Determination of organic acids in wine by zone electrophoresis on a chip with conductivity detection

Abstract

An appropriate combination of separation mechanisms (simultaneous use of differences in pK values, host-guest complexations, and the ionic strength dependences of the actual ionic mobilities) provided zone electrophoresis (ZE) resolution of 22 organic and inorganic acids expected in wines on a polymethylmethacrylate (PMMA) chip with integrated conductivity detection. These separating conditions offered a framework for the ZE determination of organic acids responsible for some important organoleptic characteristics of wines (tartrate, malate, succinate, acetate, citrate, and lactate). The ZE procedure developed in this context is simple and rapid (ca. 10 minutes' analysis time), while affording reproducible migration and quantitation data for the acids. For example, 0.8-2.0% RSD values characterized the migration times of the acids for 25 repeated ZE runs with the same sample carried out in 5 days in the background electrolyte solution prepared freshly on a daily basis, while 3-5% RSD values were typical for the accompanying peak area data. The concentration ranges within which the acids of analytical interest could be determined in one ZE run covered all wine samples included in our study (100-400-fold sample dilutions were needed to work under the conditions corresponding to the validities of the calibration data). 90-110% recoveries of the acids as obtained repeatedly for one of the reference wine samples used in our experiments indicate a good predisposition of the present method to provide accurate analytical results. This statement also supports the results from the determination of the acids in reference wine samples with claimed concentrations of malic (five samples), tartaric (one sample), and lactic (one sample) acids.

Quality control of herbal medicines by capillary electrophoresis: Potential, requirements and applications

“…There are numerous other reports for the analysis of short chain organic acid (e.g. tartaric, malic and citric acid) in food items such as wine [97][98][99][100][101], juices [102,103] or honey [104] by CE. Yet, others related to herbal medicines are scarce (Table 4).…”

Recent advances in the application of capillary electromigration methods for food analysis

“…This idea can be easily understood considering the example of microchips and their recent applications in food analysis [98,[175][176][177][178][179][180][181][182][183][184][185] (see Table 4). Thus, as can be deduced from Table 4, microchips have already been applied in food analysis to differentiate species [175], to detect food spoilage bacteria [98], to detect GMOs [176,184], and to analyze small organic and inorganic compounds such as amino acids, sugars, etc [177][178][179][180][181][182][183]. Moreover, different detection schemes have been developed to be used together with microchips including LIF [98,175,176,184], conductivity [178][179][180][181], amperometric [182,183] and MS detectors [186].…”

“…Thus, as can be deduced from Table 4, microchips have already been applied in food analysis to differentiate species [175], to detect food spoilage bacteria [98], to detect GMOs [176,184], and to analyze small organic and inorganic compounds such as amino acids, sugars, etc [177][178][179][180][181][182][183]. Moreover, different detection schemes have been developed to be used together with microchips including LIF [98,175,176,184], conductivity [178][179][180][181], amperometric [182,183] and MS detectors [186]. This will make possible to address and solve an even wider number of problems in food science.…”

Fabrication, modification, and application of poly(methyl methacrylate) microfluidic chips

“…Masar et al [118] have determined organic and inorganic acids in wine by ZE on a PMMA chip with conductivity detection. The separation and detection of 22 organic and inorganic acids expected in wines were performed on a PMMA chip with integrated conductivity detection.…”