ET-AAS in the Analysis of high-purity mercury

ET-AAS is investigated for the analysis of high purity mercury. Two possibilities are proposed: ET-AAS determination of trace analytes in the presence of high mercury concentrations or after matrix separation by reduction. The ET-AAS analysis of high-purity mercury under optimal instrumental parameters permits fast and reproducible determination of 0.03 gg^–1 Al, Cd and Mn; 0.05 gg^–1 Cu, Co, Cr, Fe, Ni and Pb and 0.2 gg^–1 V. Preliminary mercury matrix reductive separation with ascorbic acid allows determination of 0.005 gg^–1 Cd, 0.02 gg^–1 Cu, Cr and Mn, 0.03 g g^–1 Co, Ni and Pb, 0.05 g g^–1 Al and Fe and 0.1 gg^–1 V, but the reproducibility is lower. The main advantage of the second procedure is that it avoids laboratory and instrument pollution with toxic mercury.     

Determination of Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb in natural waters, alkali and alkaline earth salts by electrothermal atomic absorption spectrometry after preconcentration by column solid phase extraction

Methods are described for the determination of trace and ultra trace amounts of Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb in natural waters, alkali and alkaline earth salts. Separation and preconcentration of trace metals is achieved by a column solid phase extraction procedure using silica gel modified with derivatives of dithiocarbamates — Na-DDTC (sodium diethyldithio-carbamate and HMDTC (ammonium hexamethylene-dithiocarbamate) as column packing material. The influence of the sorbent preparation procedure on the degree of sorption of the trace analytes is examined for different pH values of the sample solution. Isobutylmethyl ketone (IBMK) is proposed as an effective eluent for quantitative elution of retained metal ions. Optimal instrumental parameters for ETAAS determination of preconcentrated elements in organic eluate are presented. Practical application of sorbents in analysis of natural waters and alkali and alkaline earth salts is demonstrated. Proposed preconcentration procedure combined with ETAAS determination of trace analytes allows the determination of 0.04 g l^–1 Cd, 0.1 g l^–1 Cr, Cu, and Mn and 0.3 g l^–1 Co, Fe, Ni and Pb in natural waters and 1.10^–7% Cd, 3.10^–7% Cr and Mn, 7.10^–7% Co, Ni and Pb and 2.10^–6% Cu and Fe in alkali and alkaline earth salts.     

New methods for acceleration of meat sample preparation prior to determination of the metal content by atomic absorption spectrometry

Focused microwave-assisted digestion and ultrasound leaching have been applied for the extraction of Pb, Cd, Cr, Cu, Fe, Zn, Ca, and Mg from raw meat. Semimembranous muscle (SM) of raw pig ham was used for optimizing both the digestion and extraction steps by multivariate approaches. The detection and quantification limits were 0.5 and 0.9 g kg^–1 for Pb, 0.06 and 0.1 g kg^–1 for Cd, 0.2 and 1.2 g kg^–1 for Cr, 0.4 and 3 g kg^–1 for Cu, 0.04 and 0.1 mg kg^–1 for Fe, 0.012 and 0.017 mg kg^–1 for Zn, 0.3 and 0.4 mg kg^–1 for Ca, and 0.01 and 0.03 mg kg^–1 for Mg. The precision, expressed as relative standard deviation (RSD), ranged between 2.5 and 9.6% for focused microwave-assisted digestion and between 3.5 and 10.6% for ultrasound leaching. The methods were then compared with a reference method and applied to a certified reference material (bovine muscle 184, from the BCR). The t-test, applied to the results obtained from focused microwave-assisted digestion, revealed that they are in agreement (p>0.01) with the certified and estimated values in the case of Pb, Cd, Cr, Cu, Fe, Ca, Mg, and Zn but not in that of Fe. In the case of ultrasound leaching, only the extraction of Pb, Cu, and Ca was quantitative. The method based on microwave digestion provides more accurate and precise results than ultrasound leaching. These new procedures have many advantages with regards to conventional methods, namely, reduction of the extraction time, simplification of the process, avoidance of chemical emissions to the atmosphere, and no losses of metals by volatilization.     

Determination of detection limits in graphite furnace atomic absorption spectrometry by using ensemble summation of signals

Summary The detection limits of Ag, As, Au, Bi, Cd, Cr, Fe, Mn, Ni, P, Pb, Sb, Se and Te in the presence of 50 g of copper are determined by Zeeman graphite furnace atomic absorption spectrometry (Zeeman/GFAAS) using the method of ensemble summation. Processing of atomic absorption signals of masses close to the detection limits is illustrated.

