Comparison of the High Cycle Fatigue Behavior of the Orthodontic NiTi Wires: An in Vitro Study

Abstract Objective: To compare the high-cycle fatigue behavior of four commercially available NiTi orthodontic wires. Material and Methods: Twelve NiTi orthodontic wires, round, 0.016-in, three per brand, were selected and divided into four groups: G1 - Heat-activated NiTi, G2 - Superelastic NiTi, G3 - Therma-Ti, and G4 - CopperNiTi. The atomic absorption spectrometry method was used to determine the chemical composition of investigated NiTi wires. We also performed a fatigue test at three-point bending using a universal testing machine for 1000 cycles in a 35 °C water bath. For the first and thousandth cycle, the average plateau load and the plateau length were determined in the unloading area of the force versus displacement diagram. In addition, we calculated the difference between the average plateau load of the first and thousandth cycle (∆F), as well as the difference between the plateau length of both cases (∆L). Results: According to our results, there were no significant differences between the average plateau load of the first and thousandth cycles of each group (p>0.05) and in the plateau length of the first and thousandth cycles of the groups (p>0.05). Conclusion: There were no significant differences between the groups changing the superelasticity property after high-cycle fatigue.

Rapid determination of cadmium in rice by portable dielectric barrier discharge-atomic emission spectrometer.

In this work, a home-made portable dielectric barrier discharge-atomic emission spectrometer (DBD-AES) was explored to the determination of heavy metal in foodstuffs. A rapid and simple method was developed for Cd determination in rice based on this instrument. Rice was pretreated with diluted acid dissolution without complex operations and apparatus. The detection time by DBD-AES is about 3 min and the total analysis time for rice sample is within 11 min. The effects of some key experiment parameters were investigated. The limit of detection was 11.9 µg kg-1 for Cd in rice, much lower than the maximum allowable level established by EC (200 µg kg-1). The practical performance of this method was demonstrated by analyzing real and CRM rice samples. With the portability of DBD-AES, the method is suitable for rapid and in-field analysis of Cd in rice. It will be a useful tool for the routine analysis of rice.

A novel gas liquid separator for direct sampling analysis of ultratrace arsenic in blood sample by hydride generation in-situ dielectric barrier discharge atomic fluorescence spectrometry.

A novel direct sampling (DS-HG) system consisting of an enlarged gas liquid separator (GLS) coupled with a foam breaker was firstly utilized for the in-situ dielectric barrier discharge atomic fluorescence spectrometer (DBD-AFS). After direct dilution using 5% HCl (v:v), a prepared blood sample was introduced into the DS-HG with a UV digestion unit, of which arsenic hydrides directly generated from sample under 5% HCl (v:v) and 5 g/L KBH4 in 1.5 g/L KOH. Herein, the newly designed DS-HG is capable of effectively eliminating foam generation deriving from protein in blood sample. Then, arsenic hydrides were trapped by 11 kV discharging at 110 mL/min air, and released by 13 kV at 180 mL/min H2 orderly. Under the optimized conditions, the linearity ranged from 0.05 to 50 ng/mL with a regression coefficient (R2) = 0.996. The method detection limit (LOD) was 7 pg arsenic (0.14 ng/mL), and relative standard deviation (RSD) of 10 repeated measurements for a real blood sample was 4.2%, indicating a good precision. The spiked recoveries for real samples were in the range of 97%-102%. Furthermore, arsenic presence in real blood samples measured by the proposed method were consistent (P > 0.05) with the microwave digestion ICP-MS. The whole analytical time can be controlled within 8 min including sample dilution. As a matter of fact, it is a favorable progress for DBD technique to eliminate matrix interferences of real samples based on the gas phase enrichment (GPE) principle, with advantages such as excellent sensitivity, digestion-free, fast and simple operation. Thus, the recommended DS-HG-in-situ DBD-AFS are suitable to the fast analysis of ultratrace arsenic in blood samples to protect human's health.

