Ultra-trace monitoring of copper in environmental and biological samples by inductively coupled plasma atomic emission spectrometry after separation and preconcentration by using octadecyl silica membrane disks modified by a new schiff's base

Ultra-trace amounts of Cu(II) were separated and preconcentrated by solid phase extraction on octadecyl-bonded silica membrane disks modified with a new Schiff,s base (Bis- (2-Hydroxyacetophenone) -2,2-dimethyl-1,3-propanediimine) (SBTD) followed by elution and inductively coupled plasma atomic emission spectrometric detection. The method was applied as a separation and detection method for copper(II) in environmental and biological samples. Extraction efficiency and the influence of sample matrix, flow rate, pH, and type and minimum amount of stripping acid were investigated. The concentration factor and detection limit of the proposed method are 500 and 12.5 pg mL-1, respectively.

A novel method for fast enrichment and monitoring of hexavalent and trivalent chromium at the ppt level with modified silica MCM-41 and its determination by inductively coupled plasma optical emission spectrometry

Chromium(III) at the ng L-1 level was extracted using partially silylated MCM-41 modified by a tetraazamacrocyclic compound (TAMC) and determined by inductively coupled plasma optical emision spectrometry (ICP OES). The extraction time and efficiency, pH and flow rate, type and minimum amount of stripping acid, and break- through volume were investigated. The method's enrichment factor and detection limit are 300 and 45.5 pg mL-1, respectively. The maximum capacity of the 10 mg of modified silylated MCM-41 was found to be 400.5±4.7 µg for Cr(III). The method was applied to the determination of Cr(III) and Cr(VI) in the wastewater of the chromium electroplating industry and in environmental and biological samples (black tea, hot and black pepper).

TREATMENT OF WASTE FROM ATOMIC EMISSION SPECTROMETRIC TECHNIQUES AND REUSE IN UNDERGRADUATE LAB CLASSES FOR QUALITATIVE ANALYSIS

Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma optical emission spectrometry (ICP OES) are widely used in academic institutions and laboratories for quality control to analyze inorganic elements in samples. However, these techniques have been observed to underperform in sample nebulization processes. Most of the samples processed through nebulization system are discarded, producing large volumes of waste. This study reports the treatment and reuse of the waste produced from ICP OES technique in a laboratory of analytical research at the Universidade Federal do Ceará, Brazil. The treatment of the waste was performed by the precipitation of elements using (NH4)2CO3. Subsequently, the supernatant solution can be discarded in accordance with CONAMA 430/2011. The precipitate produced from the treatment of residues can be reused as a potential sample in undergraduate qualitative analytical chemistry lab classes, providing students the opportunity to test a real sample.

Association of dental enamel lead levels with risk factors for environmental exposure

OBJECTIVE: To analyze household risk factors associated with high lead levels in surface dental enamel. METHODS: A cross-sectional study was conducted with 160 Brazilian adolescents aged 14-18 years living in poor neighborhoods in the city of Bauru, southeastern Brazil, from August to December 2008. Body lead concentrations were assessed in surface dental enamel acid-etch microbiopsies. Dental enamel lead levels were measured by graphite furnace atomic absorption spectrometry and phosphorus levels were measured by inductively coupled plasma optical emission spectrometry. The parents answered a questionnaire about their children's potential early (05 years old) exposure to well-known lead sources. Logistic regression was used to identify associations between dental enamel lead levels and each environmental risk factor studied. Social and familial covariables were included in the models. RESULTS: The results suggest that the adolescents studied were exposed to lead sources during their first years of life. Risk factors associated with high dental enamel lead levels were living in or close to a contaminated area (OR = 4.49; 95% CI: 1.69;11.97); and member of the household worked in the manufacturing of paints, paint pigments, ceramics or batteries (OR = 3.43; 95% CI: 1.31;9.00). Home-based use of lead-glazed ceramics, low-quality pirated toys, anticorrosive paint on gates and/or sale of used car batteries (OR = 1.31; 95% CI: 0.56;3.03) and smoking (OR = 1.66; 95% CI: 0.52;5.28) were not found to be associated with high dental enamel lead levels. CONCLUSIONS: Surface dental enamel can be used as a marker of past environmental exposure to lead and lead concentrations detected are associated to well-known sources of lead contamination.

