Determination of traces of cadmium in natural water samples by flow injection on-line preconcentration-graphite furnace atomic absorption spectrometry.

A flow injection on-line preconcentration-graphite furnace atomic absorption spectrometric method was developed for the determination of traces of cadmium in natural water samples. Cadmium in samples was adsorbed on an iminodiacetate-type chelating resin, Muromac A-1 microcolumn (3 mm i.d. and 10 mm long), and then eluted with 2 mol l-1 HNO3. The eluate was introduced into the injection tip of an autosampler. The eluate zone with the highest analyte concentration was injected into the graphite furnace by cooperation of a peristaltic pump and a syringe pump of the autosampler, which were controlled by a programmable controller. The present system was successfully applied to the determination of cadmium in natural water samples. A detection limit of 0.2 ng l-1 was obtained with 12 ml sample loading. The recoveries were 99 and 108% for tap water (4 ml loading) and underground water (12 ml loading), respectively. Analytical results obtained for a river water reference material (JAC-0031, Japan Society for Analytical Chemistry) were close to the reference value.     

Determination of trace indium in urine after preconcentration with a chelating-resin-packed minicolumn

A simple and rapid chelating-resin-packed column has been developed for preconcentration of trace indium in biological samples. A large-sized urine sample was pumped through a minicolumn at a flow rate of 1.0 mL/min by using a peristaltic pump, and the eluents were analyzed using graphite furnace atomic absorption spectrometry (GFAAS). Four commercially available chelating resins including Chelex-100, Amberlite IRC-50, Duolite GT-73, and Celite 545-AW were studied for evaluating the indium sorption performance. Several parameters, such as pH, resin amount, eluent volume, eluent flow rate, and the volume of sample, were investigated and optimized. A 100-200 mL of the sample was loaded into a column containing 1.2 g of wet Chelex-100 and subjected to the ion-exchange procedure. The retained analytes were eluted with 5.0 mL of 0.1 M HNO(3) and quantified by GFAAS. The correlation coefficient in the range 10-250 ng/mL was of 0.9994. The limit of detection of the proposed method was 2.75 ng/mL. The method developed was successfully applied to analysis of spiked urine samples with good recoveries of 93-103% (n = 6) and reproducibility (relative standard deviation < 4.9%). The accuracy of procedure was confirmed by indium determination in spiked certified reference materials.     

Field sample preconcentration of copper in sea water using chelating minicolumns subsequently incorporated on a flow-injection-flame atomic absorption spectrometry system.

A field flow preconcentration system for copper determination in seawater is described. Seawater samples are collected and preconcentrated in situ by passing them using a peristaltic pump through a minicolumn packed with Amberlite XAD-4 impregnated with the complexing agent 1-(2-pyridylazo)-2-naphthol. Thus, copper is preconcentrated without the interference of the saline matrix. Once in the laboratory, the minicolumns loaded with copper are incorporated on a flow injection system and eluted with a small volume of a 20% (v/v) ethanolic solution of 0.5 mol L-1 hydrochloric acid into the nebuliser-burner system of a flame atomic absorption spectrometer. The analytical figures of merit for the determination of copper are as follows: detection limit (3s), 0.06 microgram L-1; precision (RSD), 1.2% for 2 micrograms L-1; enrichment factor, 30 (using 25 mL of sample and 83 microL of eluent). Analysis of certified reference materials (SLEW-3 and NASS-5) showed good agreement with the certified value. This procedure was applied to the determination of copper in seawater samples from Galicia (Spain).     

On-line preconcentration of palladium(II) using a microcolumn packed with a chelating resin, and its subsequent determination by graphite furnace atomic absorption spectrometry

Palladium(II) is preconcentrated on a chelating resin microcolumn [1,5-Bis(2-pyridyl)-3-sulphophenyl methylene thiocarbonohydrazide immobilized on an anion-exchange resin (Dowex 1 X8-200)] placed in the autosampler arm, followed by the elution of the Pd-chelate with nitric acid and subsequent determination of Pd from the eluate by graphite furnace atomic absorption spectrometry. The method was applied to the recovery of Pd(II) ions from different samples.     