[Black precipitate in parenteral nutrition]. / Precipitado negro en nutrición parenteral.

INTRODUCTION: Introduction: a black precipitate was observed in the filter during the infusion of a parenteral nutrition without lipids. There are similar findings published in which copper and sulphur (from cysteine) were found in the composition of the precipitate. Objective: to determine if copper and cysteine are involved in the formation of the precipitate. Methods: samples of the parenteral nutrition solution were taken before and after its passage through the filter. Amino acids concentrations were analysed in both samples by ion exchange chromatography and post-column derivatization with ninhydrin in a Biochrom 30 device. Copper concentrations were measured by atomic absorption spectrometry in a PerkinElmer AAnalyst™ 200 device. Results: a decrease in cysteine concentration of 29.3% was found. The concentration of copper decreased by 75.9%. Conclusions: the decrease in the concentrations of cysteine and copper in the filtered solution suggest that both are involved in the formation of the black precipitate observed in the filter.

INTRODUCCIÓN: Introducción: durante la infusión de una nutrición parenteral sin lípidos se observó un precipitado negro en el filtro. Hay hallazgos similares publicados en los que se han detectado cobre y azufre (proveniente de la cisteína) en la composición del precipitado. Objetivo: comprobar que la cisteína y el cobre intervienen en la formación del precipitado. Métodos: se tomaron muestras de la solución de nutrición parenteral antes y después de su paso por el filtro. Se analizaron en ambas muestras las concentraciones de aminoácidos mediante cromatografía de intercambio iónico y derivatización post-columna con ninhidrina en un equipo Biochrom 30 y las de cobre mediante espectrometría de absorción atómica en un equipo PerkinElmer AAnalyst™ 200. Resultados: las concentraciones de cisteína y cobre en la solución disminuyeron en un 29,3% y 75,9%, respectivamente. Conclusiones: la disminución de las concentraciones de cisteína y cobre en la solución filtrada sugieren que ambos están involucrados en la formación del precipitado negro observado en el filtro.

Methylmercury determination in seafood by photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry.

A non-chromatographic method based on double liquid-liquid extraction and measurements by UV photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry was developed and characterized for methylmercury determination in seafood. Samples were prepared following the procedure recommended in JRC Technical Report of European Commission formerly proposed for the determination of methylmercury in seafood by thermal decomposition atomic absorption spectrometry, namely confinement of Hg species in 47% HBr solution, extraction of CH3Hg+ in toluene and back-extraction in 1% l-cysteine aqueous solution. Mercury cold vapor was generated by flow injection UV photo-reduction from CH3Hg+ in 0.6molL-1 HCOOH, while quantification was performed against external Hg2+ aqueous standards and measuring Hg 253.652nm emission using a low power/Ar consumption plasma microtorch (15W, 100mLmin-1) and a low resolution microspectrometer (Ocean Optics). The figures of merit and analytical capability were assessed by analyzing certified reference materials and test samples of fish fillet and discussed in relation with requirements for Hg determination in seafood in European legislation (Decisions 2007/333/EC and 2002/657/EC) as well as compared to performances achieved in thermal decomposition atomic absorption spectrometry. The limit of detection and quantification of 2µgkg-1 and 6µgkg-1 respectively, precision of 2.7-9.4% and accuracy of 99±8% of the proposed method for the determination of CH3Hg+ fulfill the demands of European legislation for Hg quantification. The limit of detection and quantification were better than those in the used reference method or other non-/chromatographic methods taken for comparison. The analysis of certified reference materials and the Bland and Altman test performed on 12 test samples confirmed trueness of the proposed method and its reliability for the determination of traces of CH3Hg+ with 95% confidence level. The proposed method fulfills several demands of the eco-scale concept, is sensitive, simple and safe related to sample preparation through elimination of classical, harmful reductants and attractive by using economical miniaturized instrumentation incorporating a low power and low Ar consumption plasma.

Inductively Coupled Plasma Mass Spectrometry (ICP-MS) Applications in Quantitative Proteomics.

