Evaluation of various digestion procedures for trace element contents of some food materials

Analysis of cadmium, nickel, and lead in commercial moist and dry snuff used in Pakistan

The extent to which smokeless tobacco endangers human health is an ongoing subject of debate. In this study, concentrations of toxic metals, cadmium (Cd), lead (Pb), and nickel (Ni), were measured in different snuff products (dry brown and black and moist green and brown), available and consumed in Pakistan. Concentrations of Cd, Pb, and Ni were determined in 23 samples of various brands of snuff by electrothermal atomic absorption spectrometry, after microwave-assisted acid digestion. The reliability of methodology was assured by analyzing certified reference material. The resulted data of toxic metals in different snuff products are comparable to the existing information with limited exceptions. It was estimated that 10 g intake of different types of snuff could contribute 14-68, 17-47, and 20-73 % of the provisional maximum tolerable daily intake for Cd, Ni, and Pb, respectively.

Fatty acids, tocopherols, selenium and total carotene of pistachios (P. vera L.) from Diyarbakir (Southeastern Turkey) and walnuts (J. regia L.) from Erzincan (Eastern Turkey)

In this study, 14 well-adapted genotypes of pistachio (Pistachio vera L.) grown in Diyarbakır (Southeastern Turkey) and 15 walnut (Juglans regia L.) genotypes grown in Erzincan (Eastern Turkey) have been studied. Pistachio genotypes contained 8.16-9.33% palmitic acid, 0.54-0.68% palmitoleic acid, 2.35-4.21% stearic acid, 67.81-76.82% oleic acid, 9.42-18:32% linoleic acid, 0.27-0.38% linolenic acid and 0.19-0.33 % arachidic acid. The range of selenium, α-tocopherol, γ-tocopherol, δ-tocopherol, α-tocotrienoid, γ-tocotrienoid and total carotenoid of these promising genotypes were found to be between 11.44 and 190.71 ng/g, 1.36 and 26.93, 36.17 and 170, 0.45 and 2.61, 0.96 and 3.76, 2.33 and 37.72 and 1.01 and 4.93 mg/kg, respectively. Linoleic acid ranging from 43.19% to 53.16% was the most abundant fatty acid in 15 pomologically selected walnut genotypes, followed by oleic and linolenic acids (31.91% and 11.46%, respectively). Their selenium contents ranged between 7.25 and 57.67 ng/g. γ-Tocopherol was the predominant tocopherol in walnut genotypes. Pistachio and walnut genotypes with higher unsaturated fatty acids, tocopherols and selenium contents may be valuable for nutritional breeding efforts.

Application of the interference standard method for the determination of sulfur, manganese and iron in foods by inductively coupled plasma mass spectrometry

The interference standard method (IFS) is evaluated to improve the accuracy of the determination of S, Mn and Fe in meat and grain samples by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). Due to ICP-QMS relatively low resolution, polyatomic interferences caused by (16)O(2)(+), ((16)OH)(2)(+), (40)Ar(14)NH(+), and (40)Ar(16)O(+), for example, can compromise determinations at m/z 32, 34, 55, and 56, respectively. In IFS, differently from traditional internal standard methods, plasma naturally occurring species are used to correct for variations in the interference signal rather than the analyte signal. The method is based on the hypothesis that the interfering ion and the IFS probe present similar behaviors in the plasma, and that by using the analytical (analyte plus interference)/IFS signal ratio one could reduce variations due to interference and, consequently, improve accuracy. In this work, this strategy is evaluated in real sample applications and significant improvements on accuracy are observed for (32)S, (34)S, (55)Mn, and (56)Fe determinations. Recoveries ranging from 72% for Mn to 105% for Fe in two different standard reference materials are obtained using the (38)Ar probe. These analytes are successfully determined in meat and grain samples with concentrations ranging from 4.42 μg g(-1) for Mn in corn to 7270 μg g(-1) for S in chicken liver. The method is compared with other strategies such as internal standardization and mathematical correction. No instrumental modification or introduction of foreign gases is required, which is especially attractive for routine applications.

Determination of some traces metal levels in cheese samples packaged in plastic and tin containers by ICP-OES after dry, wet and microwave digestion

The concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, Se and Zn in cheese samples packaged in plastic and tin containers were analyzed using inductively coupled plasma-optical emission spectrometry after microwave, wet and dry digestion processes. In order to evaluate the best digestion method, the relationships between the concentrations of trace metals in cheese samples after microwave digestion was compared by wet and dry ashings. Microwave digestion was found fast, reliable, simple, and excellent procedure in comparison with dry and wet ashing methods. The accuracy of the digestion procedures was determined by using standard reference material (GBW 07605-Tea). The order of levels of the elements in the white cheese samples packaged in tin containers was determined to be Cd<Co<Mn<Cr<Se<Pb<Cu<Ni<Zn, after microwave digestion and cream cheese samples in plastic containers Cd<Mn<Co<Cr<Se<Pb<Ni<Cu<Zn, respectively. There were considerable differences among of the studied element contents of cheese samples packaged in tin and plastic containers, indicating that cheese types and packaging materials play a key role in the content of trace metal.

Rapid and simultaneous determination of essential minerals and trace elements in human milk by improved flame atomic absorption spectroscopy (FAAS) with microwave digestion

A method for the simultaneous and economical determination of many trace elements in human milk is developed. Two multi-element hollow cathode lamps (HCLs) were used instead of single-element HCLs to improve the sample throughput of flame atomic absorption spectroscopy (FAAS). The microwave digestion of milk is optimized prior to detection, and the performance characteristics of the improved analysis method are identified. Clinical samples are detected by both FAAS and inductively coupled plasma-optical emission spectroscopy (ICP-OES) for methodology evaluation. Results reveal that the proposed FAAS with multi-element HCLs could determine six essential minerals and trace elements within 15 min. This method provides a linear analytical range of 0.01-10 mg L(-1). For Ca, Cu, Fe, Mg, Mn, and Zn, the limits of determination are 1.5, 3, 1.8, 2.2, 2.1, and 1.3 microg L(-1), respectively. The mean relative standard deviations (RSDs) of intra- and interassays are lower than 7%. Excellent operational characteristics of rapidity, simplicity, and economy make the proposed method a promising one for the quantification of trace elements in human milk in clinics of underdeveloped areas.

A fast and accurate microwave-assisted digestion method for arsenic determination in complex mining residues by flame atomic absorption spectrometry

A fast and accurate microwave-assisted digestion method for arsenic determination by flame atomic absorption spectrometry (FAAS) in typical, complex residues from gold mining is presented. Three digestion methods were evaluated: an open vessel digestion using a mixture of HCl:HNO(3):HF acids (Method A) and two microwave digestion methods using a mixture of HCl:H(2)O(2):HNO(3) in high (Method B) and medium-pressure (Method C) vessels. The matrix effect was also investigated. Arsenic concentration from external and standard addition calibration curves (at a 95% confidence level) were statistically equal (p-value=0.122) using microwave digestion in high-pressure vessel. The results from the open vessel digestion were statistically different (p-value=0.007) whereas in the microwave digestion in medium-pressure vessel (Method C) the dissolution of the samples was incomplete.