Speciation analysis of Cr(III) and Cr(VI) in bread and breakfast cereals using species-specific isotope dilution and HPLC-ICP-MS

Atomic spectrometry update: review of advances in the analysis of clinical and biological materials, foods and beverages

“…Subsequently, they went on to apply this method to assess the presence and fate of Cr species in raw and cooked milk and meat samples, 145 rice 146 and bread and breakfast cereals. 147 The procedure was based on the formation of a Cr III –EDTA complex, negatively charged, followed by the reduction of CrO 4 2− to Cr III with 1,5-diphenylcarbazide and subsequent complexation with its oxidised form (DPC) to form a positively charged Cr III –DPC complex. For the sequential complexation of Cr III and Cr VI , 0.3 g of sample were diluted with 16 mL of EDTA and heated at 70 °C for 25 min in a heating block.…”

“…Chromium speciation was also the subject of a study carried out by Saraiva et al 147 The team used SSID-HPLC-ICP-MS to ascertain Cr III and Cr VI levels in breads and breakfast cereals. Total Cr was also measured by ICP-MS after MAD.…”

Atomic Spectrometry Update: review of advances in elemental speciation

“…In a series of four papers, Jitaru, Sloth and co-workers described the development of a double-spike SSID HPLC-ICP-MS method for the determination of Cr species 89 and its application to the analysis of meat and dairy products, 89,90 bread and breakfast cereals 91 and rice. 92 The method consisted of sequential extraction/complexation of the two species: Cr III with EDTA and Cr VI with DPC (though the researchers consider that DPC reduces Cr VI to Cr III before complexation).…”

“…They also noted that Cr VI spiked into the samples was stable for a week. When the procedure was applied to the analysis of bread and breakfast cereals, 91 A method based on electrokinetic sample pre-treatment has been devised. 93 Although the researchers describe this as a "paper-based analytical device", the separation was, in fact, carried out on a glass bre lter membrane cut to give a 35 mm  4 mm rectangle that was wetted with triammonium citrate and placed above two reservoirs 33 mm apart, into which 300 mL of the same sample solution was placed.…”

“…They also noted that Cr VI spiked into the samples was stable for a week. When the procedure was applied to the analysis of bread and breakfast cereals, 91 they found that most of the Cr was erroneously identified as Cr VI . They suggested that Cr III was not released during the first step of the extraction (EDTA chelation) but was released during the second, DPC-derivatisation step and was thus erroneously identified as Cr VI .…”