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Bestimmung von Nachweisgrenzen in der Graphitofen-Atomabsorptionsspektrometrie durch Anwendung der Ensemblesummierung von Signalen

Zusammenfassung Die Nachweisgrenzen von Ag, As, Au, Bi, Cd, Cr, Fe, Mn, Ni, P, Pb, Sb, Se und Te in Anwesenheit von 50 g Kupfer wurden mit Hilfe der Zeeman Graphitofen-Atomabsorptionsspektrometrie (Zeeman/GAAS) unter Anwendung der Ensemblesummierung bestimmt. Diese ermöglicht die Bearbeitung der Atomabsorptions-Signale von Massen in der Nähe der entsprechenden Nachweisgrenzen.

     

Radiochemical separations for inorganic trace elements in some biological reference materials,foods, tissues and body-fluids

A simple radiochemical machine incorporating ion-exchange procedures has been described. The system has been tested repeatedly for the determination of Cd, Co, Cr, Cu, Mn and Mo at ultra trace concentration levels in a variety of biological samples such as reference materials, human blood serum, human milk, hair and certain dietary materials, thereby demonstrating its suitability for practical use. The procedure can also yield results for A, Au and W, without any further chemical manipulations. Results show <1, 0.12, 0.18, 983, 0.61 and 0.91 g/l for Cd, Co, Cr, Cu, Mn and Mo, respectively, in human blood serum. Corresponding concentrations in human milk are <1, 0.25, <1, 186 to 310, 4 to 40 and 5.8 g/l. Among the reference materials, IAEA milk standard A-11 shows 1.85, 5.1, 17, 380, 260 and 101 ng/g for Cd, Co, Cr, Cu, Mn and Mo, respectively. Corresponding concentrations in animal muscle H-4 are 4.1, 5, 10.2, 4000, 455 and 45 ng/g. Importantly, this scheme has been applied to process large number of samples from single investigations such as those arising from dietary studies, obtaining quick and reliable data for routine use.In memory of Knut Samsahl, the devoted Norwegian radiochemist.     

Characterization of a total diet reference material (ARC/CL HDP) for contents of essential and toxic elements

Summary A total diet reference material (RM) was prepared by employing material leftover from a nationwide Finnish hospital diet study. The material was carefully homogenized using Ti-blades, freeze-dried, rehomogenized with Ti-blades, passed through a 2 mm nylon sieve and carefully mixed in large glass cylinders. Homogeneity of the material divided into 20 g samples in polyethylene bottles was tested by taking ten 0.5 g samples from the beginning and end of the bottling line and analyzing them for Zn and Mg. The homogeneity was within 1.0% for both Zn and Mg. An interlaboratory comparison study involving reliable reference laboratories that employed a total of seven methods based on independent analytical principles was conducted on the contents of 14 mineral elements. After the exclusion of outliers the recommended concentrations (on a dry weight basis) expressed as the medians±95% confidence limits were established as follows: Ca=2.86±0.124 mg/g, Mg=785±25 g/g, K=9.42±0.30 mg/g, Na=7.87±0.57 mg/g, Fe=30.4±0.9 g/g, Mn=12.9±0.58 g/g, Zn=28.9±1.3 g/g, Cu=3.18±0.19 g/g, Mo=262±35 ng/g, Ni=271±38 ng/g, Se=181±17 ng/g, Pb=43±8 ng/g, Cd=21±3 ng/g and Hg=6.6±3.6 ng/g. All of the above recommended concentration ranges, except that for Ni, fell into category A, i.e. values recommended with a high degree of confidence according to the certification criteria established by Pszonicki.     

