Trace element content in human milk during lactation of preterm newborns

The present study has been finalized to perform the content of Zn, Cu, Cr, Se, Mn, F, Mo, Ni, and B in the preterm human milk over 21 d of lactation. Trace element (TE) contents were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-MS), and median concentrations of Zn, Cu, Cr, Se, Mn, and F observed in preterm milk did not demonstrate significant differences in comparison to levels shown in term milk. A statistical significant difference (p<0.05) has been found among Mo, Ni, and B content in preterm milk for every stage of lactation. TE content of infant blood founded concentrations of Mo in preterm babies significantly (p<0.01) lower than in term offsprings. Similar values of other TE content were obtained in blood of preterm, and term newborns. These findings point to the need for a considerable reassessment of the existing dietary recommendation for Mo content in infant feeding.     

Bioavailability of zinc and its binding to casein in milks and formulas

Differences in zinc bioavailability among milk and formulas may be attributed to binding of zinc to various ligands. We determined the distribution of zinc and protein at different pHs and zinc and calcium concentrations. We used radiolabelled cow's milk, human milk, whey-predominant (WPF) and casein-predominant (CPF) infant formula. Lowering the pH changed zinc and protein distribution: zinc shifted from pellet (casein) to whey in cow's milk, from fat to whey in human milk and from fat and pellet to whey in formulas. Protein shifted from whey to pellet in human milk and from whey and pellet to fat in formulas. Increasing zinc and calcium concentrations shifted protein and zinc from pellet to whey for cow's milk and from whey and pellet to fat for the formulas. Protein distribution was not affected by calcium or zinc addition in human milk or CPF, while zinc shifted from whey to fat in human milk and from fat and pellet to whey in CPF. Zinc and calcium binding to isolated bovine or human casein increased with pH. At 500 mg/L of zinc, bovine casein bound 32.0 +/- 1.8 and human casein 10.0 +/- 0.9 mg zinc/g protein. At 500 mg/L of calcium, calcium was preferentially bound over zinc. Adding calcium and zinc resulted in 32.0 +/- 1.8 mg zinc/g bound to bovine casein and 17.0 +/- 0.8 mg zinc/g to human casein, while calcium binding was low. Suckling rat pups dosed with 65Zn labelled infant diets were killed and individual tissues were gamma counted. Lower zinc bioavailability was found for bovine milk at pH = 4.0 (%65Zn in liver = 18.7+1.4) when compared to WPF (22.8 +/- 1.6) or human milk (26.9 +/- 0.8). Lowering the pH further decreased zinc bioavailability from human milk, but not from cow's milk or WPF. Knowledge of the compounds binding minerals and trace elements in infant formulas is essential for optimizing zinc bioavailability.     

Determination of thirty-two elements in human autopsy tissue

Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the concentrations of 32 elements in the human liver and kidney and 20 elements in the bone, obtained from 70 autopsied dead individuals (54 males, 16 females) between 18 and 76 yr of age from the North Bohemia territory of the Czech Republic. Geometric means, median, minimal-maximal range, as well as distribution and correlation analysis were calculated. Some significant differences among tissue concentrations of trace elements of the women and men were found. In the liver, medians of the concentrations of some elements were higher for men than that for women (Al: 770 vs 610 microg/kg; As: 42 vs 27 microg/kg; Cd: 1800 vs 1390 microg/kg; Rb: 3955 vs 3210 microg/kg; V: 160 vs 105 microg/kg). On the contrary, the content of other elements for men was lower (Bi: 0.8 vs 3.2 microg/kg; Cr: 57 vs 72 microg/kg; Hg: 228 vs 325 microg/kg; Zn: 57.1 vs 68.5 mg/kg). In the kidney of men, there were higher contents of Al (360 vs 245 microg/kg) and Hg (135 vs 75 microg/kg) and lower contents of Zn (47.7 vs 59.7 mg/kg) and I (135 vs 220 microg/kg) than those of women. In the case of bone, the concentrations of Cu and Rb were higher for men (1410 microg Cu/kg and 405 microg Rb/kg, respectively) than for women (655 microg Cu/kg and 285 microg Rb/kg, respectively). On the contrary, the content of Mn was considerably lower for men (110 microg Mn/kg) than for women (215 microg Mn/kg).     

