Temperature programmed reduction for measurement of oxygen content in nanoscale zero-valent iron

Nanoscale zerovalent iron (nZVI) has increasingly been used for environmental remediation and in toxic waste treatment. Most applications exploit its large surface area and high reactivity, the latter being a function of zerovalent iron content. In this work, temperature programmed reduction was applied to measure oxygen in nZVI. Iron oxides in nZVI were reduced by hydrogen to form metallic iron and water, which was then measured with an online mass spectrometer to determine oxygen content of the sample. For fresh nZVI prepared by sodium borohydride reduction of iron salts, average oxygen content was 8.21%. Total iron content was approximately 90.35% by the method of acid digestion; Fe(III) content was estimated at 14.37%, and that of zerovalent iron [Fe(0)] at 75.98%. The oxygen content quickly increased to 26.14% after purging with oxygen for four hours. Several other techniques were also used to characterize the iron nanoparticles. High resolution TEM provided direct evidence of the oxide shell structure and indicated that the shell thickness was predominantly in the range of 2-4 nm. The surface elemental composition was determined from high-resolution X-ray photoelectron spectroscopy. The nZVI oxygen content results fill a knowledge gap on nZVI composition.     

酸处理pH值及助剂对浆粕灰分和铁含量的影响

研究了酸处理终点pH值及所用助剂对浆粕灰分和铁含量的影响。结果表明,酸处理并经软水洗涤后的pH值在4以下,灰分和铁的含量均可以达到标准要求;PH超过4,灰分含量会增加,而铁的含量下降。加入六偏磷酸钠,用量0．5％～2．0％,对浆粕的灰分影响不大;在pH低于4时,对降低铁含量有明显效果,而在PH高于4时,对铁含量有负面影响。加入EDTA,用量0．3％～0．7‰对灰分含量影响不大,对降低铁含量有明显效果,用量不应超过0．3％。     

Effect of household processing on the in vitro bioavailability of iron in mungbean (Vigna radiata)

BACKGROUND: Mungbean (Vigna radiata) is a major source of energy and protein in developing countries, especially for the vegetarian population. Improvement of the bioavailability of iron in mungbean by common household processes could make a significant contribution to the nutrition of people in countries where iron-deficiency anemia is widespread. OBJECTIVE: The study was conducted to determine the effect of common household processes on nutritional and antinutritional factors as well as in vitro bioavailability of iron in mungbean. METHODS: Mungbean was subjected to various domestic processes such as dehulling, pressure cooking, germination, and fermentation. The effects of these processes on proximate composition, antinutritional factors (phytin phosphorus, polyphenols, and neutral detergent), and iron, including ionizable iron, were determined. RESULTS: No significant change in crude protein content was observed. There was a significant (p < or = .05) increase in fiber content after germination. Ash content decreased significantly (p < or = .05) after all processing methods. The processing methods resulted in a significant (p < or = .05) reduction in phytin phosphorus and polyphenols. Pressure cooking significantly (p < or = .05) decreased the neutral detergent fiber, whereas fermentation and germination increased it. The phytate:iron molar ratio of processed mungbean revealed that the maximum reduction was in germinated and fermented samples. Ascorbic acid content increased significantly (p < or = .05) after germination. The in vitro bioavailability of iron in raw mungbean was 7.32%. All of the processing methods resulted in an increase in iron bioavailability in vitro; the maximum bioavailability was in germinated cooked mungbean (12.52%), followed by fermented cooked mungbean and germinated raw mungbean (both 11.04%). CONCLUSIONS: Suitable processing techniques can improve the in vitro bioavailability of iron from mungbean. If mungbean products with enhanced iron bioavailabilty are developed, they could help improve the iron status of the population.     

Effect of phytase treatment on iron bioavailability in faba bean (Vicia faba L.) flour

The effect of dephytinisation, using an exogenous phytase under optimal conditions (pH 5.5, 37 °C), and subsequent removal of the soaking solution after processing, on the bioavailability of iron from faba bean (Vicia faba L.) flour was studied. Soaking of the faba bean flour led to a considerable reduction in the content of iron (39%), whereas a lower reduction in iron content (10%), was obtained after additional treatment with phytase, than in the soaked faba bean flour. The digestive utilisation of iron from the raw and soaked faba bean flours by growing rats was negligible, but increased significantly as a result of phytase treatment. The low iron absorption obtained for the former two treatments, during an experimental period of 10 days, was not reflected in any of the haematological indices (red blood count, haemoglobin, haematocrit) or tissues (femur, heart, kidney) studied, with the exception of the sternum. The latter appears to be a useful indicator of iron bioavailability.     