Determination of Mg,Al, P,Cu and Mn in biological fluids by neutron activation analysis

Thermal and epithermal neutron activation analysis has been applied to determine the concentrations of magnesium, aluminium, phosphorus, copper and manganese in two biological fluids: blood serum and market milk. Both epithermal neutron irradiation and radiochemical separation (a chromatographic column of HAP) were used to get rid of the interferences from 24-Na. Strongly acidic solutions of the irradiated samples were passed through the columns of HAP, where sodium was completely adsorbed while, Al, Cu, Mg and Mn were eluted with an efficiency of 99±1%. Since both Al and P were determined through the formation of²⁸Al (2.24 min) thermal and epithermal neutron activation have been applied in order to determine the contribution of each radionuclide to²⁸Al activity. The determination of Mg, Al and P in milk samples was done instrumentally, whereas in the case of blood serum with higher concentration of Na, a radiochemical separation is essential in both cases. The concentrations of Al, Cu, Mg, Mn and P in blood serum and market milk were found to be 0.24±0.02 and 1.85±0.09 g Al/ml, 1.35±0.04 and 0.068±0.005 g Cu/ml, 22.9±1 and 98.9±8.6 g Mg/ml, 22±3 and 16±2 ng Mn/ml and 167±13 and 865±32 g P/ml, respectively.     

Adsorption behaviour of some metal complexes with ferron on Zeo-Karb-226: An atomic absorption spectrophotometric (AAS) study

Summary The adsorption behaviour of ten metal complexes Cr(III), Cr(VI), Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and Pb(II) with ferron on Zeo-Karb-226 in the H⁺ form was investigated at eight different pH-values in order to develop a preconcentration technique for trace amounts of these elements in aqueous solution. The concentrations of the remaining unadsorbed metal ions were determined by atomic absorption spectrophotometry. Under the present experimental conditions, Cr(III) and Pb(II) can be quantitatively determined within the pH range 4–8, while for Cd(II), the optimum pH-range is 7–11. But at pH 11, more than 95% of Cu(II) and Co(II) can be extracted from aqueous solution. The suitability of the technique has been evaluated by analyzing cadmium in simulated water samples. The results indicate that as low as 5 g 1^–1 of CD can be recovered with more than 96% efficiency from 11 of simulated water solution.

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Adsorptionsverhalten einiger Metallkomplexe mit Ferron an Zeokarb-226: eine AAS-Untersuchung

Zusammenfassung Das Adsorptionsverhalten der Komplexe von Cr(III), Cr(VI), Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II) und Pb(II) mit Ferron an Zeokarb-226 in der H⁺-Form wurde bei acht verschiedenen pH-Werten untersucht, um eine Anreicherungsmethode für Spuren dieser Elemente zu entwickeln. Die Konzentrationen der verbliebenen nicht adsorbierten Metallionen wurden mit Hilfe der AAS bestimmt. Cr(III) und Pb(II) können im pH-Bereich 4–8 quantitativ erfaßt werden, während der optimale Bereich für Cd(II) bei pH 7–11 liegt. Bei pH 11 werden jedoch mehr als 95% Cu(II) und Co(II) aus der wäßrigen Lösung extrahiert. Der Nutzen des Verfahrens wurde durch Bestimmung von Cd(II) in simulierten Wasserproben erwiesen. Noch 5 g/l Cd können zu mehr als 96% aus 11 Wasserprobe wiedergefunden werden.

     

Application of a method for matrix correction using compton-scattering for the quantitative determination of metals in silica by wavelength dispersive X-ray fluorescence spectroscopy (WDXRF)

Summary A correction method to diminish errors caused by different mass absorption coefficients of the samples is described. Also errors caused by differing device parameters are diminished. The method is used for the determination of Fe, Cr, Ni, Co, Mn, Zn, Cd, Cu, Hg and Pb on chemically modified silica in the g/g-range.

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Anwendung einer Methode zur Matrixkorrektur durch Compton-Streupeaks für die quantitative Bestimmung von Metallen in Kieselgelen mit Hilfe der wellenlängendispersiven Röntgenfluorescenzanalyse (WDXRF)

Zusammenfassung Ein Korrekturverfahren zur Verminderung von Meßfehlern, die durch unterschiedliche Massenabsorptionskoeffizienten der Proben verursacht werden, wird beschrieben. Ebenso werden Fehler durch Schwankungen von Geräteparametern verringert. Die Methode wird benutzt zur Bestimmung von Fe, Cr, Ni, Cd, Co, Mn, Zn, Cu, Hg und Pb auf chemisch modifizierten Kieselgelen im g/g-Bereich.

     

Potentiometric studies on the complexes of tetracycline (TC) and oxytetracyclin (OTC) with some metal ions

Summary The interaction of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III), and UO₂(II) ions with tetracycline (TC) were studied by potentiometricpH titrations. The formation constants of the different binary complexes formed in such systems have been determined at 25±0.1°C and =0.1 moll^–1 (NaNO₃). PotentiometricpH equilibrium measurements have been made under the same conditions for the interaction of oxytetracycline (OTC) and Cu(II), Cd(II), Pb(II), and UO₂(II). The formation of (1:1) binary complexes are inferred from the potentiometricpH tritration curves. The protonation constants ofTC andOTC were also determined under the same conditions and refined (ESAB2M computer program). The transition metal stability constants are consistent with the Irving-Williams series.

