Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS

Lameiras, Jorge; Soares, Maria Elisa; Bastos, Maria de Lourdes; Ferreira, Milena do Prado

doi:10.1039/a804700f

Cited by 32 publications

(26 citation statements)

References 21 publications

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“…Lameiras et al 22 reported detection limits of 0.20 and 0.15 for total Cr and Cr(VI), respectively, in their studies of chromium speciation in UHT milk using ETAAS. These values are 2.20 and 1.76 times higher than the detection limits found for the method currently proposed.…”

Section: Limits Of Detection (Lod)mentioning

confidence: 99%

“…For proper comparison of the total Cr level with Cr(VI), the total Cr level in all freeze-dried milk samples, given by ng/g dry mass, were converted to mg/L ( Table 3). Considering that the solid extract of raw milk is 130 g/L, 22 and after converting the results into mg/L, levels ranging from 33.2 to 57.1 mg/L were found for total Cr. On the basis of these results, milk samples contained 1.31 to 3.28% Cr(VI).…”

Section: Concentrations Of Cr(vi) and Total Cr In Samplesmentioning

confidence: 99%

“…Pre-concentration and separation of Cr(VI) was performed according to the procedure described the in literature, 22 with slight modifications. Each 40 mL of milk was mixed with 5 mL of buffer (pH 3.5).…”

Section: Sample Preparationmentioning

confidence: 99%

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

Ambushe

McCrindle

2009

J. Anal. At. Spectrom.

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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 NH 2 ion-exchange columns were used to separate Cr(VI) from Cr(III). During the separation process, Cr(VI) was selectively adsorbed onto the Chromabond NH 2 column. The retained Cr(VI) was subsequently eluted with two column volumes of 2 M HNO 3 and diluted to a final volume of 10 mL. After separation, the Cr(VI) was quantified by DRC-ICP-MS, using O 2 as the reactive gas, to alleviate polyatomic ion interference. An O 2 gas flow rate of 0.85 ml/min and a high-pass rejection parameter q (Rpq) ¼ 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 mg/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.

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Section: Limits Of Detection (Lod)mentioning

confidence: 99%

Section: Concentrations Of Cr(vi) and Total Cr In Samplesmentioning

confidence: 99%

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

Ambushe

McCrindle

2009

J. Anal. At. Spectrom.

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“…Entre os trabalhos encontrados na literatura sobre determinação de metais em açúcar, a maioria utiliza AAS, preferencialmente com atomização eletrotérmica em forno de grafite. 18 quantificaram o teor de Cr (VI) e Cr total em leite por atomização eletrotérmica em forno de grafite. O Cr total foi determinado em leite através da adição de Triton X-100 e uma mistura de Pd e Mg utilizado como modificador químico.…”

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Determinação direta de crômio em açúcar e leite por espectrometria de absorção atômica com atomização eletrotérmica em forno de grafite

