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.

Flow analysis-hydride generation-gas phase derivative molecular absorption spectrophotometric determination of antimony in antileishmanial drugs

In the present work, the development of a method based on the coupling of flow analysis (FA), hydride generation (HG), and derivative molecular absorption spectrophotometry (D-EAM) in gas phase (GP), is described in order to determine total antimony in antileishmanial products. Second derivative order (D²224nm) of the absorption spectrum (190 - 300 nm) is utilized as measurement criterion. Each one of the parameters involved in the development of the proposed method was examined and optimized. The utilization of the EAM in GP as detection system in a continuous mode instead of atomic absorption spectrometry represents the great potential of the analytic proposal.

Design and evaluation of a continuous flow, integrated nebulizer-hydride generator for flame atomic absorption spectrometry

An evaluation of the performance of a continuous flow hydride generator-nebulizer for flame atomic absorption spectrometry was carried out. Optimization of nebulizer gas flow rate, sample acid concentration, sample and tetrahydroborate uptake rates and reductant concentration, on the As and Se absorbance signals was carried out. A hydrogen-argon flame was used. An improvement of the analytical sensitivity relative to the conventional bead nebulizer used in flame AA was obtained (2 (As) and 4.8 (Se) µg L-1). Detection limits (3σb) of 1 (As) and 1.3 (Se) µg L-1 were obtained. Accuracy of the method was checked by analyzing an oyster tissue reference material.

Thiamin, selenium, and copper levels in patients with idiopathic dilated cardiomyopathy taking diuretics

OBJECTIVE: To analyze the association of thiamin, selenium, and copper serum levels with cardiac function in patients with idiopathic dilated cardiomyopathy using diuretics, and also to compare them with levels in control patients with no evidence of disease. METHODS: The study comprised 30 patients with heart disease and 30 healthy control individuals. Thiamin was analyzed by measuring the activity of erythrocytic transketolase and the effect of thiamin pyrophosphate. Selenium and copper serum levels were measured by hydride generation and flame atomic absorption spectrophotometry, respectively. RESULTS: Thiamin deficiency was observed in 10% of the control individuals and in 33% of the patients with heart disease (p=0.02). The mean selenium and copper serum levels in control individuals and patients with heart disease were, respectively, 73.2±9.9 µg/L (56.5 to 94.5 µg/L) and 72.3±14.3 µg/L (35.5 to 94 µg/L) (p=0.77); 1.1±0.4mg/L (0.6 to 1.8mg/L) and 1.2± 0.4mg/L (0.6 to 2.2mg/L) (p=0.27). No association between the levels of these nutrients and cardiac function was observed. CONCLUSION: Thiamin deficiency was significantly more frequent in patients with heart disease. No significant difference was observed between the mean selenium and copper serum levels in control individuals and in patients with heart disease. The results suggest possible benefits with thiamin replacement in patients taking diuretics.

Geração eletroquímica do hidreto de selênio em sistema de injeção em fluxo com detecção por espectrometria de absorção atômica com chama Ar-Glp

This paper presents a system for electrochemical hydride generation using flow-injection and atomic absorption spectrometry to determine selenium in biological materials. The electrolytic cell was constructed by assembling two reservoirs, one for the sample and the other for the electrolytic solution separated by a Nafion membrane. Each compartment had a Pt electrode. The sample and electrolyte flow-rates, acidic media, and applied current were adjusted to attain the best analytical performance and ensure the membrane lifetime. The atomisation system used a T quartz tube in an air-LPG flame. The composition of the flame, the observation height, and the argon flow rate used to carry the hydrides were critically investigated. The system allowed to perform thirty determinations per hour with a detection limit of 10 mug L-1 of Se. Relative standard deviations were in general lower than 1.5% for a solution containing 20.0 and 34.0 mug L-1 of Se in a typical sample digest. Accuracy was assessed analysing the certified materials: rice flour (NIST-1568) from National Institute of Standard and Technology and dried fish (MA-A-2), whole animal blood (A-2/1974) from the International Atomic Energy Agency.

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.

Determinação de arsênio em águas contaminadas usando fluorescência de raios-X por energia dispersiva

This work proposes a simple, fast and inexpensive method to determine As in natural waters, using X-ray fluorescence. 50 µL of each sample containing 100 mg L-1 of yttrium as internal standard were deposited over a 2.5 µm thickness MylarTM film. The samples were dried at 50 °C for 2 h. X-ray spectra were obtained using an EDXRF apparatus. The accuracy was determined by analyte addition/recovery and by comparison with Hydride Generation Atomic Absorption Spectrometry (HG AAS). A recovery of about 100% was obtained and the results were in good agreement with HG AAS. The method showed a relative standard deviation of 6.8% and a detection limit of 10.5 µg L-1 of As.

Determinação de As, Cd e Pb em amêndoas e mesocarpo de babaçu, sapucaia, xixá e castanha-do-pará por espectrometria de absorção atômica

This work describes methods for the simultaneous determination of Cd and Pb by graphite furnace atomic absorption spectrometry and As by hydride generation atomic absorption spectrometry in Brazilian nuts. The samples (~ 0.300 g) were digested to clear solutions in a closed vessel microwave oven. The pyrolysis and atomization temperatures for simultaneous determinations of Cd and Pb were 1100 and 2100 °C, respectively, using 0.5% (w v-1) NH4H2PO4 + 0.03% (w v-1) Mg(NO3)2 as chemical modifier. The limits of detection (3Δ) were 3.8 μg kg-1 for As, 0.86 μg kg-1 for Cd and 13 μg kg-1 for Pb. The reliability of the entire procedures was confirmed by peach leaves (No. 1547 - NIST) certified reference material analysis and addition and recovery tests. The found concentrations presented no statistical differences at the 95% confidence level.

