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The biological effects of black garlic are stronger than those of fresh garlic, but despite the increasing manufacture of black garlic products, no specifications for controlling their quality have been identified. The most commonly used biological marker of quality is S-allylcysteine (SAC), which is a core active compound in the aforementioned products. SAC content is typically determined using high-performance liquid chromatography with ultraviolet detection, but this method presents many problems because of its complex matrices. To determine the content of SAC in black garlic, this study established a sensitive and reproducible method grounded in ultrahigh- performance liquid chromatography coupled with tandem mass spectrometry. The instrument used is equipped with a triple quadrupole mass detector with an electrospray ionization source. The analysis involved solid-phase extraction using a strongly acidic cationic exchange agent, which enabled the direct examination of samples without the need for derivatization and the determination of SAC content in 5 min. The established method was fully validated in terms of linearity, sensitivity, precision, repeatability, and recovery and was successfully applied in characterizing the quality of some black garlic products manufactured in Vietnam. The proposed procedure exhibited high linearity (R2 = 0.9993) at a limit of detection of 0.25 ng/mL, which is lower than those of other assay techniques. The results indicated that various black garlic products have different SAC contents. This study may be useful in the development of standards for the quality of black garlic. [ABSTRACT FROM AUTHOR]

Focuses on capillary electrophoresis and contactless conductivity detection of ions in narrow inner diameter capillaries. Ability of the device to work without a galvanic contact of the electrolyte and the electrodes; Basis of the conductivity sensor on two metal tubes that act as cylindrical capacitors.

Looks at a study on the contactless conductivity detection for capillary electrophoresis. Results of the study; Factors influencing the detection for capillary electrophoresis.

Focuses on coelectoosmotic capillary electrophoresis, pertaining to the separation of priority pollutant phenols. Indepth look at mixtures containing priority pollutant phenols; Evaluation on the influence of acetonitrile on the micellar solubilization; Factors of cresol and xylenol isomers on the CTAB concentration.

Discusses the influence of organic solvents in coelectroosmotic capillary electrophoresis of phenols. Peak shapes and separation of positional isomers as they relate to the addition of organic solvents as modifiers in capillary electrophoresis; Achievement of a reversal of electroosmotic flow (EOF) to reduce analysis time by migration of the anionic analytes.

Presents the author's accounts of the 2nd Conference on Ion Analysis in Berlin, Germany in February 2003. Analysis of small inorganic and organic ions; Determination of anions and cations; Description of the scientific program.

Capillary Electrophoresis (CE) has become an accepted method for the separation of inorganic and organic ions. Usually, direct and indirect optical detection methods are used in conventional CE. However, with contactless conductivity detection, much better detection limits in the low ppb range are obtained compared to optical detection modes. Besides offering great flexibility in capillary handling, this detection technique can be performed on-capillary also with capillaries made of other materials than fused silica (PEEK, Teflon) and with capillaries having very small inner diameters.

A miniaturized capacitively coupled contactless conductivity detector (mini-C(4)D) cell has been designed which is small enough to allow it to slide along the effective capillary length inside the capillary cassette of an Agilent capiillary electrophoresis system (CE) (or other CE brand of similar construction), including the possibility of positioning it close to the point of optical detection (4 cm), or even putting two such detector cells in one cassette. The cell was tested and the performance characteristics (noise, sensitivity, and peak width) were compared with those obtained with the previously used large C(4)D cell. No significant differences were observed. The mini-C(4)D was used in simultaneous separations of common cations and anions where its advantage over a larger C(4)D cell is the ability to vary the point of detection with the mini-C(4)D cell continuously at any point along the capillary length, so that the optimum apparent selectivity can be chosen. Other applications include providing a convenient second point of detection in addition to photometric detection, such as to measure accurately the linear velocity of a zone, or to allow placement of two mini-C(4)D cells in one capillary cassette simultaneously.

Capacitively coupled contactless conductivity detection (C(4)D) has become an accepted detection method in capillary electrophoresis (CE) for a variety of analytes. Advantages of this technique over optical detection modes and galvanic contact conductivity detection include great flexibility in capillary handling and rather simple mechanical parts and electronics, as it can be performed in an on-capillary mode. Furthermore, the detection principle can be used with capillaries made of other materials than fused silica (PEEK, Teflon), with chip-based separation technologies, or with capillaries having very small inner diameters. This review presents a discussion of the published literature on C(4)D for CE and capillary electrochromatography.

A number of small inorganic anions and cations were separated after injection of the sample into both ends of a separation capillary. The ions were detected using a capacitively coupled contactless conductivity detector (CCCCD) which could be placed at various positions along the capillary length. Counter-directional migration of anions and cations occurs towards the detector, which is placed at an appropriate position along the capillary so that the migration order is determined by the respective effective separation capillary lengths for both anions and cations. As the CCCCD detector can be easily moved to any position along the capillary, virtually any effective separation length can be attained. Depending on the number of analytes in the sample, one can choose to obtain either electropherograms with inter-migrating zones of cations and anions or separations with distinct regions of anion and cation zones, respectively. A new term 'apparent separation selectivity' is introduced to describe the manner in which the position of the detector can be varied in order to determine the final separation.