Effects of some rare elements on nicotine content of the tobacco plant

Fifty-four rare elements were tested for their effects on the nicotine level of tobacco (Nicotiana tabacum L.) plants grown in solution culture. Be, Cu, Pd, Pt, and Sm definitely increased nicotine yield (over 25%), whereas Bi, Co, Ho, Pb, Ni, Rb, Ag, Tl, Sn, U. V. and Zr definitely decreased nicotine yield. Cs, Er, Li, Rh, Ru, Se, Sr, Ti, and Yb possibly increased (less than 25%) nicotine yield, whereas As, Ce, Cr, Dy, Gd, I, Mo, Nd, Re, Ta, and Th possibly decreased nicotine yield. Other elements including Al, Ge, Au, Hf, In, Ir, La, Lu, Hg, Os, Pr, Sc, Te, Tb, Tm, W, and Zn showed no significant effects.     

Dietary intake of platinum and gold by children from Germany using duplicate portion sampling

The dietary intake of platinum and gold by 84 small children, 42 boys and 42 girls at the age of 14 to 83 months, with different food consumption behaviour living in urban and rural areas of Germany was measured by the duplicate method with a seven day sampling period from May to September 1998. The levels in the food duplicates were in the range of < 0.01 to 450 ng Pt/kg (dry weight) (median: 22) and < 0.14 to 28 microg Au/kg (dry weight) (median: 0.645). Related to the body weight, Pt was in the range of < 0.81 to 32 ng/(kg (body weight) x week) (median: 2.3) and Au was < 0.015 to 2.6 microg/(kg (body weight) x week) (median: 0.068). Children consuming exclusively products from the super market showed slightly higher Pt concentrations in the food duplicates and a higher dietary intake per body weight than children with food consumption including products from the family owned vegetable gardens or the surrounding area and/or products from domestic animals of the surrounding area. No influence of the food consumption behaviour was found for the concentrations in the food duplicates or the dietary intake of Au.     

Concentrations of copper, zinc, manganese, rubidium, and magnesium in thoracic empyemata and corresponding sera

In this study, a number of selected trace elements and clinically relevant parameters were compared between thoracic empyemata and the corresponding sera for a better understanding of the trace element distribution between these two compartments. Serum-empyema pairs were obtained from 13 patients and quantified for selected and essential trace elements, namely copper (Cu), zinc (Zn), manganese (Mn), rubidium (Rb), and magnesium (Mg), by inductively coupled plasma-mass spectrometry (ICP-MS). In addition, the concentrations of the following clinical laboratory parameters were analyzed by standard methods: total protein, leukocyte count, lactate dehydrogenase, glucose, pH, and the C-reactive protein. Individual concentrations of the elements determined in the empyemata were frequently higher than in pleural effusions of any other benign or malignant condition except for Cu. Serum Cu exceeded the normal range (600–1400 μg/kg) in 6 out of 13 patients (median 1410 μg/kg). In the empyemata, Zn concentrations (median 2000 μg/kg) were characteristically higher than in the sera (median 450 μg/kg) and exceeded the upper limit for serum (1200 μg/kg) in 8 of the 13 patients. Manganese concentrations in the empyemata (median 2.7 μg/kg) were also higher compared to corresponding sera, although they stayed within the limits considered normal for serum of healthy adults (upper limit 2.9 μg/kg). Rubidium was also moderately higher in most empyemata (median 290 μg/kg) and exceeded the upper limit for serum (560 μg/kg) in two patients. The median concentration of the essential element magnesium was higher in the empyemata (23 mg/kg) than in the sera (21 mg/kg). However, all serum Mg concentrations except three remained within the normal range (17–22 mg/kg). Removal of large amounts of empyematous fluid may deprive the body of trace elements and can cause suboptimal or deficient trace element status and homeostasis. Recuperation will be accelerated by compensatory supplementation of trace elements. Therefore, selective medication with adequate trace element compounds in patients with thoracic empyema can be generally recommended for zinc. The other elements need not necessarily be monitored or substituted, because of their stable concentrations in the serum. Rb may have a biological impact, but deficiency symptoms in man are not clearly defined. Deceased.     

