Orange juice: benzoic acid

An inter-laboratory study to determine benzoie acid in orange juices was reported, where a Hamilton PRP-1 column and a mobile phase mixture of 4 + 6 of aeetonitrile / phosphate buffer was used [36]. In this work, the juices were fortified with 0.5-10 ppm of benzoic acid. Statistical analysis of the results showed a relative reproducibility between laboratories ranged in the range of 6.92% to 15.97% for juice fortified with 1-10 ppm and 27.90% for juice fortified with 0.5 ppm. Mean recoveries ranged from 94.5% to 114%. 

AOAC Official Method 994.11 Benzoic acid in orange juice. In P Cunniff, ed. Official Methods of Analysis of AOAC International. 16th ed. Arlington, VA AOAC International, 1995, p 21. 

A validated method (No. 63) for the analysis of benzoic acid, sorbic and para-hydroxybenzoic acids in fruit juices has been published in the IFU handbook (Anon, 1995e). In this method the resolution takes place on a C8 reverse-phase column. With this solvent system (methanolic/ammonium acetate, pH 4.55) sorbic and benzoic acids elute quite quickly and the less polar para-hydroxybenzoate esters elute much later. The method does stipulate that caution has to be taken by orange juice due to possible interferences by natural materials in the juice that elute close to benzoic acid. As sorbic and benzoic acids elute quite early in the chromatogram using this method, it would... 

There is also a method in the AOAC manual for the analysis of benzoic acid in orange juice (994.11). However, this method was not designed to detect benzoic acid as a preservative. In Florida, when pulpwash was prepared benzoic acid used to be added as a marker, so that if the pulpwash was added to a juice it would be detected. However, it is believed that this practice has now been stopped. 

The same investigators qualitatively examined the organic acids in orange juice by GLC (100). They reported the following acids lactic, oxalic, malonic, phosphoric, succinic, benzoic, adipic, malic, tartaric, iso-citric, aconitic and citric. They (100,101) also examined commercial sucrose and citric acid in an attempt to detect acidic impurities in these adulterants. Differences in the acid patterns were observed, but they concluded that the levels in sugar and citric acid were too low to be useful in detecting adulterations. 

In comparing the same compounds while using PDMS sorbent, recovery from aqueous solution by SBSE was demonstrated [141] to be greater than recovery by SPME. Tredoux et al. [146] noted enrichment factors for benzoic acid in beverages to be approximately 100 times higher for SBSE relative to SPME, and Hoffmann et al. [147] reported sensitivities 100 to 1000 times higher by SBSE than by SPME for the extraction of analytes in orange juice and wine. 

Benzoic acid extracted from orange juice was the subject of a collaborative study that used a PRP-1 colunm (2. = 230 nm) and a 40/60 acetonitrile/water (SOn M phosphate buffer at pH 2.3) mobile phase [1048]. Elution was complete in <8 min and a detection limit of 0.5 ppm (S/N = 10] was reported. The working range was 0.5-10 ppm. 

Marsili, N. R., A. Lista, B. S. Fernandez Band, H. C. Goicoechea, and A. C. Olivieri. 2004. New method for the determination of benzoic and sorbic acids in commercial orange juices based on second-order spectrophotometric data generated by a pH gradient flow injection technique. J. Agric. Food Chem. 52(9) 2479-845. 

UV detection (185 nm) after capillary electrophoresis Oxalic, formic, malic, succinic, maleic, glutaric, pyruvic, acetic, lactic, citric, butyric, benzoic, sorbic, ascorbic, and gluconic acids Red and white wine, grape, apple, orange, and pineapple juice Capillary ion analyzer and fixed-wavelength UV-Vis detector with 185 nm wavelength filter 0.38 mg/L 1.31-40 mg/L Mato et al. (2006) ... 

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