Using Single-Particle Inductively Coupled Plasma Mass Spectrometry to Determine the Changes of Silver Nanoparticles in Bread Induced via Simulated Digestion.

Silver nanoparticles (AgNPs), widely used in various fields of technology as an antimicrobial agent, represent a new type of environmental pollutant. Through various routes, AgNPs might penetrate into agricultural crops and foodstuffs. It is important to know if AgNPs contained in food persist in digested food and are therefore available for entering the inner organs of the consumer's body. Using the technique of single-particle ICP-MS, we analysed the changes in the number and size distribution of AgNPs added to a sample of bread submitted to in vitro simulated gastrointestinal digestion. The majority of silver, in terms of mass, was transformed from the state of particles to the dissolved state during bread digestion, but the number of particles was reduced by 25% only. The most abundant particle size was reduced from 60 nm to 49 nm. Hence, a substantial part of transformed nanoparticles is still present in food digestate. This means that AgNPs consumed together with food can theoretically enter the inner cells of human body.

Trimethylselenonium ion determination in human urine by high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry optimization of the hydride generation step.

This work describes the intricacies of the determination of the trimethylselenonium ion (TMSe) in human urine via high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). By definition, this technique requires that the separated TMSe can be online converted into a volatile compound. Literature data for the determination of TMSe via the hydride generation technique are contradictory; i.e., some authors claim that direct formation of volatile compounds is possible under reduction with NaBH4, whereas others reported that a digestion step is mandatory prior to conversion. We studied and optimized the conditions for online conversion by varying the mobile phase composition (pyridine, phosphate, and acetate), testing different reaction coils, and optimizing the hydride generation conditions, although technically no hydride (H2Se) is formed but a dimethylselenide (DMSe). The optimized conditions were used for the analysis of 64 urine samples of 16 (unexposed) volunteers and the determination of low amounts of TMSe (LOD = 0.2 ng mL-1). Total (specific gravity-corrected) selenium concentrations in the urine samples ranged from 7.9 ± 0.7 to 29.7 ± 5.0 ng mL-1 for individual volunteers. Four volunteers were characterized as TMSe producers (hINMT genotype GA) and 12 were non-producers (hINMT genotype GG). Urine of TMSe producers contained 2.5 ± 1.7 ng mL-1 of TMSe, compared to 0.2 ± 0.2 ng mL-1 for non-producers.

Can ultrafast single-particle analysis using ICP-MS affect the detection limit? Case study: Silver nanoparticles.

Ultrafast measurement using dwell times below 100 µs down to 10 µs is a relatively new feature of single particle analysis using ICP-MS. In this study, we tested the effect of shorter dwell times on the particle size detection limit (Dd.l.). Decreasing dwell times below 100 µs did not lead to a statistically significant decrease in Dd.l. The particle size detection limit (quadrupole ICP-MS) of silver nanoparticles (NP) was estimated to be approx. 10-11 nm. Ag NPs close to Dd.l. were analysed. The 14-nm NPs showed low detection yield; only 5% of number of NPs estimated from transport efficiency was detected. The 20-nm NPs showed 44% detection yield; only in the case of 30-nm NPs did the number of detected NPs correspond to transport efficiency. It is obvious that near Dd.l. estimates of NP concentrations should be made with great caution.

Non-spectral interferences in single-particle ICP-MS analysis: An underestimated phenomenon.

