Plastic Quantification and Polyethylene Overestimation in Agricultural Soil Using Large-Volume Pyrolysis and TD-GC-MS/MS.

Quantification of microplastics in soil is needed to understand their impact and fate in agricultural areas. Often, low sample volume and removal of organic matter (OM) limit representative quantification. We present a method which allows simultaneous quantification of microplastics in homogenized, large environmental samples (>1 g) and tested polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS) (200-400 µm) overestimation by fresh and diagenetically altered OM in agricultural soils using a new combination of large-volume pyrolysis adsorption with thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS/MS). Characteristic MS/MS profiles for PE, PET, and PS were derived from plastic pyrolysis and allowed for a new mass separation of PET. Volume-defined standard particles (125 × 125 × 20 µm3) were developed with the respective weight (PE: 0.48 ± 0.12, PET: 0.50 ± 0.10, PS: 0.31 ± 0.08 µg), which can be spiked into solid samples. Diagenetically altered OM contained compounds that could be incorrectly identified as PE and suggest a mathematical correction to account for OM contribution. With a standard addition method, we quantified PS, PET, and PEcorrected in two agricultural soils. This provides a base to simultaneously quantify a variety of microplastics in many environmental matrices and agricultural soil.

Reliable biological indicator identification and evaluation of tobacco-derived nicotine using an ultra-sensitive gas chromatography-tandem mass spectrometric method.

Several countries have exempted synthetic nicotine from existing regulatory frameworks, resulting in the widespread substitution of synthetic nicotine (SN) in almost all e-cigarette products available. However, it remains uncertain whether the purported synthetic nicotine is indeed genuine SN. There is a need to develop biological indicators and an analytical method that more clearly distinguishes between the two sources. Impurities in neat tobacco-derived nicotine (TDN) were characterized and identified through non-targeted and targeted analysis. Gas chromatography-tandem mass spectrometry (GC-MS/MS) conditions were optimized for detecting biological indicators in e-cigarette products. Nine tobacco-related alkaloids were identified and selected as biological indicators for TDN. A liquid-liquid extraction and GC-MS/MS quantitative method were developed to detect nine biological indicators in e-cigarette products with the limit of quantification ranging from 0.2 to 4.2 µg L-1 using 0.5 mL of e-liquid. This method was applied to 50 e-cigarette brands purchased in the Korean market. The developed method was able to easily and accurately identify the origin of nicotine even using a small amount of e-liquid sample. It is expected that effective e-cigarette regulation will be possible if the nicotine biological indicator and high-sensitivity analysis method developed in this study are used.

Discrimination and simultaneous quantification of poly(ethylene terephthalate) and poly(butylene terephthalate) microplastics in environmental samples via gas chromatography-tandem mass spectrometry.

A method has been developed to quantify PET and PBT microplastics (MPs) based on depolymerization and detection of depolymerization products by gas chromatography-tandem mass spectrometry (GC-MS/MS) without a complex separation process from environmental samples. Under the optimal depolymerization conditions, PET and PBT were efficiently converted to ethylene glycol (78%) and 1,4-butanediol (87%), respectively. Subsequently, the linear curves were constructed between signal intensities of depolymerization products and polymer masses by GC-MS/MS, and the correlation coefficients of PET and PBT were 0.996 and 0.997, respectively. The spiking and recovery experiments of PET and PBT in the environmental samples showed that the recovery was stable in the range 89-100%, and the limit of detection was 4.95 µg and 1.39 µg of PET and PBT, respectively. The method has been proven to be capable of simultaneous identification and quantification of PBT and PET MPs in real environmental water samples without complex separation process, which provided a scheme for the determination of microplastics.

Comparison of gas chromatographic techniques for the analysis of iodinated derivatives of aromatic amines.

Some aromatic amines (AA) have been classified as carcinogens to humans. After entering the body, mainly through tobacco smoke, they can be detected in urine. Thus, their trace analysis as biomarkers in biofluids is of high relevance and can be achieved with gas chromatography (GC-MS), usually after derivatization. This study compares three gas chromatographic methods for the analysis of ten iodinated derivatives of AA: GC-MS in single-ion monitoring (SIM) mode with (1) electron ionization (GC-EI-MS) and (2) negative chemical ionization (GC-NCI-MS), and (3) GC-EI-MS/MS in multiple reaction monitoring (MRM) mode using electron ionization. All methods and most analytes showed good coefficients of determination (R2 > 0.99) for broad linear ranges covering three to five orders of magnitude in the picogram-per-liter to nanogram-per-liter range, with one and two exceptions for (1) and (2) respectively. Excellent limits of detection (LODs) of 9-50, 3.0-7.3, and 0.9-3.9 pg/L were observed for (1), (2), and (3) respectively, and good precision was achieved (intra-day repeatability < 15% and inter-day repeatability < 20% for most techniques and concentration levels). On average, recoveries between 80 and 104% were observed for all techniques. Urine samples of smokers and non-smokers were successfully analyzed, and p-toluidine and 2-chloroaniline could be found at significantly (α = 0.05) higher concentrations among smokers.