Brazil nuts: determination of natural elements and aflatoxin

A study was carried out to evaluate the association of levels of radioactivity, selenium and aflatoxin in shelled Brazil nuts, which were classified in different sizes, for export. The selenium determinations were performed by inductively coupled plasma optical emission spectrometry (LOQ = 3.0 µg g-1), and aflatoxins were detected by Liquid chromatography-mass spectrometry (LOQ = 0.85 µg kg-1), recovery rates were between 92 and 100%. Radioactivity was measured by high-resolution gamma spectrometry. The selenium mean concentration was (22.7 ± 7.4) µg g-1. (n = 30). Mean activities determined for the following radium isotopes were: 15.77 Bq kg-1 for 224Ra, 104.8 Bq kg-1 for 226Ra and 99.48 Bq kg-1 for 228Ra. For 226Ra, the levels did not vary significantly with nut sizes, although such differences were observed for 224Ra and 228Ra. There was no statistically significant association between the level of selenium and the activity of radionuclides, however, there was correlation between the radionuclides. Aflatoxins above the quantification limit were not found.

Chemical composition of phytoplankton from the estuaries of Eastern Amazonia

Phytoplankton is important bioindicator of chemical and biological modifications of natural ecosystems. The objective of this study was to determine the total chemical composition of the phytoplankton of the Pará and Mocajuba estuaries on the eastern coast of the Amazon region in the Brazilian state of Pará. The chemical composition of the surface water, bottom sediments (total sample and bioavailable fraction), and the phytoplankton were determined by inductively coupled plasma optical emission spectrometry. Phytoplankton contained high concentrations of Ca, P, Mn, Fe, Zn, Al, Ba, and Pb. The phytoplankton of the Mocajuba estuary is rich in Fe (2,967-84,750 µg g-1), while those from the Pará is rich in Al (1,216-15,389 µgg-1), probably reflecting divergent anthropogenic inputs. Both samples indicated a high bioconcentration factor derived from both the water and the bioavailable fraction, reflecting the efficiency of these organisms in the concentration of metals.

Speciation of antimony (III) and antimony (V) using hydride generation for meglumine antimoniate pharmaceutical formulationsquality control

The pentavalent antimonies, mainly the meglumine antimoniate, are recommends as first-choice medicines for leishmaniasis therapy. In this work we described the development of formulations of meglumine antimoniate injectable medication, as well as the analytical methodology used in the selective determination of Sb(III) and Sb(Total) by hydride generation - inductively coupled plasma atomic emission spectrometry (HG-ICP-AES) and ICP-AES, respectively. On that purpose the analytical methodology was developed focusing on the HG-ICP-AES technique. The formulations using propylene glycol/water as vehicles in a 20:80 proportion were more appropriate for subsequent use in industrial scale. These formulations also showed a lower variation on Sb(III) percentage, no need of buffer solution to stabilize the formulation and no influence of the autoclaving in the quality of the product. The results of the development of the analytical methodology point out the proposed method as an efficient alternative for the determination of Sb(III) in the presence of large quantities of Sb(V) in injectable solutions of meglumine antimoniate, in a selective, linear, accurate and precise manner. In addition, the method showed a low limit of quantification, less interference of the matrix, and more resilience than batch techniques proposed in the Brazilian Pharmacopeia.

Quantification of aluminium in soil of the Solimões Formation, Acre State, Brazil

The variety of soils in the State of Acre is wide and their chemical profiles are still not fully understood. The nature of the material of origin of these soils is indicated by the high aluminium (Al) content, commonly associated with high calcium (Ca) and magnesium (Mg) contents. The study objective was to use different methods to quantify Al in soils from toposequences formed from material of a sedimentary nature originating from the Solimões Formation, in Acre, Brazil. Trenches were opened at three distinct points in the landscape: shoulder, backslope and footslope positions. Soil samples were collected for physical, chemical, mineralogical analyses. The Al content was quantified using different methods. High Al contents were found in most of these horizons, associated with high Ca and Mg levels, representing the predominant cations in the sum of exchangeable bases. The mineralogy indicates that the soils are still in a low weathering phase, with the presence of significant quantities of 2:1 minerals. Similar Al contents were determined by the methods of NaOH titration, xylenol orange spectrometry and inductively coupled plasma optical emission spectrometry. However, no consistent data were obtained by the pyrocatechol violet method. Extraction with KCl overestimated the exchangeable Al content due to its ability to extract the non-exchangeable Al present in the smectite interlayers. It was observed that high Al contents are related to the instability of the hydroxyl-Al smectite interlayers.

Use of legal reserve areas as geochemical background in hydrosedimentology studies¹

In hydrosedimentology studies the determination of the trace element concentrations at the study site is imperative, since this background can be used to assess the enrichment of sediments with these elements. This enrichment can be the result of the natural process of geological formation or of anthropogenic activities. In the latter case, guidelines are used to indicate the concentrations at which trace elements cause ecotoxicity effects on the environment. Thus, this study used legal reserve areas in the municipality of Toledo, PR, where natural forests are maintained, with no or minimal human interference to establish background levels. The results of atomic emission spectrometry with inductively coupled argon plasma showed that the legal reserves have lower levels of trace elements than other theoretical references, but equivalent concentrations to the safety levels recommended by international guidelines. It was concluded that determining values is fundamental to recommend this background as scientific database for research in the area of hydrosedimentology of this site and also as a way of environmental management of the watershed of this municipality.

