Carrez reagents

Bakery Extraction with HjO, purification by Carrez reagent, centrifugation Spherisorb S5 ODS2(25x0.40cm) H2O/ACN (95/5) UV(284nm) [80]... 

Clarification of extracts can be accomplished with Carrez reagents (44). Purification has been performed by solid phase or partition. Wu et al. (47) absorbed saccharin onto ODS-4 cartridges and then eluted with methanol phosphate buffer. Puttemans et al. (28,50) extracted saccharin from soft drinks and yogurt by ion-pair extraction with tri-n-octylamine and back-extraction to an aqueous phase with perchlorate. Tereda and Sakabe (48) used cetrimide and Sep-Pak Cl8 in the cleanup of saccharin in coffee drink. The column was preconditioned with methanol, water, and 5 mM cetrimide. The sample, diluted in phosphate buffer pH 3.0 containing cetrimide was poured into the cartridge, washed with water, and eluted with acetonitrile water (1 1, v/v). Moriyasu et al. (40) added n-propylammonium bromide to the extract, passed it through a Bond Elut Cl 8 column, and eluted the sweetener with a mixture of methanol-water (4 6, v/v). The eluate was passed through a Bond Elut SAX column and washed with 0.5% phosphoric acid and water, and the sweetener was eluted with 0.3 N hydrochloric acid. 

Sample preparation for the determination of cyclamate by HPLC can be performed as described in Sec. I.C. (17,24,35,43). Potassium bromide can be used as an internal standard (17). In order to reduce interference, extracts can be clarified with Carrez reagents (24,35) or by solid-phase extraction. Nakazato et al. (43) added tetrabutylammonium bromide to the extract, adjusted pH to 4.0 -5.0, passed it through a Mega Bond Elut Cl 8 cartridge, and eluted cyclamate with a mixture of acetonitrile water (3 7, v/v). Lehr and Schmid (71) used an amino-anion-exchange column for the purification of cyclamate. After activation of the column with n-heptane, methanol, water, and 30% acetic acid, the sample was passed through the column and washed with water. Cyclamate was eluted with 2 M NaOH solution. 

The salts associated with cured meats, nitrates and nitrites, are assayed by aqueous extraction and colorimetric determination. The ISO methods involve extraction in hot water containing borax solution and deproteination of a portion of the extract with Carrez reagents. Nitrite (ISO 2918 1975) is determined directly by formation of an azo dye with sulfanilamide and N-(l-naphthyl)ethylenediamine dihydrochloride which is measured at 538 mn. Nitrate (including nitrite) (ISO 3091 1975) is determined by cadmium reduction to nitrite and azo dye formation. Reduction of nitrate to nitrite may be carried out on a special column (as in the ISO method) or using spongy cadmium. Care must be taken to prevent interference from ascorbic acid if it is present in the sample at relatively high levels (>20pgml ). 

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