Determination of 3-chloro-1,2-propanediol in biological samples by quick-easy-cheap-effective-rugged-and-safe extraction coupled with gas chromatography-mass spectrometry and its biodistribution in rats.

3-Chloro-1,2-propanediol is a common food contaminant, but reports on its determination in biological tissues are lacking. In the present study, a method was developed to detect 3-chloro-1,2-propanediol contents in rat tissues by quick-easy-cheap-effective-rugged-and-safe extraction and gas chromatography-mass spectrometry analysis. Biological samples were extracted with ethyl acetate and purified with adsorbents. The optimized adsorbent for each sample was selected from 4-5 combinations of N-propylethylenediamine, octadecylsilane, graphitized carbon black, strong anion exchange, and florisil. Extracted 3-chloro-1,2-propanediol was derivatized with heptafluorobutyric anhydride and subjected to gas chromatography-mass spectrometry. This method had good linearity (correlation coefficients >0.99) in the range of 2-2000 ng/g for blood, kidney, liver, testis, and brain samples. The limits of detection were under 0.8 ng/g; the limits of quantification were 2 ng/g; the recovery rates were 85%-102%; and the matrix effects were 1.98%-7.67%. This method also had good precision. The dynamic changes in 3-chloro-1,2-propanediol in rats gavaged with 20 mg/kg b.w. for 24 h were detected using this method. The 3-chloro-1,2-propanediol content in each tissue sharply increased to a peak, rapidly decreased within 2 h, and stabilized at 12 h. 3-Chloro-1,2-propanediol persisted in the kidney, testis, and liver 24 h after gavage.

In situ biomonitoring using caged lumpfish (Cyclopterus lumpus) eggs reveal plastic and rubber associated chemicals in a harbour area in Central Norway.

Plastics- and rubber-derived chemicals are given increasing focus due to their migration into the environment and potential for causing detrimental effects. The current study demonstrates the use of a novel biomonitoring platform using caged fertilized eggs of lumpfish (Cyclopterus lumpus) in combination with gas chromatography tandem mass spectrometry analysis of a selection of target chemicals extracted from the lumpfish eggs after deployment. A monitoring campaign in the Trondheim harbor and off the coast of Trøndelag in Norway was executed using the described system. Here we found accumulation of UV stabilizers (benzophenone and benzothiazoles), plasticizers (n-butylbenzenesulfonamide), reagents, and polymer synthesis precursors (bisphenol A, acetophenone, phthalide, and phthalimide) in deployed eggs. Several of the compounds were detected in concentrations above previously quantified legacy contaminants in the same study areas.

Translocation of Fungicides and Their Efficacy in Controlling Phellinus noxius, the Cause of Brown Root Rot Disease.

Brown root rot disease (BRRD), caused by Phellinus noxius, is an important tree disease in tropical and subtropical areas. To improve chemical control of BRRD and deter emergence of fungicide resistance in P. noxius, this study investigated control efficacies and systemic activities of fungicides with different modes of action. Fourteen fungicides with 11 different modes of action were tested for inhibitory effects in vitro on 39 P. noxius isolates from Taiwan, Hong Kong, Malaysia, Australia, and Pacific Islands. Cyproconazole, epoxiconazole, and tebuconazole (Fungicide Resistance Action Committee [FRAC] 3, target-site G1) inhibited colony growth of P. noxius by 99.9 to 100% at 10 ppm and 97.7 to 99.8% at 1 ppm. The other effective fungicide was cyprodinil + fludioxonil (FRAC 9 + 12, target-site D1 + E2), which showed growth inhibition of 96.9% at 10 ppm and 88.6% at 1 ppm. Acropetal translocation of six selected fungicides was evaluated in bishop wood (Bischofia javanica) seedlings by immersion of the root tips in each fungicide at 100 ppm, followed by liquid or gas chromatography tandem mass spectrometry analyses of consecutive segments of root, stem, and leaf tissues at 7 and 21 days posttreatment. Bidirectional translocation of the fungicides was also evaluated by stem injection of fungicide stock solutions. Cyproconazole and tebuconazole were the most readily absorbed by roots and efficiently transported acropetally. Greenhouse experiments suggested that cyproconazole, tebuconazole, and epoxiconazole have a slightly higher potential for controlling BRRD than mepronil, prochloraz, and cyprodinil + fludioxonil. Because all tested fungicides lacked basipetal translocation, soil drenching should be considered instead of trunk injection for their use in BRRD control.

Covalent organic framework-based magnetic solid-phase extraction coupled with gas chromatography-tandem mass spectrometry for the determination of trace phthalate esters in liquid foods.