Influence of food processing on iron availability in vitro from extruded maize-based snack foods

Samples of an extruded maize-based snack food taken at various points during manufacture were digested in vitro under simulated physiological conditions. The proportion of iron diffusing across a semi-permeable membrane was used as an index of bioavailability. Iron diffusibility increased from less than 3 % in raw whole maize to over 20 % in the finished product. Four processing stages were found to be responsible for this enhancement: (I) refining of raw maize, (2) product formulation, (3) extrusion cooking, (4) addition of flavourings. The extrusion cooking process itself was responsible for only a small part of the increase in iron diffusibility. There was a reduction in iron content due to refining, but a small increase in iron content due to product formulation and extrusion cooking. The various factors associated with each stage of snack food manufacture are discussed in relation to their potential influence on iron availability.     

Effects of reducing phytate content in sorghum through genetic modification and fermentation on in vitro iron availability in whole grain porridges

Improved iron availability from sorghum porridges will benefit many malnourished communities in rural Africa, where there is a high prevalence of iron deficiency. This research compared the efficacy of reducing sorghum phytate content by genetic modification (GM) and natural lactic acid fermentation on in vitro iron availability in porridges. GM low phytate, non-tannin (38% phytate reduction) and tannin (36% phytate reduction) sorghums and their null controls were processed into thick unfermented and fermented porridges. The inhibitory effect of the tannins seemed to prevent any increase in in vitro iron availability, regardless of the level of phytate reduction. Only the additive effect of GM in combination with fermentation in reducing the phytate content appeared to cause a substantial increase in in vitro iron availability in the GM fermented porridge (30%) made from the non-tannin line, compared to the GM unfermented porridge (8.9%) or the fermented porridge (17.6%) of the control sorghum. This could be of nutritional significance.     

Interaction of iron and folate during reproduction.

Biochemical evidence collected from both clinical and non-institutionalized populations indicate that iron and folate deficiencies frequently occur simultaneously. Supplementation trials of iron-deficient patients with either iron or iron and folate has helped to illustrate that a complex interrelationship exists between these two nutrients. Controlled animal trials in which dietary iron and folate content has been systematically manipulated reveal that iron deficiency can cause altered folate utilization. The impact of iron deficiency on folate metabolism is most dramatic during the reproductive and neonatal stages of the life cycle. Rat pups and piglets nursed by dams fed iron-depleted diets exhibit signs of altered folate utilization. Depressed milk folate secretion is an early manifestation of iron deficiency in the rat dam and is a prime factor responsible for folate depletion in their nursing pups. Impaired milk folate secretion during iron deficiency is not due to a decrease in the amount of folate supplied to the mammary gland; rather, the defect causing this reduction is specific to the mammary gland.     

农村寄宿制学校用铁强化酱油状况及铁含量分析

贫血在我国属于中度公共卫生问题,铁强化酱油是安全有效的人体铁营养改善方法。本研究采集了24个省寄宿制学校使用的43个铁强化酱油产品,采用原子吸收分光光度法测定铁强化酱油总铁含量。结果显示,抽样地区农村寄宿制学校用铁强化酱油产品铁含量均值为（216.1±17.9） mg/kg,铁含量分布范围为191.5～263.8 mg/kg。农村寄宿制学校铁强化酱油中一级酱油占51.2%,桶装酱油占60.5%,高盐稀态发酵工艺的酱油占88.4%,生抽占55.8%。铁含量与酱油保存时间没有相关性,不同等级、不同包装形式铁强化酱油中铁含量无显著性差异,不同品种酱油中铁含量有显著差异,生抽中铁含量显著高于老抽。所有农村寄宿制学校铁强化酱油中铁含量均符合我国相应的食品安全国家标准。     

Comparison of the availability of iron in white bread, fortified with iron powder, with that of iron naturally present in wholemeal bread

The amounts of iron extracted from white bread and wholemeal bread by water and by simulated gastric juice (pepsin-hydrochloric acid)were estimated. Taking the ionisable iron content of the pepsin-hydrochloric acid extract as the standard by which the availability of iron was assessed, then the availability of iron in normally fortified white bread, expressed as a proportion of the total iron present, at least equalled, and possibly exceeded, that in wholemeal bread; in absolute terms the amount of available iron in wholemeal bread was greater than in white bread. Using the Same method, the availability of iron from white bread, fortified with iron powder to the same level as wholemeal was also estimated; approximately 24% more iron was available than from wholemeal. Results for the availability of iron obtained by this method were lower than those found by earlier workers using other methods of extraction which did not include pepsin.     

