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Absorption Spectrophotometry (absorption + spectrophotometry)
Kinds of Absorption Spectrophotometry Selected AbstractsAdding magnesium to the silver-gill binding model for rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001Melissa L. Schwartz Abstract Rainbow trout (Oncorhynchus mykiss; 2,17 g) were exposed to approximately 0.1 ,M silver as AgNO3 for 3 to 4 h in synthetic, ion-poor water (20 ,M Ca, 100 ,M Na, 150 ,M Cl, pH 7) to which was added Mg, Ca, or thiosulfate (S2O3). Gills were extracted and assayed for Ag using graphite furnace atomic absorption spectrophotometry. Up to 210 mM Mg (four fold the concentration of Mg in seawater) did not reduce accumulation of Ag by trout gills. The conditional equilibrium stability constant (K) for Mg at silver-binding sites on the gills was calculated to be log KMg-gillAg = 3.0, or approximately half-as-strong binding as for Ca at these sites. The inclusion of the Mg-gill stability constant into the original Ag-gill binding model increases the flexibility of the model, although the competitive effects of Mg are only important in sodium-poor systems. [source] Antibacterial effect of silver-zeolite containing root-canal filling materialJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009Abstract The aim of this study was to determine the in vitro antibacterial effect of two experimental glass ionomer cements (GICs) on Streptococcus milleri, Staphylococcus aureus, and Enterococcus faecalis after 24 and 48 h incubation by using the agar diffusion inhibitory test. Silver zeolite (SZ) was added at 0.2 and 2% mass fraction concentration to GIC (Endion). The control group was Endion with no SZ. Each of them were prepared to uniform size using a custom-made Teflon mold, and the GIC materials were prepared to form disks (n = 5 per group). The effect of these materials on the growth of three bacteria associated with endodontic infections was determined using the agar diffusion inhibitory test. The amounts of silver ion release from these materials were measured with atomic absorption spectrophotometry at 10 min, 24- and 48-h periods. The pH of samples was measured with a pH-meter at 10 min, 24- and 48-h periods. After the incubation period, the agar plates were evaluated and the degrees of bacterial inhibition were measured in millimeters. A comparison of the mean of the test materials was statistically different in each group of specimens (p < 0.05). Between the two tested materials 2% SZ containing GIC showed the largest zone of inhibition on the agar plates of all the tested strains (p < 0.05). The most inhibition in bacterial growth occurred in E. faecalis. Adding 2% SZ to GIC resulted in a significant increase in the silver release into deionized water. This study demonstrated that GIC had an inhibitory affect on Streptococcus milleri, Staphylococcus aureus, and Enterococcus faecalis and that adding SZ increases that affect proportional to its concentration. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] Characterization by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry of the major photoproducts of temoporfin (m -THPC) and bacteriochlorin (m -THPBC)JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2001Marc Angotti Abstract The photobleaching of 5,10,15,20-tetrakis(m -hydroxyphenyl)chlorin (temoporfin, m -THPC) and 5,10,15,20-tetrakis(m -hydroxyphenyl)bacteriochlorin (bacteriochlorin, m -THPBC) was studied in ethanol,water (1 : 99, v/v) and in physiological medium (phosphate-buffered saline, PBS) with or without fetal calf serum (FCS). m -THPC solution was irradiated with the laser radiation of 650 nm, whereas m -THPBC solution underwent two consecutive irradiations at 532 and 650 nm. The photoproducts were characterized by UV,visible absorption spectrophotometry and by matrix-assisted laser desorption/ionization (MALDI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Independent of the solvent used, the phototransformation of either photosensitizer yielded the formation of 5,10,15,20-tetrakis (m -hydroxyphenyl)porphyrin (m -THPP) through a major dehydrogenation process. Copyright © 2001 John Wiley & Sons, Ltd. [source] Four-year study of cobalt and chromium blood levels in patients managed with two different metal-on-metal total hip replacementsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2003Christian