Trace Metals In Biological Samples Research Articles

Comparison of the ICP OES viewing modes efficiency in the estimation of cadmium (Cd) and lead (Pb) in whole blood samples

In forensic toxicology, precise determination of toxic trace metals in biological samples is critical. Inductively coupled plasma optical emission spectrometry (ICP OES), which has a low limit of detection, high sensitivity, accurate testing, and high analytical efficiency, is one of the most widely used techniques for determining the level of toxic trace metals in biological samples. This study aimed to assess the efficiency of ICP-OES in estimating cadmium (Cd) and lead (Pb) in whole blood samples when viewed axially, dual, and radially. All the samples that were analyzed were digested in 1.5 ml HNO3 and 2 ml H2O2. Selectivity, linearity, recovery, limits of detection (LOD), and quantification (LOQ) were used to validate the system. Cd-axial and radial recovery values were between 82–96 and 84–97%, while Pb-axial and radial recovery values were between 85–94 and 83–99%. Dual Cd-axial and radial recovery values were between 80–92 and 82–94%, while dual Pb-axial and radial recovery values were between 77–92 and 75–96%. The results demonstrated that the axillary and radially view is preferable to the dual view when using separate axially and radially view inductively coupled plasmas (ICP). In axillary and radially views, Cd's recovery rates were better than Pb's in the separate mode, but overall they were satisfactory. The recovery values for Cd and Pb in the dual view were acceptable but not sufficient.

Experimental demonstration of novel imaging geometries for x‐ray fluorescence computed tomography

X-ray fluorescence computed tomography (XFCT) is an emerging imaging modality that maps the three-dimensional distribution of elements, generally metals, in ex vivo specimens and potentially in living animals and humans. At present, it is generally performed at synchrotrons, taking advantage of the high flux of monochromatic x rays, but recent work has demonstrated the feasibility of using laboratory-based x-ray tube sources. In this paper, the authors report the development and experimental implementation of two novel imaging geometries for mapping of trace metals in biological samples with ∼50-500 μm spatial resolution. One of the new imaging approaches involves illuminating and scanning a single slice of the object and imaging each slice's x-ray fluorescent emissions using a position-sensitive detector and a pinhole collimator. The other involves illuminating a single line through the object and imaging the emissions using a position-sensitive detector and a slit collimator. They have implemented both of these using synchrotron radiation at the Advanced Photon Source. The authors show that it is possible to achieve 250 eV energy resolution using an electron multiplying CCD operating in a quasiphoton-counting mode. Doing so allowed them to generate elemental images using both of the novel geometries for imaging of phantoms and, for the second geometry, an osmium-stained zebrafish. The authors have demonstrated the feasibility of these two novel approaches to XFCT imaging. While they use synchrotron radiation in this demonstration, the geometries could readily be translated to laboratory systems based on tube sources.

Evaluation of Status of Zinc, Copper, and Iron Levels in Biological Samples of Normal and Arthritis Patients in Age Groups 46 - 60 and 61 - 75 years

A great number of studies have investigated the possible role of trace elements in the etiology and pathogenesis of rheumatoid arthritis (RA). The aim of the study was to evaluate copper (Cu), iron (Fe), and zinc (Zn) levels in three biological samples (scalp hair, blood, and urine) in patients with rheumatoid arthritis (RA) in two groups, age ranges 46 - 60 and 61-75 years, of both genders compared to age-matched healthy individuals. A microwave assisted wet acid digestion procedure was developed as a sample pretreatment for the determination of Cu, Fe, and Zn in biological samples. The digests of all biological samples were analysed for Cu, Fe, and Zn by flame atomic absorption spectrometry (FAAS) using an air/acetylene flame. The proposed method was validated by analyzing certified reference samples of hair, blood, and urine. The results indicated significantly lower levels of Fe, Cu, and Zn in the biological samples (blood and scalp hair) of male and female rheumatoid arthritis patients as compared to control subjects of both genders (p < 0.01). These data present guidance to clinicians and other professional investigating deficiency of essential trace metals in biological samples (scalp hair and blood) of RA patients.

