Trace Amounts Of Lead Research Articles

Extraction-spectrophotometric determination of lead in heavy metal salts with cryptand (2.2.2) and eosin

A rapid, extraction-spectrophotometric determination of trace amounts of lead in heavy metal salts is proposed. Owing to application of ammonia as masking agent, the extraction system cryptand (2.2.2)-eosin-chlorobenzene exhibits very high selectivity towards transition metal cations. Using standard addition method, lead is determined without matrix separation in nitrates, chlorides, acetates and sulphates of such metals as Ag, Cd, Ni, Cu and Zn. The effect of matrix on lead extraction efficiency and blank value is also discussed. The high sensitivity and selectivity of the proposed method allow to determine of lead at the level 10−3−10−4%.

Application of the radioreagent method for trace determination of lead

A radioreagent method of analysis was developed and applied to the determination of trace quantities of lead in several types of samples. The method is based on the extraction of radioactive cobalt, displaced by lead from the cobalt chelate of ethylenediaminetetraacetate labelled with60Co, into a tetracycline-benzyl alcohol solution. The radioactivity of the released cobalt, extracted into the organic phase, is proportional to the lead concentration. Interference caused by some elements was eliminated by means of a previous separation of lead using dithizone. The method was applied for lead determination in aerosol samples, gasoline and samples from the International Atomic Energy Agency, namely: simulated-air filter (Air-3), fresh water (W-3), dried animal whole blood (A-2) and calcined animal bone (A-3/1). The sensitivity, accuracy and precision of the method were also studied.

Trace Amounts of Lead and Bromine in Soot Studied by X-Ray Photoelectron Spectroscopy

Abstract Forensic science laboratories are sometimes confronted with the question of whether or not a flammable solvent has been used to initiate a fire. One of the most efficient accelerants is gasoline. Some gasoline for use in motor vehicles contains lead and bromine (tetraethyl lead, tetramethyl lead, and ethylene dibromide) as additives amounting to about 0.4 g/litre. The lead alkyls are added to improve the resistance against knocking, whereas ethylene dibromide is used to expel the lead from the cylinder walls.

Trace analysis of lead in oil by TLC

Trace amounts of lead contaminating a specimen of mineral oil were succesfully determined by TLC after concentrating the metal on microcrystalline cellulose, calcining and preparing final samples by take-up of the residues in small volumes of HCl. This method may also be applicable to other oils and to fats. Final determinations are made, after chromatographic separation of lead from other elements, by fluorimetric scanning of the chromatograms. Results are reliable with samples containing between 0.002 and 0.1 ppm of Pb, using a sample size of 25 cm3. With Pb contents below 0.002 ppm, lead contamination of the chemicals used may cause difficulties, and the sample size must be increased. In contrast, when more than 0.1 ppm of Pb is expected, sample sizes should be reduced. Sulphate ions interfere, and should be removed with BaCl2 before chromatography.

Determination of lead and antimony in firearm discharge residues on hands by anodic stripping voltammetry

When a person fires a gun, trace quantities of lead, antimony and barium are deposited on the hand. Detection of high levels of these trace metals on the hand of a suspect may therefore be significant evidence in an investigation. In this study conditions for the determination of lead and antimony in gunshot residues by anodic stripping voltammetry using a mercury-coated graphite electrode are established. A sample is collected by washing the hand in 1 M hydrochloric acid. Lead is determined in a portion of this sample, with 1 M hydrochloric acid as electrolyte. Antimony is determined in a second portion, with 4 M hydrochloric acid as electrolyte. Prior separation or preconcentration steps are not required for either analysis. The procedure has been applied to samples obtained from five “normal” hands and five hands after they have fired a weapon.

Exploration and mapping around a base metal sulphide deposit using trace lead isotopes

Isotopic ratios of trace amounts of lead in pyrite and pyrrhotite have been successfully used to distinguish unmineralized Ordovician from mineralized Silurian black shales around the Woodlawn copper-lead-zinc prospect.

Applicability of proton activation analysis to describe the occurrence of lead along a freeway in a rural area

The applicability of proton activation analysis to the determination of trace amounts of lead in atmospheric particulate matter and the problem of evaluating background levels for measuring the characteristic sources of emissions is discussed.

Concentration of lead in various endodontic filling materials

The percentage of lead in several brands of gutta-percha cones and root canal sealers was determined. The samples were solubilized by a combination of chloroform dissolution and nitric acid oxidation. The solubilized samples were then analyzed, by atomic absorption spectrometry. Only trace amounts of lead were found in the conventional endodontic materials. The gutta-percha cones had lead contents in the ran.ge from 0.0047 % to 0.0052%. The conventional root canal sealers had lead contents in the range from 0.0001% to 0.0004%. The sample of N2 powder had a lead content of 18.3%.