Graphite-mediated reduction of 2,4-dinitrotoluene with elemental iron

The mechanism and pathway through which 2,4-dinitrotoluene (DNT) is reduced with elemental iron were investigated through batch experiments performed utilizing the same iron surface area, with high-purity iron powder and Master Builders scrap iron. In addition to different kinetics and adsorption patterns, the distribution of two intermediates, 4-amino-2-nitrotoluene (4A2NT) and 2-amino-4-nitrotoluene (2A4NT), contrasted sharply. This suggests that different mechanisms are involved in DNT reduction with pure iron and scrap iron. We hypothesized that exposed graphite in scrap iron transferred reductants from iron to adsorbed nitroaromatic molecules. This hypothesis was supported by an experiment conducted using two-compartment dialysis cells in which ONT and pure iron powder were separated by a graphite sheet. Results indicate that graphite-mediated, indirect reduction of DNT occurred primarily through reduction of the ortho nitro group to form 2A4NT, whereas DNT reduction at the iron (hydr/oxide) surface occurred via para nitro reduction to give 4A2NT. Based on pH and product analysis, atomic hydrogen probably accounted for most of the reducing equivalents that passed through the graphite, reacting with adsorbed DNT mainly through ortho nitro reduction. In contrast, electron was a minor fraction of the reducing equivalents, reducing DNT mainly through para nitro reduction. The implications of graphite as a reaction site and conductor of electron and atomic hydrogen are discussed with respect to treatment processes involving iron.     

Effects of iron supplementation versus dietary iron on the nutritional iron status: Systematic review with meta-analysis of randomized controlled trials

ABSTRACT

This meta-analysis compared the effects of dietary intervention versus iron supplementation on biochemical parameters related to the iron nutritional status in humans. The PubMed, CENTRAL, LILACS, SCIELO, OPENGREY.EU and ClinicalTrials.gov databases were searched for randomized clinical trials that assigned individuals to a dietary intervention or to an iron supplementation regimen, for 12 weeks or more. The primary outcome was the hemoglobin concentration, and secondary outcomes were ferritin, RDW, mean corpuscular volume, soluble transferrin receptor, total iron binding capacity, serum iron, and transferrin saturation. From the 6095 records identified, twelve studies were included, six with children, five with adolescents/adults, and one with pregnant women. In the subgroup of studies that included anemic/iron deficient children, supplementation significantly increased the hemoglobin concentration (weighted mean difference (WMD): 3.19 g/L [95% CI: 1.31, 5.07]) and induced a significantly greater reduction of the soluble transferrin receptor (WMD: ?0.46 mg/L [95% CI: ?0.70, ?0, 21]), when compared to dietary intervention. It also induced a greater reduction of the total binding capacity of iron in adolescents/adults (WMD: ?6.96 μmol/L [95% CI: ?12.70, ?1.21]). Supplementation showed a better effect on hemoglobin recovery in anemic/iron deficient children, while no differences were observed between supplementation and dietary intervention in treating adolescents/adults.     