Simultaneous X-ray fluorescence and ptychographic microscopy of Cyclotella meneghiniana

Scanning X-ray fluorescence microscopy (XFM) is a particularly useful method for studying the spatial distribution of trace metals in biological samples. Here we demonstrate the utility of combining coherent diffractive imaging (CDI) with XFM for imaging biological samples to simultaneously produce high-resolution and high-contrast transmission images and quantitative elemental maps. The reconstructed transmission function yields morphological details which contextualise the elemental maps. We report enhancement of the spatial resolution in both the transmission and fluorescence images beyond that of the X-ray optics. The freshwater diatom Cyclotella meneghiniana was imaged to demonstrate the benefits of combining these techniques that have complementary contrast mechanisms.

Quantitative comparison of preparation methodologies for x-ray fluorescence microscopy of brain tissue

X-ray fluorescence microscopy (XFM) facilitates high-sensitivity quantitative imaging of trace metals at high spatial resolution over large sample areas and can be applied to a diverse range of biological samples. Accurate determination of elemental content from recorded spectra requires proper calibration of the XFM instrument under the relevant operating conditions. Here, we describe the manufacture, characterization, and utilization of multi-element thin-film reference foils for use in calibration of XFM measurements of biological and other specimens. We have used these internal standards to assess the two-dimensional distribution of trace metals in a thin tissue section of a rat hippocampus. The data used in this study was acquired at the XFM beamline of the Australian Synchrotron using a new 384-element array detector (Maia) and at beamline 2-ID-E at the Advanced Photon Source. Post-processing of samples by different fixation techniques was investigated, with the conclusion that differences in solvent type and sample handling can significantly alter elemental content. The present study highlights the quantitative capability, high statistical power, and versatility of the XFM technique for mapping trace metals in biological samples, e.g., brain tissue samples in order to help understand neurological processes, especially when implemented in conjunction with a high-performance detector such as Maia.

Synchrotron radiation X-ray fluorescence microscopy reveals a spatial association of copper on elastic laminae in rat aortic media

Copper, an essential trace metal in humans, plays an important role in elastic formation. However, little is known about the spatial association between copper, elastin, and elastin producing cells. The aorta is the largest artery; the aortic media is primarily composed of the elastic lamellae and vascular smooth muscle cells, which makes it a good model to address this issue. Synchrotron radiation X-ray fluorescence microscopy (SRXRF) is a new generation technique to investigate the spatial topography of trace metals in biological samples. Recently, we utilized this technique to determine the topography of copper as well as other trace elements in aortic media of Sprague Dawley rats. A standard rat diet was used to feed Sprague Dawley rats, which contains the normal dietary requirements of copper and zinc. Paraffin embedded segments (4 μm of thickness) of thoracic aorta were analyzed using a 10 keV incident monochromatic X-ray beam focusing on a spot size of 0.3 μm × 0.2 μm (horizontal × vertical). The X-ray spectrum was measured using an energy-dispersive silicon drift detector for elemental topography. Our results showed that phosphorus, sulfur, and zinc are predominately distributed in the vascular smooth muscle cells, whereas copper is dramatically accumulated in elastic laminae, indicating a preferential spatial association of copper on elastic laminae in aortic media. This finding sheds new light on the role of copper in elastic formation. Our studies also demonstrate that SRXRF allows for the visualization of trace elements in tissues and cells of rodent aorta with high spatial resolution and provides an opportunity to study the role of trace elements in vasculature.

Evaluation of Status of Cadmium, Lead, and Nickel Levels in Biological Samples of Normal and Night Blindness Children of Age Groups 3–7 and 8–12 Years

The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood trace metals toxicity, which is the most common problem found in underdeveloped countries. This study was designed to compare the levels of cadmium (Cd), lead (Pb), and nickel (Ni) in scalp hair, blood, and urine of night blindness children age ranged 3-7 and 8-12years of both genders, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of Cd, Pb, and Ni in biological samples of night blindness children. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The digests of all biological samples were analyzed for Cd, Pb, and Ni by electrothermal atomic absorption spectrometry. The results indicated significantly higher levels of Cd, Pb, and Ni in the biological samples (blood, scalp hair, and urine) of male and female night blindness children, compared with control subjects of both genders. These data present guidance to clinicians and other professional investigating toxicity of trace metals in biological samples of night blindness children.