Recent advances in inductively coupled plasma mass spectrometry (ICP-MS) hyphenated to different separation techniques have promoted it as a valuable tool in protein/peptide quantification. These emerging ICP-MS applications allow absolute quantification by measuring specific elemental responses. One approach quantifies elements already present in the structure of the target peptide (e.g. phosphorus and sulphur) as natural tags. Quantification of these natural tags allows the elucidation of the degree of protein phosphorylation in addition to absolute protein quantification. A separate approach is based on utilising bi-functional labelling substances (those containing ICP-MS detectable elements), that form a covalent chemical bond with the protein thus creating analogs which are detectable by ICP-MS. Based on the previously established stoichiometries of the labelling reagents, quantification can be achieved. This technique is very useful for the design of precise multiplexed quantitation schemes to address the challenges of biomarker screening and discovery. This review discusses the capabilities and different strategies to implement ICP-MS in the field of quantitative proteomics.

Nonthermal Optical Emission Spectrometry: Direct Atomization and Excitation of Cadmium for Highly Sensitive Determination.

The low atomization and excitation capability of nonthermal microplasma, e.g., dielectric barrier discharge (DBD), has greatly hampered its potential applications for the determination of metals in solution. In the present work, an inspiring development is reported for direct atomization and excitation of cadmium in aqueous solution by DBD and facilitates highly sensitive determination. A DBD microplasma is generated on the nozzle of a pneumatic micronebulizer to focus the DBD energy on a confined space and atomize/excite metals in the spray. Meanwhile, an appropriate sample matrix and nebulization in helium further improves the atomization and excitation capability of DBD. With cadmium as a model, its emission is recorded by a CCD spectrometer at 228.8 nm. By using an 80 µL sample solution nebulized at 3 µL s(-1), a linear range of 5-1000 µg L(-1) along with a detection limit of 1.5 µg L(-1) is achieved, which is comparable to those obtained by commercial bulky inductively coupled plasma (ICP)-based instrumentations.

Lead screening in DBS by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry: application to newborns and pregnant women.

BACKGROUND: DBS have become a clinical specimen especially adequate for establishing home-based collection protocols. In this work, high-resolution continuum source graphite furnace atomic absorption spectrometry is evaluated for the direct monitoring of Pb in DBS, both as a quantitative tool and a screening method. METHODOLOGY: The development of the screening model is based on the establishment of the unreliability region around the threshold limits, 100 or 50 µg l(-1). More than 500 samples were analyzed to validate the model. CONCLUSION: The screening method demonstrated high sensitivity (the rate of true positives detected was always higher than 95%), an excellent LOD (1 µg l(-1)) and high throughput (10 min per sample).

Use of radiation sources with mercury isotopes for real-time highly sensitive and selective benzene determination in air and natural gas by differential absorption spectrometry with the direct Zeeman effect.

A new analytical portable system is proposed for the direct determination of benzene vapor in the ambient air and natural gas, using differential absorption spectrometry with the direct Zeeman effect and innovative radiation sources: capillary mercury lamps with different isotopic compositions ((196)Hg, (198)Hg, (202)Hg, (204)Hg, and natural isotopic mixture). Resonance emission of mercury at a wavelength of 254 nm is used as probing radiation. The differential cross section of benzene absorption in dependence on wavelength is determined by scanning of magnetic field. It is found that the sensitivity of benzene detection is enhanced three times using lamp with the mercury isotope (204)Hg in comparison with lamp, filled with the natural isotopic mixture. It is experimentally demonstrated that, when benzene content is measured at the Occupational Exposure Limit (3.2 mg/m(3) for benzene) level, the interference from SO2, NO2, O3, H2S and toluene can be neglected if concentration of these gases does not exceed corresponding Occupational Exposure Limits. To exclude the mercury effect, filters that absorb mercury and let benzene pass in the gas duct are proposed. Basing on the results of our study, a portable spectrometer is designed with a multipath cell of 960 cm total path length and detection limit 0.5 mg/m(3) at 1 s averaging and 0.1 mg/m(3) at 30 s averaging. The applications of the designed spectrometer to measuring the benzene concentration in the atmospheric air from a moving vehicle and in natural gas are exemplified.

