Direct determination of manganese in vitamin?mineral tablets using SS-GFAAS

Elektrotermal Atomik Absorpsiyon Spektrometrisi ile geleneksel olarak yapılan analizlerde, örneklerin çözülmesi, istenmeyen maddelerin uzaklaştırılması ve eğer gerekiyor ise seyreltme veya ön zenginleştirme işlemlerine gerek vardır. Örneklerin çözülmesi ve analize hazır hale getirilmesi genel olarak analizin en zahmetli ve zaman alıcı bölümüdür. Eser ve ultra eser element analizlerinde yukarıdaki işlemler nedeniyle analat kaybı veya örneğin kirlenme riski oldukça artmaktadır. Bu çalışmanın amacı çözme işlemi gerektirmeden çeşitli örmekler içerisindeki metal analizleri için katı örnekleyici grafi fırınlı atomik absorpsiyon spektrometrisi (GFAAS) ile yöntem geliştirmektir. Doğrudan katı örneklerden edilen değerler çözelti tekniği sonuçlarıyla karşılaştırıldığında katıların doğrudan analizi tekniğinin vitamin-mineral tabletlerdeki Mn analizleri için başarıyla uygulanmasının gerçekleştirildiği görülmektedir. Anahtar Kelimeler: Katı örnekleme, mangan, eser element analizi, ETAAS.Analysis of trace elements using electrothermal atomic absorption spectrometry requires dissolution of samples, removal of unwanted materials from sample solutions or some pre concentration processes. Dissolution of samples and preparation of samples to analysis are the most troublesome and time consuming steps of any analysis. In case of trace and ultra trace elements, the loss of analyte and risk of contamination of sample increases due to above processes. The only way of overcoming this problem is to analyze sample directly without any pre-treatment. It can be only possible by using solid sampling system. The aim of this study is to investigate new methods for determination of trace metals in different samples without dissolution by using solid sampling graphite furnace atomic absorption spectrometry (SS-GFAAS). Working conditions (effects of pyrolysis temperature, atomization temperature and sample mass on absorbance) of solid sampling systems were investigated. Using optimum working conditions, Mn concentration of vitamin-mineral tablets was determined by using different calibration techniques. After dissolving samples with acid mixtures Mn content of vitamin-mineral tablets found as   193 + 5 mgkg-1. Mn concentration of vitamin-mineral tablets was determined by using solid sampling ETAAS with different calibration techniques. When these values are compared with the result of conventional solution technique, the results obtained by different direct solid sampling calibration techniques were in agreement with that found by solution technique. Keywords: Solid sampling, manganese, trace element analysis, ETAAS

Investigation of interference mechanisms on the determination of bismuth by GFAAS