Evaluation of Status of Zinc, Copper, and Iron Levels in Biological Samples of Normal Children and Children with Night Blindness with Age Groups of 3–7 and 8–12 Years

The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence hair composition. This study was designed to compare the levels of zinc (Zn), copper (Cu), and iron (Fe) in scalp hair, blood, and urine of both genders of children with night blindness with age range of 3-7 and 8-12 years, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of zinc, copper, and iron in biological samples of children with night blindness. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The digests of all biological samples were analyzed for Cu, Fe, and Zn by flame atomic absorption spectrometry using an air/acetylene flame. The results indicated significantly lower levels of Fe, Cu, and Zn in the biological samples (blood and scalp hair) of male and female children with night blindness, compared with control subjects of both genders. These data present guidance to clinicians and other professionals investigating the deficiency of essential trace metals in biological samples (scalp hair and blood) of children with night blindness.

Status of essential trace metals in biological samples of diabetic mother and their neonates

There is accumulating facts that the metabolism of essential trace elements is altered in diabetic patients. The aim of present study was to compare the status of essential trace elements, chromium (Cr), manganese (Mn), and zinc (Zn) in biological samples (whole blood, urine and scalp hair) of insulin dependent diabetic mothers (age ranged 30-40) and their newly born infants (n = 76). An age matched 68 non-diabetic mothers and their infants, residing in the same locality, were selected as referents. For a comparative study, the biological samples of non-diabetic and diabetic pregnant and non pregnant of same age group and socio-economics status were also analysed. The biological samples (scalp hair, blood and urine) were collected from study and referent groups. The Cr, Mn and Zn concentrations in all three biological samples were determined by a flame/electrothermal atomic absorption spectrometer, prior to microwave assisted acid digestion. The validity and accuracy of the methodology was checked by certified reference materials (CRMs) and using conventional wet acid digestion method on same CRMs. The mean values of Cr, Mn and Zn in scalp hair and blood samples of diabetic mothers and their infants were significantly lower as compared to the referent mothers-infants pairs (p < 0.01), while urinary excretion of all these elements were high in diabetic mother-infant pair samples. The deficiencies of essential trace elements, Cr, Mn and Zn in biological samples of diabetic women, may play role in the pathogenesis of diabetes mellitus and impacts on their neonates.

Synthesis and application of XAD-2/Me-BTAP resin for on-line solid phase extraction and determination of trace metals in biological samples by FAAS

Synthesis and application of XAD-2/Me-BTAP resin for on-line solid phase extraction and determination of trace metals in biological samples by FAAS

Synthesis and application of XAD-2/Me-BTAP resin for on-line solid phase extraction and determination of trace metals in biological samples by FAAS

A new XAD-2/Me-BTAP resin has been developed and applied in an on-line system for the preconcentration followed by metal determination by FAAS. The reagent used in the resin synthesis was 2-[2'-(6-methyl-benzothiazolylazo)]-4-aminophenol (Me-BTAP), a compound produced by first time for the application described in this work. The reagent and resin were characterized and the sorbent was used as packing for the minicolumn in an on-line system preconcentration system for cobalt, copper and nickel determination. The enrichment factors calculated were 19 (Co), 12 (Cu) and 12 (Ni), for 60 s preconcentration time, and 30 (Co), 30 (Cu) and 24 (Ni), if used 180 s preconcentration time. The proposed procedure allowed the determination of cobalt, copper and nickel with limits of detection 0.34, 0.87 and 0.81 µg L-1, respectively, when used preconcentration periods of 180 s. The accuracy of the developed procedure was evaluated by the analysis of certified reference materials. The method was applied to the analysis of food samples (black tea and rice flour).

On-Line Separation and Preconcentration of Trace Metals in Biological Samples Using a Microcolumn Loaded with PAN-Modified Nanometer-Sized Titanium Dioxide, and Their Determination by ICP-AES

A flow injection analysis system incorporating a microcolumn of nanometer-sized TiO2 loaded with 1-(2-pyridylazo)-2-naphthol (PAN) has been used for the development of an on-line multi-element method for simultaneous separation and preconcentration and subsequent determination of Cu2+, Co2+, Cr3+, Y3+, Yb3+ and Bi3+ by ICP-AES. Effects of pH, sample flow rate and volume, elution conditions, adsorption capacity and interfering ions on analyte recovery were examined. The adsorption capacity of nanometer-sized TiO2 loaded with PAN was 4.73, 18.57, 3.81, 6.14, 4.52 and 20.35 mg g−1 for Cu2+, Cr3+, Y3+, Yb3+, Co2+ and Bi3+, respectively. The method has been applied to the analysis of trace elements in standard reference biological samples, and the results are in good agreement with the certified values.