Lhotka Abstract Background: Metal-on-metal total hip prostheses will produce a certain amount of wear debris. This results in increased whole-blood metal levels, which may cause adverse effects. It is not known to what extent the problem has been overcome by advances in alloy technology. Methods: In 259 patients who with total hip replacement, blood cobalt and chromium concentrations were measured with atomic absorption spectrophotometry over a period of four years after arthroplasty. Of the patients enrolled in the study, 131 had been managed with a METASUL® cobalt-chromium alloy metal-on-metal bearing combination, while 128 had been given a SIKOMET®-SM21® cobalt-chromium alloy metal-on-metal combination. The control group consisted of 31 age- and gender-matched subjects. Results: Compared with the controls, all the patients had higher cobalt and chromium levels. Cobalt concentrations were up to 50 times higher, while chromium concentrations were up to 100 times higher. Conclusions: Both systems showed evidence, in the whole-blood samples, of wear debris production by the implants. Therefore, patients managed with metal-on-metal bearing combinations should be carefully monitored in order to ensure that any local or systemic complications are detected early on. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Trace elements in edible tissues of three shrimp species (Penaeus semisulcatus, Parapenaeus longirostris and Paleomon serratus)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2008Nalan Gokoglu Abstract Accumulation levels of trace elements in edible tissues of three shrimp species (Penaeus semisulcatus, Parapenaeus longirostris and Paleomon serratus) from the Gulf of Antalya, Turkey were investigated. Copper (Cu), cadmium (Cd), zinc (Zn), iron (Fe) and manganese (Mn) concentrations were determined by atomic absorption spectrophotometry. The lowest Cu (1.33 mg kg,1) and Cd (0.23 mg kg,1) and highest Mn (1.52 mg kg,1) concentrations were found in P. longirostris, the lowest Zn (6.25 mg kg,1), Fe (1.84 mg kg,1) and Mn (0.25 mg kg,1) concentrations in P. serratus and the highest Cu (6.19 mg kg,1), Cd (2.36 mg kg,1), Zn (30.84 mg kg,1) and Fe (33.89 mg kg,1) concentrations in P. semisulcatus. The Cd levels detected in P. semisulcatus and P. serratus were above legislative limits. Our results show that there were significant differences in trace element concentrations among the three shrimp species. The highest levels of the five trace elements investigated, with the exception of Mn, were found in edible tissue of P. semisulcatus. Copyright © 2007 Society of Chemical Industry [source] Cadmium and lead in Hungarian porcine products and tissuesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2005Zoltan Gyõri Abstract Samples of kidney, blood, lungs, hair, heart, liver, spleen, muscle, ear, rib, skin and faeces were obtained from 200 fattened pigs in 10 abattoirs across Hungary. These were analysed in triplicate for cadmium and lead concentrations by atomic absorption spectrophotometry. The highest concentrations of cadmium were found in the kidney, followed by hair and faeces and then liver, heart and lungs. Lead concentrations were greater in the hair and faeces than other tissues. Both lead and cadmium concentrations in meat and offal were below the legal limits. There was more variation in lead than cadmium concentrations between abattoirs, and across abattoirs there was no correlation between concentrations of the two elements. Blood lead concentration was correlated with the lead concentration in bone, kidney, liver, spleen and lungs, and was a better indicator of lead contamination than hair lead concentration. The cadmium concentrations of the kidney, liver, spleen, lungs and faeces were highly correlated, and it is suggested that faeces is the best on-farm indicator of cadmium contamination. Across animals, blood cadmium correlated less closely with the cadmium concentration of the body tissues than it did with the lead concentration, demonstrating positive interaction between the two elements. By contrast, hair and to a lesser extent bone cadmium concentrations were negatively correlated with the lead concentration of most tissues. It is concluded that lead and cadmium concentrations in pigs are best monitored in blood and faeces concentrations, respectively. Copyright © 2005 Society of Chemical