Comparison of standard and reaction cell inductively coupled plasma mass spectrometry in the determination of chromium and selenium species by HPLC–ICP–MS

Simultaneous speciation analysis of Hg and Se in fish by high-performance liquid chromatography and inductively coupled plasma-mass spectrometry following microwave-assisted enzymatic hydrolysis

This study reports the development and validation of a new analytical method for simultaneous speciation analysis of Se and Hg in fish muscle. For this purpose, four Se species (selenite/Se(IV), selenate/Se(VI), selenomethionine/SeMet, and selenocysteine/SeCys) and two Hg species (inorganic mercury/iHg and methylmercury/MeHg) were extracted simultaneously by microwave-assisted enzymatic hydrolysis and then separated by HPLC in less than 15 min by using a column with both anion and cation exchange mechanisms and a mobile phase consisting of a mixture of methanol 5% (v/v), 45 mM HNO3, 0.015% 2-mercaptoethanol, and 1.5 mM sodium 3-mercapto-1-propanesulfonate. The separated species of Hg and Se were detected online by inductively coupled plasma-mass spectrometry (ICP-MS). The speciation analysis method was validated by means of the accuracy profile approach by carrying out three series of measurements in duplicate on three different days over a time-span of 3 weeks. The limits of quantification (LOQ) are in the range of 0.010-0.013 mg/kg wet weight (ww) for all selenium species, except for Se(IV) (0.15 mg/kg ww), while the coefficient of variation in terms of intermediate reproducibility (CVR) was < 7%. The LOQ for MeHg was 0.006 mg/kg ww, while the CVR was 3%. The method was successfully applied to the analysis of muscle samples from four different fish species: rainbow trout, tuna, swordfish, and dogfish.

Evaluation of the Radiological and Chemical Risk for Public Health from Flour Sample Investigation

Flour investigation, in terms of physical and chemical pollutants and mineral content, is of great interest, in view of its high consumption for nutritional purposes. In this study, eleven types of flour (five samples for each one), coming from large retailers and employed by people for different cooking food purposes, were investigated through high-purity germanium (HPGe) gamma spectrometry, in order to estimate natural (40K) and anthropogenic (137Cs) radioisotope specific activity and thus, to assess the radiological risk due to the flour ingestion. Inductively-coupled plasma mass spectrometry (ICP-MS) and inductively-coupled plasma emission spectroscopy (ICP-OES) were also employed to evaluate any possible heavy metal contamination and the mineral composition, and to perform multivariate statistical analysis to deduce the flour authenticity. The evaluation of dose levels due to flour ingestion was performed, for the age category higher than 17 years, taking into account the average yearly consumption in Italy and assuming this need to be satisfied from a single type of flour as a precaution. All obtained results are under the allowable level set by Italian legislation (1 mSv y−1), thus excluding the risk of ionizing radiation effects on humans. As far as heavy metal contamination is concerned, Cd and Pb concentrations turned out to be lower than the threshold values, thus excluding their presence as pollutants. Finally, the multivariate statistical analysis allowed to unambiguously correlate flour samples to their botanical origin, according to their elemental concentrations.

Effective separation of chromium species in technological solutions using amino-immobilized silica prior to their determination

Amino-immobilized (poly(4,9-dioxadodecane-1,12-guanidine, polydiallyldimethylammonium, hexadimethrin bromide, polyhexamethylene guanidine) silicas were proposed for chromium speciation for the first time. Adsorbents surface was characterized by TGA-DSC, FT-IR, CHN, XRD and SEM analysis. Polyamines were strongly fixed on the silica surface and were not washed off with solutions of 3М HNO₃ and 20 g L^-1 NaCl. Аmino-immobilized silica quantitatively removed (R ≥ 99%) Cr(VI) from solutions at pH 4-7. Cr(III) was not recovered in this pH range, which makes it possible to separate Cr(VI) from Cr(III). The separation factor (К_{Cr(VI)/Cr(III)}) was ≥ 1∙10⁴. Silica-based adsorbents layer-by-layer immobilized with polyamines and 2-(1,8-dihydroxy-3,6-disulfo-2-naphthylazo)benzenearsonic acid were proposed for quantitative removal of Cr(III) from aqueous solutions with pH 4-6 at 90 °C. A system of sequentially connected columns filled with selective adsorbents was used to separate the chromium species in stream at рН= 5 and a flow rate of 1 mL min^-1. Chromium was determined after its elution with 5 mL of 2 M HNO₃ at a flow rate of 1 mL min^-1 using ICP-OES or ICP-MS. The pre-concentration factors for Cr(VI) and Cr(III) was 60. A two-column system was used for chromium speciation in technological solutions. The efficiency of chromium speciation was confirmed by state standard procedure.

