Contents of chlorogenic acids and caffeine in various coffee-related products.

Coffee is the most popular beverage in the Republic of Korea, other than Korea's traditional green tea. Coffee contains many physiologically active substances, such as chlorogenic acids (CGAs) and caffeine. Previous studies have focused on the content of CGAs and caffeine in brewed coffee. This study quantified the total amounts of CGAs and caffeine using high-performance liquid chromatography coupled with a diode array detector in 83 various coffee-related products, such as instant coffee, roasted and ground coffee sold in supermarkets, ready-to-drink coffee, and Americano coffee sold in franchise restaurants in the Republic of Korea. According to the results of this study, the coffee with the highest content of CGAs was unblended roasted and ground coffee sold in supermarkets, with a mean value of 194.1 ±â€¯67.7 mg/serving, and the most caffeine-rich coffee was Americano coffee from coffee shops, with a mean value of 166.1 ±â€¯37.5 mg/serving. The caffeine/CGA ratios were determined in various coffee beverages because they are useful parameters for estimating the human health. The lowest mean caffeine/CGAs ratio of 0.5 ±â€¯0.1 was found in unblended ground coffee sold in supermarkets, and the highest mean ratio of 2.5 ±â€¯1.4 was found in milk-added ready-to-drink coffee. Adult caffeine tolerance is defined as 400 mg a day in the Republic of Korea. However, this value highlights the importance of medicines, carbohydrate beverages, tea, chocolate, cocoa products, energy drinks and other sources of caffeine that can contribute to the total intake of caffeine.

Development and validation of a solid-phase extraction method coupled with LC-MS/MS for the simultaneous determination of 16 antibiotic residues in duck meat.

The present study was carried out to determine 16 antibiotics belonging to seven different groups (tetracyclines, sulfonamides, penicillins, fluoroquinolones, macrolides, lincosamides and trimethoprims) in duck meat. A solid-phase extraction method based on Oasis HLB cartridges coupled with liquid chromatography-electrospray ionization tandem mass spectrometry was developed. Solutions of 0.1 m ethylenediaminetetraacetic acid disodium salt and 2% trifluoroacetic acid were used for the preliminary extraction of the target antibiotics from duck meat and n-hexane was used for purification prior to solid-phase extraction. Mobile phases composed of 0.1% trifluoroacetic acid in distilled water (solvent A) and 0.1% trifluoroacetic acid in methanol (solvent B), combined with a reversed-phase C18 analytical column, provided the optimal separation and signal intensity. The linearity of the method was assessed using six concentrations (5, 10, 20, 30, 40, and 50 µg/kg), and the recoveries, which were calculated at three spiking concentrations (5, 10 and 20 µg/kg), were in the range 69.8-103.3% with relative standard deviations (RSDs) ≤ 6.9% for the 16 tested antibiotics. Matrix effects ranging from -47.2 to -13.5% were observed for all the analytes, and the limits of quantitation (LOQ), which ranged from 4.93 to 26.21 µg/kg, were much lower than the maximum residue limits (MRLs) set by various regulatory authorities. Ten samples from a market were tested, and none of the target analytes were detected. Thus, a simple and versatile protocol has been developed to detect and quantify 16 antibiotics in duck meat samples.

Dynamic residual pattern of azoxystrobin in Swiss chard with contribution to safety evaluation.

This study aimed at quantifying the residual amount of azoxystrobin in Swiss chard samples grown under greenhouse conditions at two different locations (Gwangju and Naju, Republic of Korea). Samples were extracted with acetonitrile, separated by salting out, and subjected to purification by using solid-phase extraction. The analyte was identified using liquid chromatography-ultraviolet detection. The linearity of the calibration range was excellent with coefficient of determination 1.00. Recovery at three different spiking levels (0.1, 0.5, and 4 mg/kg) ranged between 82.89 and 109.46% with relative standard deviation <3. The limit of quantification, 0.01 mg/kg, was considerably much lower than the maximum residue limit (50 mg/kg) set by the Korean Ministry of Food and Drug Safety. The developed methodology was successfully used for field-treated leaves, which were collected randomly at 0-14 days following azoxystrobin application. The rate of disappearance in/on Swiss chard was ascribed to first-order kinetics with a half-life of 8 and 5 days, in leaves grown in Gwangju and Naju greenhouses, respectively. Risk assessments revealed that the acceptable daily intake percentage is substantially below the risk level of consumption at day 0 (in both areas), thus encouraging its safe consumption.

Determination of chlorogenic acids and caffeine in homemade brewed coffee prepared under various conditions.

Coffee, a complex mixture of more than 800 volatile compounds, is one of the most valuable commodity in the world, whereas caffeine and chlorogenic acids (CGAs) are the most common compounds. CGAs are mainly composed of caffeoylquinic acids (CQAs), dicaffeoylquinic acids (diCQAs), and feruloylquinic acids (FQAs). The major CGAs in coffee are neochlorogenic acid (3-CQA), cryptochlorogenic acid (4-CQA), and chlorogenic acid (5-CQA). Many studies have shown that it is possible to separate the isomers of FQAs by high-performance liquid chromatography (HPLC). However, some authors have shown that it is not possible to separate 4-feruloylquinic acid (4-FQA) and 5-feruloylquinic acid (5-FQA) by HPLC. Therefore, the present study was designated to investigate the chromatographic problems in the determination of CGAs (seven isomers) and caffeine using HPLC-DAD. The values of determination coefficient (R2) calculated from external-standard calibration curves were >0.998. The recovery rates conducted at 3 spiking levels ranged from 99.4% to 106.5% for the CGAs and from 98.8% to 107.1% for the caffeine. The precision values (expressed as relative standard deviations (RSDs)) were <7% and <3% for intra and interday variability, respectively. The tested procedure proved to be robust. The seven CGAs isomers except 4-FQA and 5-FQA were well distinguished and all gave good peak shapes. We have found that 4-FQA and 5-FQA could not be separated using HPLC. The method was extended to investigate the effects of different brewing conditions such as the roasting degree of green coffee bean, coffee-ground size, and numbers of boiling-water pours, on the concentration of CGAs and caffeine in homemade brewed coffee, using nine green coffee bean samples of different origins. It was reported that medium-roasted, fine-ground coffees brewed using three pours of boiling water were the healthiest coffee with fluent CGAs.