Accurate assessments of the iron (Fe) intake from food is mandatory for mass balance studies. The reliability of such assessments is strongly dependent on the representativeness of the analytical test portion and, as such, the quality of the homogenization of the double portions collected. Large sample Instrumental Neutron Activation Analysis (INAA) circumvents these problems as the entire double portions can be analysed without homogenization. Fe was measured both in approximately 1 kg freeze-dried food as well as in moist products. A (commercially available) porridge fine wheat grain was used as a reference sample (assumed to be homogeneous in the Fe content). The amount of iron in the fine wheat grain was also measured using small sample INAA. The moisture content of the fresh food did not cause any problem during the irradiation such radiolysis and excessive gas formation due to low radiation dose during the irradiation. The results obtained for the moist sample were statistically equivalent to those found for the dried sample ( 73.1± 4, 74± 3 mg/kg respectively, zeta (ζ ) score = 0.18) . The applicability of LS-NAA was further illustrated by measurement of Fe in commercially available microwave meals which was found to be 30±2 mg/kg. Large Sample INAA is a novel and attractive approach for measurement of element content of the dietary intake by the double portion technique collected during 5-7 day in mass balance experiments. Similarly, it can be directly applied without sample preparation for the analysis of faeces collected in such studies. @en

Iron deficiency anaemia is a major health problem worldwide, but may be complicated in underdeveloped nations by deficiencies of other micronutrients with consequences for adequate treatment. The World Health Organization (WHO) estimates that 2 billion people – over 30% of the world’s population – are anaemic, approximately 50% of cases of anaemia are considered to be due to iron deficiency. Aim: Since a combined deficiency of trace elements has great consequences in the approach of this problem, zinc status was assessed in blood of iron deficient anaemic patients in Sudan representing sub-Saharan Africa and compared with Dutch anaemic patients representing Western Europe. Method: Zinc as well as iron were measured with instrumental neutron activation analysis (INAA) in 22 Sudanese anaemic patients and four controls as well as in 17 Dutch anaemic patients and four controls. Result: In the Sudanese patients very low concentrations of zinc were measured, 3 ± 1 mg/L compared to a control group of healthy individuals (5 ± 1 mg/L), while all Dutch patients had normal zinc levels (5 ± 1 mg/L). When matched for haemoglobin level, the Sudanese patients still showed lower zinc concentrations. Even in the Sudanese patients without a known history of malnutrition and in patients with the anaemia of chronic disease zinc levels were significantly lower than in the controls. A positive correlation was observed between Fe and Zn in blood of the Sudanese subjects (r=0.654), while there is no or a very week relation between Fe and Zn in blood of the Dutch group (r=0.08). The low level of Fe and Zn for the Sudanese group might be ascribed to the poor intake of these two nutrients with the main dietary food (cereals) in this area. Conclusion: In iron deficiency anaemia in Sudanese patients, a deficiency of zinc should be taken into account in case of supplementation. @en

Iron is an essential trace element involved in many processes in the human body. Some disorders like iron deficiency anaemia and haemochromatosis directly result from changes in iron status, while on the other hand iron metabolism changes during illness. Since these adjustments in the iron handling of the body may have consequences for the clinical outcome and treatment of patients, a reliable and accurate test to measure iron concentrations and to study iron metabolism in normal and pathological conditions is required. A number of studies in this thesis demonstrate that instrumental neutron activation analysis (INAA) is an adequate method to measure even low concentrations of iron reliably not only in blood, but also in urine, faeces and red blood cells. A great advantage of this technique in contrast to techniques such as mass spectrometry is, that materials in which iron should be measured, hardly need preparation before measurement. It is even possible to measure iron concentrations in complete meals without the need to take small samples. INAA is also able to measure low concentrations of an enriched stable iron isotope facilitating the use of such an isotope in clinical studies without exposure to radiation. In a first clinical study using INAA it could be demonstrated that Sudanese patients with severe iron deficiency anaemia also have severe zinc deficiency. Since in INAA access to a nuclear reactor facility is necessary, the technique should be considered more suitable for research than for routine use. @en

As a safer alternative for the use of radioactive tracers, the enriched stable 58Fe isotope has been introduced in studies of iron metabolism. In this study this isotope is measured with instrumental neutron activation analysis (INAA) in blood samples of patients with iron related disorders and controls after oral ingestion of a 58Fe containing pharmaceutical. Results were compared with those derived from MC-ICP-MS, applied on the same samples, and analytical and practical aspects of the two techniques were compared. Both techniques showed an increased absorption and incorporation in red blood cells of the 58Fe isotope in iron deficient patients in contrast to the controls. In all individuals results of INAA measurements were in good agreement with those of MC-ICP-MS ( |zeta| < 2 ). Uncertainties in INAA are substantially higher than those achievable by MC-ICP-MS but the INAA technique offers a high specificity and selectivity for iron close to 100%. In contrast to INAA, sample preparation before measurement is very critical in MC-ICP-MS and interferences with 58Ni and 54Cr may hamper the measurement of 58Fe and 54Fe respectively. Since it takes at least five days after irradiation to reduce the activity of interfering radionuclides (mainly 24Na), INAA is a more time consuming procedure; the need of a nuclear reactor facility makes it also less accessible than MC-ICP-MS. Costs are comparable. Both INAA and MC-ICP-MS are able to adequately measure changes in iron isotope composition in blood when an enriched stable iron isotope is applied in clinical research. Although MC-ICP-MS is more sensitive, is faster and has easier access, in INAA preparative steps before measurement are simpler and there are hardly demands on the kind and size of the samples. This may be relevant working with biomaterials in a clinical setting. @en

As a safer alternative for the use of radioactive tracers, the enriched stable 58Fe isotope has been introduced in studies of iron metabolism. In this study this isotope is measured with instrumental neutron activation analysis (INAA) in blood samples of patients with iron related disorders and controls after oral ingestion of a 58Fe containing pharmaceutical. Results were compared with those derived from MC-ICP-MS, applied on the same samples, and analytical and practical aspects of the two techniques were compared. Both techniques showed an increased absorption and incorporation in red blood cells of the 58Fe isotope in iron deficient patients in contrast to the controls. In all individuals results of INAA measurements were in good agreement with those of MC-ICP-MS ( |zeta| < 2 ). Uncertainties in INAA are substantially higher than those achievable by MC-ICP-MS but the INAA technique offers a high specificity and selectivity for iron close to 100%. In contrast to INAA, sample preparation before measurement is very critical in MC-ICP-MS and interferences with 58Ni and 54Cr may hamper the measurement of 58Fe and 54Fe respectively. Since it takes at least five days after irradiation to reduce the activity of interfering radionuclides (mainly 24Na), INAA is a more time consuming procedure; the need of a nuclear reactor facility makes it also less accessible than MC-ICP-MS. Costs are comparable. Both INAA and MC-ICP-MS are able to adequately measure changes in iron isotope composition in blood when an enriched stable iron isotope is applied in clinical research. Although MC-ICP-MS is more sensitive, is faster and has easier access, in INAA preparative steps before measurement are simpler and there are hardly demands on the kind and size of the samples. This may be relevant working with biomaterials in a clinical setting. @en