This work demonstrates the effect of NaCl and carbon-related interferences on the analysis of arsenic and silver nanoparticles (NPs) by single-particle inductively coupled plasma mass spectrometry. Spectral interference caused by ArCl+ ions disturbing arsenic NPs analysis was eliminated using ammonia as reaction gas in a dynamic reaction cell of inductively coupled plasma mass spectrometer. In comparison to aqueous dispersions, non-spectral interferences caused by sodium lead to under-evaluation of arsenic and silver NPs diameter by about 7% and 15% at NaCl concentration of 450 mg L-1 and about 28% and 41% at NaCl concentration of 4500 mg L-1, respectively. As a consequence of lower transport efficiency, sodium non-spectral interferences also lead to about a 9% lower number of detected NPs for dispersions of both arsenic and silver NPs in 4500 mg L-1 NaCl. On the contrary, measurement of NPs in matrices containing methanol gives results where Ag and As NPs diameter is over-evaluated by about 3% and 15% at a methanol content of 1% (v/v) and about 6% and 20% at a methanol content of 2% (v/v), respectively, in comparison to aqueous dispersions. In addition, the organic carbon species behave as surfactants and increase the transport efficiency; this leads to an increase in the determined number concentration of NPs. In comparison to aqueous dispersions, this is over-evaluated by about 17% for Ag NPs and about 10% for As NPs at a methanol content of 5% (v/v).

Peak bordering for ultrafast single particle analysis using ICP-MS.

The characterisation of inorganic nanoparticles (NPs) by single particle inductively coupled plasma mass spectroscopy is possible only if the spectrometer is capable of measurement with high time-signal resolution. The latest generation of spectrometers allow for measurements with dwell times (dt) shorter than the 100 µs gold standard, i.e. as low as 10 µs. The statistical behaviours of signals obtained with dt values of 10, 20, 50, and 100 µs were tested for 40, 60, and 100 nm silver NPs. Very low measured signals (units of counts) led to the occurrence of zero signal values inside the peaks corresponding to individual NPs. The probability of the occurrence of a zero signal inside the peak increased with decreasing dt and decreasing NP size. The standard approach to the bordering of the beginning and end of the peak by one zero signal point failed here and lead to the false detection of a larger number of smaller peaks. For example, in the case of 40 nm NPs a quadruple number of peaks were detected for a dt value of 10 µs compared to the 100 µs dt value; the mean peak width at 10 µs dt was approximately 220 µs, while at 100 µs dt it was 550 µs. The results tended to be less distorted when dt was longer and the NP size was larger. Low dt values also led to a distortion of the peak area distribution. For 40 nm NPs and 10 µs, the most frequent peak area and the width of the peak area distribution were not evaluated due to a non-Gaussian course; 20 µs dt caused (compared to 100 µs) a decrease in the most frequent peak area by approximately 35% (33 counts for 100 µs dt vs. 22 counts for 20 µs dt) and an increase in the width of the peak area distribution by 70% (10 counts for 100 µs dt vs. 17 counts for 20 µs dt). Therefore, new approaches to bordering peaks were tested, which consisted of searching for an uninterrupted zero signal point sequence with a total length of 50 µs or 100 µs. Only the criterion of a 100 µs delay between the two adjacent peaks resulted in values of the number of detected peaks, the most frequent peak areas, and the width of peak area distribution virtually independent of dt.

Internal standardisation for arsenic and its species determination using inductively coupled plasma mass spectrometry.

The signal of As measured by inductively coupled plasma mass spectrometry (ICP-MS) suffers from strong non-spectral interferences due to carbon and alkali metals. The accuracy of the determination of total As using ICP-MS and its species using anion-exchange chromatography coupled to ICP-MS was increased by using selenium as an internal standard. For chromatography, selenium was used in the form of a trimethylselenonium cation, which did not interact with the stationary phase and could be added directly to the mobile phase as the selenite was sufficient for total As determination. Selenium is able to correct non-spectral interferences caused by carbon or sodium up to concentrations of 3000 mg L-1 C and 35 mg L-1 Na, respectively, in the case of total As determination, and up to 3000 mg L-1 C and 3450 mg L-1 Na in the case of speciation analysis. Selenium as an internal standard was tested for the analysis of arsenobetaine in the DORM-2 standard reference material. The results were in good accordance with certified values regardless of NaCl spikes. Also, the results of total As determination in canned fish using a selenium internal standard were not affected by residual carbon in an imperfectly decomposed sample.

