Liquid Chromatographic Determination of Residual Nitrite/Nitrate in Foods: NMKL Collaborative Study

Nitrite and nitrate are used as additives in the food industry to provide color and taste and to control undesirable gas and flavor production by anaerobic bacteria by virtue of their antimicrobial properties. The analytical method that has been widely used to determine nitrite and nitrate involves the use of toxic cadmium. In response to a request from the Nordic Committee on Food Analysis, a study was performed to obtain an alternative chromatographic method to determine residual nitrite and nitrate in meat products. The study was done in 3 stages: (1) comparative evaluation of the performance of 3 liquid chromatographic methods, (2) internal validation of the selected ion chromatographic method, and (3) a collaborative study in which 17 laboratories from European countries participated. Furthermore, the applicability of the method to matrixes other than meat and meat products was demonstrated. The results of the collaborative study show that the European Prestandard prENV 12014-4 is well suited for the determination of nitrite and nitrate in different foods (e.g., meat products, vegetables, baby food, and cheese). The limits of detection for nitrite and nitrate ions are 1 and 10 mg/kg, respectively. Recoveries of residual nitrite/nitrate ranged from 96 to 108%. Repeatability and reproducibility were satisfactory.

Phlorotannins from the Brown Alga Analipus japonicus1

New phloroglucinol derivatives were isolated from the ethanolic extract of ANALIPUS JAPONICUS (Harv.) Wynne, a north Pacific brown alga. Most of the compounds are fucols, i.e. phlorotannins in which the phloroglucinol units are connected by biaryl bonds. In addition to the four known oligomers difucol hexaacetate, trifucol nonaacetate, and tetrafucol-A and B dodecaacetates, two atropisomeric pentafucol pentadecaacetates, four atropisomeric hexafucol octadecaacetates, a heptafucol uneicosaacetate mixture, the following halogenated compounds could be isolated: bromo- and chlorotrifucol nonaacetate, 5'-bromo- and 5'-chlorotetrafucol-A dodecaacetate as well as 5'-bromo- and 5'-chloropentafucol-A pentadecaacetate. Three other phlorotannin derivatives belong to the phlorethol and fucophlorethol groups, respectively.