Methods to Quantify Nickel in Soils and Plant Tissues

In comparison with other micronutrients, the levels of nickel (Ni) available in soils and plant tissues are very low, making quantification very difficult. The objective of this paper is to present optimized determination methods of Ni availability in soils by extractants and total content in plant tissues for routine commercial laboratory analyses. Samples of natural and agricultural soils were processed and analyzed by Mehlich-1 extraction and by DTPA. To quantify Ni in the plant tissues, samples were digested with nitric acid in a closed system in a microwave oven. The measurement was performed by inductively coupled plasma/optical emission spectrometry (ICP-OES). There was a positive and significant correlation between the levels of available Ni in the soils subjected to Mehlich-1 and DTPA extraction, while for plant tissue samples the Ni levels recovered were high and similar to the reference materials. The availability of Ni in some of the natural soil and plant tissue samples were lower than the limits of quantification. Concentrations of this micronutrient were higher in the soil samples in which Ni had been applied. Nickel concentration differed in the plant parts analyzed, with highest levels in the grains of soybean. The grain, in comparison with the shoot and leaf concentrations, were better correlated with the soil available levels for both extractants. The methods described in this article were efficient in quantifying Ni and can be used for routine laboratory analysis of soils and plant tissues.

Determinação de Cd, Ni e Zn por espectrometria de emissão atômica com plasma indutivamente acoplado, após separação e pré-concentração em coluna contendo p-dimetilaminobenzilidenorodanina adsorvida sobre sílica gel

A column packed with 5-(4-dimethylaminobenzylidene)rhodanine adsorbed on silica gel was used for the preconcentration of Cd, Ni and Zn at different spiked solutions prior to their determination by inductively coupled plasma atomic emission spectrometry. This column allowed recoveries over than 98% for the above elements and accurate analyses of coastal sea-water certified reference material were also achieved.

Avaliação da salinização de açudes no semi-árido brasileiro por ICP-AES

The salt accumulation process in some reservoirs of regular and irregular use (from 10 to 50 years of constrution), located in the Southeast of Bahia State was evaluated. Inductively coupled plasma atomic emission spectrometry was used to evaluate the concentrations of Na, K, Ca and Mg in water samples from inside and upstream of the reservoirs. The results showed that for reservoirs of irregular use, the salt accumulation, indicated by the tracer Na, increases with the age of the reservoirs, however for the reservoirs of regular use the hydraulic retention time is the main parameter.

Dissolução eletrolítica para a determinação de elementos de liga em aço ferramenta por ICP-AES

Different methods have been applied to solve special problems of metal analysis. First, the solid samples of tool steels were analyzed by X-ray fluorescence. Alternatively, an on-line electrodissolution implemented in a flow injection system and conventional dissolution procedure for determination of W, Mo, V and Cr in tool steels by ICP-AES is described. The resulting analyte solutions were compared with conventional dissolution procedure and determination by ICP-AES. The electrolytic procedure presented a good performance characterized by a sample throughput of 164 determinations per hour. Results were in agreement with those obtained by conventional acid dissolution.

Alternativas analíticas para determinação de ferro e titânio em cimento Portland

In the present work four different analytical methodologies were studied for the determination of iron and titanium in Portland cement. The cement samples were dissolved with hot HCl and HF, being compared Fe and Ti concentrations through four analytical methods: molecular absorption spectrophotometry using the reagents 1,2-hydroxybenzene-3,5-disulfonic acid (Tiron) and the 5-chloro-salicylic acid (CSA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and flame atomic absorption spectrophotometry (FAAS). In the spectrophotometric determinations were studied pH conditions, reagents addition order, interferences, amount of reagents, linear range and stability of the system. In the techniques of ICP-AES and FAAS were studied the best lines, interferences, sensibility and linear range. The obtained results were compared and the agreement was evaluated among the methods for the determination of the metals of interest.

A geração química de vapor em espectrometria atômica

The historical development of atomic spectrometry techniques based on chemical vapor generation by both batch and flow injection sampling formats is presented. Detection via atomic absorption spectrometry (AAS), microwave induced plasma optical emission spectrometry (MIP-OES), inductively coupled plasma optical emission spectrometry (ICP-OES) , inductively coupled plasma mass spectrometry (ICP-MS) and furnace atomic nonthermal excitation spectrometry (FANES) are considered. Hydride generation is separately considered in contrast to other methods of generation of volatile derivatives. Hg ¾ CVAAS (cold vapor atomic absorption spectrometry) is not considered here. The current state-of-the-art, including extension, advantages and limitations of this approach is discussed.