Dietary tea reduces the iron content of beef

We hypothesized that the lightness of Japanese beef was related to the concentration of heme iron. In Experiment 1, six Japanese Black heifers were allotted randomly to one of three treatment groups: a basal concentrate ration (40% flaked corn) or the same diet and either 2 kg/d wheat bran or 0.5 kg/d green tea. After feeding the diets for 174 d, the cattle were slaughtered and the M. longissimus thoracis, M. semimembranosus, and M. gluteus medius were sampled for meat color, iron, and lipid content. The iron content of the M. semimembranosus from the tea-fed cattle was lower than in M. semimembranosus from the control cattle, and a* (redness) and √(a^*2+b^*2) (saturation) values were lower in M. semimembranosus from bran- and tea-fed cattle than in control cattle. Treatment main effects (across muscles) indicated that inclusion of tea in the diet increased intramuscular lipid and reduced the muscle iron content. There was a significant negative correlation (r²=0.79) between muscle iron content and L^* value (lightness). For Experiment 2, the effect of beef breed type on meat color and iron content of M. longissimus thoracis was investigated using stored meat samples from six breeds from a previous fattening experiment done under a high nutritional plane. Muscle iron content was significantly lower in Japanese Black cattle than in Japanese Black × Holstein or Japanese Black × Japanese Black/Holstein. There was no relationship between muscle iron content and intramuscular lipid content (r²=0.001). In Experiment 3, samples of M. longissimus dorsi were obtained from 17 Wagyu crossbred and 3 Angus crossbred cattle fed a corn concentrate diet in the USA for 148 d. Iron content of the M. longissimus thoracis from Japanese Black and Japanese Brown × Holstein cattle fattened in Japan was significantly less than the iron content of M. longissimus dorsi from cattle raised in the USA. Overall, the data indicate that it is possible to lower muscle iron, and lighten muscle color, by feeding green tea to Japanese cattle; also, there may be a genetic basis for the lower iron, and lighter color, of beef produced in Japan.     

火焰原子吸收光谱法测定葡萄酒中铁的不确定度评定

目的评定火焰原子吸收法测定葡萄酒中铁的不确定度。方法根据GB/T 15038-2006《葡萄酒、果酒通用分析方法》,建立测定葡萄酒中铁含量的不确定度的数学模型。结果该方法测定葡萄酒中铁含量为3.806 mg/L的扩展不确定度为0.376 mg/L。结论不确定度主要来源为标准溶液配制和工作曲线拟合。     

The effect of fruit extracts with polyphenol oxidase (PPO) activity on the in vitro accessibility of iron in high-tannin sorghum

Dephytinized high-tannin sorghum flour was incubated with crude extracts from pear, banana or avocado, respectively, followed by investigation of the effects on the phenolic content and on in vitro accessible iron. All fruits contained polyphenol oxidase (PPO) activity and incubation resulted in significant reduction of phenolic compounds. Incubation with avocado extract resulted in the lowest levels of phenolic compounds, as well as the highest amount of in vitro accessible iron. Peroxidase activity and some organic acids in the fruit extracts might also have contributed to the positive effect on iron accessibility. Nevertheless, incubation of the sorghum flour with the fruit extracts under conditions enabling the PPO to oxidize phenolic compounds, resulted in the highest accessibility of iron. The results from this study suggest that the PPO activity in simple fruit extracts can be utilized to increase the accessibility of iron in dephytinized polyphenol-containing cereal foods.     

Production of dialysable iron by in vitro digestion of chicken muscle protein fractions: the size of the dialysable iron

Muscle foods enhance the absorption of non‐haem iron. We studied the size of the dialysable iron species produced following in vitro digestion of soluble and insoluble chicken muscle proteins and compared the results with those for egg white and whey protein. Digestion of chicken muscle proteins caused a four‐ to fivefold increase in dialysable iron, whereas egg white showed only a slight increase and whey protein caused a reduction, as compared with the control. All the dialysable iron species produced by egg white and whey were smaller than 1 kDa. In contrast, chicken muscle proteins produced dialysable iron species of all sizes up to 10 kDa, but the majority were in the range 2–3.5 kDa for both soluble and insoluble muscle proteins. Copyright © 2005 Society of Chemical Industry     

The inhibitory effect of albumin extracts from white beans (Phaseolus vulgaris L.) on in vitro iron and zinc dialysability: role of phytic acid