Spectrofluorimetric determination of Cr(VI) and Cr(III) by quenching effect of Cr(III) based on the Cu-CDs with peroxidase-mimicking activity

The study presents a spectrofluorimetric method for the determination of Cr(III) based on 2,3-diaminophenazine (DAP) as fluorescent nano sensor. With the peroxidase-mimicking activity of copper-doped carbon dots (Cu-CDs), colorless o-phenylenediamine (OPD) was oxidized to fluorescent DAP in the presence of H₂O₂ via generation of hydroxyl radicals. The Cr(III) was found to decrease the fluorescent intensity of the Cu-CDs-mediated OPD oxidation system. Cr(VI) species were reduced to Cr(III) by employing 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) as the reductant, and a novel spectrofluorimetric method for the highly sensitive detection of speciation Cr(VI) and Cr(III) was developed. The Cu-CDs nanozyme was prepared from ethylenediaminetetraacetic acid copper disodium salt (Na₂[Cu (EDTA)]) by one-step pyrolysis method. Under optimal conditions, the fluorescence intensity of DAP is linearly proportional to the Cr(III) ion concentration in the range of 5 × 10^-6 to 1.5 × 10^-4 mol L^-1 and the detection limit is 1.2 × 10^-7 mol L^-1. The method has a good anti-interference performance against some metal ions, such as, Hg²⁺, Co²⁺, Cu²⁺, Mg²⁺, Ba²⁺, K⁺, Mn²⁺, Ni²⁺, Al³⁺, and Fe³⁺. The proposed method was successfully applied in the determination of Cr(VI) and Cr(III) in water samples.

Potential of Selected Trace Elements in Patients with Diabetes Mellitus

Based on the high prevalence, diabetes mellitus (DM) is considered as a worldwide problem. More than 8.3 % of the world population is suffering from this disease. One of the causing factors of this disease can be the absence or imbalance of trace, essential elements. It can cause collapses of antioxidant defence and glucose intolerance. It plays a role in the pathogenesis and progression to diabetes mellitus. This review focuses on chromium, copper, selenium, vanadium, and zinc. Many studies deal with these elements but there is variability in opinions. Insulin-mimetic activity and ability to control the concentrations of blood glucose were confirmed. However, these effects were of more importance in patients with prediabetes. In patients with prediabetes, due to the supplementation of selected trace elements, it is possible to normalize the blood glucose level and prevent the development of diabetes mellitus. The importance of supplementation was confirmed for chromium and zinc. The supplementation of vanadium has a positive effect on the normalization of glycaemia but it is necessary to control the level as it can have toxic effects during long-term treatment. Conversely, higher copper concentrations in the body adversely affect patients and chelation therapy is needed. Selenium must be kept in the standard concentration and regular control of the concentration in the body is necessary. For this reason it is necessary to continue with analysis and the creation of new methodologies that could unify the view on the issue.

New procedure for multielemental speciation analysis of five toxic species: As(III), As(V), Cr(VI), Sb(III) and Sb(V) in drinking water samples by advanced hyphenated technique HPLC/ICP-DRC-MS

Analytical procedure dedicated for multielemental determination of toxic species: As(III), As(V), Cr(VI), Sb(III) and Sb(V) in drinking water samples using high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-DRC-MS) technique was developed. Optimization of the detection and separation conditions was conducted. Dynamic reaction cell (DRC) with oxygen as a reaction gas was involved in the experiments. Obtained analytical signals for species separation were symmetrical, as studied by anion-exchange chromatography. Applied mobile phase consisted of 3 mM of EDTANa2 and 36 mM of ammonium nitrate. Full separation of species in the form of the following forms: H3AsO3, H2AsO4(-), SbO2(-), Sb(OH)6(-), CrO4(2-) was achieved in 15 min with use of gradient elution program. Detailed validation of analytical procedure proved the reliability of analytical measurements. The procedure was characterized by high precision in the range from 1.7% to 2.4%. Detection limits (LD) were 0.067 μg L(-1), 0.068 μg L(-1), 0.098 μg L(-1), 0.083 μg L(-1) and 0.038 μg L(-1) for As(III), As(V), Cr(VI), Sb(III) and Sb(V), respectively. Obtained recoveries confirmed the lack of interferences' influence on analytical signals as their values were in the range of 91%-110%. The applicability of the proposed procedure was tested on drinking water samples characterized by mineralization up to 650 mg L(-1).