The Content of Elements in Infant Formulas and Drinks Against Mineral Requirements of Children

The present study aimed at analysing the content of fluorine (F), calcium (Ca), magnesium (Mg), iron (Fe) and zinc (Zn) in the drinks for children and infant formulas, a popular supplement or substitute for breast milk produced from cow milk on an industrial scale. Ca, Mg, Zn and Fe concentrations were determined using atomic absorption spectrophotometer, while F levels using a potentiometric method. F levels in the examined formula samples increased with the intended age range, until the intended age of 1 year, and then decreased. A lower content of Ca, Mg and Zn was observed in formulas intended for children <1 year of age and higher for older children. Fe content increased with the age range. A statistically significant higher content of Ca, Mg, Zn and Fe in samples intended for children with phenylketonuria in comparison to those intended for healthy children or children with food allergies was noted. The content of the analysed elements in juices and nectars showed the highest contents in products intended for infants (under 6 months of age). The lowest levels of elements tested were found in drinks for children over 6 months of age. In conclusion, the concentrations of the examined elements in infant formulas and juices for children were decidedly greater than the standards for the individual age groups. Although the absorption of these elements from artificial products is far lower than from breast milk, there is still the fear of consequences of excessive concentrations of these minerals.     

Trace elements in formulas based on cow and soy milk and in austrian cow milk determined by inductively coupled plasma mass spectrometry

With inductively coupled plasma-mass spectrometry (ICP-MS), the 18 trace elements Ba, (Be), (Bi), Cd, Co, Cs, Cu, La, Li, Mn, Mo, Pb, Rb, (Sb), (Sn), Sr, (Tl), and Zn were quantified in the digests of 13 formulas based on cow milk, of two formulas based on soy protein, of two milk powders, from which formulas were prepared, of two samples of Austrian cow milk, and in the water, with which the powders were suspended. Concentrations in parentheses were at or below the method detection limits in the formulas. The accuracy and precision of the analytical procedure tested with milk powder reference materials BCR 063 and BCR 150 were satisfactory. The concentrations of trace elements in the powders vary considerably from batch to batch. The ratios of high to low concentrations ranged from 1.1 to 4.8 and were higher for the essential trace elements Co, Cu, Mn, Mo, Sn, and Zn than for nonessential or toxic elements. The contribution of tap water from the water system of the city of Graz, Austria to the concentrations of trace elements in the formulas ranges from 45% for Pb to 0.2% for Rb and is negligible, for instance, for Cd, Cs, La, Mo, and Sn. Preformulas and follow-up formulas are partly supplemented with the essential trace elements Cu, Mn, and Zn and, therefore, concentrations of these trace elements in the formulas vary considerably. However, supplementation of a formula with a particular element must not necessarily result in higher concentrations compared to nonsupplemented formulas. Concentrations of the essential elements were in the following ranges for preformulas, follow-up formulas, soy-based formulas (in μg/kg): Co, 8.3–11.2, 4.5–13, 5.0–5.7; Cu, 330–750, 27–730, 440–530; Mn, 33–580, 40–390, 440–530; Mo, 10–32, 9–39, 44-6; Sn, <0.44-3.8, <0.44-1.0, <0.44-5.8; Zn, 3340-11,380, 4120–7100, 5590-6,840. A preformula supplemented with Mn had a 10 times higher manganese concentration than preformulas without supplementation. Concentrations of all trace elements quantified were lower in cow milk than in formulas and do not meet the dietary requirements of infants.     

Elemental metabolomics in human cord blood: Method validation and trace element quantification