Application of laser microdissection ICP-MS for high resolution elemental mapping in mouse brain tissue: a comparative study with laser ablation ICP-MS.

Mapping of elements in biological tissue by laser induced mass spectrometry is a fast growing analytical methodology in life sciences. This method provides a multitude of useful information of metal, nonmetal, metalloid and isotopic distribution at major, minor and trace concentration ranges, usually with a lateral resolution of 12-160 µm. Selected applications in medical research require an improved lateral resolution of laser induced mass spectrometric technique at the low micrometre scale and below. The present work demonstrates the applicability of a recently developed analytical methodology - laser microdissection associated to inductively coupled plasma mass spectrometry (LMD ICP-MS) - to obtain elemental images of different solid biological samples at high lateral resolution. LMD ICP-MS images of mouse brain tissue samples stained with uranium and native are shown, and a direct comparison of LMD and laser ablation (LA) ICP-MS imaging methodologies, in terms of elemental quantification, is performed.

Validation of an optimized method for the determination of iodine in human breast milk by inductively coupled plasma mass spectrometry (ICPMS) after tetramethylammonium hydroxide extraction.

In this study a novel method to determine iodine concentrations in human breast milk was developed and validated. The iodine was analyzed by inductively coupled plasma mass spectrometry (ICPMS) following tetramethylammonium hydroxide (TMAH) extraction at 90°C in disposable polypropylene tubes. While similar approaches have been used previously, this method adopted a shorter extraction time (1h vs. 3h) and used antimony (Sb) as the internal standard, which exhibited greater stability in breast milk and milk powder matrices compared to tellurium (Te). Method validation included: defining iodine linearity up to 200µgL(-1); confirming recovery of iodine from NIST 1549 milk powder. A recovery of 94-98% was also achieved for the NIST 1549 milk powder and human breast milk samples spiked with sodium iodide and thyroxine (T4) solutions. The method quantitation limit (MQL) for human breast milk was 1.6µgL(-1). The intra-assay and inter-assay coefficient of variation for the breast milk samples and NIST powder were <1% and <3.5%, respectively. NIST 1549 milk powder, human breast milk samples and calibration standards spiked with the internal standard were all stable for at least 2.5 months after extraction. The results of the validation process confirmed that this newly developed method provides greater accuracy and precision in the assessment of iodine concentrations in human breast milk than previous methods and therefore offers a more reliable approach for assessing iodine concentrations in human breast milk.

Determination of Hg(2+) by on-line separation and pre-concentration with atmospheric-pressure solution-cathode glow discharge atomic emission spectrometry.

A simple and sensitive method to determine Hg(2+) was developed by combining solution-cathode glow discharge atomic emission spectrometry (SCGD-AES) with flow injection (FI) based on on-line solid-phase extraction (SPE). We synthesized l-cysteine-modified mesoporous silica and packed it in an SPE microcolumn, which was experimentally determined to possess a good mercury adsorption capacity. An enrichment factor of 42 was achieved under optimized Hg(2+) elution conditions, namely, an FI flow rate of 2.0 mL min(-1) and an eluent comprised of 10% thiourea in 0.2 mol L(-1) HNO3. The detection limit of FI-SCGD-AES was determined to be 0.75 µg L(-1), and the precision of the 11 replicate Hg(2+) measurements was 0.86% at a concentration of 100 µg L(-1). The proposed method was validated by determining Hg(2+) in certified reference materials such as human hair (GBW09101b) and stream sediment (GBW07310).

Toxic metal concentrations in mainstream smoke from cigarettes available in the USA.