Development of a novel, fast, sensitive method for chromium speciation in wastewater based on an organic polymer as solid phase extraction material combined with HPLC-ICP-MS

Speciation analysis of inorganic chromium in wastewater is of great significance for the monitoring of environmental pollution. In this work, N,N-bis(2-aminoethyl)ethane-1,2-diamine functionalized poly(chloromethyl styrene-co-styrene) was synthesized, characterized and used as the adsorbent to preconcentrate chromium species in environmental waters by on line solid-phase extraction (SPE). The trace speciation analysis of Cr(III) and Cr(VI) in wastewater has been used by short-column high-performance liquid chromatography hyphenated to inductively coupled plasma spectrometry (HPLC-ICP-MS) after on-line SPE. Cr(III) and Cr(VI) have been adsorbed on the anion exchange column after transforming the cationic Cr(III) to an anionic [Cr(III)-EDTA](-) complex devoid of re-dox reagent, and then eluted rapidly (within seconds) with a very low concentration of tetrabutylammonium hydroxide (TBAH) solution. This method provides a reliable on-line preconcentration method and detection coupled technique. Under the optimized conditions, high enrichment factors have been obtained for Cr(VI) and [Cr(III)-EDTA](-) with 30mL sample solution up to 105 and 128, respectively. The low detection limits of 0.0068ng mL(-1) and 0.0041ng mL(-1), with the relative standard deviations (RSDs) of 4.3% and 3.6% were obtained for Cr(VI) and [Cr(III)-EDTA](-), respectively. The developed method was validated by analyzing Certified Reference Materials GSBZ50027-94, and the spike tests were also performed. At the same time, thanks to the merit of simple operation, rapid adsorption/desorption dynamics, high enrichment and low LODs, the established method was applied to analyze three wastewater samples from different discharge port.

Antimony, Arsenic and Chromium Speciation Studies in Biała Przemsza River (Upper Silesia, Poland) Water by HPLC-ICP-MS

In this paper the total concentration of As, Cr, Sb, pH and the red-ox potential of water and sediment samples of the Biała Przemsza River were determined. The arsenic (AB, MMA, DMA, As(III), As(V)), chromium (Cr(III), Cr(VI)) and antimony (Sb(III), Sb(V)) forms were studied by HPLC-ICP-MS. Ions were successfully separated on Hamilton PRP-X100: (AB, MMA, DMA, As(III), As(V)), Dionex Ion Pac AS-7 (Sb(III), Sb(V)) and Dionex IonPac AG7 columns: Cr(III), Cr(VI) with LOD 0.16 μg/L, 0.08 μg/L, 0.09 μg/L, 0.012 μg/L, 0.08 μg/L, 0.12 μg/L, 0.009 μg/L, 0.012 μg/L, 0.19 μg/L, 0.37 μg/L, respectively. The simplified BCR three-step sequential chemical extraction was performed on the bottom sediment samples. The samples were collected monthly, between April and December 2014, at five sampling points. Large contents of manganese, lead, cadmium and zinc were found in the Biała Przemsza River water. In December 2014, the lead content in the bottom sediment in Sławków was nearly 6000 mg/kg. In the river water, only the inorganic arsenic speciation forms were found. Sb(V), As(V) and Cr(III) were dominant. Studies have shown that arsenic, antimony and chromium were mainly bound to oxides, organic matter and sulphides in the bottom sediments.

