zinc levels in saliva samples from 44 healthy volunteers, 15 male and 29 female, with ages between 20 and 51 years (mean 30.50 ± 9.14 years) were in the range 22–98 μg L⁻¹ (mean of 55 ± 17 μg L⁻¹), similar to some and different from others reported in the literature. It was found that zinc values for male were statistically higher (p = 0.006) than for female.