Grafit fırınlı atomik absorpsiyon spektrometresinde (GFAAS) tayin elementinin ortamda bulunan matriks bileşenleri ile gaz ve/veya yoğun fazda etkileşmesi sonucu ortaya çıkan çeşitli girişim mekanizmalarının aydınlatılması genellikle çok zor ve yoruma açıktır. Bunun en önemli nedeni farklı girişimlerin genellikle benzer etkilere neden olması ve bunların birbirlerinden ayrılamamasıdır. Özellikle aynı anda birden fazla mekanizmanın oluşumu bu durumu daha da karmaşık hale getirmektedir. Bu mekanizmalar matriks ve tayin maddesinin cinsine, konsantrasyonuna ve grafit fırın programına bağlıdır. Bu çalışmada kullanılan ve özel olarak imal ettirilen çift oyuklu platformun iki ayrı oyuğuna tayin elementinin ve matriksin ayrı ayrı enjekte edilmesi sonucu bunların birbirleri ile yoğun fazda teması önlenmekte ve gözlenen girişimler sadece gaz fazı etkileşmeleri nedeniyle olmaktadır. Böylece çift oyuklu platform klasik tek oyuklu platformla teşhis edilemeyen gaz ve yoğun faz girişimlerinin birbirlerinden ayrılarak belirlenmesinde çok önemli rol oynamaktadır. Bu çalışmada bizmut elementinin GFAAS ile tayini sırasında nikel klorür (NiCl2) tuzunun girişim etkisi araştırılmıştır. Uygulanan piroliz sıcaklığına bağlı olarak analatın matriks ile uçucu bir bileşik oluşturması, matriks gazları ile birlikte sürüklenmesi, matriks parçalanma ürünleri ile gaz fazında reaksiyona girmesi gibi mekanizmaların varlığı ispatlanmıştır. Ayrıca çift oyuklu platformun kullanılmasıyla analat ile matriks parçalanma ürünleri arasında gaz/yoğun faz reaksiyonlarının varlığı gösterilmiştir. Bizmut ile ilgili olarak gözlenen girişim mekanizmaları Ni(NO3)2, Zr(NO3)4, Pd(NO3)2 ve kolloidal palladyum modifierleri kullanıldığında ortadan kalkmaktadır. Anahtar Kelimeler: Bizmut, grafit fırınlı atomik absorpsiyon spektrometresi, girişim etkisi, çift oyuklu platform.  In the presence of matrix, interferences occuring in graphite furnace atomic absorption spectrophotometer (GFAAS) causes errors. In graphite furnace, the interferences between analyte and matrix can be summarized as follows: (i) Formation of a volatile compound between analyte and matrix before the atomization step and its loss by vaporization in molecular form at the beginning of atomization step or during the pyrolysis step (ii) Expulsion of analyte together with rapidly expanding matrix gases in the atomization step (iii) Occlusion of analyte atoms in microcrystals of matrix in the condensed phase and their carrying out of the furnace without being atomized (iv) Gas phase reaction between analyte and matrix decomposition products in the atomization step (v) Formation of a thermally stable compound between analyte and matrix in the condensed phase. The occurrence of those mechanisms depends on experimental conditions and the kind of analyte and matrix. Although the most of the interferences have been reduced using STPF (Stabilized Temperature Platform Furnace) conditions, appropriate modifier and advanced techniques, it can be completely removed. Therefore, elucidation of interference mechanisms as well as the use of optimum experimental conditions is equally important. In this study, the interference effects of nickel chloride(NiCl2) on the determination of bismuth by graphite furnace atomic absorption spectrometry (GFAAS) was investigated. For this purpose, by using a specially designed dual cavity platform (DCP), the condensed phase and gas phase interferences can be distinguished due to being allowed the analyte and matrix to be volatized from different cavities. Depending on applied pyrolysis temperature, the occurence of interference mechanisms such as the formation of volatile compound between analyte and matrix, expulsion with matrix decomposition products and gas phase reaction with matrix decomposition products were proved. In addition, the existence of gas/condensed phase reactions between analyte and matrix decomposition products was shown using o dual cavity platform.  The effects of various experimental conditions such as pyrolysis temperature, pyrolysis time, atomization temperature, heating rate in the atomization step, matrix mass and atomization from wall or platform on sensitivity as well as atomization signals were investigated to explain the interference mechanisms.  If the pyrolysis temperature was lower than 400 oC and analyte and interferent were mixed in the same cavity of the DCP, a 30 % temperature-independent depressive effect was observed. If analyte and interferent were mixed, in a temperature range between 400 oC and 600 oC, integrated absorbances increased about 20 % and then slightly reduced with temperature up to 1200 oC and finally suddenly drop to baseline at 1300 oC whereas integrated absorbances for matrix-free Bi begin to drop above 500 oC dramatically and continously, and become always lower than those in the presence of nickel chloride. If the analyte and interferent were separated, integrated absorbances for bismuth were reduced 10-15 % at 200 oC and remain almost the same up to 1000 oC and then drop to baseline at 1300 oC. Similar to the case for mixture of analyte and interferent, integrated absorbances were higher than those for matrix-free bismuth above 600 oC. The results show that the interference mechanism depends on the pyrolysis temperature. Different mechanisms become dominant under different experimental conditions. If the pyrolysis temperature is lower than 600 oC the interferences of NiCl2 on bismuth in the atomization step is due to gas-phase reaction. On the other hand, at temperatures higher than 600 oC, NiCl2.6H2O should be very effectively converted to a non-interfering form of (possibly NiO), which may be further converted to Ni upon reduction by carbon. In addition, at elevated temperatures, anhydrous NiCl2 should be removed from the furnace by volatilization. As a result, no reaction with Cl atoms in the gas-phase occurs in the atomization step as well as NiO or Ni does not cause any interference. When colloidal palladium were used as a modifier, the integrated absorbances of bismuth increased and its determination in the presence of nickel chloride was free from interference.It is found that colloidal palladium modified both the analyte and the matrices. Keywords: Bismuth, graphite furnace atomic absorption spectrometry, interference effects, dual cavity platform. 

