Assessment of levels of V, Cr, Mn, Sr, Cd, Pb and U in bovine meat

Pollution of the environment with heavy metals can be a serious problem. In SouthAfrica, particularly, there are many sources of heavy metals, often due to smelter and mining activities. This has led to toxic metals in the environment that directly affect air, water and food. The presence of heavy metal residues in foodstuffs is potentially hazardous to humans and animals. Heavy metals accumulate in certain organs, particularly in the liver and kidney. The objective of this study was to determine the levels of V, Cr, Mn,Sr, Cd, Pb and U in bovine organs and tissues obtained from polluted areas of North West Province, South Africa. Bovine liver, kidney, muscle, fat and bone samples were freeze-dried, homogenized and mineralized using a microwave-assisted digestion system. The levels were quantified using dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS). A bovine muscle (NIST-RM8414) and bovine liver, reference material (NIST-RM1577b), were also analyzed and results agreed with certified values. The study revealed accumulation of Sr in bone, Cd, Pb and U in kidney and bone, Mn in liver and, V and Cr in kidney tissues of cattle.Tshwane University of Technology (TUT) and National Research Fund (NRF).http://journals.sabinet.co.za/sajchem/nf201

Heavy metal partitioning in sediments from rivers flowing through coal fields in Mpumalanga, South Africa

The association of elements Cd, Co, Cr, Fe, Mn, Pb, Ti and V with various geochemical phases in the sediments from the Olifants, Klein Olifants, Wilge rivers and a tributary of the Olifants River was studied using a four step sequential extraction scheme. By employing enrichment factors these elements were found to be contaminating the sediments. Sequential extraction enabled partitioning of the metals into exchangeable, reducible, oxidizable and residual fractions. Most of the elements were found to exist in the residual fraction, characterized by stable compounds. Application of risk assessment code (RAC) to the exchangeable fraction revealed that most of the elements posed a medium risk to aquatic life, with the exception of Co, Pb, and Mn which were classified into the high risk category. Non-residual/more bioavailable fractions were examined using statistics. Correlation analysis was employed to understand the interaction between the more bioavailable fractions of the metals with the reducible phase consisting of oxides of Fe-and Mn. These oxides contribute to the adsorption of trace metals onto sediments. Elements Co, V, Pb, Cr and Cd in the reducible fraction were found to be associated with Fe-oxides, while some V, Cr and Ti were associated with Mnoxides, as indicated by significantly high correlation coefficients. Through cluster and factor analysis three anthropogenic activities associated with mining and use of coal and iron and steel manufacturing were found to be contributing metals to the sediments.Tshwane University of Technology (TUT) and the National Research Fund (NRF).http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1863-06692016-06-30hb201

Investigation of biological samples for monofluoroacetate and Dichapetalum cymosum poisoning in southern Africa

A need has existed for the accurate identification of monofluoroacetate (MFA) poisoning in southern Africa. The development of a new method for the determination of MFA has made the analysis of a variety of biological samples (n=50) feasible. The method has been used in the laboratory over 24 months. Monofluoroacetate was present in 66% of samples from cases of suspected poisoning, reflecting the extent of the problem. Stability of MFA in samples was also determined so as to have a time-bound baseline for the acceptance of samples submitted. It was found that there was a decrease in the level of MFA and, after 14 days at room temperature, only 50% of the spiked dose could be identified. It is suggested that samples be analyzed within 7 days of mortality if they not kept frozen.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Speciation of chromium in cow’s milk by solid-phase extraction/dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS)

Chromium can act either as an essential micronutrient or a chemical carcinogen, depending on its oxidation state. Of the two most stable chromium oxidation states, Cr(VI) is a known carcinogen, while Cr(III) is an essential element. Determination of total Cr cannot therefore be used to evaluate food safety of dairy products, as speciation is required for accurate assessment of potential toxicity. In this study, total Cr was determined by DRC-ICP-MS after mineralisation of freeze-dried milk samples. Chromabond NH2 ion-exchange columns were used to separate Cr(VI) from Cr(III). During the separation process, Cr(VI) was selectively adsorbed onto the Chromabond NH2 column. The retained Cr(VI) was subsequently eluted with two column volumes of 2 M HNO3 and diluted to a final volume of 10 mL. After separation, the Cr(VI) was quantified by DRC-ICP-MS, using O2 as the reactive gas, to alleviate polyatomic ion interference. An O2 gas flow rate of 0.85 ml/min and a high-pass rejection parameter q (Rpq) = 0.5, provided the best compromise signal-to-noise ratio. The method was validated through determining the recovery in milk samples spiked with Cr(VI). The recoveries were quantitative and ranged from 96.4 to 99.2%. A whole milk powder reference material (NIST SRM 8435) was used to evaluate the accuracy of the total Cr quantification method. The observed value showed concordance with the certified value. The limits of detection (LOD) were 0.091 and 0.085 µg/L for total Cr and Cr(VI), respectively. These findings are important for the determination of maximum residue levels (MRLs) of Cr(VI) in dairy products