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Potentiometrische Untersuchungen der Komplexe von Tetracyclin (TC) and Oxytetracyclin (OTC) mit einigen Metall-Ionen

Zusammenfassung Die Wechselwirkungen von Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III) und UO₂(II) Ionen mit Tetracyclin (TC) wurden mittels potentiometrischerpH-Titrationen untersucht. Die Komplexbildungskonstanten wurden bei 25±0.1°C und =0.1 mol/1(NaNO₃) bestimmt. Unter den gleichen Bedingungen wurden die Komplexierung von Cu(II), Cd(II), Pb(II) und UO₂(II) mit Oxytetracyclin (OTC) mittel potentiometrischerpH Gleichgewichtsmessungen untersucht. Aus den potentiometrischenpH-Titrationskurven ergab sich die Bildung von (1:1) binären Komplexen. Die Protonierungskonstanten vonTC undOTC wurden ebenfalls bestimmt und rechnerisch verfeinert (ESAB2M Computer Programm). Die Stabilitätskonstanten für die Übergangsmetalle stimmen mit der Irving-Williams Reihe überein.

     

A contribution to the trace analysis of high-purity iron by atomic spectrometry (flame-AAS, furnace-AAS, ICP-OES)

Summary Various possibilities for the determination of trace impurities in high-purity iron by atomic spectrometry were investigated in detail. For Ba, Bi, Cd, Co, Cr, Cu, Mn, Ni, Pb, Ti and V, flame AAS, furnace AAS and ICP-OES were firstly evaluated in terms of their power of detection. Detection limits in the g/g-range could be achieved by direct determination. For determination in the ng/g-range a removal of iron by a solvent extraction technique prior to the instrumental measurement was required. The power of detection of direct determination, and of combined procedures were compared with regard to routine applicability and a minimization of systematic errors.     

Die gleichzeitige Bestimmung von Cu,Fe, Mn,Zn, Pb und Cd in Pflanzengewebe mittels Differential-Puls-Polarographie

Zusammenfassung Die Ionen des Cu, Pb, Cd, Zn, Fe und Mn in Pflanzenmaterial können mittels Differential-Puls-Polarographie ineinem Analysengang bestimmt werden, wenn man eine erste Grundlösung ohne Wechsel des Meßgefäßes durch Zusatz so variiert, daß jeweils eine andere Gruppe aus den genannten Ionen störungsfrei bestimmbar ist. Nach Veraschung und Lösung in Weinsäure lassen sich Cu, Pb, Cd und Zn, nach Zusatz von Ammoniak Cd, Zn und Fe, nach weiterem Zusatz von Kaliumcyanid Mn bestimmen. Benötigte Probenmenge 0,2–0,5 g, untere Bestimmungsgrenze um 1g/g. Die Methode eignet sich besonders für Serienanalysen. Ein Analysenbeispiel ist angegeben.

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Simultaneous assay of Cu, Fe, Mn, Zn, Pb and Cd in plant tissue by means of differential pulse polarography

Summary Cu, Pb, Cd, Zn, Fe and Mn ions in plant material can be assayed by means of differential pulse polarography in one analysis operation if the first basic solution is varied without changing the measurement vessel by addition in such a way that in each case one other group of the named ions can be assayed without interference. After incineration and dissolution in tartaric acid, Cu, Pb, Cd and Zn can be assayed. After addition of ammonia Cd, Zn and Fe, and after further addition of potassium cyanide, Mn can be determined. Required sample amount: 0.2 to 0.5 g; lower limit of detection is around 1g/g. The method is especially suitable for serial analyses. An analysis example is given.