Determinação seletiva de tributilestanho na presença de Sn(IV) em amostras ambientais usando HG-ICP OES e Saccharomyces cerevisiae como material sorvente

A method for selective determination of tributyltin in the presence of Sn(IV) by combining hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP OES) and solid phase extraction (SPE) using baker's yeast is proposed. The procedure is based on selective retention of TBT by the yeast at pH = 6. Detection limit of 1.9 µg L-1 and quantification limit of 6.3 µg L-1 were obtained. TBT and San(IV) were determined in the range of 0-25 µg L-1 and the proposed approach was applied to analyze river water, sea water and biological extracts, with recoveries of 114, 101 and 86%, respectively.

Especiação química de arsênio inorgânico no estuário da Laguna dos Patos (RS, Brasil)

This study optimized and validated a method to perform chemical speciation of inorganic arsenic in water samples collected under the Monitoring Program of the Port of Rio Grande-RS in July and October 2010 from the Laguna dos Patos Estuary (RS, Brazil). The flow injection hydride generation atomic absorption spectrometry technique was employed, allowing quantification of As3+ and As5+ present in estuarine water samples. Data interpretation for results generated using the improved method for analyzing water samples collected from Laguna dos Patos Estuary was done by main components analysis.

Selenium plasma levels in hemodialysis patients: Comparison between North and Southeast of Brazil

Introduction: Patients with chronic kidney disease present selenium (Se) plasma deficiency which is an essential trace element with important biological functions and, the best known biological role is attributed to its presence in the antioxidant enzyme, glutathione peroxidase (GPx). The Se content of foods depends on soil and some authors have suggested that Amazon soil (North Brazilian region) has high Se concentrations when compared to other regions of Brazil. Objective: The objective of this work was to compare the Se status in hemodialysis (HD) patients from North and Southeast of Brazil. Methods: Thirty-eight patients from Southeast region (22 men and 16 women, 15% diabetic, 53.5 ± 26.4 yrs) were compared to 40 patients from North region (28 men and 12 women, 22.5% diabetic, 63.5 ± 11.9 yrs). Se in plasma was determined through atomic absorption spectrophotometry with hydride generation. Results: The plasma Se levels in patients from Southeast region were significantly lower (17.5 ± 11.9 μg/L) when compared to patients from the North (37.1 ± 15.8 μg/L) (p < 0.001). However, both patient groups presented low Se plasma levels when compared to recommended values (60- 120 μg/L). There was no correlation between plasma Se levels and analyzed parameters. Conclusion: We concluded that patients from North (Amazon) region present higher plasma Se levels when compared to the patients from Southeast of Brazil. However, independently of the region, HD patients presented Se deficiency.

Congenital Chagas disease of second generation in Santiago, Chile. Report of two cases

Congenital Chagas disease (CChD) has been reported in different countries, mostly in Latin America. In 1987 a fatal case of CChD of second generation (CChDSG) was published. Within a period of six months - 1989-1990 - two cases of CChDSG were diagnosed and studied in the city of Santiago. Two premature newborns, sons of two sisters, with moderate liver and spleen enlargement, were found to have positive serology for Chagas disease and xenodiagnoses. The mothers, urban residents all their lives, without antecedents of triatomine bugs contact or blood transfusions, showed positive serology and xenodiagnoses. Their mother (grandmother of the infants), lived 20 years in a Northern rural Chagas disease endemic locality, in a triatomine infested house. Afterwards, she moved to Santiago, where she married and has resided up to now. Serology and xenodiagnoses were also positive. All the Trypanosoma cruzi infected individuals were successfully treated with nifurtimox.

First- Versus Second-Generation Drug-Eluting Stents in Acute Coronary Syndromes (Katowice-Zabrze Registry)

Abstract Background: There are sparse data on the performance of different types of drug-eluting stents (DES) in acute and real-life setting. Objective: The aim of the study was to compare the safety and efficacy of first- versus second-generation DES in patients with acute coronary syndromes (ACS). Methods: This all-comer registry enrolled consecutive patients diagnosed with ACS and treated with percutaneous coronary intervention with the implantation of first- or second-generation DES in one-year follow-up. The primary efficacy endpoint was defined as major adverse cardiac and cerebrovascular event (MACCE), a composite of all-cause death, nonfatal myocardial infarction, target-vessel revascularization and stroke. The primary safety outcome was definite stent thrombosis (ST) at one year. Results: From the total of 1916 patients enrolled into the registry, 1328 patients were diagnosed with ACS. Of them, 426 were treated with first- and 902 with second-generation DES. There was no significant difference in the incidence of MACCE between two types of DES at one year. The rate of acute and subacute ST was higher in first- vs. second-generation DES (1.6% vs. 0.1%, p < 0.001, and 1.2% vs. 0.2%, p = 0.025, respectively), but there was no difference regarding late ST (0.7% vs. 0.2%, respectively, p = 0.18) and gastrointestinal bleeding (2.1% vs. 1.1%, p = 0.21). In Cox regression, first-generation DES was an independent predictor for cumulative ST (HR 3.29 [1.30-8.31], p = 0.01). Conclusions: In an all-comer registry of ACS, the one-year rate of MACCE was comparable in groups treated with first- and second-generation DES. The use of first-generation DES was associated with higher rates of acute and subacute ST and was an independent predictor of cumulative ST.