Design of a field flow preconcentration system for cadmium determination in seawater by flow-injection-atomic absorption spectrometry

A field flow preconcentration system (FFPS) for cadmium determination in seawater is described. Seawater samples are collected and preconcentrated in situ by passing them with a peristaltic pump through a minicolumn packed with Amberlite XAD-4 impregnated with the complexing agent 1-(2-pyridylazo)-2-naphthol. Thus, cadmium is complexed, retained, and preconcentrated without the interference of the saline matrix. Minicolumns loaded with cadmium are then returned to the laboratory where they are incorporated into a flow injection system and eluted with a small volume of an ethanolic solution of hydrochloric acid into the nebuliser-burner system of a flame atomic absorption spectrometer. The optimization of FFPS design is presented, and the stability and characteristics of the Cd-loaded minicolumns are studied in detail. The detection limit for Cd in seawater based on an enrichment factor of 1059 was 3.8 ng l(-1). The precision (R.S.D.) obtained for different amounts of cadmium was in the range 4.1-6.5% at the 25-100 ng l(-1) level. Analysis of certified reference materials (SLEW-3 and NASS-5) showed good agreement with the certified value. This procedure was applied to the determination of cadmium in seawater samples from Galicia (Spain).     

Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods

A study was carried out on the preconcentration of ultratrace amounts of cadmium, lead, manganese, copper and iron from high-salinity aqueous samples and determination by atomic spectrometry methods. Sample volume, amount of resin, loading flow rate, and elution volume were optimized in order to obtain the simultaneous preconcentration of all the analytes. Quantitative recoveries were obtained by using 200 mg of iminodiacetic resin with a loading flow rate of 2 mL min(-1), elution volume of 3 mL and sample volume of 50-450 mL. Only copper in seawater samples was not completely retained by the resin (60-70% recovery), due to unfavorable competition of iminodiacetic-active groups with organically bound metal.To quantify the metals in the eluates, two atomic spectrometry techniques were compared: electrothermal atomization atomic absorption spectrometry (ETAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) with simultaneous CCD detection system. Both techniques are suitable for sample analysis with detection limits of 1.0, 4.7, 3.3, 6.8, and 53 ng L(-1) using ETAAS and 12, 122, 3.4, 17, and 21 ng L(-1) using ICP-OES for Cd, Pb, Mn, Cu, and Fe, respectively. Relative standard deviations of the procedures ranged from 1.7 to 14% at the sub-microg L(-1) concentration level. The accuracy of both methods was verified by analyzing various certified reference materials (river water, estuarine water, coastal and off-shore seawater).     

Determination of beryllium in solid samples by flame atomic absorption spectrometry after preconcentration on activated carbon.

It is generally supposed that the preconcentration procedure is used for the determination of metal concentrations under the sensitivity of the measurement method. This study showed that preconcentration is also need for the beryllium (Be) concentration over the sensitivity of atomic absorption spectrometry. For this purpose, a simple and selective method for the determination of Be in solid samples is modified. The method is based on the preconcentration of the complexes of beryllium-acetylacetone plus morin, oxine, PAN and PAR on activated carbon at different pH values. The adsorbed beryllium was eluted with aqua regia and measured by flame atomic absorption spectrometry (FAAS). Recoveries of up to 85% were achieved. For removing chemical interferences and applying the method to Be determination in solid samples, the masking studies and reproducibility were examined. The detection limit was found to be 0.12 ng mL(-1). The relative sandard deviations (RSD) were found to be 8% for 60 mL of 10.0 ng mL(-1) using 10 replicate enrichment procedures. Beryllium concentrations in the studied solid samples were found in the range of 0.28 - 3.95 mg kg(-1).     

对磺基苯偶氮变色酸螯合形成树脂分离富集微量铂和钯

采用对磺基苯偶氮变色酸（ＳＰＣＡ）作为螯合剂制备具有相应的螯合基团形成树脂。研究了ＳＰＣＡ螯合形成树脂的分析特性及其各种条件对分离富集和测定的影响。实验表明：ＳＰＣＡ螯合形成树脂能在ｐＨ＜５的盐酸溶液中稳定存在；并在ｐＨ１．００时ＳＰＣＡ树脂将微量铂和把的氯络阴离子进行交换并与常见的金属离子分离，采用酸性硫脲溶液定量洗脱。通过对样品加标准回收试验，用原子吸收光谱法测定回收率均在９４％－1０５％之间。     

Determination of platinum and palladium in road dust after their separation on immobilized fungus by electrothermal atomic absorption spectrometry

A flow solid phase extraction procedure based on biosorption of Pt(IV) and Pd(II) on Aspergillus sp. immobilized on cellulose resin Cellex-T was proposed for the separation and preconcentration of Pt and Pd before their determination by electrothermal atomic absorption spectrometry (ETAAS). The analytical conditions including sample pH, eluent type, flow rates of sample and eluent solutions were examined. The analytes were selectively retained on the biosorbent in acidic medium (pH 1) and subsequently eluted from the column with 1 mL of thiourea solution (0.25 mol L^− 1 thiourea in 0.3 mol L^− 1 HCl). The reproducibility of the procedure was below 5%. The limit of detection of the method was 0.020 ng mL^− 1 for Pt and 0.012 ng mL^− 1 for Pd. The method validation was performed by analysis of certified reference materials BCR-723 (tunnel dust) and SARM-76 (platinum ore). The developed separation procedure was applied to the determination of Pt and Pd in road dust samples by ETAAS.The applied biosorbent is characterized by high sorption capacity: 0.47 mg g^− 1 for Pt and 1.24 mg g^− 1 for Pd.     