Public health officials and leaders of 168 nations have signaled their concern regarding the health and economic impacts of smoking by becoming signatory parties to the World Health Organization Framework Convention on Tobacco Control (FCTC). One of FCTC's purposes is to help achieve meaningful regulation for tobacco products in order to decrease the exposure to harmful and potentially harmful constituents (HPHCs) delivered to users and those who are exposed to secondhand smoke. Determining baseline delivery ranges for HPHCs in modern commercial tobacco products is crucial information regulators could use to make informed decisions. Establishing mainstream smoke delivery concentration ranges for toxic metals was conducted through analyses of total particulate matter (TPM) collected with smoking machines using standard smoking regimens. We developed a rapid analytical method with microwave digestion of TPM samples obtained with smoking machines using electrostatic precipitation under the ISO and Intense smoking regimens. Digested samples are analyzed for chromium, manganese, cobalt, nickel, arsenic, cadmium and lead using inductively coupled plasma-mass spectrometry. This method provides data obtained using the ISO smoking regimen for comparability with previous studies as well as an Intense smoking regimen that represents deliveries that fall within the range of human exposure levels to toxic metals.

The aluminium content of breast tissue taken from women with breast cancer.

The aetiology of breast cancer is multifactorial. While there are known genetic predispositions to the disease it is probable that environmental factors are also involved. Recent research has demonstrated a regionally specific distribution of aluminium in breast tissue mastectomies while other work has suggested mechanisms whereby breast tissue aluminium might contribute towards the aetiology of breast cancer. We have looked to develop microwave digestion combined with a new form of graphite furnace atomic absorption spectrometry as a precise, accurate and reproducible method for the measurement of aluminium in breast tissue biopsies. We have used this method to test the thesis that there is a regional distribution of aluminium across the breast in women with breast cancer. Microwave digestion of whole breast tissue samples resulted in clear homogenous digests perfectly suitable for the determination of aluminium by graphite furnace atomic absorption spectrometry. The instrument detection limit for the method was 0.48 µg/L. Method blanks were used to estimate background levels of contamination of 14.80 µg/L. The mean concentration of aluminium across all tissues was 0.39 µg Al/g tissue dry wt. There were no statistically significant regionally specific differences in the content of aluminium. We have developed a robust method for the precise and accurate measurement of aluminium in human breast tissue. There are very few such data currently available in the scientific literature and they will add substantially to our understanding of any putative role of aluminium in breast cancer. While we did not observe any statistically significant differences in aluminium content across the breast it has to be emphasised that herein we measured whole breast tissue and not defatted tissue where such a distribution was previously noted. We are very confident that the method developed herein could now be used to provide accurate and reproducible data on the aluminium content in defatted tissue and oil from such tissues and thereby contribute towards our knowledge on aluminium and any role in breast cancer.

Arsenic and antimony determination in non- and biodegradable materials by hydride generation capacitively coupled plasma microtorch optical emission spectrometry.

A sensitive method using a miniature analytical system with a capacitively coupled plasma microtorch (25 W, 13.56 MHz, 0.4 l min(-1) Ar) was developed and evaluated for the determination of As and Sb in recyclable plastics and biodegradable materials by hydride generation optical emission spectrometry. Given their toxicity, As and Sb should be subject to monitoring in such materials despite not being included within the scope of Restriction of Hazardous Substances Directive. The advantages of the proposed approach are better detection limits and lower analysis cost relative to conventional systems based on inductively coupled plasma optical emission and flame atomic absorption spectrometry with/without derivatization. Samples were subjected to acidic microwave-assisted digestion in a nitric-sulfuric acid mixture. Chemical hydride generation with 0.5% NaBH4 after the prereduction of As(V) and Sb(V) with 0.3% L-cysteine in 0.01 mol l(-1) HCl (10 min contact time at 90±5°C) was used. Under the optimal hydride generation conditions and analytical system operation the detection limits (mg kg(-1)) were 0.5 (As) and 0.1 (Sb), whereas the precision was 0.4-7.1% for 10.2-46.2 mg kg(-1) As and 0.4-3.2% for 7.1-156 mg kg(-1) Sb. Analysis of two polyethylene CRMs revealed recoveries of 101±2% As and 100±1% Sb.