The Response of Macro- and Micronutrient Nutrient Status and Biochemical Processes in Rats Fed on a Diet with Selenium-Enriched Defatted Rapeseed and/or Vitamin E Supplementation.

The response of nutrient status and biochemical processes in (i) Wistar and (ii) spontaneously hypertensive (SHR) rats upon dietary intake of selenium- (Se-) enriched defatted rapeseed (DRS) and/or vitamin E fortification was examined to assess the health benefit of DRS in animal nutrition. Twenty-four individuals of each type of rat were used: The control group was fed with an untreated diet (Diet A). In Diets B and C, soybean meal was replaced with defatted DRS, which comprised 14% of the total diet. The selenized DRS application resulted in ~3-fold increase of Se content in the diet. Diet C was also fortified with the addition of vitamin E, increasing the natural content by 30%. The Se content of the blood and kidneys tended to increase in the DRS groups, where the changes were significant (P < 0.05) only in the case of SHR rats. The iodine (I) content and the proportion of iodide in rat livers indicated a lower transformation rate of iodide into organoiodine compounds compared to the control. Slight and ambiguous alterations in the antioxidative response of the rat were observed in the DRS groups, but the addition of vitamin E to the diet helped to moderate these effects.

Transfer of thallium from rape seed to rape oil is negligible and oil is fit for human consumption.

Rape and other Brassicaceae family plants can accumulate appreciable amounts of thallium from the soil. Because some species of this family are common crops utilised as food for direct consumption or raw materials for food production, thallium can enter the food chain. A useful method for thallium determination is inductively coupled plasma mass spectrometry. The limit of detection (0.2 pg ml(-1) Tl or 0.02 ng g(-1) Tl, taking in the account dilution during sample decomposition) found in the current study was very low, and the method can be used for ultra-trace analysis. Possible transfer of thallium from rape seed to the rape oil was investigated in two ways. The balance of thallium in rape seed meal (content 140-200 ng g(-1) Tl) and defatted rape seed meal indicated that thallium did not pass into the oil (p < 0.05). Moreover, the analyses of thallium in six kinds of edible rape seed oil and three kinds of margarines showed that the amount of thallium in rape seed oil is negligible.

Technical note: Efficient removal of a PCR inhibitory agent (vivianite) found on excavated bones.

During a rescue excavation in October 2011, archaeologists discovered a mass grave with 10 individuals. The skeletons should belong to victims of the battle of Reichenberg between the Austrian and Prussian armies on April 21, 1757. Several bones of the skeletons were covered with a blue colored encrustation. Initial DNA analysis failed due to strong inhibition. Chemical analysis of the bluish encrustation indicated the presence of the iron phosphate mineral vivianite (Fe3(PO4)2·(H2O)8). This technical note describes a novel procedure for the removal of this inhibitory substance.

The response of broccoli (Brassica oleracea convar. italica) varieties on foliar application of selenium: uptake, translocation, and speciation.

A model small-scale field experiment was set up to investigate selenium (Se) uptake by four different varieties of broccoli plants, as well as the effect of Se foliar application on the uptake of essential elements for plants calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), phosphorus (P), sulfur (S), and zinc (Zn). Foliar application of sodium selenate (Na2SeO4) was carried out at two rates (25 and 50 g Se/ha), and an untreated control variant was included. Analyses of individual parts of broccoli were performed, whereby it was found that Se in the plant accumulates mainly in the flower heads and slightly less in the leaves, stems, and roots, regardless of the Se rate and broccoli variety. In most cases, there was a statistically significant increase of Se content in all parts of the plant, while there was no confirmed systematic influence of the addition of Se on the changing intake of other monitored elements. Selenization of broccoli leads to an effective increase in the Se content at a rate of 25 g/ha, whereas the higher rate did not result in a substantial increase of Se content compared to the lower rate in all varieties. Therefore, the rate of 25 g/ha can be recommended as effective to produce broccoli with an increased Se content suitable for consumption. Moreover, Se application resulted in an adequate increase of the main organic compounds of Se, such as selenocystine (SeCys2), selenomethionine (SeMet), and Se-methylselenocysteine (Se-MeSeCys).