BackgroundTrace elements are an essential requirement for human health and development and changes in trace element status have been associated with pregnancy complications such as gestational diabetes mellitus (GDM), pre-eclampsia (PE), fetal growth restriction (FGR), and preterm birth. Elemental metabolomics, which involves the simultaneous quantification and characterisation of multiple elements, could provide important insights into these gestational disorders.MethodsThis study used an Agilent 7900 inductively coupled plasma mass spectrometer (ICP-MS) to simultaneously measure 68 elements, in 166 placental cord blood samples collected from women with various pregnancy complications (control, hypertensive, PE, GDM, FGR, pre-term, and post-term birth).ResultsThere were single element differences across gestational outcomes for elements Mg, P, Cr, Ni, Sr, Mo, I, Au, Pb, and U. Hypertensive and post-term pregnancies were significantly higher in Ni concentrations when compared to controls (control = 2.74 μg/L, hypertensive = 6.72 μg/L, post-term = 7.93 μg/L, p < 0.05), iodine concentration was significantly higher in post-term pregnancies (p < 0.05), and Pb concentrations were the lowest in pre-term pregnancies (pre-term = 2.79 μg/L, control = 4.68 μg/L, PE = 5.32 μg/L, GDM = 8.27 μg/L, p < 0.01). Further analysis was conducted using receiver operating characteristic (ROC) curves for differentiating pregnancy groups. The ratio of Sn/Pb showed the best diagnostic power in discriminating between control and pre-term birth with area under the curve (AUC) 0.86. When comparing control and post-term birth, Mg/Cr (AUC = 0.84), and Cr (AUC = 0.83) had the best diagnostic powers. In pre-term and post-term comparisons Ba was the best single element (81.5%), and P/Cu provided the best ratio (91.7%).ConclusionsThis study has shown that analysis of multiple elements can enable differentiation between fetal cord blood samples from control, hypertensive, PE, GDM, FGR, pre and post-term pregnancies. This data highlights the power of elemental metabolomics and provides a basis for future gestational studies.     

A comparative study of elemental composition of human breast milk and infant milk substitutes

Instrumental neutron activation analysis (INAA) and protoninduced X-ray emission (PIXE) analysis have been employed to determine the concentration of 13 elements in human breast milk, various infant formulas, and locally produced cereals from Nigeria, as well as from various infant formulas and natural cow and goat milk available in the UK. The study shows that if the locally produced cereal is to be used on a regular basis for babies in Nigeria, then their diet must be supplemented with essential trace elements. Furthermore, parents should be discouraged from giving their infants cow and goat milk because of the high concentration of major elements compared to human breast milk.     

Trace elements in human transitory milk

Multielement analysis was performed on human milk collected on 5-9-d postpartum from 51 Japanese females using inductively coupled plasma (ICP) mass spectrometry (MS), ICP atomic emission spectrometry (ICP-AES) and fluorometry. Thirty-one elements were detected by these analytical methods in milk. Twelve elements (Na, Mg, P, S, K, Ca, Cu, Zn, Se, Sr, Rb, and Mo) were detected in all of the samples. Al, Cs, and Ba were the elements detected by ICP-MS in more than half of the samples. Multiple regression analysis extracted biological attributes of mother and infant, such as maternal stature, maternal wt, or infant's birth wt, as statistically significant factors contributing to the variation in elemental concentration in milk. However, the rates of contribution were small in all cases. It was concluded that the biological attributes of mother and infant examined in this study were not the major factors that contribute to elemental variation in human milk.     

Multi-elemental determination of metals,metalloids and rare earth element concentrations in whole blood from the Canadian Health Measures Survey, 2009-2011

BackgroundAs part of Government of Canada’s Chemical Management Plan, substances containing aluminum (Al), bismuth (Bi), cerium (Ce), chromium (Cr), germanium (Ge), lanthanum (La), lithium (Li), neodymium (Nd), praseodymium (Pr), tellurium (Te), titanium (Ti) and yttrium (Y) were identified as priorities for risk assessment. Generating exposure estimates from all routes of exposure from multiple sources using a traditional approach for these elements can be challenging. The use of human biomonitoring (HBM) data would allow for direct and more precise assessment of the internal concentrations from all routes and all sources of exposure. There are no Canadian or North American population-level whole blood HBM data for the elements listed above. Therefore, this is the first biomonitoring project carried out to determine the concentrations of these elements from a nationally representative sample of Canadians.ObjectivesThe objective of this study was to generate whole blood concentrations for Al, Bi, Ce, Cr, Ge, La, Li. Nd, Pr, Te, Ti and Y in the Canadian population using biobank samples from the Canadian Health Measures Survey (CHMS) cycle 2 (2009–2011) for use in characterizing exposure in screening assessments and for establishing baseline concentrations to determine how exposures are changing over time.MethodsThe sample analysis was conducted by ICP-MS. A rigorous quality control and quality assurance process was implemented in order to generate data with high accuracy and precision while measuring low concentrations and minimizing possible inadvertent contamination.ResultsOf the elements analysed, the whole blood concentrations (μg/L) of Al, Ce, Cr, Ge, La, Nd, Pr, Te, Ti and Y in the Canadian population aged 3–79 years were below their respective method reporting limit (MRL). Two elements, Bi and Li were detected in 5 % and 66 % of the Canadian population. The median Li concentration was 0.47 μg/L.ConclusionThe results of this study provide information on concentrations of these elements in the Canadian population which can be utilized to characterize exposure in screening assessments and there by the potential for harm to human health. In addition, this study provides baseline HBM data which can be used as a comparative HBM dataset for other populations with similar exposure patterns.     