Arsenic, Antimony, Chromium, and Thallium Speciation in Water and Sediment Samples with the LC-ICP-MS Technique

Chemical speciation is a very important subject in the environmental protection, toxicology, and chemical analytics due to the fact that toxicity, availability, and reactivity of trace elements depend on the chemical forms in which these elements occur. Research on low analyte levels, particularly in complex matrix samples, requires more and more advanced and sophisticated analytical methods and techniques. The latest trends in this field concern the so-called hyphenated techniques. Arsenic, antimony, chromium, and (underestimated) thallium attract the closest attention of toxicologists and analysts. The properties of those elements depend on the oxidation state in which they occur. The aim of the following paper is to answer the question why the speciation analytics is so important. The paper also provides numerous examples of the hyphenated technique usage (e.g., the LC-ICP-MS application in the speciation analysis of chromium, antimony, arsenic, or thallium in water and bottom sediment samples). An important issue addressed is the preparation of environmental samples for speciation analysis.

Chromium and its speciation in water samples by HPLC/ICP-MS--technique establishing metrological traceability: a review since 2000

Chromium holds a special position among living organisms because depending on its species it can be either essential or toxic. Cr(VI) even at very low concentrations is harmful and carcinogenic, while Cr(III) is a necessary microelement for cellular metabolism. Therefore, a simple analysis of Cr concentration in collected samples will not be able to distinguish these differences effectively: for a proper chemical analysis we need to perform a reliable detection and quantification of Cr species. Separation and detection of chromium can be accomplished with high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC/ICP-MS) in a one-step. Our review assembles articles published since 2000 regarding chromium speciation in water samples with the use of HPLC/ICP-MS. It addresses the following issues: chromium chemistry, the possibilities of dealing with interferences, metrological aspects, analytical performance and speciated isotope dilution mass spectrometry (SIDMS) which is a definitive measurement method. The authors would like to advocate this hyphenated advanced technique as well as the metrological approach in speciation analysis of chromium.

Characterization of metals released from coal fly ash during dredging at the Kingston ash recovery project

A storage-pond dike failure occurred on December 22, 2008 at the Tennessee Valley Authority Kingston Fossil Plant resulting in the release of over 4million cubic meters (5million cubic yards) of fly ash. Approximately half of the released ash was deposited in the main channel of the Emory River, Tennessee, USA. Remediation efforts of the Emory River focused on hydraulic dredging, as well as mechanical excavation in targeted areas. However, agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could promote dissolution and desorption of metals from the solid fly ash material. Furthermore, aeration of the dredge slurry could alter the redox state of metals in the fly ash material and thereby change their sorption, mobility, and toxicity properties. The research presented here focuses on the concentrations and speciation of metals during the fly ash recovery from the Emory River. Our results indicate that arsenite [As(III)] released from the fly ash material during dredging was slowly oxidized to arsenate [As(V)] in the slurry recovery system with subsequent removal through precipitation or sorption reactions with suspended fly ash material. Concentrations of other dissolved metals, including iron and manganese, also generally decreased in the ash recovery system prior to water discharge back to the river.

Speciation of chromium in water samples by solid-phase extraction on a new synthesized adsorbent

Poly(1,3-thiazol-2-yl methacrylamide-co-4-vinyl pyridine-co-divinylbenzene) was prepared and used as a sorbent for the solid-phase extraction of Cr(VI) ions from aqueous solution. Two forms of chromium showed different exchange capacities at different pH values; Cr(VI) was selectively retained especially at pH 2. The total chromium was determined after the oxidization of Cr(III) to Cr(VI) by potassium permanganate as an oxidizing agent. Then, Cr(III) was calculated by subtracting the Cr(VI) concentration from the total chromium concentration. The optimum conditions were found for species of Cr(VI) (pH 2; eluent, 4 mol L(-1) NH3; sample flow rates, 2 mL min(-1) and eluent flow rates, 1 mL min(-1) etc.). The adsorption capacity and binding equilibrium constant were calculated to be 80.0 mg g(-1) and 0.018 L mg(-1), respectively. A preconcentration factor of 30 and a three-sigma detection limit of 2.4 μg L(-1) (n = 20) were achieved for Cr(VI) ions. The developed method was applied to stream water and waste water samples. At the same time, the polymer was applied to a certified reference material (CRM) (TMDA-52.3) sample.

