Additives, determination high-performance liquid

H Terada, Y Sakabe. Studies on the analysis of food additives by high-performance liquid chromatography. V. Simultaneous determination of preservatives and saccharin in foods by ion pair chromatography. J Chromatogr 346(5) 333-340, 1985. 

Y Ikai, H Oka, N Kawamura, M Yamada. Simultaneous determination of nine food additives using high performance liquid chromatography. J Chromatogr 457 333-343, 1988. 

Martin-Calero, A., Pino, V., Ayala, J.H., Gonzalez, V. Alfonso, A.M. (2009). Ionic liquids as mobile phase additives in high-performance liquid chromatography with electrochemical detection Application to the determination of heterocyclic aromatic amines in meat-based infant foods. Talanta Vol.79 (No.3) 590-597. 

Clark et al. [81] determined the time course of A-acetylation of primaquine by Streptomyces roseochromogenous and Streptomyces rimosus by quantitative high performance liquid chromatographic analyses of the culture broths. The A-5-bistri-fluoroacetyl derivative of primaquine was used as an internal standard in the analysis for the quantitation of primaquine A-acetate in microbial culture broths. S. roseochromogenous forms the highest level of primaquine A-acetate at 24—36 h after substrate addition, while S. rimosus is slower in its acetylation, peaking at 3 days after substrate addition. The formation of a novel dimeric compound from the reaction of primaquine with 8-(4-phthalimido-l-methylbutylamino)-6-methoxy quinoline is also reported. 

Dean et al. [93] used a high performance liquid chromatographic method for the simultaneous determination of primaquine and carboxyprimaquine in plasma with electrochemical detection. After the addition of the internal standard, plasma was deproteinized by the addition of acetonitrile. Nitrogen-dried supernatants, resuspended in mobile phase were analyzed on a C8 reversed-phase column. Limits of detection for primaquine and carboxyprimaquine were 2 and 5 ng/mL with quantitation limits of 5 and 20 ng/mL, respectively. The assay sensitivity and specificity are sufficient to permit quantitation of the drug in plasma for pharmacokinetics following low dose (30 mg, base) oral administration of primaquine, typically used in the treatment of malaria and P. carinii pneumonia. 

Determination of brinzolamide and its 3 principal metabolites (the N-desethyl, A -desmethoxypropyl and O-desmethyl analogs) in whole blood and plasma from clinical and pre-clinical studies was performed using high performance liquid chromatography (HPLC) with UV detection. After addition of a known amount of internal standard (AL-5138, the 4-methoxybutyl analog of brinzolamide), the sample was acidified with 50 mM sodium phosphate buffer, pH 3.0 and extracted with ethyl acetate. 

The method of complete electrolysis is also important in elucidating the mechanism of an electrode reaction. Usually, the substance under study is completely electrolyzed at a controlled potential and the products are identified and determined by appropriate methods, such as gas chromatography (GC), high-performance liquid chromatography (HPLC), and capillary electrophoresis. In the GC method, the products are often identified and determined by the standard addition method. If the standard addition method is not applicable, however, other identification/determination techniques such as GC-MS should be used. The HPLC method is convenient when the product is thermally unstable or difficult to vaporize. HPLC instruments equipped with a high-sensitivity UV detector are the most popular, but a more sophisticated system like LC-MS may also be employed. In some cases, the products are separated from the solvent-supporting electrolyte system by such processes as vaporization, extraction and precipitation. If the products need to be collected separately, a preparative chromatographic method is use-... 

V Seidel, E Poglits, K Schiller, W Lindner. Simultaneous determination of ochratoxin A and zearalenone in maize by reversed-phase high-performance liquid chromatography with fluorescence detection and/8-cyclodextrin as mobile phase additive. J Chrom 635 227-235,1993. 

M Jimidar, TP Hamoir, A Foriers, DL Massart. Comparison of capillary zone electrophoresis with high-performance liquid chromatography for the determination of additives in foodstuffs. J Chromatogr 636 179-186, 1993. 

JF Lawrence, FE Lancaster. Determination of total non-sulphonated aromatic amines in food colour amaranth by dithionite reduction followed by derivatization and high performance liquid chromatography. Food Addit Contam 6(4) 415 -423, 1989. 

The reaction of sulfite with formaldehyde to form hydroxymethylsulfonate (HMS), which is very stable under the controlled conditions of this assay, was used as the first step in an analytical procedure to determine food-borne sulfite. The effect of mobile-phase pH on the stability of HMS during high-performance liquid chromatography was studied. It was found that on-column HMS dissociation to formaldehyde and bisulfite increased with the pH of the mobile phase therefore the relatively low pH 4.7, at which the dissociation of HMS was approximately 2%, was selected for the analysis. In addition, the release of sulfite from its reversibly bound forms in wine and other foods was examined as a function of the pH of the extraction medium by following the appearance of HMS formed from the reaction of the freed sulfite with formaldehyde. The rate of dissociation of the reversibly bound sulfite was relatively slow at pH 3 but very rapid at pH 7. 

A paired-ion, reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of sweeteners (dulcin, saccharin-Na, and acesulfame-K), preservatives (sodium dehydroacetate, SA, salicyclic acid, BA, succinic acid, methyl-para-hydroxybenzoic acid, ethyl-para-hydroxybenzoic acid, n-propyl-para-hydroxybenzoic acid, n-butyl-para-hydroxybenzoic acid, and isobutyl-para-hydroxybenzoic acid), and antioxidants (3-tertiary-butyl-4-hydroxyanisole and tertiary-butyl-hydroquinone). A mobile phase of acetonitrile-50 ml aqueous tr-hydroxyisobutyric acid solution (pH 4.5) (2.2 3.4 or 2.4 3.6, v/v) containing 2.5 mM hexadecyltrimethylammonium bromide and a Clg column with a flow rate of 1.0 ml/min and detection at 233 nm were used. This method was found to be very reproducible detection limits ranged from 0.15 to 3.00 p,g. The retention factor (k) of each additive could be affected by the concentrations of hexadecyltrimethylammonium bromide and a-hydroxyisobu-tyric acid and the pH and ratio of mobile phase. The presence of additives in dried roast beef and sugared fruit was determined. The method is suitable for routine analysis of additives in food samples (81). 

Mercapturates are proving to be very useful phase II reaction products for measuring exposure to xenobiotics, especially because of the sensitive determination of these substances by high-performance liquid chromatography (HPLC) separation, and fluorescence detection of their o-phthaldialdehyde derivatives. In addition to toluene, the xenobiotics for which mercapturates may be monitored include styrene, structurally similar to toluene acrylonitrile allyl chloride atrazine butadiene and epichlorohydrin. 

---