     

Trace element analysis of high-purity copper

Summary In copper samples trace impurities of the elements As, Bi, Cr, Fe, Pb, Sb, Se and Te in the low g/g range were coprecipitated with lanthanum hydroxide and determined by flame AAS (Fe) and electrothermal AAS (other elements). Reduction of the sample weight results in a considerable saving of time compared to elder procedures and allows to apply centrifugation instead of filtration as separation technique, by which the risk of contamination is decreased. The completeness of separation was examined by analyzing standard solutions. Additionally radio tracer experiments were employed with Sb and Se. Based on recovery data, a classification scheme was set up with regard to adsorption behaviour. High-purity copper samples were analyzed by the procedure described; INAA and ICP-MS were used as comparison methods. Parameters affecting the precision were examined; the main influence was caused by the separation step. The procedure is well suitable for the determination of 2–10 g/g As, Cr and Pb and 5–50 g/g Fe in high-purity copper.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Bestimmung von Spurenelementen in Flu?wasser mit Hilfe der Voltammetrie

Zusammenfassung Bei der Bestimmung von Spurenelementen in Flußwasser durch Voltammetrie treten Störungen auf, die überwiegend von organischen Verunreinigungen verursacht werden. Die Einflüsse dieser Verunreinigungen können durch oxidative UV-Photolyse beseitigt werden.Im Anschluß an die Bestrahlung der Proben konnten in filtriertem Rheinwasser Zn, Cd, Pb, Cu, Ni, Co, Tl und mit Einschränkungen auch Mn voltammetrisch bestimmt werden. Die Konzentrationen an Bi und Se lagen unterhalb der Nachweisgrenze. Die Nachweisgrenzen für die genannten Elemente in Flußwasser bewegten sich in der Größenordnung zwischen 0,1 und 1 g/l. Vergleichsbestimmungen mit Hilfe der flammenlosen AAS (Graphitrohrküvette) ergaben gute Übereinstimmung für die Elemente Cu, Zn und Mn, während die Konzentrationen der anderen Elemente unterhalb der Nachweisgrenze der AAS lagen.Die Komplexierungskapazität des Rheinwassers für Zn, Cd, Pb und Cu wurde durch voltammetrische Titration ermittelt. Sie lag zwischen 5,0 und 0,7 g/l und nahm in der Reihenfolge Cu > Zn > Pb > Cd ab.

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Determination of trace elements in river water by means of voltammetry

Summary The determination of trace elements in river water by voltammetry is disturbed by the presence of organic substances. The influence of these substances can be eliminated by oxidative UV-photolysis.After UV irradiation the following elements were determined in Rhine water by voltammetry: Zn, Cd, Pb, Cu, Ni, Co, Tl and — with reservations — Mn. The concentrations of Bi and Se were below the detection limits. The detection limits in river water for the elements mentioned were determined and found to be between 0.1 and 1 g/l. Comparative determinations by AAS (graphite tube) showed good agreement for Cu, Zn and Mn, whereas the concentrations of the other elements were below the detection limits of AAS.The complexing capacity of Rhine water for Zn, Cd, Pb and Cu was determined by voltammetric titration. It decreased in the order Cu > Zn > Pb > Cd and was between 5.0 and 0.7 g/l.

     

Rapid multi-element analysis of groundwater by high-resolution inductively coupled plasma mass spectrometry

A rapid and sensitive method was developed to determine, with a single dilution, the concentration of 33 major and trace elements (Na, Mg, Si, K, Ca, Li, Al, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, In, Sn, Sb, Cs, Ba, Re, Hg, Pb, Bi, U) in groundwater. The method relies on high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS) and works across nine orders of magnitude of concentrations. For most elements, detection limits for this method are considerably lower than methods based on quadrupole ICP-MS. Precision was within or close to ±3% (1) for all elements analyzed, with the exception of Se (±10%) and Al (±6%). The usefulness of the method is demonstrated with a set of 629 groundwater samples collected from tube wells in Bangladesh (Northeast Araiharzar). The results show that a majority of tube well samples in this area exceed the WHO guideline for As of 10 g L^–1, and that those As-safe wells frequently do not meet the guideline for Mn of 500 µg L^–1 and U of 2 µg L^–1.     

Solid sampling analysis by means of autoprobe-GFAAS

Summary A recently developed solid sampling graphite system for automatic probe atomisation (SAP-GFAAS) was applied for the direct determination of Pb and Cd in untreated bovine liver matrix.The study was based on 30 livers with a low content of lead (0.045 to 0.27 g Pb/g fresh matter) and of cadmium (0.031–0.24 g Cd/g fresh matter). The basic comparative data for the evaluation of the SAP-GFAAS method were supplied by a standardized GFAAS method with preliminary sample homogenization and matrix decomposition. Additionally, data were obtained by two further solid sampling methods: a front entry graphite system with direct Zeeman effect background correction and a side entry graphite system with high-energy deuterium continuum background correction. The combination of the autoprobe technique and solid sampling was shown to provide analytical results — in terms of handling, accuracy and precision — comparable to those obtained by means of the conventional solid sampling systems. Differences between the results of the sample decomposition method and the solid sampling methods, as well as between the three solid sampling methods must be regarded as being of no practical significance. Part I: see [1].     