Diagnostic and prognostic value of presepsin in preterm deliveries.

PROBLEM: To evaluate the association between serum presepsin (soluble CD14 antigen subtype, sCD14-ST) levels soon after the appearance of signs of preterm delivery and preterm delivery within 48 h, before the 34th and 37th gestational weeks and the possible additional value of concurrently evaluated ultrasound vaginal cervicometry with serum presepsin measurement. METHODOLOGY: A total of 60 females were included. Serum presepsin was measured by a chemiluminescent immunoassay. Sonographic evaluation of cervical length in all females was conducted by transvaginal ultrasound. RESULTS: Patients who delivered within 48 h after analysis showed significantly higher presepsin concentrations compared to females with later deliveries. Higher presepsin was proven also for deliveries before/after weeks 34 and 37. A combined finding of cervical length shortening below 18 mm and presepsin level increasing above 623.5 pg/mL could point to the significantly high risk of preterm delivery. CONCLUSION: Elevated maternal serum concentration of sCD14-ST could be an independent and relevant risk factor for preterm delivery.

Receptor for advanced glycation end products (RAGE) and glyoxalase I gene polymorphisms in pathological pregnancy.

OBJECTIVES: The aim of the study was to analyze polymorphisms of receptor for advanced glycation end products (RAGE) gene, and glyoxalase I gene and soluble RAGE, sRAGE, in physiological and pathological pregnancy. DESIGN AND METHODS: Polymorphisms of RAGE gene (-429 T/C, -374 T/A, 557 G/A, 2184 A/G) and glyoxalase I gene (A419C) and sRAGE serum levels were determined in 284 women with pathological and physiological pregnancy. RESULTS: No differences in distribution of genotype and allelic frequencies of studied polymorphisms were found. GA genotype of RAGE 557 G/A polymorphism (known as Gly82Ser) is associated with lower sRAGE serum levels in healthy pregnant women compared to GG genotype (483 ± 104 vs. 692 ± 262 pg/mL, p=0.008). sRAGE correlates negatively with ALT in patients with pregnancy intrahepatic cholestasis (r=-0.536, p=0.05). CONCLUSIONS: We did not show any association of RAGE and glyoxalase I gene polymorphisms with pathological pregnancy, however further studies are needed to confirm the results.

Soluble receptor for advanced glycation end-products (sRAGE) and polymorphisms of RAGE and glyoxalase I genes in patients with pancreas cancer.

OBJECTIVES: The receptor for advanced glycation end-products (RAGE) takes part in the pathogenesis of many diseases, including diabetes mellitus and cancer. AGE-precursors are detoxified by glyoxalase (GLO). sRAGE, soluble RAGE, is an inhibitor of pathological effects mediated via RAGE. The aim was to study sRAGE and polymorphisms of RAGE (AGER) and GLO genes in patients with pancreas cancer (PC). DESIGN AND METHODS: The studied group consisted of 51 patients with PC (34 with impaired glucose tolerance-IGT, 17 without IGT), 34 type 2 DM and 154 controls. For genetic analysis, the number of patients was increased to 170. Serum sRAGE was measured by ELISA and all polymorphisms (RAGE -429T/C, -374T/A, 2184A/G, Gly82Ser and GLO A419C) were determined by PCR-RFLP and confirmed by sequencing. RESULTS: Soluble RAGE is decreased in patients with PC compared to patients with DM and controls (975+/-532 vs. 1416+/-868 vs. 1723+/-643pg/mL, p<0.001). Patients with PC and IGT have lower sRAGE levels compared to patients with PC without IGT (886+/-470 vs. 1153+/-616pg/mL, p<0.05). No relationship of sRAGE to the stage was found. We did not show any difference in allelic and genotype frequencies in all RAGE and GLO polymorphisms among the studied groups. CONCLUSION: This is the first study demonstrating decreased sRAGE in patients with pancreas cancer. Its levels are even lower than in diabetics and are lowest in patients with PC and IGT. Our study supports the role of glucose metabolism disorder in cancerogenesis. Further studies are clearly warranted, especially with respect to potential preventive and therapeutic implications.

