Carcinogenic risk associated with popular Korean dishes: An approach of combined risk assessments using Oral Slope Factor and BMDL10 values.

Cooking-related carcinogens are formed during the heating or processing of foods. To date, numerous studies analyzing carcinogens present in cooking ingredients or formed through different cooking methods have been conducted. However, combined risk assessment is important for practical reasons. The purpose of this study was to conduct a combined risk assessment of five cooking-related genotoxic carcinogens encompassing 25 chemicals: heterocyclic amines, acrylamide, furan, polycyclic aromatic hydrocarbons, and nitrosamines. Oral Slope Factor (OSF) and benchmark dose lower-bound confidence limit 10% (BMDL10) of the compounds were obtained from public databases, and the values for the compounds that did not have published reference values were approximated using related toxicity values. The high-risk contributing food items and cooking methods for each carcinogen were selected for the study based on the Korean Total Diet Study (TDS) and Korea National Health and Nutrition Examination Survey (KNHANES). Exposure to the carcinogens from selected dishes per serving was estimated based on concentrations determined in TDS and consumption data gathered from 24-h recalls in the 2014 to 2016 KNHANES. The combined cancer risks were obtained by summing the risks of individual compounds in a dish, which were calculated by multiplying the OSF values by the concentrations of carcinogens per serving. The combined risks were used to compare the risk of different dishes, not to calculate the lifetime risk from the individual dishes. The risks of the dishes prepared with potatoes were found to be high, whereas namul (vegetable dish) had the lowest risk. Soup or stew dishes exhibited relatively high risks. Estimated combined risks based on BMDL10 showed similar trends, except for fried potatoes and roasted or fried meat dishes. Combined risks of cooking-related carcinogens may vary based on the major contributors of individual carcinogens. The results of this study could provide an insightful guideline for selecting menus for consumers.

Simultaneous analysis and exposure assessment of migrated bisphenol analogues, phenol, and p-tert-butylphenol from food contact materials.

A simple, rapid, and novel liquid chromatography tandem-mass spectrometry (LC-MS/MS) method was developed and validated to determine levels of eight bisphenol analogues (A, S, F, B, P, AF, AP, and Z), phenol, and p-tert-butylphenol migrated from food contact material (FCM) into food simulants. Method validation showed acceptable values in terms of linearity, precision, and accuracy. The limits of detection and quantification were 0.53-29.6 and 1.77-29.6 µg L-1, respectively. Water, 4% acetic acid, 50% ethanol, and n-heptane were employed as food simulants for the migration tests, and the proposed method was applied to 234 articles of 11 FCMs including polycarbonate, polyethersulfone, polypropylene, and polyethyleneterephthalate, obtained from domestic markets and manufacturers in Korea. Only phenol was found in the FCMs poly(cyclophexane-1,4-dimethylene terephthalate), polylactide, and thermoplastic polyurethane. Eight bisphenol analogues and p-tert-butyl phenol were not found in any samples. Using the obtained migration results, the estimated daily intake (EDI) of phenol was calculated. Exposure assessments were carried out to compare the EDI with the tolerable daily intake (TDI), showing a low percentage (0.18%) of the TDI reported. This is the first study to examine eight bisphenol analogues and two phenols simultaneously in FCMs using the LC-MS/MS.

Determination of Heterocyclic Amines and Acrylamide in Agricultural Products with Liquid Chromatography-Tandem Mass Spectrometry.

Heterocyclic amines (HCAs) and acrylamide are unintended hazardous substances generated by heating or processing of foods and are known as carcinogenic and mutagenic agents by the animal experiments. A simple method was established for a rapid and accurate determination of 12 types of HCAs (IQ, MeIQ, Glu-P-1, Glu-P-2, MeIQx, Trp-P-1, Trp-P-2, PhIP, AαC, MeAαC, Harman and Norharman) and acrylamide in three food matrices (non-fat liquid, non-fat solid and fat solid) by isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). In every sample, a mixture of internal standards including IQ-d3, MeIQx-d3, PhIP-d3, Trp-P-2-(13)C2-(15)N and MeAαC-d3 was spiked for quantification of HCAs and (13)C3-acrylamide was also spiked for the analysis of acrylamide. HCAs and acrylamide in sample were extracted with acetonitrile and water, respectively, and then two solid-phase extraction cartridges, ChemElut: HLB for HCAs and Accucat: HLB for acrylamide, were used for efficiently removing interferences such as pigment, lipid, polar, nonpolar and ionic compounds. Established method was validated in terms of recovery, accuracy, precision, limit of detection, limit of quantitation, and linearity. This method showed good precision (RSD < 20%), accuracy (71.8~119.1%) and recovery (66.0~118.9%). The detection limits were < 3.1 ng/g for all analytes. The correlation coefficients for all the HCAs and acrylamide were > 0.995, showing excellent linearity. These methods for the detection of HCAs and acrylamide by LC-MS/MS were applied to real samples and were successfully used for quantitative monitoring in the total diet study and this can be applied to risk assessment in various food matrices.

Microwave-assisted extraction of human hair proteins.