Determination of cadmium and zinc in vegetables with online FAAS after simultaneous pre-concentration with 1,5-diphenylthiocarbazone immobilised on naphthalene.

The concentration of cadmium and zinc in vegetables was determined by using an online flame atomic absorption spectrophotometer after simultaneous pre-concentration based on the complexation of Cd and Zn with 1,5-diphenylthiocarbazone immobilised on naphthalene. The effect of pH, sample flow rate and amount of 1,5-diphenylthiocarbazone on adsorption was investigated. After pre-concentration, Cd and Zn were eluted from the sorbent with hydrochloric acid. A pre-concentration factor of 20 and 33 was achieved for Cd and Zn, respectively. The calibration curve was linear in the range of 0.2-1 µg ml(-1) for Cd and Zn. The regression coefficients for the lines were 0.9914 and 0.9989 for Cd and Zn, respectively. The detection limits were calculated as three times the standard deviation of nine replicates of blanks: 0.00123 µg ml(-1) for Cd and 0.00176 µg ml(-1) for Zn.

Novel multicompartment 3-dimensional radiochromic radiation dosimeters for nanoparticle-enhanced radiation therapy dosimetry.

PURPOSE: Gold nanoparticles (AuNps), because of their high atomic number (Z), have been demonstrated to absorb low-energy X-rays preferentially, compared with tissue, and may be used to achieve localized radiation dose enhancement in tumors. The purpose of this study is to introduce the first example of a novel multicompartment radiochromic radiation dosimeter and to demonstrate its applicability for 3-dimensional (3D) dosimetry of nanoparticle-enhanced radiation therapy. METHODS AND MATERIALS: A novel multicompartment phantom radiochromic dosimeter was developed. It was designed and formulated to mimic a tumor loaded with AuNps (50 nm in diameter) at a concentration of 0.5 mM, surrounded by normal tissues. The novel dosimeter is referred to as the Sensitivity Modulated Advanced Radiation Therapy (SMART) dosimeter. The dosimeters were irradiated with 100-kV and 6-MV X-ray energies. Dose enhancement produced from the interaction of X-rays with AuNps was calculated using spectrophotometric and cone-beam optical computed tomography scanning by quantitatively comparing the change in optical density and 3D datasets of the dosimetric measurements between the tissue-equivalent (TE) and TE/AuNps compartments. The interbatch and intrabatch variability and the postresponse stability of the dosimeters with AuNps were also assessed. RESULTS: Radiation dose enhancement factors of 1.77 and 1.11 were obtained using 100-kV and 6-MV X-ray energies, respectively. The results of this study are in good agreement with previous observations; however, for the first time we provide direct experimental confirmation and 3D visualization of the radiosensitization effect of AuNps. The dosimeters with AuNps showed small (<3.5%) interbatch variability and negligible (<0.5%) intrabatch variability. CONCLUSIONS: The SMART dosimeter yields experimental insights concerning the spatial distributions and elevated dose in nanoparticle-enhanced radiation therapy, which cannot be performed using any of the current methods. The authors concluded that it can be used as a novel independent method for nanoparticle-enhanced radiation therapy dosimetry.

Aluminium, iron and copper in human brain tissues donated to the Medical Research Council's Cognitive Function and Ageing Study.