Atık lastik ile bakırın ayrılması ve ön-zenginleştirilmesi

The presence of heavy metals such as cadmium(II), chromium(III), zinc(II), and copper(II), etc. in water and wastewater has been of great public concern. Heavy metals are frequently discharged into the environment from a number of industrial processes, including extractive metallurgy processes, electroplating, refining, leather tanning, metal finishing, printed circuit board manufacturing, and dyeing. Heavy metals are not biodegradable and tend to build up in living organisms, causing several diseases and disorder. It has been shown that copper deposited in human skin, liver, pancreas, brain, and myocardium may result in Wilson's disease.  The maximum contaminant level goal under the Lead and Copper Rule, promulgated by the U.S. EPA in 1991 to limit the concentration of lead and copper in public drinking water at the consumer's tap, is 1.3 mg/L of copper. A wide range of methods have been used to remove heavy metals from aqueous solutions, such as electro-chemical precipitation, ultra-filtration, ion exchange, reverse osmosis, and sorption onto solid substrates such as activated carbon. Each of these methods has some significant drawbacks in practice. A major disadvantage of precipitation is the production of sludge. Ion exchange is considered a better alternative than precipitation. But, it is not economically feasible due to high operational cost. Adsorption using commercial activated carbon (CAC) can remove heavy metals from wastewater, such as Cd, Ni, Cr, Zn, and Cu. However, CAC is an expensive material for heavy metal removal. As a result, researchers have focused on finding low-cost adsorbents and investigated several absorbents such as bagasse sugar, starch xanthate, sawdust of pinus sylvestris, chitosan, bentonite, and discarded automobile tires. Discarded tires are an interesting and inexpensive medium for the sorption of toxic metals from aqueous solutions. In this study, crumb rubber was chosen for the removal of copper from aqueous solution and used for the pre-concentration/separation of copper prior to its determination by flame atomic absorption spectrometry (FAAS). At first the adsorption properties of crumb rubber were investigated by batch technique using inductively coupled plasma-optical emission spectrometry (ICP-OES). The effects of pH, contact time and initial metal concentration on the removal of Cu(II) were studied. Experiments with solution pH as a variable were conducted to determine the optimum pH range for maximum Cu adsorption by crumb rubber at different initial Cu(II) ion concentrations. In all cases, it was found that the uptake increased as the initial pH increased from 1.5 to 6 and slightly changed at the pH value of 7.  Therefore, the following experiments were performed in the solution pH of 6. The effect of contact time on the removal of copper by crumb rubber   at different initial Cu(II) ion concentrations was studied. In all cases, the removal increases with time and attains equilibrium in 72 hr. The metal uptakes versus time curves are single, smooth and continuously leading to saturation, suggesting the possible monolayer coverage of metal ions on the surface of the adsorbent. The removal of Cu(II) by adsorption on crumb rubber has been shown to take place rapidly for all initial concentrations. With the increase in the initial concentration of Cu(II) from 1 to 50 mg L-1, the amount adsorbed increased from 0.0951 mg (99.8%) to 1.5152 mg g-1  (33.0%). The maximum adsorption capacity for copper was 1.56 mg g-1. At higher initial concentration the available sites of adsorption become fewer and hence the percentage adsorption depends on the initial concentration. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherms constants. Equilibrium data agreed very well with the Langmuir model. Results showed that crumb rubber was a favorable adsorber. By taking the advantages of fast kinetics, availability in pure form, quantitative adsorption and suitable capacity obtained from batch technique, it was found suitable for the preconcentration/separation of ultra-trace copper prior to its determination by on-line Flow-Injection FAAS. The effects of sample pH, eluent type, sample and eluent volumes, flow rates on the recovery were investigated. The sample prepared at pH 6 was passed through the micro-column at 60 rpm filled with crumb rubber and eluted with 1.0 M HNO3 prepared in acetone at 60 rpm. When the sample and eluent volumes were 250 mL and 0.5 mL, respectively, 500 fold enrichment was maintained. The recovery was quantitative and limit of detection was 0.9 µg L-1(3; N=8). Keywords: Crumb rubber, Copper, Atomic absorption spectrometry, On-line pre-concentration.Bu çalışmada, atık lastik bakırın sulu çözeltilerden uzaklaştırılması için adsorban olarak seçilmiştir ve  bakırın alevli atomik absorpsiyon spektrometresi (FAAS) ile tayini öncesi ön-zenginleştirilmesi/ayrılması için kullanılmıştır. Öncelikle indüktif olarak eşleşmiş plazma emisyon spektrometresi (ICP-OES) kullanılarak çalkalama yöntemiyle atık lastiğin adsorpsiyon özellikleri araştırılmıştır. Analitlerin adsorpsiyonuna pH, çalkalama süresi ve örnek kütlesinin etkileri incelenmiştir. Analitler için kantitatif adsorpsiyon pH 6’da sürdürülmüştür. Bakırın maksimum adsorpsiyon kapasitesi 1.56 mg g-1 dir. Adsorpsiyon izoterm denemeleri, Langmuir eşitliğinin izoterm verilerine Freundlich eşitliğinden daha iyi uyduğunu açığa çıkarmıştır. Adsorpsiyon özellikleri atık lastiğin analitlerin uzaklaştırılmasında kullanılabileceğini göstermiştir. Çalkalama tekniğinden elde edilen, hızlı kinetik, saf halde bulunabilirlik, kantitatif adsorpsiyon ve uygun kapasite avantajlarıyla  Örnek pH’ı, eluent tipi, örnek ve eluent hacimleri, akış hızlarının geri kazanıma etkileri araştırılmıştır. pH 6’da hazırlanan örnek atık lastik ile doldurulmuş mini kolondan 60 rpm akış hızında geçirilmiş ve asetonda hazırlanmış 1 M HNO3 ile 60 rpm akış hızında elde edilmiştir. Örnek ve eluent hacimleri sırasıyla 250 mL ve 0.5 mL olduğunda, 500 kat zenginleştirme elde edilmiştir. Geri kazanım kantitatiftir (>%95) ve belirleme değeri 0.9 µg L-1 (3σ; N=8) dir.  Anahtar Kelimeler: Atık lastik, bakır, atomik absorpsiyon spektrometri, Hat-üstü ön-zenginleştirme