Dithione as chelator in the flow injection separation and pre-concentration system of trace metals in biological samples

Dithione was used as chelator in the flow injection-knotted reactor separation and pre-concentration system coupled to flame atomic absorption spectrometry to determine trace amounts of Cu, Cd, Zn, Co in biological standard samples. Peak height was used for quantitative purpose. Alkali and alkaline earth elements, which could not chelate with dithione were separated from the objective metals; competition between trace metals were avoided for the strong chelating ability of dithione. Compared to diethyldithiocarbamate and pyrrolidine dithiocarbamate (APDC), dithione was used for multi-element detection with lower chelator concentration and better analytical performance. Concentration factors of 23.4–69.3 were obtained using dithione, with the detection limits of 1.06–2.56 μg/l. The system developed was used to determine trace metals in certified biological reference materials of human hair, pig liver and sea prawn after routine digestion, the results obtained agreed well with the certified values, relative standard deviations of the determinations were at the range of 2.10–3.02%.

Automated on-line sample pretreatment system for the determination of trace metals in biological samples by inductively coupled plasma mass spectrometry.

A fully automated on-line sample pretreatment system combining microwave digestion with sample preconcentration/matrix separation for the determination of trace metals (Fe, Ni, Cu, Zn, and Pb) in blood and serum samples by inductively coupled plasma mass spectrometry (ICPMS) was designed and evaluated. The samples were mixed with an appropriate reagent and digested in a flow-through, focused microwave-heated oven. After digestion, the sample solution was transferred on-line to a column packed with iminodiacetate-based resin for separation of matrix elements like Na, K, Ca, Mg, Cl, P, and S that might interfere with the measurement by ICPMS. The analytes chelated on the resin were subsequently eluted and led to ICPMS for multielement determination. The whole sample pretreatment process was automatically controlled by a self-designed expert system. The analytical reliability of data from this on-line system was confirmed to be good with the analysis of SRM samples (Seronorm Whole Blood and NIST SRM 1598 Bovine Serum), and the limits of detection (3 sigma) for Fe, Ni, Cu, Zn, and Pb were 68, 0.34, 3.5, 13.4, and 0.22 microgram/L, respectively. With this fully automated on-line system, the determination of analytes in biological fluid samples down to micrograms-per-liter levels has been proven to be feasible, and the sample throughput can achieve up to 6 samples/h.

In-Furnace Standard Addition Method for the Determination of Trace Metals in Biological Samples by Electrothermal Vaporization-Inductively Coupled Plasma Atomic Emission Spectrometry

Electrothermal vaporization-inductively coupled plasma atomic emission spectrometry was applied to the determination of trace metals in some biological samples on in-furnace standard addition method. Powdered samples were decomposed using a sealed PTFE vessel and a microwave oven; the sample solution served for measurements without any additional treatment. The sample solution was injected into a graphite furnace and a standard solution containing ammonium dihydrogenphosphate, as a matrix modifier, was added; the two solutions were mixed in the furnace. The present method was applied to the determination of trace metals in some reference materials; the analytical results agreed well with the certified values.

Determination of Trace Metals in Biological Samples by Inductively Coupled Plasma Atomic Emission Spectrometry with Discrete Nebulization after Microwave Decomposition

Trace metals in some biological samples were measured by the discrete nebulization technique in inductively coupled plasma atomic emission spectrometry. The small spray chamber and the time-sharing background correction system were used for the rapid measurements. Small amounts of the samples were decomposed quickly in a sealed PTFE vessel in a microwave oven. The analytical results for Al, Cu, Fe, Mn and Zn agreed well with the certified values and also with those obtained by continuous nebulization.

Trace analysis of lead in blood, aluminium and manganese in serum and chromium in urine by graphite furnace atomic absorption spectrometry

A graphite furnace atomizer with automatic sampler is used to measure low levels of trace metals in biological samples by atomic absorption spectrometry. With blood and serum, the sample treatment consists of diluting (1:1) with aqueous Triton X-100 solution, centrifuging in the case of blood, and dispensing the liquid directly into a pyrolytic coated graphite tube. Sample volumes for blood and serum range from 5 to 10 microL. Stabilized urine (25 microL) is analyzed directly. The possibility of contamination is minimized by this simple procedure. The methods described minimize sample handling and involve reagents which are virtually free of contamination of the analytes. Background correction is necessary except for the determination of aluminium in serum, and precisions range from 0.7% to 4.3% RSD. The standard additions technique is used to establish the calibration and the required volume of sample and aqueous addition is automatically dispensed directly into the graphite tube.