Aluminium, iron and copper are all implicated in the aetiology of neurodegenerative diseases including Alzheimer's disease. However, there are very few large cohort studies of the content of these metals in aged human brains. We have used microwave digestion and TH GFAAS to measure aluminium, iron and copper in the temporal, frontal, occipital and parietal lobes of 60 brains donated to the Cognitive Function and Ageing Study. Every precaution was taken to reduce contamination of samples and acid digests to a minimum. Actual contamination was estimated by preparing a large number of (170+) method blanks which were interspersed within the full set of 700+ tissue digests. Subtraction of method blank values (MBV) from tissue digest values resulted in metal contents in all tissues in the range, MBV to 33 µg g(-1) dry wt. for aluminium, 112 to 8305 µg g(-1) dry wt. for iron and MBV to 384 µg g(-1) dry wt. for copper. While the median aluminium content for all tissues was 1.02 µg g(-1) dry wt. it was informative that 41 brains out of 60 included at least one tissue with an aluminium content which could be considered as potentially pathological (> 3.50 µg g(-1) dry wt.). The median content for iron was 286.16 µg g(-1) dry wt. and overall tissue iron contents were generally high which possibly reflected increased brain iron in ageing and in neurodegenerative disease. The median content for copper was 17.41 µg g(-1) dry wt. and overall tissue copper contents were lower than expected for aged brains but they were commensurate with aged brains showing signs of neurodegenerative disease. In this study we have shown, in particular, the value of carrying out significant numbers of method blanks to identify unknown sources of contamination. When these values are subtracted from tissue digest values the absolute metal contents could be considered as conservative and yet they may still reflect aspects of ageing and neurodegenerative disease in individual brains.

Determination of selenium in serum samples of preterm newborn infants with bronchopulmonary dysplasia using a validated hydride generation system.

Bronchopulmonary dysplasia (BPD), also known as chronic lung disease, is one of the most challenging complications in premature newborn infants. Selenium plays a role in antioxidant system by protecting cell membranes and neutralizing the deleterious effects of free radicals. The aim of this study was to determine the relationship between selenium concentration and incidence of bronchopulmonary dysplasia using a validated analytical method. Umbilical cord blood and blood samples 30 days after the birth were collected from 38 preterm newborn infants with gestation age of 32 weeks or less, and the separated serums were kept at -70°C until analysis time. Selenium concentration of serum was determined using an atomic absorption spectrophotometer. The method was validated on the basis of standard validation techniques. The analytical method was linear in the range of 1 to 500 µg/L with the limit of detection of 0.4 µg/L. Samples were collected from 38 infants whose gestation age was 32 weeks or less. The blood samples were collected from the umbilical cord blood at birth in 19 cases. In 25 cases, blood samples were collected 1 month after birth. Of the 15 patients diagnosed with BPD, 10 were boys (p = 0.02). The mean serum selenium concentration was not different at birth between patients with and without BPD, but it was significantly lower at 30 days after birth in patients with BPD (38.5 ± 14.1vs. 45.4 ± 18.7 µg/L, p = 0.02). Preterm newborn infants with BPD had lower serum selenium concentrations 1 month after birth.

Comparative evaluation of GFAAS and ICP-MS for analyses of cadmium in blood.

Cadmium in blood (Cd-B) is an important indicator, next to Cd in urine, in biological monitoring of exposure to Cd. The present study was initiated to examine compatibility in results of analysis for Cd-B between graphite furnace atomic absorption spectrophotometry (GFAAS) and inductively-coupled plasma mass-spectrometry (ICP-MS). For this purpose, 1,159 blood samples were collected from adult women (with no occupational exposure to Cd) in eight prefectures nation-widely in Japan. The samples were analyzed by the two methods; geometric mean (the maximum) concentrations were 1.22 (6.90) µg/l by ICP-MS, and 1.47 (7.40) µg/l by GFAAS. Statistical analyses showed that there was a close correlation between the results by the two methods. The regression line (with ICP-MS and GFAAS results as an independent variable and a dependent variable, respectively) had a slope close to one and an intercept next to zero to suggest that ICP-MS gave values compatible with that of GFAAS. Further analysis with the ratio of Cd-B by GFAAS over that by ICP-MS revealed that the two results were close to each other, and that the agreement was even closer when Cd-B was >2 µg/l. Thus, the two methods can be employed inter-convertibly when Cd-B is relatively high, e.g. >2 µg/l. Care may need to be practiced, however, for possible 'between methods' difference when Cd-B is low, e.g., ≤2 µg/l.