Observations on the tolerance of the isopod Asellus meridianus Rac. to copper and lead

Asellus meridianus Rac. from sites receiving mine-drainage in the rivers Hayle and Gannel in Cornwall have been shown, by toxicity tests and growth rate experiments to be particularly tolerant to copper and lead. Animals from the Hayle, where there are high concentrations of copper in both waters and sediments but only trace amounts of lead, are tolerant to both copper and lead. Animals from the River Gannel where there are moderately high concentrations of copper and exceptionally high concentrations of lead, are markedly tolerant to only lead. Tolerance to lead was shown to persist in animals from the Gannel F 2 generation which had been cultured in the laboratory.

Clay-lead sorption relations

Bays, lagoons, and estuaries are sites where normal physicochemical processes result in accumulations of sediment and certain chemicals. Changes in water velocity and chemistry, and chemical interactions of sediment, biota, and water are factors that contribute to concentrating trace metals in coastal and lake sediments. To evaluate whether lead concentration is affected by mineralogy, kaolinite, illite, montmorillonite, and a zeolitic tuff were suspended in 10 and 20 mg/l concentrations of lead solutions [Pb(NO3)2] which were pH-adjusted incrementally through a range of 2.5 to 11.0. Samples were centrifuged after 24 hours to separate liquid from suspended sediment. Sediment-free solutions were run as controls. Lead concentrations were determined by atomic adsorption spectrophotometry. Results indicate that montmorillonite (Wyoming Bentonite) particles serve as lead adsorption nuclei over a broad pH range. Maximum sorption occurs as the solution reaches a pH of about 7.5. The kaolinite clay from Georgia strongly adsorbs trace amounts of lead at pH ranging from 3.0 to 4.5, where up to 95 percent of the lead is adsorbed by the clay. Little adsorption difference was found between the Fithian illite clay and zeolitic tuff from the Nevada Test Site in comparison to sediment-free solutions which were pH-adjusted. In concentrations of 10 to 20 mg/l montmorillonite and kaolinite clays serve as nucleation sites capable of adsorbing up to 95 percent of trace concentrations of lead within 24 hours. It appears that accumulations of lead in coastal lake and estuarine sediments are significantly influenced by:

The determination of traces of lead(II) by solid-state luminescence

Microgram ammount of lead(II) are selectively determined by solid-state luminescence(λ cx—350nm,λ cm—530nm) of CaO:Pb phosphor after co-precipitation with calcium oxalate and ignition at 850–900°C. Trace quantities of lead have been directly determined in leaves, after dry and wet ashing, and in synthetic blood.

ChemInform Abstract: RECENT DEVELOPMENTS IN THE ANALYSIS OF TOXIC ELEMENTS

AbstractIn einer Übersicht werden neue Metheden zur Spurenbestimmung von toxischen Elementen (Ag, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Hg, CH3‐Hg, Li, Mn, Mo, Ni, Pb, Se, Sn, Sr, Tl, V, Zn, Zr) behandelt.

Recent developments in the analysis of toxic elements.

One may conclude that it is impractical to confine oneself to any one analytical method since ever more sensitive instrumentation continues to be produced. However, in certain methods such as anodic stripping voltammetry and flameless atomic absorption it may be background contamination from reagent impurities and surroundings rather than instrument sensitivity which controls the limits of element detection. The problem of contamination from dust or glassware is greatly magnified when the sample size becomes ever smaller. Air entering laboratories near highways may contain trace quantities of lead, cadmium, barium, antimony, and other elements from engine exhaust. Even plastic materials contacting the sample may be suspect as a source of contamination since specific metals may be used as catalysts in the synthesis of the plastic and traces may be retained in it. Certain elements may even be deliberately added to plastics during manufacture for identification purposes. Nondestructive methods such as neutron activation and x-ray techniques thus offer great advantages not only in time but in the elimination of impurities introduced during sample ashing. Future improvements in attainable limits of detection may arise largely from progress in the ultrapurification of reagents and "clean-room" techniques. Finally, the competence of the analyst is also vitally important in the skillful operation of modern complex analytical instrumentation and in the experienced evaluation of data.

A method for the determination of lead in blood by atomic-absorption spectrophotometry.

A method for the determination of trace amounts of lead in blood is described. The organic material in the blood is oxidised by dry ashing at 500° C and a solution of the ash in dilute hydrochloric acid prepared. The lead in the ash solution is determined by atomic absorption at 217 nm in an air-propane flame after isolation by a double-extraction procedure with dithizone and ammonium tetramethylenedithiocarbamate as complexing agents. Recovery tests are carried out and the lead content of the blood of workers from a lead mine, determined by this method, is compared with results obtained by using the mixed colour method of the Analytical Methods Committee. Comparative tests with wet-oxidation and dry-ashing techniques are made on samples of blood to which known amounts of lead have been added. The interference caused by bismuth is also investigated.