Effect of Magnesium Deficiency on Various Mineral Concentrations in Rat Liver

Magnesium (Mg) deficiency is well known to affect metabolism of some trace minerals. We investigated the effect of Mg deficiency on hepatic concentration of various minerals in rats. Twelve 5-week-old male rats were divided into the groups given a control diet and an Mg-deficient diet. After 4?weeks, liver sample was collected from each rat. The concentrations of 36 minerals were simultaneously determined by a semiquantitative method of inductively coupled plasma-mass spectrometry (ICP-MS). The semiquantitative analysis showed that Mg deficiency significantly increased iron (Fe), copper (Cu), zinc (Zn), gallium (Ga), yttrium (Y), zirconium (Zr), molybdenum (Mo), rhodium (Rh), silver (Ag), and barium (Ba) concentrations, and significantly decreased scandium (Sc) and niobium (Nb) concentrations in rat liver. Then, hepatic Fe, Cu, Zn, Sc, Zr, and Mo concentrations were quantitatively measured, which indicated the similar effects as observed by the semiquantitative analysis. Additionally, the semiquantitative measurements of these minerals were highly correlated to these measurements with the quantitative method, but the measurements were not completely consistent between these analyses. The present study is the first research indicating the changes of hepatic Ga, Y, Zr, Mo, Rh, Ag, Ba, Sc, and Nb concentrations in Mg-deficient rats. The present study also indicates that the semiquantitative analysis with ICP-MS is a valid method for screening analysis to investigate various mineral concentrations in animal tissues.     

Comparison of silver, gold and modified platinum electrodes for the electrochemical detection of iodide in urine samples following ion chromatography

The electrochemical (EC) detection of iodide at gold, silver and platinum electrodes under similar experimental conditions was evaluated. To achieve optimal amperometric detection, the electrode sensitivity, selectivity, and stability was compared. Isocratic separation of iodide was attained by ion chromatography (IC) using an anion-exchange column with nitrate as an eluent ion (25 mM HNO(3) + 50 mM NaNO(3)). Although the Ag electrode showed the highest selectivity due to the relatively low applied potential (+0.10 V versus Ag|AgCl), it requires continuous surface polishing upon injection of standard solutions or real samples; in addition, the chromatographic peak of iodide exhibited a pronounced dip-tailing. The limit of detection (LoD) of iodide was estimated to be 3.5 microg/L (S/N=3) with an injection volume of 50 microL. Likewise, pulsed electrochemical detection at the silver electrode did not demonstrate the expected results in terms of peak shape and low detection limit. Using the same chromatographic conditions, iodide detection at the Au electrode (E(app)= +0.80 V versus Ag|AgCl) exhibited a regular peak shape accompanied by a sensitivity comparable to the silver one. Yet, upon continuous injections the signal intensity displayed a progressive lowering up to ca. 40% in 6h. Best results in terms of signal stability, peak shape and analytical response were obtained with a modified platinum electrode which allowed to achieve a LoD of 0.5 microg/L (S/N=3). The present IC-EC detection method using a modified Pt electrode (E(app)= +0.85 V versus Ag|AgCl) was successfully applied to determine low contents of iodide in human urine with solid phase extraction as pretreatment. Such a developed method correlated very well with the reference colorimetric method in urine (r=0.95273), and it is specifically suggested when the iodide content is relatively low, i.e., <20 microg/L.     