Determination of noble metals in silicate rocks, ores and metallurgical samples by simultaneous multi-element graphite furnace atomic absorption spectrometry with Zeeman background correction

A new method has been developed for rapid determination of mug/g and ng/g amounts of noble metals in silicate rocks, ores and metallurgical samples by attacking with hydrofluoric acid and aqua regia, preconcentration by ion-exchange chromatography and measuring in a simultaneous multi-element graphite furnace atomic absorption spectrometer equipped with a polarized Zeeman background correction device which eliminated interferences from any incompletely separated common elements. The method was tested for Ru, Rh, Pt, Ir, Pd, Ag and Au with three Canadian certified reference materials, and then applied to the determination of ng/g amounts of these elements in four new Canadian candidate reference materials.     

Determination of lead in sea-water with a graphite furnace atomic absorption spectrometer and an improved automatic on-line pre-concentration system

An improved automatic on-line pre-concentration system for graphite furnace atomic absorption spectrometry (GFAAS) for the determination of trace metals in sea-water was developed. This system was modified from a Perkin-Elmer AS-40 autosampler by mounting a silica gel C₁₈ microcolumn near the tip of the autosampler capillary. The pre-concentration procedure was performed by using a four-way distribution valve and controlled by a programmable controller. The pre-concentration system developed previously was improved by using a peristaltic pump to replace the reciprocating pumps, a newly designed tube bed adjuster to release the back-pressure in the pre-concentration system, and a better control program, such that on-line pre-concentration became more reliable and fully automatic. The chelating agent ammonium pyrolidinedithiocarbamate (APDC) and a miniature column packed with 5 mg of C₁₈ silica gel were used for pre-concentration. This system was tested by analyzing the lead content in reference standard sea-water samples. A sample volume of only 2 ml was required to determine lead in sea-water. The relative limit of detection of lead was 3.5 pg/ml.     

On-line separation and preconcentration of silver ion on amidino-thiourea immobilized glass beads packing in flow injection analysis with atomic absorption spectrometric detection.

Amidino-thiourea immobilized glass beads (AGB I) were prepared and used as the microcolumn packing for the flow injection (FI) on-line separation and preconcentration of Ag(I) coupled with atomic absorption spectrometry (AAS) determination. Base metal ions and anions with a concentration of 2.0 mg mL(-1) had no interference with the determination of Ag(I). The limit of detection (LOD) of Ag(I) for a preconcentration time of 60 s with a sampling flow rate of 5.0 mL min(-1) for 40.0 ng mL(-1) of Ag(I) were 0.50 ng mL(-1) with the peak-height absorbance mode and 1.26 ng mL(-1) with the peak-area absorbance mode, respectively. The relative standard deviations (RSD) of 7 replicate determinations were 0.9% and 0.7% for the peak-height absorbance (H) and the peak-area absorbance (A), respectively. The method was successfully applied to the determination of Ag(I) in ore samples.     

Application of flow injection on-line electrothermal atomic absorption spectrometry to the determination of rhodium

A fully automated procedure for the determination of rhodium has been developed using flow injection (FI) on-line microcolumn preconcentration coupled with electrothermal atomic absorption spectrometry (ETAAS). The proposed FI manifold and its operation make possible the introduction of the total eluate volume into the graphite atomizer, avoiding the necessity for optimisation of subsampling the eluate. Rhodium is adsorbed on a microcolumn packed with 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide immobilized on silica gel (DPTH-gel). Under the optimum conditions, using a 60 s preconcentration time, a sample flow rate of 3.5 mL min(-1) and an injection volume of eluent of 50 microL, a linear calibration graph was obtained from 1 to at least 40 ng mL(-1) and the detection limit was 1 ng mL(-1). The proposed method has been successfully applied to the analysis of samples. Its performance was investigated against certified reference catalyst sample SRM-2557 and by recovery measurements on spiked samples (soil, foods and beverages).     