The effectiveness of microwave-assisted extraction of proteins from human hair samples was evaluated. Extractions were performed from 2-mg hair samples in an extraction solution consisting of 25 mM Tris-HCl (pH 8.5), 2.6 M thiourea, 5 M urea, and 5% mercaptoethanol. During extraction, samples were exposed to microwave radiation (600 W) for a specified incubation period (5-120 min). The extraction efficiency of samples that had been incubated for 60 min was similar to that of samples that had been heated at 50°C for 24 h using the conventional Shindai method.

Measurement of progesterone in human serum by isotope dilution liquid chromatography-tandem mass spectrometry and comparison with the commercial chemiluminescence immunoassay.

Progesterone is one of the steroid hormones. The hormone is especially important in preparing the uterus for the implantation of the blastocyst and in maintaining pregnancy. Its concentration in serum is measured to determine ovarian function and to predict early pregnancy. The progesterone concentration is also important for in-vitro fertilization and embryo-transfer outcomes. We have established isotope dilution liquid chromatography-tandem mass spectrometry as a primary method for the measurement of progesterone in human serum. Progesterone and its isotopic analogue, progesterone-(13)C(2), in serum were monitored at mass transitions of m/z 315.2/109.2 and 317.2/111.2 respectively in multiple-reaction monitoring (MRM) mode with electrospray positive ionization. For validation of the method, progesterone in a National Institute of Standards and Technology standard reference material (NIST SRM) was measured, and the measured results were in good agreement with the reference values within the uncertainty. On the basis of the established method, progesterone certified reference material (CRM) was developed in this work. The certified value was (1.41 ± 0.036) µg kg(-1). The repeatability of 1.1% and reproducibility of 0.14% showed that ID LC-MS-MS is a reliable and reproducible method. The expanded uncertainty for the measurement of progesterone in the CRM was approximately 2.6% within 95% confidence limits. The detection limit of progesterone was approximately 0.6 µg kg(-1). The progesterone CRMs were distributed to representative clinical laboratories in the Republic of Korea for comparison with the chemiluminescence immunoassay (CLIA), which is the most sensitive immunoassay method. The results from the comparison showed quite a large bias among the participating laboratories. This implies that the CRM is a very important material for establishment of traceability to its practical use.

A multiresidue method for the determination of 118 pesticides in vegetable juice by gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.

An analytical method has been developed for measuring 118 pesticides in vegetable juice. The extraction of pesticides was carried out based on dispersive solid-phase extraction, and determination was performed using gas chromatography with mass spectrometric detection (GC-MS-SIM) and liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). Pesticides were confirmed by their retention time and their quantification and identification ions by GC-MS-SIM or multiple reaction monitoring of two fragment ions by LC/ESI-MS/MS, respectively. Spiking experiments from 10 to 120 microg/kg were carried out to determine the recovery, precision, and limit of quantification (LOQ) of the method. The overall recoveries of all pesticides were between 77 and 114% with relative standard deviations lower than 14%. The LOQ for most compounds was below 5 microg/kg. The proposed method was applied successfully for the residue determination of the 118 pesticides in commercial vegetable juice samples.

A multi-residue method for the determination of 203 pesticides in rice paddies using gas chromatography/mass spectrometry.

This work reports a rapid, specific and sensitive multi-residue method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography with mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM) using one quantification ion and two identification ions for the routine analysis of 203 pesticides in rice paddies. Analyses of fortified rice paddy samples were performed at different levels (0.05, 0.20 and 0.50 mg kg(-1)). Mean recoveries from five replicates ranged from 75% to 115%, with coefficients of variation lower than 17%. The limit of quantification was in the range of 0.002-0.05 mg kg(-1) for the pesticides. 1040 rice paddy samples were analyzed for method application.

A multiresidue method for the determination of 107 pesticides in cabbage and radish using QuEChERS sample preparation method and gas chromatography mass spectrometry.

A rapid, specific and sensitive multiresidue method based on the modified Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography with the electron impact mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM) using one target and two qualifier ions for the routine analysis of 107 pesticides in cabbage and radish has been developed. The recoveries for all the pesticides studied were from 80% to 115% with relative standard deviation lower than 15% in the concentration range of 0.030-0.360mg/kg. The limit of quantitation (LOQ) for most compounds met MRLs for pesticides in cabbage and radish in Korea. This method was successfully applied to analysis commercial cabbage and radish samples.

Determination of the strontium isotope ratio by ICP-MS ginseng as a tracer of regional origin.