RAGE polymorphisms, renal function and histological finding at 12 months after renal transplantation.

OBJECTIVES: Rage (receptor for advanced glycation end products) is involved in pathogenesis of many diseases. The aim of the study was to test whether polymorphisms of RAGE gene are associated with the outcome of kidney transplantation. DESIGN AND METHODS: Four polymorphisms of the RAGE gene (-429T/C, -374T/A, Gly82Ser and 2184A/G) were assessed in 145 renal transplant recipients and their relationship to histological changes in 12 months protocol kidney graft biopsy and renal function was examined. RESULTS: Genotype frequencies of each polymorphism corresponded to expected frequencies according to Hardy-Weinberg equilibrium. No differences between allelic and genotype frequencies among patients with normal histological findings, chronic allograft nephropathy and subclinical rejection were observed. CONCLUSION: This is the first study on polymorphisms of the RAGE gene in patients with the transplanted kidney. No association of RAGE selected gene polymorphisms with 12-months outcome of renal transplants was shown in study.

A419C (E111A) polymorphism of the glyoxalase I gene and vascular complications in chronic hemodialysis patients.

Advanced glycation end products (AGEs) take part in the pathogenesis of vascular, diabetic, and uremic complications. Their precursors are detoxified by the glyoxalase system. Our aim was to study A419C (E111A) single nucleotide polymorphism (SNP) of the glyoxalase I gene in hemodialysis (HD) patients. A419C SNP, several laboratory parameters including soluble receptor for AGEs (sRAGE), and clinical data were studied in 214 HD patients and 89 controls. Allelic and genotypic frequencies did not differ between HD patients and controls. A419C SNP was significantly linked with serum sRAGE, which sensitively reflects the AGE burden of the organism (3986 +/- 1638 pg/mL in the CC variant versus 3277 +/- 1398 pg/mL in the AC variant and 3297 +/- 1445 pg/mL in the AA variant, P < 0.01). In the CC variant, significantly higher prevalence of cardiovascular disease and peripheral vascular disease was found, while the prevalence of hypertension, diabetes mellitus, and dyslipidemia did not differ between genotypes. In summary, in this study we demonstrate for the first time the association of A419C polymorphism of the glyoxalase I gene with sRAGE levels and show the genetic predisposition to vascular complications in HD patients.

Receptor for advanced glycation end products (RAGE)--soluble form (sRAGE) and gene polymorphisms in patients with breast cancer.

Receptor for advanced glycation end products (RAGE) may be involved in the pathogenesis of the cancer progression and metastasis. Pathological effects mediated via RAGE are physiologically inhibited by soluble RAGE (sRAGE), so the higher sRAGE levels may confer the patients with cancer with better outcome. The aim was to study sRAGE and RAGE gene polymorphisms in patients with breast cancer. The authors studied sRAGE and RAGE polymorphisms in 120 patients with breast cancer (subdivided based on the clinical stage, histologic grading, expression of hormonal and Her2/neu receptors) and in 92 healthy controls. Despite higher serum concentrations of AGEs, serum concentrations of sRAGE were lower in patients with breast cancer compared to healthy controls (1581 +/- 777 versus 1803 +/- 632 ng/mL, p < 0.05). Serum levels of sRAGE were higher in patients with advanced breast cancer (stage III), lower grade and positive estrogen receptors, and intermediate positivity of Her2/neu receptors and were also influenced genetically (Gly82Ser and 2184 AG polymorphisms of the RAGE gene). Decreased sRAGE levels in patients with breast cancer may contribute to the progression of the disease. Patients with better outcome (low grade and positive estrogen receptors) have higher sRAGE levels. Progression of the disease, may, however, increase sRAGE levels, possibly as a compensatory mechanism to counteract further progression.