Industry [source] Factors influencing anthocyanin content in red cabbage (Brassica oleracea var capitata L f rubra (L) Thell)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2002Roberta Piccaglia Abstract In North and Central Italy an experiment was conducted for two consecutive years to optimise the anthocyanin yield of red cabbage. Two hybrids (,Roxy' and ,Gradur') were grown under a factorial combination of increasing rates of potassium sulphate (0, 50, 100,kg K ha,1) and superphosphate (0, 39, 78,kg P ha,1) applied before planting. Cabbages were transplanted at the beginning of August and harvested in winter. Anthocyanins were extracted from cabbage heads with HCl in methanol (1% v/v solution) and quantified by absorption spectrophotometry at 530,nm. Results showed that red cabbage can give high yields of anthocyanins (more than 90,kg,ha,1) which are characterised by strong acylation and therefore, presumably, by good stability. However, differences over sites and years were marked. In the first year, yields in North Italy were reduced by a heavy infection of soft rot disease. The choice of variety, linked to a different anthocyanin content in the heads, appeared to be the major factor for a successful crop. P and K fertilisation had only a small influence. On clay soils in Central Italy the highest rates of both elements had a negative effect on the anthocyanin concentration in cabbage heads. © 2002 Society of Chemical Industry [source] Variations in the contents of heavy metals in arable soils of a major urban wetland inlet drainage system of Lake Victoria, UgandaLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2010Jolocam Mbabazi Abstract Little is known about the effects of urbanization on the chemical quality of soils in suburban wetland inlet drainage systems to the Uganda side of Lake Victoria, on which food crops are extensively grown. It is feared that pollution in the soils might eventually enter food chains through such crops being consumed by urban populations unaware of their occurrence. Soil samples were collected from cultivated areas of a major wetland drainage system (Nakivubo Channel), at Kampala, Ubanda, near Lake Victoria and from a rural control wetland site (Senge). The soil from this site had similar properties as those from the urban test site (i.e., soil texture; porosity; humus content). Analysis of heavy metals with atomic absorption spectrophotometry (AAS) yielded the following soil concentration ranges: manganese (190,780), cadmium (<0.001,1.0), zinc (6.0,10.0) and lead (10,20 mg kg,1) dry weight for the control site, and 450,900, 1.0,2.0, 131,185, 40,60 mg kg,1 dry weight, respectively, for the urban wetland, indicative of relatively heavy metal pollution in the suburban drainage system. Heavy metal levels in cocoyam (Colocasia Esculenta) and sugarcane (Saccharum Officinarum) grown on both wetland soils also were evaluated via AAS with a modified wet-acid-digestion technique. The results highlighted high cadium and lead levels (P , 0.0003) in the crops from urban wetland cultivation. Cadmium and lead concentrations in cocoyam from urban wetland soils exceeded those from the control site by 0.17 and 3.54 mg kg,1, respectively. The corresponding results for sugarcane indicated a similar increase of 0.56 and 2.14 mg kg,1 of juice extract. Cadmium and lead levels in both urban wetland crops were higher than the maximum permissible limits of the Codex Alimentarius Commission, indicating that these concentrations pose potential health risks to urban consumers, and call for early counter-measures to combat urban pollution entering the lake. [source] Trace Metals' Abnormalities in Hemodialysis Patients: Relationship with MedicationsARTIFICIAL ORGANS, Issue 11 2000Su-Hui Lee Abstract: A multicenter collaborative study was performed to investigate the prevalence of abnormal blood contents of 6 trace metals, copper (Cu), zinc (Zn), aluminum (Al), lead (Pb), cadmium (Cd), and mercury (Hg), in hemodialysis (HD) patients and to analyze their relationship with the medications, such as CaCO3, Ca acetate, Al containing phosphate-binding agents, 1,25-dihydroxy vitD3, 1-hydroxy vitD3, and erythropoietin (EPO), as well as hematocrit level, by chi-square statistics. From 6 medical centers in Taiwan, we included 456 patients in maintenance HD for more than 4 months for this study, and they had continued