Determination of lead, copper and manganese by graphite furnace atomic absorption spectrometry after separation/concentration using a water-soluble polymer

In this study, a water-soluble polymer, polyvinylpyrrolidinone (PVP) having chelating functionalities was used for the preconcentration and separation of traces of Pb, Cu, Ve and Mn prior to their determination by graphite furnace atomic absorption spectrometry. For this purpose, the sample and the PVP solutions were mixed and the metal bound polymer was precipitated by adding the mixture onto acetone. The precipitate was separated by decantation and dissolved with water. By increasing the ratio of the volumes of sample to water used in dissolving the precipitate, the analyte elements were concentrated as needed. The concentration of trace elements was determined using graphite furnace atomic absorption spectrometry. The analyte elements in matrix free aqueous solutions were quantitatively recovered. The validity of the proposed method was checked with a standard reference material (NIST SRM 1577b bovine liver) and spiked fruit juice, sea water and mineral water samples. The analytical results were found to be in good agreement with certified and added values. Detection limits (3delta) were 1.7, 3.6 and 4.1 mug l(-1) for Pb, Cu and Mn, respectively, using 10 mul of sample volume. The method is novel and can be characterized by rapidity, simplicity, quantitative recovery and high reproducibility. (C) 2004 Elsevier B.V. All rights reserved

The use of water soluble polymers for the pre-concentration and separation of copper, lead, and chromium prior to their determination by graphite furnace atomic absorption spectrometry

In this study, a water-soluble polymer, polyacrylamide containing R-(+)-Cysteine end groups was used for the separation and preconcentration of copper, lead and chromium prior to their analysis by graphite furnace atomic absorption spectrometry. The sample and polymer solution were mixed and metal-bound polymer was precipitated upon addition of acetone. The precipitate was separated from solution and dissolved directly with distilled water. By this way. analyte elements were again transferred into the liquid phase and analyzed by graphite furnace atomic absorption spectrometry. The advantages and disadvantages of the method compared to those of the traditional batch and column techniques using water insoluble solid materials were described in all aspects. The method is simpler and faster compared to other preconcentration and separation techniques. Recoveries from matrix free aqueous solutions are higher than 96% and relative standard deviations were lower than 3%

Polymer-derived ceramic adsorbent for pollutant removal from water

Polymer-derived ceramic components (SiOC, sample W) were produced from preceramic polymer mixture and a catalyst. After curing and pyrolysis, some of the samples etched by hydrofluoric acid to obtain carbonaceous SiOC (C-rich SiOC, sample W-HF). W and W-HF were tested as an adsorbent material to remove both heavy-metal ions (Cr (III), Pb (III), and Cd (II)) and cationic dyes (Methylene Blue (MB), Rhodamine B (RB), and Crystal Violet (CV)) from aqueous solutions. HF-treated high surface area SiOC samples had quite high adsorption affinity for cationic dyes. According the Langmuir isotherm model the maximum dye uptake values were found to be around to 50 mg/g for sample W, whereas those for sample W-HF ranged from 104 to 186 mg/g. Regeneration studies were conducted both by heat treatment and leaching, high recovery yields (always above 97%) of MB adsorption were obtained.TUBITAK (113Y533