Atomic absorption determination of traces of elements in ammonium perrhenate of high purity

Summary Methods for the determination of traces of As, Bi, Ca, Cd, Co, Cu, Cr, Fe, In, K, Mg, Mn, Mo, Na, Ni, Pb, Se, Si, Sb, Sn, Te, Tl, V and Zn in ammonium perrhenate of 99.99% –99.999% purity grade are proposed. Na, K, Ca, Mg and Si are determined directly in the aqueous sample solution, while the remaining elements, except Mo, are determined after preliminary extractive separation of their dithiocarbamate complexes at two different pH-values (8-9 and 5–6). Mo is separated from the matrix by extraction with -benzoinoxime. The analaysis is carried out by FAAS or ETAAS, depending on the concentration of the corresponding trace elements. The recovery factor is checked for impurity amounts of 1 g/ml and 0.2 g/ml, respectively.

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AAS-Bestimmung von Elementspuren in hochreinem Ammoniumperrhenat

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Dedicated to Prof. Dr. G. Tölg on the occasion of his 60th birthday     

137Cs,trace and toxic elements distribution in Austrian mushrooms

Various mushroom species have been analyzed for their elemental composition (i.e., Al, B, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn) by means of ICP-AES. The accuracy of the measurements was confirmed by analyzing a series of the same samples by short time activation analysis. The data were evaluated statistically including the values of¹³⁷Cs. The results denote that the distribution of these elements and their correlation of these elements and their correlation coefficients are highly distinctive for each mushroom species. K, Na and P were found to correlate negatively with¹³⁷Cs in most species. Suillus grevillei and Cantharellus cibarius show high Be values (0.27 and 0.30 g g^–1, respectively), while Pb was high in Suillus grevillei (16.3 g g^–1) and Amanita rubescens (9.3 g g^–1). Higher levels of Cd were found in Rozites caperata and Russula vesca with a mean of 9.2 and 16.1 g g^–1, respectively. Cluster analysis was applied to classify these samples according to their botanical species using their elemental composition. The concentrations of Al, Cr, Mn, Na and¹³⁷Cs have no influence on the classification of these samples.     

Quantitative determination of transferrin in cerebrospinal fluid using an enzyme linked immunosorbent assay

An enzyme linked immunosorbent assay (ELISA) based method for the determination of transferrin in cerebrospinal fluid (CSF) is described. This method allows transferrin determinations in ultra-small ( 5 L) sample volumes. The proposed method offers the possibility to determine transferrin at very low concentrations at which existing methodologies fail because of their insufficient detection limits. The accuracy of the proposed technique was validated by comparing the results of 20 CSF samples obtained by ELISA to those measured by nephelometry yielding mean ± SD values of 21.1±5 mg/L and 20.6 ± 6 mg/L, respectively (y = 1.13X – 2.97, r = 0.899). The interassay CV was below 10% whereas the detection limit was 2.9 g/L.     

Lead determinations in human bone by particle induced X-ray emission (PIXE) and graphite furnace atomic absorption spectrometry (GFAAS)

Chronic lead (Pb) intoxication has been linked to Alzheimer's disease (AD). Lead, like many heavy elements, tends to accumulate in bone. PIXE is a powerful analytical tool which permits the determination of Pb at the g/g level without requiring sample digestion. GFAAS is one of the most sensitive methods for the determination of Pb and is capable of determining ng/g levels in solution. For bone analyses by GFAAS, sample dissolution and a matrix modifier are required. Rib bone samples were analyzed for Pb by PIXE and GFAAS. IAEA Animal Bone (H-5) was used as a secondary standard for Pb with both methods to ensure accuracy. The range of Pb concentrations in human rib bone was 1.4–11.5 g/g for the trabecular surface by PIXE, 1.3–45 g/g for the cortical surface by PIXE, and 1.54–11.75 g/g for whole bone by GFAAS. No significant difference (p>0.05) was found for AD versus control for either surface or for whole bone.