This study presents the inductively coupled plasma mass spectrometry (ICP-MS) as a method for tracing the regional origin of ginseng. The results of the analysis of 15 Korean ginsengs from three different regions and of 15 Chinese ginsengs from three different regions reveal that the Sr isotope ratios (87)Sr/(86)Sr of the ginsengs differed according to their origin. For pretreatment, the ginseng samples were dried, and were dissolved through microwave digestion, then were each made to amount to 6ml with 11.9M HCl. Rb was then separated from Sr to enable an interference-free measurement through cation exchange chromatography. Six millilitres of the ginseng sample were injected in the column, and 60ml of 11.9M HCl was passed through the column at a 1mlmin(-1) flow rate to separate Rb from Sr. After Rb was eluted completely, 60ml of 5.0M HCl was passed at a 1mlmin(-1) flow rate to collect Sr. In the Sr collection step, the first 10ml portion of 30ml eluate was discarded, and the next 10ml portion was taken and was diluted with de-ionized water at a ratio of 1:3, for analysis purposes. The results of the analysis of 30 ginseng samples revealed that the Chinese ginsengs have an (87)Sr/(86)Sr ratio range of 0.672-0.701, and the Korean ginsengs 0.705-0.714. The Korean ginsengs, therefore, have a higher (87)Sr/(86)Sr ratio range than the Chinese ginsengs. Of the Korean ginsengs, (87)Sr/(86)Sr ratio range of ginsengs from Punggi, Geumsan and Hongcheon are about 0.706-0.709, 0.705-0.706, and 0.710-0.714, respectively.

A multiresidue method for the determination of 109 pesticides in rice using the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography/mass spectrometry with temperature control and vacuum concentration.

A rapid, specific and sensitive multiresidue method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography with mass spectrometric detection by selected ion monitoring (GC/MS-SIM) has been developed for the routine analysis of 109 pesticides in rice. The method uses one quantification ion and two identification ions. Temperature control during sample preparation helps improve the recovery of thermally labile pesticides such as captan. The method was validated by the analysis of samples spiked at 0.025-0.150 mg/kg in rice matrix. The recoveries of all pesticides were between 80% and 115% with a relative standard deviation of less than 15%. The limit of quantitation (LOQ) for most compounds met the maximum residue limits (MRLs) for pesticides in rice in Korea.

Development of a candidate reference method for determination of tyrosine in serum by isotope dilution liquid chromatography-tandem mass spectrometry.

An isotope dilution liquid chromatography/tandem mass spectrometry is proposed as a reference method to determine the level of tyrosine in human serum. The advantages of this method include simple sample preparation without derivatization, the selective detection of compounds of interest in complex matrices, and the use of an isotopically labeled analogue as an internal standard. Tyrosine and its isotopically labeled analogue were monitored at a transfer m/z of 182.1/136.2 and 188.1/142.2, corresponding to [M+H]+/[M+H-HCOOH]+ in a multiple reaction monitoring mode. The expanded uncertainty for the measurement of tyrosine in the serum was approximately 0.95% within a 95% confidence level. For the verification of this method, a standard reference material with a certified value was analyzed. The analyzed result was in good agreement with the certified value. The isotope dilution liquid chromatography/tandem mass spectrometry result of the human serum was also compared with results obtained from clinical laboratories, and showed inconsistent results. These inconsistent results suggest that standards certified by the proposed reference method are required in order to improve measurement reliability in clinical fields.

Determination of phenylalanine in human serum by isotope dilution liquid chromatography/tandem mass spectrometry.

Isotope dilution liquid chromatography/tandem mass spectrometry (ID-LC/MS/MS) has been developed as a candidate reference method to determine the level of phenylalanine in human serum. The advantages of this method include a simple sample preparation without derivatization, selective detection of analytes, and the use of an isotopic analogue as an internal standard. Phenylalanine and its isotopic analogue, phenylalanine-ring-(13)C(6), were monitored at the transitions m/z 166.2/120.2 and 172.2/126.2 in the multiple-reaction monitoring (MRM) mode, respectively. The expanded uncertainty of the measurement result of phenylalanine in the serum was approximately 1.2% within a 95% confidence level. A standard reference material, with a certified value of phenylalanine, was analyzed in order to verify this method. The result obtained by the ID-LC/MS/MS method differed somewhat from the certified value, but agreed well with the gravimetric value. The measurement result of phenylalanine in serum by ID-LC/MS/MS was compared with the results from the commercial HPLC method, which was carried out in clinics. The results from the commercial HPLC method showed inconsistent results with each other. The busted results from the commercial HPLC method suggest that it should be possible to trace the results of the commercial fields to well-characterized reference materials or methods.

Determination of optimum conditions for the analysis of volatile components in pine needles by double-shot pyrolysis-gas chromatography-mass spectrometry.

The optimum conditions for the analysis of the volatile organic components of pine needles from Pinus densiflora using double-shot pyrolysis-gas chromatography-mass spectrometry (DSP-GC-MS) were investigated with respect to thermal desorption temperature and duration of heating. A total of 41 compounds were identified using thermal desorption temperatures of 150 degrees C, 200 degrees C, 250 degrees C and 300 degrees C. Thermal decomposition products, which include acetol, acetic acid, furfurals and phenols, were observed only at thermal desorption temperatures exceeding 250 degrees C: they were not observed in the extract from a simultaneous distillation extraction (SDE) method. Heating times of 1 s, 6 s, 30 s, 150 s and 300 s were investigated at the thermal desorption temperature of 200 degrees C, whence it was found that thermal decomposition products were produced only at heating times over 30 s. The optimum pyrolyzer conditions for the analysis of pine needles using DSP-GC-MS is 200 degrees C for 6 s. Under these conditions, this method gives comparable results to the SDE method.