Quantification of trace elements in raw cow’s milk by inductively coupled plasma mass spectrometry (ICP-MS)

The levels of trace elements are an important component of safety and quality of milk. While certain elements such as chromium are essential at low levels, an excess can result in deleterious effects on human health. International quality control standards for milk are published by the Codex Alimentarious Commission and levels of heavy metals in milk intended for human consumption are routinely monitored. This paper describes a new method for demonstrating the levels of V, Cr, Mn, Sr, Cd and Pb in raw cow’s milk, using an ICP-MS. Samples (n = 24) of raw cow’s milk were collected from dairy farms close to mines in Gauteng and North West Provinces of South Africa. In order to destroy organic matrix, each freeze dried milk sample was mineralised by using a microwave assisted digestion procedure. Concentrations of trace elements in digested milk samples were measured by ICP-MS. A whole milk powder reference material (NIST SRM 8435) was used to evaluate the accuracy of the proposed method. It was found that the levels of V, Cr, Mn, Sr, Cd and Pb obtained using the new method showed concordance with certified values.National Research Fund (NRF) and Tshwane University of Technology (TUT

Infrared plasmonic filters integrated with an optical and terahertz multi-spectral material

Infrared plasmonic filters, consisting of subwavelength holearrays etched into metal films, exhibit characteristics that aretypically associated with the formation of surface plasmonpolaritons, namely enhanced transmission and wavelengthfiltering of the incident light. In this article, the properties thatdictate the plasmonic response of a material from the optical tothe infrared regime are investigated, followed by the design,simulation, fabrication and characterisation of an infraredplasmonic filter set. Infrared plasmonic filters have also beenintegrated with optical plasmonic filters and a terahertzmetamaterial to create a new hybrid multi-spectral materialthat can filter blue, green, red, near infrared, short waveinfrared and two mid infrared wavelengths whilst simulta-neously absorbing a single terahertz frequency. The multi-spectral material could be integrated with appropriate imagesensors to create a multi-spectral camera capable of operatingat optical, infrared and terahertz wavebands simultaneously

Identification and Occurrence of Analogues of Dechlorane 604 in Lake Ontario Sediment and their Accumulation in Fish

The dechlorane family of flame retardants, which includes Mirex (also known as Dechlorane), Dechlorane Plus (DP), and Dechloranes (Dec) 602, 603, and 604, were manufactured at a facility along the Niagara River, upstream of Lake Ontario. Some of these compounds remain in use. In a previous study, we found Mirex and Dec602 to have greater bioaccumulation potentials than Dec604 and DP based on calculated biota-sediment accumulation factors (BSAFs). In this study, analogues of Dec604, containing fewer bromines and mixed substitutions of bromine and chlorine, were identified in Lake Ontario sediment and fish using high and ultrahigh resolution mass spectrometric techniques. The tribromo-Dec604 (Br₃Dec604) analogue, known as Dechlorane 604 Component B (Dec604 CB), was present in lake trout and whitefish at concentrations of 10–60 ng/g lipid weight, approximately 50–200 times greater than concentrations measured for Dec604. In addition, BrDec604 and Br₂Dec604 analogues, and mixed Br₂Cl₂Dec604, Br₃ClDec604, Br₂ClDec604, and BrCl₂Dec604 analogues were also present. We have shown that solutions of Dec604 and Dec604 CB exposed to UV-light undergo photodebromination and give rise to the analogues found in sediment and fish. Dec604 CB and other lesser halogenated analogues of Dec604 show greater bioaccumulation potentials than Dec604, Dec602 and DP, based on BSAFs, which highlight the need to consider likely impurities and degradation products in the assessment of persistent, bioaccumulative, and toxic compounds