the previously mentioned medications for at least 3 months. Blood samples were collected before initiating HD, and atomic absorption spectrophotometry was used to measure plasma levels of Cu, Zn, and Al as well as whole blood levels of Pb, Cd, and Hg. Three hundred seventy-five (78%) of the HD patients had low plasma Zn levels, that is, <800 ,g/L, and the mean (±SD) concentration was 705.8 (±128.23) ,g/L in all subjects. One hundred forty-one (31%) of the HD patients had high plasma Al, that is, >50 ,g/L, and the mean (±SD) was 44.30 (±28.28) ,g/L in all subjects. Three hundred thirty-three (73%) of the dialysis patients had high Cd levels, that is, >2.5 ,g/L, and the mean (±SD) was 3.32 (±1.49) ,g/L in all subjects. The majority of HD patients had normal blood levels of Cu, PB, and Hg. Only 21 (4.6%), 5 (1.1%), and 3 (0.06%) patients had elevated blood levels of Cu, Pb, and Hg, respectively. Their mean (±SD) blood concentration of Cu, Pb, and Hg were 1,049.78 (±233.25) ,g/L, 7.45 (±3.95) ,g/dL, and 3.17 (±25.56) ,g/L, respectively. Three patients had elevated plasma Hg concentrations, that is, 546, 12.6, and 24.0 ,g/L, respectively. In the 152 normal healthy age and sex matched control group, the blood levels of Al, Cd, and Pb were all significantly lower than the HD patients. However, the levels of Cu and Zn were higher in the control group. The Hg level was not significantly different in both groups. There was no statistical difference between patients with normal and abnormal blood levels of trace metals in various medications except Al containing phosphate binder. The Al containing phosphate binder users had significantly higher plasma Al levels (54.71 ± 26.70 versus 41.15 ± 28.03 ,g/L, p < 0.001) and hematocrit levels (29.61 ± 4.61 versus 27.81 ± 3.91, p < 0.0005). There was no statistical correlation between erythropoietin (EPO) dose and hematocrit level in these patients. In conclusion, the blood level of trace metals of these HD patients except Al was not related to their medications. However, caution must be exercised in interpreting this result as dose and duration of medication; efficiency of HD and water treatment may play an important role. Otherwise, environmental factors, diet, and the aging process may contribute to the trace metal burden in uremia. Thus, Zn and Cu are abundant in seafood, and Cd is abundant in contaminated plants such as rice. [source] Serum Aluminium Levels in Glue-Sniffer Adolescent and in Glue ContainersBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 5 2008Cemal Akay Various chemical substances such as toluene and benzene containing glues have been reported to be toxic. It has been demonstrated that some toxic metals such as lead are elevated in the blood of solvent-addicted patients. Whereas aluminium is an element that has toxic effects on neurological, hematopoetic system and bone metabolism. We want to determine the serum levels of aluminium in glue-sniffer adolescents in comparison with healthy subjects. In addition, we compared aluminium levels of different commercial glue preparations (i.e. metal and plastic containers), to determine which type of container is better for less aluminium toxicity. We measured serum levels of aluminium in 37 glue-sniffer and 37 healthy subjects using atomic absorption spectrophotometry. The average duration of glue-sniffer was 3.8 ± 0.8 years. We also measured aluminium levels of 10 commercial glue preparations that seven of them with metal and three with plastic containers. We found that serum levels of aluminium were 63.29 ± 13.20 ng/ml and 36.7 ± 8.60 ng/ml in glue-sniffer and in control subjects, respectively (P < 0.001). The average aluminium level in the glues was 8.6 ± 3.24 ng/g in the preparations with metal containers, whereas 3.03 ± 0.76 ng/g with plastic containers (P < 0.001). Therefore, to decrease the incidence of aluminium toxicity in glue-sniffers, it may be a good step to market of glue preparations in plastic instead of metal containers. [source] Effect of chronic Li+ treatment on free intracellular Mg2+ in human neuroblastoma SH-SY5Y cellsBIPOLAR DISORDERS, Issue 1 2003Abde M Abukhdeir Objectives:, Previous findings have demonstrated Li+/Mg2+ competition at therapeutic intracellular Li+ levels after acute Li+ treatment in human neuroblastoma SH-SY5Y cells. In the current study, we examined whether Li+/Mg2+ competition