The role of phytic acid in determining iron and zinc dialysability in albumin extracts from raw, cooked and cooked/dephytinized white beans, has been investigated. Albumin extract from raw beans was characterized by high iron (19mg/100g), zinc (6.9mg/100g) and phytic acid (11.5μmol g⁻¹) contents and a low mineral dialysablity (Fe 0.48%, Zn 2.5%). Cooking did not influence the mineral dialysability from beans but significantly increased the dialysability of iron (1%, p < 0.001) and zinc (5.3%, p < 0.001) from the albumin extract. Slight modifications in the composition of inositol phosphates after cooking, both in beans and in albumin extract, were observed. The improvement in iron and zinc dialysability from cooked/dephytinized samples was strictly dependent on the residual IP(6 + 5) (inositol hexa + pentaphosphates) content. Compared to cooked beans, in cooked/dephytinized bean a reduction of IP(6 + 5) of 49% led to an increase of the iron and zinc dialysability (29% p < 0.05 and 42%, p < 0.001, respectively). Albumin extract from this sample showed a reduction of 58% in iron and of 45% in zinc content, an almost complete reduction in IP(6 + 5) content (0.6 μmol g⁻¹) and a strong increase in the iron and zinc dialysability. The albumin digests showed peptides of similar MW profiles but of different amino acid compositions. In particular, in peptides which derived from digestion of albumin extracted from cooked/dephytinized beans, a strong increase in cysteine content was found, indicating that, after the disruption of phytate-mineral-protein complexes cysteine-rich fragments were released. The study indicates that phytic acid is responsible for the low iron and zinc dialysability from the albumin bean fraction and indicates the significance of the amino acid composition of the protein digestion products for the enhancement of mineral dialysability.     

Rate and extent of aqueous perchlorate removal by iron surfaces

The rate and extent of perchlorate reduction on several types of iron metal was studied in batch and column reactors. Mass balances performed on the batch experiments indicate that perchlorate is initially sorbed to the iron surface, followed by a reduction to chloride. Perchlorate removal was proportional to the iron dosage in the batch reactors, with up to 66% removal in 336 h in the highest dosage system (1.25 g mL(-1)). Surface-normalized reaction rates among three commercial sources of iron filings were similar for acid-washed samples. The most significant perchlorate removal occurred in solutions with slightly acidic or near-neutral initial pH values. Surface mediation of the reaction is supported by the absence of reduction in batch experiments with soluble Fe2+ and also by the similarity in specific reaction rate constants (kSA) determined for three different iron types. Elevated soluble chloride concentrations significantly inhibited perchlorate reduction, and lower removal rates were observed for iron samples with higher amounts of background chloride contamination. Perchlorate reduction was not observed on electrolytic sources of iron or on a mixed-phase oxide (Fe3O4), suggesting that the reactive iron phase is neither pure zerovalent iron nor the mixed oxide alone. A mixed valence iron hydr(oxide) coating or a sorbed Fe2+ surface complex represent the most likely sites for the reaction. The observed reaction rates are too slow for immediate use in remediation system design, but the findings may provide a basis for future development of cost-effective abiotic perchlorate removal techniques.     

缺铁对葡萄生理效应的影响

以盆栽红地球葡萄为试材,采用MS营养液,研究了全铁、1/2铁、缺铁对葡萄生理特性的影响。结果表明,缺铁30d叶片叶绿素含量显著开始下降,并且叶绿素a降解比叶绿素b幅度大;而1/2铁和全铁60d后才开始下降,降解幅度小;缺铁胁迫30～60d后是葡萄对铁最敏感的时期。不同铁处理(60d)可显著影响丙二醛(MDA)、过氧化物酶(POD)活性和叶片光合速率。     

Iron levels of muscle after various iron and protein intakes

In a 2 X 3 factorial experiment with growing rats (starting weight 32 g) the Fe content (5, 25, 625 mg/kg) and the protein content (5, 25, 45%) of the diet was varied. The diets were fed ad libitum for 35 days. At the end of the experiment the animals were sacrificed. The iron content was determined in a defined sample of musculus supraspinalis after dry ashing with AAS. An insufficient protein supply produced an overall increased iron content and a reduced muscle mass. A deficient iron supply caused a lowered iron content in the muscle in the case of sufficient and excessive protein content of the diet. On the other hand an iron supply exceeding the requirement did not lead to higher iron contents.     

PHEN-CTMAB体系分光光度法测定小麦粉中铁含量

该文报道测定铁的新方法,利用PHEN-CTMAB体系通过湿法消解对食用小麦粉铁含量进行分光光度测定,结果与结论:摩尔吸光系数ε510=1.1×104L·mol-1·cm-1;最大吸收波长为510nm,铁含量在0～4.0μg/mL范围内符合比尔定律。该法与国标法中原子吸收分光光度法测定小麦粉样品铁含量进行比较,结果令人满意。