Time-resolved fluoroimmunoassays of the complete set of secreted phospholipases A2 in human serum

Time-resolved fluoroimmunoassays (TR-FIA) were developed for all human secreted phospholipases A(2) (PLA(2)), viz. group (G) IB, GIIA, GIID, GIIE, GIIF, GIII, GV, GX and GXIIA PLA(2) and the GXIIB PLA(2)-like protein. Antibodies were raised in rabbits against recombinant human PLA(2) proteins and used in sandwich-type TR-FIAs as both catching and detecting antibodies, the latter after labeling with Europium. The antibodies were non-cross-reactive. The analytical sensitivities were 1 microg/L for the TR-FIA for GIB PLA(2), 1 microg/L (GIIA), 35 microg/L (GIID), 3 microg/L (GIIE), 4 microg/L (GIIF), 14 microg/L (GIII), 11 microg/L (GV), 2 microg/L (GX), 92 microg/L (GXIIA) and 242 microg/L (GXIIB). All secreted PLA(2)s were assayed by these TR-FIAs in serum samples from 34 patients (23 men and 11 women, mean age 53.2 years) treated in an intensive care unit for septic infections, and in control samples from 28 volunteer blood donors (14 men and 14 women, mean age 57.0 years). Five serum samples (3 in the sepsis group and 2 in the blood donor group) gave high TR-FIA signals that were reduced to background (blank) levels by the addition of non-immune rabbit IgG to the sera. This reactivity was assumed to be due to the presence of heterophilic antibodies in these subjects. In all other subjects, including septic patients and healthy blood donors, the TR-FIA signals for GIID, GIIE, GIIF, GIII, GV, GX and GXIIA PLA(2) and the GXIIB PLA(2)-like protein were at background (blank) levels. Four patients in the sepsis group had pancreatic involvement and elevated concentration of GIB PLA(2) in serum (median 19.0 microg/L, range 13.1-33.7 microg/L, n = 4) as compared to the healthy blood donors (median 1.8 microg/L, range 0.8-3.4 microg/L, n = 28, P < 0.0001). The concentration of GIIA PLA(2) in the sera of septic patients (median 315.7 microg/L, range 15.9-979.6 microg/L, n = 34) was highly elevated as compared to that of the blood donors (median 1.8 microg/L, range 0.8-5.8 microg/L, n = 28, P < 0.0001). Our current results confirmed elevated concentrations of GIB and GIIA PLA(2) in the sera of patients suffering from acute pancreatitis or septic infections, respectively, as compared to healthy subjects. However, in the same serum samples, the concentrations of the other secreted PLA(2)s, viz. GIID, GIIE, GIIF, GIII, GV, GX and GXIIA PLA(2) and the GXIIB PLA(2)-like protein were below the respective analytical sensitivities of the TR-FIAs. It is concluded that generalized bacterial infections do not lead to elevated serum levels of GIIE, GIIF, GIII, GV and GX PLA(2)s above the detection limits of the current TR-FIAs.     

Chitosan-Zn Chelate Downregulates TLR4-NF-κB Signal Pathway of Inflammatory Response and Cell Death-Associated Proteins Compared to Inorganic Zinc

The object of this study is to analyze the levels of seven toxic elements residues in raw bovine milk in China and assess the potential health risk of those residues. The 178 raw bovine milk samples were collected from eight main milk-producing provinces and from three types of milk stations in China, and were analyzed for arsenic (As), lead (Pb), cadmium (Cd), chromium (Cr), mercury (Hg), aluminum (Al), and nickel (Ni) using inductively coupled plasma-mass spectrometry (ICP-MS). Al, Pb, Hg, Ni, Cr, and As were detected in 47.8, 29.2, 28.1, 23.6, 12.4, and 9.0% of total milk samples, respectively, and Cd were not detected in all samples. The raw bovine milk samples with high levels of toxic elements were found in industrial areas, such as Heilongjiang and Shanxi. Nemerow pollution index analysis showed that the levels were lower in the samples from the processing plants than that from the large-scale farms and small farm cooperatives. The margin of exposure (MOE) values suggest that the levels of As, Pb, Hg, Cr, Al, and Ni in the raw milk samples are not causing a health risk for Chinese consumers, including adults and children. Nevertheless, the risk of Pb for infant and young children was more serious than adult.     