Impact assessment of dredging to remove coal fly ash at the Tennessee Valley Authority Kingston Fossil plant using fathead minnow elutriate exposures

On December 22, 2008, failure of an earthen containment structure resulted in the release of approximately 4.1 million m(3) of coal fly ash into the Emory River and the surrounding area from the Tennessee Valley Authority Kingston Fossil Plant near Kingston, Tennessee, USA. The purpose of the present study was to assess the potential of dredging activities performed to remove the fly ash from the river to result in increased risk to pelagic fish, with special consideration of mobilization of metals. Elutriates were created using two sources of fly ash by bubbling with air over 10 d. This elutriate preparation method was designed to represent worst-case conditions for oxidation, metal release, and dissolution. Larval and juvenile Pimephales promelas underwent 10-d exposures to these elutriates. Larval end points included survival and biomass, and juvenile end points included survival, length, biomass, liver somatic index, and bioaccumulation. No significant toxicity was observed. Bioaccumulation of metals in juveniles was found to be primarily attributable to metals associated with particles in the gut. Results suggest little potential for toxicity to related fish species due to fly ash removal dredging activities given the extreme conditions represented by the elutriates in the present study.

Microwave-assisted extraction and ion chromatography dynamic reaction cell inductively coupled plasma mass spectrometry for the speciation analysis of arsenic and selenium in cereals

An ion chromatography dynamic reaction cell inductively coupled plasma mass spectrometric (IC-DRC-ICP-MS) method for the speciation of arsenic and selenium compounds is described. Chromatographic separation was performed in a gradient elution mode using 0.5 mmol L(-1) ammonium citrate in 1% methanol (pH 4.5) and 15 mmol L(-1) ammonium citrate in 1% methanol (pH 8.0). The potentially interfering (38)Ar(40)Ar(+) and (40)Ar(40)Ar(+) at selenium masses of m/z 78 and 80 were reduced in intensity by approximately 3 orders of magnitude by using 1.0 mL min(-1) CH(4) as a reactive cell gas in the DRC. Arsenic was determined as the adduct ion (75)As(12)CH(2)(+) at m/z 89. The detection limits of the procedure were in the ranges of 0.006-0.009 ng As mL(-1) and 0.009-0.03 ng Se mL(-1), respectively. This method has been applied to determine various arsenic and selenium compounds in cereal samples. The accuracy of the method has been verified by comparing the sum of the concentrations of individual species obtained by the present procedure with the total concentration of elements. The arsenic and selenium compounds were quantitatively extracted with a Protease XIV and α-amylase solution in a microwave field at 70°C during a period of 30 min. The spike recoveries were in the range of 94-105% for all determinations.

Dynamic reaction cell ICP-MS for determination of total As, Cr, Se and V in complex matrices: still a challenge? A review

Mass interferences, caused by atomic or polyatomic species and having the same mass/charge ratio of the analyte, can be a severe limit for a reliable assay of trace and ultratrace elements by ICP-MS. The DRC™ technology uses a reaction gas to overcome these interferences. Reactions of charge exchange, atom transfer, adduct formation, condensation and analyte association/condensation are the main mechanisms. Interfering ions tend to react with the gas exothermally, while, the analyte reacts endothermally. Selecting the most appropriate reaction gas in DRC-ICP-MS is the very critical point for the determination of strongly interfered elements. A careful evaluation of the reaction mechanisms and the chemistry involved are required. The DRC allows the use of different gases, among them, ammonia (NH(3)), methane (CH(4)), hydrogen (H(2)) and oxygen (O(2)) are the most known, but there are other potentially useful gases like nitrous oxide (N(2)O), nitrogen oxide (NO), carbon dioxide (CO(2)), fluoromethane (CH(3)F), sulphur hexafluoride (SF(6)) and carbon disulfide (CS(2)). This paper provides a review on the analytical challenges for a reliable assay of As, Cr, Se and V by DRC-ICP-MS and illustrates different approaches and mechanisms involved in the analysis of polymers, biological fluids (serum, urine and whole blood), rock, soil and particulate matter.