Receptor for advanced glycation end products--soluble form and gene polymorphisms in chronic haemodialysis patients.

BACKGROUND: The receptor for advanced glycation end products (RAGE) is involved in the pathogenesis of vascular and inflammatory diseases. The pathological effects mediated via RAGE are physiologically inhibited by soluble RAGE (sRAGE). Our aim was to study sRAGE and RAGE gene polymorphisms in haemodialysis (HD) patients. METHODS: A total of 261 stable HD patients were enrolled in the study and prospectively followed up for 30 months. At the begining of the study, sRAGE inflammatory and nutritional parameters were determined. RAGE polymorphisms were determined in a subgroup of 214 HD patients. A group of 100 healthy controls was used for comparison. RESULTS: In HD patients, sRAGE is elevated in comparison with healthy controls (3427+/-1508 vs 1758+/-637 pg/ml, P<0.001). It correlates negatively with residual diuresis (r=-0.193, P<0.05), with the acute phase reactants fibrinogen (r=-0.174, P<0.05) and orosomucoid (r=-0.135, P<0.05) and with the leucocyte count (r=-0.158, P<0.05). On the other hand, it is not related to the presence of diabetes mellitus, cardiovascular disease, nutritional status and mortality. The highest sRAGE levels are found in -429 CC and 2184 GG polymorphisms of the RAGE gene. The same results as for sRAGE were obtained for endogenous secretory RAGE (esRAGE), which correlated significantly with sRAGE (r=0.88, P<0.001). CONCLUSION: We conclude that in HD patients, sRAGE is increased due to decreased renal function, which is a very strong determinant of sRAGE levels, and is inversely related to inflammation. The highest sRAGE levels are influenced genetically. In our study, sRAGE levels were not related to mortality of HD patients.

Application of size-exclusion chromatography-inductively coupled plasma mass spectrometry for fractionation of element species in seeds of legumes.

Fractionation of soluble species of P, Mn, Fe, Co, Ni, Cu, Zn, Se and Mo in pea and lentil seeds was made by on-line hyphenation of size-exclusion chromatography (SEC) and inductively coupled plasma mass spectrometry. Seed samples were extracted with 0.02 mol l(-1) Tris-HCl buffer solution, pH 7.5. SEC was performed on Superdex 75 and Superdex Peptide columns (300 x 10 mm) with the same buffer solution as the mobile phase. Monitoring of oxide ion 47(PO)+ was used for detection of phosphorus compounds. Other elements were detected as ions of 55Mn, 57Fe, 59Co, 62Ni, 65Cu, 66Zn, 82Se and 95Mo nuclides. Elements in individual elution zones were quantified using external calibration. Complete chromatographic recoveries of elements were found in cases of phosphorus, nickel and copper. Substantial parts of manganese and zinc, as well as traces of cobalt, selenium and molybdenum are retained on the column. Injection of EDTA solution removes these elements from the column. Chromatographic profiles of pea and lentil samples are very similar for all elements except Mo. Main element species in the high-molecular-mass region (approx. 190,000 rel. mol. mass unit) were detected in case of Fe. Low-molecular-mass species (<2000 rel. mol. mass unit) as major element forms are typical for Cu and Zn.

Fractionation of phosphorus and trace elements species in soybean flour and common white bean seeds by size exclusion chromatography-inductively coupled plasma mass spectrometry.