exists at therapeutically relevant extra- and intracellular [Li+] after chronic Li+ loading times. Methods:, In human neuroblastoma cells, intracellular free Mg2+ was determined by fluorescence spectroscopy with the fluorophore furaptra. Intracellular Li+ and Mg2+ were measured by atomic absorption spectrophotometry. Results:, After loading of the neuroblastoma cells with 1,2 mM extracellular Li+ for 24,72 h, the observed, increased intracellular free [Mg2+] levels were significantly higher (p <,0.03) than those in matched Li+ free cells, and intracellular [Li+] was found to be at therapeutic intracellular levels (0.7,1.5 mM). Conclusions:, The results demonstrate that Li+/Mg2+ competition exists after chronic treatment with Li+ at therapeutically relevant intracellular Li+ levels in neuroblastoma cells. We found differences between acute and chronic Li+ treatment effects on the extent of Li+/Mg2+ competition. Possible reasons for these differences are discussed. [source] Evaluation of zinc level in skin of patients with necrolytic acral erythemaBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2010H.A.M. Moneib Summary Background, Necrolytic acral erythema (NAE) is considered a cutaneous sign of hepatitis C virus infection. Its exact pathogenesis is still not fully understood, with some reports about decreased serum zinc levels but none about its level in the skin. Objectives, To assess skin (lesional and perilesional) and serum zinc levels in patients with NAE and compare them with levels in control subjects. Methods, Fifteen patients with NAE and 10 healthy controls were included in this study. Assessment of zinc level, in serum by graphite furnace atomic absorption spectrophotometry and in lesional and perilesional skin biopsies by flame atomic absorption spectrometry, was done in all subjects. Re-evaluation of serum and lesional skin zinc level was done after oral zinc treatment. Results, Mean ± SD zinc levels were significantly lower in patients (serum 0·44 ± 0·13 mg L,1; lesional skin 42·6 ± 18·9 mg L,1; perilesional skin 32·5 ± 17·2 mg L,1) than controls (serum 1·17 ± 0·29 mg L,1; skin 100·1 ± 2·77 mg L,1), with a positive correlation between lesional and perilesional skin zinc (r = 0·91, P < 0·01). Oral zinc supplementation significantly increased serum and skin zinc levels (by 159% and 4%, respectively; P < 0·05). Conclusions, NAE is associated with decreased serum and skin zinc levels. Oral zinc supplementation corrects decreased levels of plasma and skin zinc much earlier than the desired clinical benefits appear. [source] Macrocyclic Hexaureas: Synthesis, Conformation, and Anion BindingCHEMISTRY - A EUROPEAN JOURNAL, Issue 19 2009Denys Meshcheryakov Dr. Abstract Varied flexibility: Cyclic oligoureas are formed by using anions as templates. Linking of six xanthene and/or diphenyl ether fragments by urea groups leads to the formation of five macrocyclic compounds with a 48-membered ring with variable flexibility (see picture). Their interaction with anions shows a strong influence of acetate and chloride ions on the cyclization from four precursor molecules. Five macrocylic compounds XXXXXX, XXDXXD, XDXDXD, XDDXDD, and DDDDDD with 48-membered rings, in which six xanthene and/or diphenyl ether fragments are linked through six urea (-NH-C(O)-NH-) groups, have been synthesized. In the cyclization step, a linear diamine was allowed to react with the appropriate diisocyanate by using a [5+1] (i.e., "XDXDX+D" for XDXDXD), [4+2] (DDDDDD), or [3+3] (XDDXDD) procedure. Compounds XXXXXX and XXDXXD were prepared from two molecules of the dimeric amine XX and two molecules of the respective monomeric diisocyanate (X or D) in a [2+1+2+1] (or 2×[2+1]) reaction. The (nonoptimized) yields in the cyclization step ranged from 45 to 80,%. The linear precursor diamines or diisocyanates were obtained by analogous condensation reactions by using partial protection with a tert -butoxycarbonyl group. All the macrocyclic compounds and synthetic intermediates were characterized by 1H,NMR and mass spectra. Three different crystal structures were obtained for XDDXDD, which show the molecule in a more or less strongly folded conformation determined by intramolecular hydrogen bonding. The interaction of the hexaureas with selected anions was studied by 1H,NMR spectroscopy and UV absorption spectrophotometry. [source] | ||||||||||||||||