Collision/reaction cell ICP-MS with shielded torch and sector field ICP-MS for the simultaneous determination of selenium isotopes in biological matrices

The determinations of selenium isotopes in biological samples were performed using both inductively coupled plasma collision/reaction cell quadruple mass spectrometer (CRC-ICP-QMS) and inductively coupled plasma sector field mass spectrometers (SF-ICP-MS). To significantly decrease the argon-based interferences at m/z 74 ((36)Ar(38)Ar), 76 ((38)Ar(38)Ar, (40)Ar(36)Ar), 78 ((38)Ar(40)Ar), and 80 ((40)Ar(40)Ar), the gas-flow rates of a helium and hydrogen mixture used in the collision cell were optimized to 1.0 mL/min H(2) and 3.5 mL/min He. Under the optimized condition, the precisions for natural selenium isotope ratio measurements of both instruments were evaluated and compared using 100 ppb Se standard solution. A modified external calibration quantification method was applied for the simultaneous determination of clinically used enriched selinocompounds ((77)Se-selenate, (82)Se-selenite, (76)Se-methylseleninic acid(IV), (78)Se-methylselenonic acid(VI)) and to examine their fate in rat organs (liver, kidney, and lung).

Geochemical investigations of metals release from submerged coal fly ash using extended elutriate tests

A storage pond dike failure occurred at the Tennessee Valley Authority Kingston Fossil Plant that resulted in the release of over 3.8 million cubic meters (5 million cubic yards) of fly ash. Approximately half of this material deposited in the main channel of the Emory River, 3.5 km upstream of the confluence of the Emory and Clinch Rivers, Tennessee, USA. Remediation efforts to date have focused on targeted removal of material from the channel through hydraulic dredging, as well as mechanical excavation in some areas. The agitation of the submerged fly ash during hydraulic dredging introduces river water into the fly ash material, which could alter the redox state of metals present in the fly ash and thereby change their sorption and mobility properties. A series of extended elutriate tests were used to determine the concentration and speciation of metals released from fly ash. Results indicated that arsenic and selenium species released from the fly ash materials during elutriate preparation were redox stable over the course of 10d, with dissolved arsenic being present as arsenate, and dissolved selenium being present as selenite. Concentrations of certain metals, such as arsenic, selenium, vanadium, and barium, increased in the elutriate waters over the 10d study, whereas manganese concentrations decreased, likely due to oxidation and precipitation reactions.

Development of a simple and fast voltammetric procedure for determination of trace quantity of Se(IV) in natural lake and river water samples

A simple and fast cathodic stripping voltammetric procedure for determination of trace quantity of Se(IV) in natural samples containing high concentrations of surfactants and humic substances was developed. The procedure exploiting selenium accumulation (from sample solution spiked with 0.1 mol L(-1) HClO(4) and 4 x 10(-4)mol L(-1) Cu(NO(3))(2)) as Cu(2)Se was employed as the initial method. The deposited Cu(2)Se was stripped by differential pulse cathodic potential scan. The interference from dissolved organic matter such as surfactants and humic substances was eliminated by adding Amberlite XAD-7 resin to the voltammetric cell. The whole procedure was applied to a single cell, which allows one to monitor the voltammetric scan. Optimum conditions for removing the surfactants and humic substances due to their adsorption on XAD-7 resin were evaluated. The method was tested on synthetic samples spiked with surfactants and humic substances. The calibration graph for Se(IV) under optimized conditions following the accumulation of 30s was linear in the range from 2 x 10(-9) to 2 x 10(-7)mol L(-1) and was found to obey the equation y=0.74x-0.61, where y and x are the peak current (nA) and Se(IV) concentration (nmol L(-1)), respectively. The linear correlation coefficient was r=0.9993. The relative standard deviation for determination of Se(IV) at the concentration of 1 x 10(-8)mol L(-1) was 3.7% (n=5). The detection limit estimated from three times the standard deviation for low Se(IV) concentration and accumulation time of 30s was about 7.8 x 10(-10)mol L(-1). The presented procedure was successfully applied to selenium determination in TMRAIN-95 certified reference material and to real samples including spiked lake and river waters for selenium speciation.

Selective detection of trace Cr3+ in aqueous solution by using 5,5'-dithiobis (2-nitrobenzoic acid)-modified gold nanoparticles

A simply prepared gold nanoparticle-based sensor, 5,5'-dithiobis (2-nitrobenzoic acid) (DTNBA)-modified gold nanoparticles, was prepared to explore the sensitive and selective detection of metal ions using a colorimetric technique. The selective detection of trace levels (93.6 ppb) Cr3+ in aqueous solution was achieved over 15 other metal ions. The functionalized gold nanoparticles became aggregated in solution in the presence of Cr3+ by an ion-templated chelation process, which caused an easily measurable change in the extinction spectrum of the particles and provided an inherently sensitive method for Cr3+ detection in aqueous solution.