The determination of lead in tapwater by resin pre-concentration followed by flame atomic absorption spectrometry

The preparation and use of a polystyrene-supported poly(maleic anhydride) resin for the preconcentration of lead from tapwater samples is described. After elution with dilute nitric acid, lead is determined by flame atomic absorption spectrometry down to levels well below the 50 ng cm^-3 E.E.C. limit.     

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.     

Determination of Lead in Heavy Oil by Flow Injection-Flame Atomic Absorption Spectrometry

A simple on-line flow injection analysis pre-concentration technique has been developed. The flow injection system consisted of a 4-channel peristaltic pump, two 6-way rotary injection valves containing a microcolumn of Chelex-100 resin, and a flame atomic absorption spectrometer, allowing the determination of lead at a concentration as low as ppb. The degree of pre-concentration depended on the injected sample volume. Lead contained in NBS 1634b and other heavy oil samples was determined using the system. Samples were ashed directly in a furnace at 550°C for two hours, dissolved with perchloric acid and then injected into the system. The sampling frequency also depended on the injected sample volume.     

Lead ultra-trace on-line preconcentration and determination using selective solid phase extraction and electrothermal atomic absorption spectrometry: applications in seawaters and biological samples

In this work, a new chelating resin [1,5-bis (2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide immobilised on aminopropyl-controlled pore glass (550 A; PSTH-cpg) was synthesised and packed in a microcolumn which replaced the sample tip of the autosampler arm. The system was applied to the preconcentration of lead. When microliters of 10% HNO3, which acts as elution agent, pass through the microcolumn, the preconcentrated Pb(II) is eluted and directly deposited in a tungsten-rhodium coated graphite tube. With the use of the separation and preconcentration step and the permanent modifiers, the analytical characteristics of the technique were improved. The proposed method has a linear calibration range from 0.012 to 10 ng ml(-1) of lead. At a sample frequency of 36 h(-1) with a 90 s preconcentration time, the enrichment factor was 20.5, the detection and determination limits were 0.012 and 0.14 ng ml(-1), respectively and the precision, expressed as relative standard deviation, was 3.2% (at 1 ng ml(-1)). Results from the determination of Pb in biological certified reference materials were in agreement with the certified values. Seawaters and other biological samples were analysed too.     

Automated on-line preconcentration of palladium on different sorbents and its determination in environmental samples

The determination of noble metals in environmental samples is of increasing importance. Palladium is often employed as a catalyst in chemical industry and is also used with platinum and rhodium in motor car catalytic converters which might cause environmental pollution problems. Two different sorbents for palladium preconcentration in different samples were investigated: silica gel functionalized with 1,5-bis(di-2-pyridyl)methylene tbiocarbohydrazide (DPTH-gel) and [1,5-Bis(2-pyridyl)-3-sulphophenyI methylene thiocarbonohydrazide (PSTH) immobilised on an anion-exchange resin (Dowex lx8-200)]. The sorbents were tested in a micro-column, placed in the auto-sampler arm, at the flow rate 2.8 mL min(-1). Elution was performed with 4 M HCl and 4 M HNO3, respectively. Satisfactory results were obtained for two sorbents.     

基于吸力洗脱的流动注射在线富集与火焰原子吸收联用测定水样中的镉

建立了一种基于吸力洗脱的流动注射(FI)在线富集与火焰原子吸收光谱法(FAAS)联用测定水样中痕量镉的新方法.洗脱过程依靠蠕动泵的吸力而不是推力实现洗脱剂的输送,明显降低了被分析物在洗脱过程中的分散,提高了原子吸收信号峰值(A),同时提高了富集系数(EF).进样流速6.0 mL/min;进样时间60 s,测定20 μg/L Cd2+,EF由传统方法的15提高到38;检出限为0.29 μg/L;测样频率为40个/h;相对标准偏差(RSD,n=11)为2.5%.以01‰ (V/V)的三乙醇胺(TEA)为掩蔽剂,Cd2+在水样中的回收率为93.8%～98.5%.     

流动注射-火焰原子吸收光度法测定矿泉水中的锶

用流动注射离子交换系统于酸性条件下在线富集饮用天然矿泉水中的锶,火焰原子吸收光度法测定,共存成分无干扰,方法简便快速,富集倍数可随意调节。在 60 h～(-1)的进样频率下,灵敏度提高 17倍。用于矿泉水中锶的测定,当含量为 60～250 ng/ml时,相对标准偏差为 0.68％～0.94％。回收率为 94.4％～110.3％,检测限为 15ng/ml。