Selenium, zinc, and copper concentrations in the blood and milk of lactating women

The aim of the study was to determine Se, Zn, and Cu concentrations in blood plasma and milk of lactating women from central Poland who were in different stages of lactation and to investigate the relationship between the content of trace elements in mothers’ blood and concentrations of microelements in their milk. Se and Zn concentrations in blood plasma of mothers were the lowest and Cu was the highest on the first 4 d of lactation (colostrum, n=43) and were found to be 34.9±11.8 μg/L, 0.51±0.13 mg/L, and 1.70±0.55 mg/L, respectively. The highest plasma level of Se and Zn and the lowest content of Cu could be observed between d 10 and 30 of lactation (mature milk, n=41), and were found to be 54.3±14.6 μg/L for Se (p<0.001), 0.76±0.20 mg/L for Zn (p<0.001), and 1.03±0.30 mg/L (p<0.001) for Cu. The results of Se, Zn, and Cu determination in breast milk samples demonstrate a pattern of decline in their concentration with advancing stages of lactation. We found out that Se, Zn, and Cu concentrations were the highest in colostrum (n=43) and amounted to 24.8±10.1 μg/L, 8.2±2.8 mg/L, and 0.45±0.11 mg/L, respectively. The content of all determined microelements declined significantly during the time of lactation. Statistically significant linear correlation was found between concentrations of Zn in blood plasma and milk in the first stage of lactation. Weak but statistically significant linear correlations were also found between plasma Se content in plasma and in transitional and mature milk of breast-feeding women.     

Alterations of Mg<Superscript>2+</Superscript> After Hemorrhagic Shock

The objectives of this study were to measure the concentrations of elements in raw milk by inductively coupled plasma-mass spectrometry (ICP-MS) and evaluate differences in element concentrations among animal species and regions of China. Furthermore, drinking water and feed samples were analyzed to investigate whether the element concentrations in raw milk are correlated with those in water and feed. All samples were analyzed by ICP-MS following microwave-assisted acid digestion. The mean recovery of the elements was 98.7 % from milk, 103.7 % from water, and 93.3 % from a certified reference material (cabbage). Principal component analysis results revealed that element concentrations differed among animal species and regions. Correlation analysis showed that trace elements Mn, Fe, Ni, Ga, Se, Sr, Cs, U in water and Co, Ni, Cu, Se, U in feed were significantly correlated with those in milk (p < 0.05). Toxic and potential toxic elements Cr, As, Cd, Tl, Pb in water and Al, Cr, As, Hg, Tl in feed were significantly correlated with those in milk (p < 0.05). Results of correlation analysis revealed that elements in water and feed might contribute to the elements in milk.     

Determination of iodine in human milk and infant formulas

The aim of this study was to develop a method to determine iodine in human milk and infant formulas using ICP-MS. The milk samples were digested using an alkaline digestion (5% NH₃, 45 W, 2 min and 30 s), and the method was validated using a certified reference material (CRM) BCR CRM151. On the other hand the milk was separated in three fractions, whey, fat and caseins using ultracentrifugation (15 min, 4 °C, 50,000 rpm) and the iodine was determined in the different fractions. About 27 samples of different infant formulas and 14 samples of human milk have been studied. In the human milk the values found were between 144±93.2 μg kg⁻¹, whereas in the infant formulas the values were 53.3±19.5. For both types of samples the bigger amount of iodine is in the whey fraction, between 80% and 90%, whereas in the fat there is about a 2% of the total iodine and in the casein fraction the levels are between 5% and 10% depending on the type of sample.     

Preparation of hair for measurement of elements by inductively coupled plasma-mass spectrometry (ICP-MS)

The preparation of hair for the determination of elements is a critical component of the analysis procedure. Open-beaker, closedvessel microwave, and flowthrough microwave digestion are methods that have been used for sample preparation and are discussed. A new digestion method for use with inductively coupled plasma-mass spectrometry (ICP-MS) has been developed. The method uses 0.2 g of hair and 3 mL of concentrated nitric acid in an atmospheric pressurelow-temperature microwave digestion (APLTMD) system. This preparation method is useful in handling a large numbers of samples per day and may be adapted to hair sample weights ranging from 0.08 to 0.3 g. After digestion, samples are analyzed by ICP-MS to determine the concentration of Li, Be, B, Na, Mg, Al, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, As, Se, Rb, Sr, Zr, Mo, Pd, Ag, Cd, Sn, Sb, I, Cs, Ba, Pt, Au, Hg, Tl, Pb, Bi, Th, and U. Benefits of the APLTMD include reduced contamination and sample handling, and increased precision, reliability, and sample throughput.