Determination of glyoxal, methylglyoxal, and diacetyl in red ginseng products using dispersive liquid-liquid microextraction coupled with GC-MS.

A simple and rapid dispersive liquid-liquid microextraction method coupled with gas chromatography and mass spectrometry was applied for the determination of glyoxal as quinoxaline, methylglyoxal as 2-methylquinoxaline, and diacetyl as 2,3-dimethylquinoxaline in red ginseng products. The performance of the proposed method was evaluated under optimum extraction conditions (extraction solvent: chloroform 100 µL, disperser solvent: methanol 200 µL, derivatizing agent concentration: 5 g/L, reaction time: 1 h, and no addition of salt). The limit of detection and limit of quantitation were 1.30 and 4.33 µg/L for glyoxal, 1.86 and 6.20 µg/L for methylglyoxal, and 1.45 and 4.82 µg/L for diacetyl. The intra- and interday relative standard deviations were <4.95 and 5.80%, respectively. The relative recoveries were 92.4-103.9% in red ginseng concentrate and 99.4-110.7% in juice samples. Red ginseng concentrates were found to contain 191-4274 µg/kg of glyoxal, 1336-4798 µg/kg of methylglyoxal, and 0-830 µg/kg of diacetyl, whereas for red ginseng juices, the respective concentrations were 72-865, 69-3613, and 6-344 µg/L.

Identification of volatile markers for the detection of adulterants in red ginseng (Panax ginseng) juice using headspace stir-bar sorptive extraction coupled with gas chromatography and mass spectrometry.

Red ginseng (Panax ginseng) products are frequently adulterated by manufacturers with cheaper medicinal plant products including deodeok (Codonopsis lanceolata) and doraji (Platycodon grandiflorum) to increase profits. To identify possible volatile markers for the adulteration of red ginseng juices with deodeok or doraji, a headspace stir-bar sorptive extraction method was developed. Gas chromatography with mass spectrometry and untargeted metabolomics analysis revealed that 1-hexanol, cis-3-hexen-1-ol, and trans-2-hexen-1-ol are abundantly present in deodeok and doraji but not red ginseng. The peak area ratios in gas chromatograms of these compounds in red ginseng juices mixed with deodeok or doraji indicate that these volatile chemicals can be used as markers to detect the adulteration of red ginseng juice.

Development and Method Validation of Analysis of Urushiol in Sumac and Food Ingredients in Korea.

This study developed an analytical method to determine the urushiol content in sap and several foods. The full process for urushiol analysis consists of extraction, trimethylsilyl silylation, analysis, and identification via GC-MS, with each step optimized to attain the required accuracy and precision. Urushiol was separated from sap via liquid-liquid extraction and was derivatized via silylation. The components were analyzed using a polar capillary column and identified using GC-MS. The deviations of relative retention times and retention time windows were within 0.001 and 0.02 min, which satisfied the criteria of 0.06 and 0.03 min, respectively. The response of the urushiol standards tested was found to be linear in the investigated concentration range, with a correlation coefficient of 0.998. The LODs were between 1.74 and 2.67 µg/mL.

Rapid method for determination of anthocyanin glucosides and free delphinidin in grapes using u-HPLC.

A rapid method for the determination of anthocyanin glucosides and free delphinidin in food using ultra-high-performance liquid chromatography (u-HPLC) was validated through tests of precision, accuracy and linearity. The u-HPLC separation was performed on a reversed-phase C18 column (particle size 2 µm, i.d. 2 mm, length 100 mm) with a photodiode array detector. The limits of detection and quantification of the u-HPLC analyses ranged from 0.07 to 0.65 mg/kg for nine types of anthocyanin glucosides and from 0.08 to 0.26 mg/kg for delphinidin aglycone. The intra-day and inter-day precision of individual anthocyanin glucosides and delphinidin aglycone were less than 9.42%. All calibration curves showed good linearity (coefficient of determination = 0.99) within the tested ranges. The rapid and simultaneous u-HPLC method presented in this study significantly improved the speed, sensitivity and resolution of the analyses of nine types of anthocyanin glucosides and free delphidinin aglycone in grapes.

Determination of 22 ginsenosides in ginseng products using ultra-high-performance liquid chromatography.

A reverse-phase ultra-high-performance liquid chromatography (u-HPLC) method was developed for the rapid quantification of 22 ginsenosides in ginseng products. The proposed method for the analysis of ginsenosides is based on a heating-block method without further treatment. The u-HPLC separation was performed on a reversed C18 column (100 × 2 mm id, particle size 2 µm) followed by ultraviolet detection at 203 nm. Aqueous 50% methanol was used as the extraction solvent. The optimum amount of extraction solvent and the optimum extraction time were 20 mL and 20 min (extracted twice with 10 mL), respectively. The method validation parameters yielded good results for linearity, precision, accuracy and recovery. The recovery of ginsenosides from ginseng powder was greater than 98.1% and the limits of detection and quantification of the u-HPLC analysis were >0.6 and >1.8 mg/kg for ginsenosides. The calibration graphs for ginsenosides were linear from approximately 2.6 to 40.4 mg/kg for u-HPLC. The inter-day and intra-day precisions (relative standard deviation values) were <14.6 and 14.7%, except for Rg2(R) + Rh1(R).

Determination of hexanal in rice using an automated dynamic headspace sampler coupled to a gas chromatograph-mass spectrometer.

The aim of this study was to establish a method for the determination of hexanal as a lipid oxidation marker in rice. For the sample preparation, ground rice exhibited better sensitivity and reproducibility for the analysis of hexanal than whole rice. A total flow of purge gas of 300 mL at 20 mL/min of purge was sufficient to obtain the necessary sensitivity for the analysis of hexanal in rice. The total time for sample preparation and analysis for individual samples was approximately 15 min. A low incubation temperature of 30°C was chosen, not only to reduce the effect of water, but also to avoid excess lipid oxidation and loss of hexanal during the analysis. The limits of detection and quantification were 3.7 and 5.1 ng/g, respectively. Good linearity was obtained in the range from 5.1-500.0 ng/g. The recoveries of hexanal in rice were greater than 97.0 and 107.0% at the spiked levels of 5 and 50 ng/g, respectively, with relative standard deviations of 3.3 and 6.1%, respectively.

Determination of hexanal as an oxidative marker in vegetable oils using an automated dynamic headspace sampler coupled to a gas chromatograph/mass spectrometer.

An automated dynamic headspace sampler coupled to a gas chromatograph/mass spectrometer was evaluated as an oxidative marker to determine hexanal content in vegetable oils. For the effective analysis, a cooled injection system (CIS) was used to focus and to introduce the hexanal desorbed from the Tenax TA. The temperature of the CIS was maintained at -60 °C for 12 min before desorbing the hexanal. Hexanal was separated on a capillary column (DB-5, 0.25 mm × 60 m, 0.25 µm in film thickness) from 50 to 230 °C, followed by mass spectrometer-selected ion monitoring analysis at m/z 56. The instrumental response to hexanal was highly linear from 10 ng mL(-1) to 1 µg mL(-1) (r(2) = 0.9999). The relative standard deviation (RSD) of intra- and inter-day repeatability was acceptable, with values of less than 3.88 and 4.25%, respectively. The LOD and LOQ of hexanal were determined by gas chromatograph/mass spectrometer-selected ion monitoring to be 3.3 and 9.8 ng mL(-1), respectively. The acid value, peroxide value and fatty acid composition revealed a good correlation with the hexanal concentration.