Soluble species of phosphorus, sulfur, selenium and eight metals (Mn, Fe, Co, Ni, Cu, Zn, Mo and Cd) in soybean flour and common white bean seeds were investigated by size exclusion chromatography (SEC) and inductively coupled plasma mass spectrometry (ICP-MS). Samples were extracted by 0.02 mol l(-1) Tris-HCI buffer solution (pH 7.5). Fractionation of sample extracts by preparative scale SEC was accomplished using a Fractogel EMD BioSEC column (600 x 16 mm) and 0.02 mol l(-1) Tris-HCl buffer solution (pH 7.5) as mobile phase (flow rate: 2 ml min(-1)). A 2-ml sample was injected. Contents of elements in chromatographic fractions were determined by AAS, ICP-AES and ICP-MS. The elution profiles of P, Fe, Co, Ni, Cu, Zn and Mo in both samples were similar. Main species of Co, Ni, Cu, Zn and Mo were found in the low molecular weight region (2-5 kDa), whereas Fe is predominantly bound to high molecular weight compounds (180 kDa). The dominant phosphorus fraction was detected in the medium molecular weight region (10-30 kDa) and the other fraction in the low molecular weight region. Isotachophoretic analysis of chromatographic fractions revealed that the main phosphorus compound in the medium molecular weight region is phytic acid. SEC on Superdex 75 and Superdex Peptide columns (300 x 10 mm) was performed in on-line hyphenation with ICP-MS. The same mobile phase was used with a flow rate of 0.5 ml min(-1); volume of injected sample was 200 microl. Element specific chromatograms were obtained by continuous nebulization of effluent into ICP-mass spectrometer measuring intensities of 47(PO)+ and 48(SO)+ oxide ions and 55Mn, 57Fe, 59Co, 62Ni, 65Cu, 66Zn, 82Se, 95Mo and 114Cd nuclides. Chromatographic profiles of elements are generally analogous to those obtained with a Fractogel column, but better chromatographic resolution of separated species was achieved so that slight differences between samples were revealed. Estimated molecular weights of major phosphorus species in soybean flour and common white bean seed extracts are 6 and 3.6 kDa, respectively, whereas those of minor phosphorus species in both samples are 0.7 kDa. Traces of phosphorus were also detected in the high molecular weight region (130 kDa). Chromatograms of P, Ni, Cu, Zn and Mo compounds in both extracts are similar but not identical. Molecular weights of major Cu and Zn species are approximately 1 and 0.4 kDa for soybean flour and white bean seeds, respectively. In cases of Mn, Fe, Co and Se, the element profiles of soybean flour and white bean seed extracts are significantly different.

Quantification of copper and zinc species fractions in legume seeds extracts by SEC/ICP-MS: validation and uncertainty estimation.

Fractions of Cu and Zn species in legume samples (common white bean, pea, chick pea and lentil seeds and defatted soybean flour) were analysed by on-line hyphenation of size exclusion chromatography and inductively coupled plasma-mass spectrometry. Samples were extracted by 0.02 mol l(-1) Tris-HCl buffer solution, pH 7.5. The extraction efficiency lay in the region 60-90 and 60-80% for Cu and Zn, respectively. Quantification of elements in the individual chromatographic fractions was carried out by isotope dilution (ID) and external calibration (EC) techniques. For ID analysis the chromatographic effluent was mixed with the flow of (65)Cu and (68)Zn isotope enriched solution and the isotope ratio values (63)Cu/(65)Cu and ((64)Zn+(66)Zn)/(68)Zn were measured. In the case of EC technique calibration solutions of elements were injected to the flow of mobile phase by the second injector. Prior entering detector the effluent was mixed with the flow of internal standard solution (In, 50 mug l(-1)). Both methods have similar precision, however the behaviour of both studied elements was not the same. The chromatographic analysis itself was the main source of variability in the case of Cu. For Zn species analysis, the extraction process and the manipulation with the extract, played the significant role too. It was probably caused by lower stability of the present zinc chelates. The total amounts of Zn found in all chromatographic fractions represented 85-95% of Zn in sampled extract whereas those of Cu approached 100%. In case of small peaks the results of ID and EC were not the same. The EC results were lower then ID results. The great deal of results uncertainty accounts for the precision.