Quináia

Nóbrega

2000

Quím. Nova

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Recebido em 26/1/99; aceito em 26/7/99 DIRECT DETERMINATION OF CHROMIUM IN SUGAR AND MILK USING GRAPHITE FUR-NACE ATOMIC ABSORPTION SPECTROMETRY.A fast and direct method for the determination of Cr in milk and cane sugar suspensions using graphite furnace atomic absorption spectrometry with Zeeman-effect background correction is described. No sample pre-treatment was necessary, minimizing the risk of contamination. The concentration of chromium in cane sugar was evaluated using Cr reference solutions prepared in 1% v/v HNO 3 solution. The milk samples were introduced into the furnace with a mixture of amines for avoiding the autosampler blockage and foaming of milk. Chromium determination in milk was based on the standard additions method (SAM). The limit of detection and characteristic mass for cane sugar sample (30 µL) were 0,13 ng/ ml and 4,3 pg, and for milk sample (10 µL) were 0,23 ng/ml and 7,8 pg, respectively. The graphite tube lifetime was 300 firings for sugar-cane sample and 100 firings for milk sample. The heating program was implemented in 68 s.Keywords: milk; sugar-cane; chromium; graphite furnace; electrothermal atomization. ARTIGO INTRODUÇÃOA determinação de baixas concentrações de Cr é relevante considerando-se os efeitos fisiológicos desse elemento. O Cr possui papel importante no metabolismo da glicose, formando um complexo com moléculas de ácido nicotínico que auxiliam os processos de degradação do açúcar no sangue pela ação da insulina. Por outro lado, concentrações elevadas são letais, principalmente do metal na forma mais oxidada 1 . A determinação de Cr em matrizes complexas ainda é um desafio analítico criticamente afetado por contaminação durante processos de preparo de amostras, que podem causar elevados sinais para o branco analítico 2 . A cana contém 73-76% de água e 24-27% de sólidos, sendo que 10-17% são sólidos solúveis e 11-16 % são fibras. Considerando a baixa concentração de Cr e a complexidade do açúcar, que é essencialmente composto por material orgânico, como glicose (2-4%), sacarose (70-88%), frutose (2-4%), sais de áci-dos inorgânicos e orgânicos, proteínas, amido, goma, ceras e gorduras, a determinação de Cr nessa matriz não é trivial. Os principais aminoácidos encontrados na cana são ácido aspartático e glutâmico e os principais sais inorgânicos são cloretos e sulfatos de potássio, cálcio e magnésio 3 . O conteúdo de metais em cana de açúcar é variável e dependente da região de cultivo. Quanto maior for o número de processos envolvidos no tratamento para refino, menor será a quantidade de metais encontrados no açúcar 4 . O processo de refino do açúcar de cana envolve três etapas de clarificação (fosfatação, talo-fosfatação e carbonação) seguidas por procedimentos combinados com resinas de troca iônica e carvão ativo 3 . Dessa forma, o refinamento do açúcar geralmente causa completa eliminação do Cr 4 . Assim, maiores teores de Cr devem ser encontrados no açúcar mascavo e em derivados desse, como por exemplo a rapadura. Na legislação brasileira, segundo o Decreto 55871 5 ...

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“…The application tested here is the NH 2 column method, which selectively sorbed Cr(VI) while Cr(III) remains unsorbed. Originally, it was developed to determine Cr(VI) levels in infant milk products by Lameiras et al (1998) and Soares et al (2000). They found that the method was precise and accurate with good sensitivity for low Cr(VI) concentration.…”

Section: Introductionmentioning

confidence: 99%

Modification of the NH<sub>2</sub> column method for chromium speciation in surface water and soil water

Koivuhuhta¹,

Räisänen²,

Hämäläinen³

et al. 2008

Bull Geol Soc Finland

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A new application of the NH 2 column method has been tested for speciation of Cr(VI) in soil water and surface water. Soil water and surface water samples were collected from two sites near the world's largest stainless steel production plant, Outokumpu Tornio Works, about 10 km south of the City of Tornio, Finland. Dissolved chromium species [Cr(VI) and Cr(III)] were quantified immediately from the water samples with the NH 2 (aminopropylmodified silica) column method and a graphite furnace atomic absorption spectrophotometer (GFAAS) and then three months later after the collection. The sum of Cr species concentration determined by the method was equal to total dissolved Cr concentration measured by inductively coupled plasma mass spectrometry (ICP-MS). The method was precise and selective for environmental water samples at low concentrations, and it fractionated Cr species with 100 % specificity without noteworthy interference from other metals. Some difficulties appeared with Cr standard solutions made with deionised water. In addition, the soluble form of Cr(VI) was preserved in a stable form for three months both in the refrigerator and freezer, and almost all the dissolved Cr was in the Cr(VI) form.

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Quantification of total chromium and hexavalent chromium in UHT milk by ETAAS

Cited by 32 publications

References 21 publications

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

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

Determinação direta de crômio em açúcar e leite por espectrometria de absorção atômica com atomização eletrotérmica em forno de grafite

Modification of the NH<sub>2</sub> column method for chromium speciation in surface water and soil water

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