Covalent organic framework-coated magnetite particles (Fe3O4@COF) were synthesized and applied as the adsorbent to the selective capture of phthalate esters (PAEs) in liquid foods. Combined with the magnetic solid-phase extraction (MSPE) technology, a gas chromatography-tandem mass spectrometry (GC-MS/MS) method was employed for the separation and quantification of PAEs. Following optimization of the magnetic extraction and elution parameters, the developed analytical method offered a satisfactory linear range (0.1-5 µg L-1) with determination coefficients ranging from 0.9934 to 0.9975 for the five different PAEs studied. The limits of detection (LOD) were in the range 1.9-12.8 ng L-1. The recoveries ranged from 70.0 to 119.8% with a relative standard deviation (RSD) less than 9.7%. Density functional theory (DFT) calculations established that the dominant adsorption mechanism used by the COF to bind PAEs involved π-π stacking interactions. Results encourage the wider use of COF-based adsorbents and MSPE methods in the analytical determination of PAEs in foods.

The Comprehensive Steroidome in Complete TSPO/PBR Knockout Mice under Basal Conditions.

The 18 kDa translocator protein (TSPO/PBR) is a multifunctional evolutionary highly conserved outer mitochondrial membrane protein. Decades of research has reported an obligatory role of TSPO/PBR in both mitochondrial cholesterol transport and, thus, steroid production. However, the strict dependency of steroidogenesis on TSPO/PBR has remained controversial. The aim of this study was to provide insight into the steroid profile in complete C57BL/6-Tspotm1GuWu(GuwiyangWurra)-knockout male mice (TSPO-KO) under basal conditions. The steroidome in the brain, adrenal glands, testes and plasma was measured by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). We found that steroids present in wild-type (WT) mice were also detected in TSPO-KO mice, including pregnenolone (PREG), progestogens, mineralo-glucocorticosteroids and androgens. The concentrations of PREG and most metabolites were similar between genotypes, except a significant decrease in the levels of the 5α-reduced metabolites of progesterone (PROG) in adrenal glands and plasma and of the 5α-reduced metabolites of corticosterone (B) in plasma in TSPO-KO compared to WT animals, suggesting other regulatory functions for the TSPO/PBR. The expression levels of the voltage-dependent anion-selective channel (VDAC-1), CYP11A1 and 5α-reductase were not significantly different between both groups. Thus, the complete deletion of the tspo gene in male mice does not impair de novo steroidogenesis in vivo.

GC-MS/MS Determination of Synthetic Cathinones: 4-chloromethcathinone, N-ethyl Pentedrone, and N-ethyl Hexedrone in Oral Fluid and Sweat of Consumers under Controlled Administration: Pilot Study.

This study presents a validated GC-MS/MS method for the detection and quantification of 4-chloromethcathinone or clephedrone (4-CMC), N-ethyl Pentedrone (NEP), and N-ethyl Hexedrone (NEH, also named HEXEN) in oral fluid and sweat and verifies its feasibility in determining human oral fluid concentrations and pharmacokinetics following the administration of 100 mg of 4-CMC orally and 30 mg of NEP and NEH intranasally. A total of 48 oral fluid and 12 sweat samples were collected from six consumers. After the addition of 5 µL of methylone-d3 and 200 µL of 0.5 M ammonium hydrogen carbonate, an L/L extraction was carried out using ethyl acetate. The samples, dried under a nitrogen flow, were then derivatized with pentafluoropropionic anhydride and dried again. One microliter of the sample reconstituted in 50 µL of ethyl acetate was injected into GC-MS/MS. The method was fully validated according to international guidelines. Our results showed how, in oral fluid, the two cathinones taken intranasally were absorbed very rapidly, within the first hour, when compared with the 4-CMC which reached its maximum concentration peak in the first three hours. We observed that these cathinones were excreted in sweat in an amount equivalent to approximately 0.3% of the administered dose for 4-CMC and NEP. The total NEH excreted in sweat 4 h after administration was approximately 0.2% of the administered dose. Our results provide, for the first time, preliminary information about the disposition of these synthetic cathinones in the consumers' oral fluid and sweat after controlled administration.

Multiresidue analysis of pesticides in three Indian soils: method development and validation using gas chromatography tandem mass spectrometry.

The paper reports a multiresidue method that was validated on 220 multi-class pesticides in three major Indian soils, namely, (i) new alluvial soil (NAS); (ii) red lateritic soil (RS) and (iii) black soil (BS) from three different regions. An ethyl acetate-based extraction method with a freezing-out cleanup step was employed for sample preparation, followed by gas chromatography-tandem mass spectrometric analysis. The method that was initially optimized on BS worked satisfactorily for the other two soil matrices. At the spiking level of 10 µg/kg (LOQ), the recoveries were satisfactory (within 70-120%) with precision-RSDs, ≤20% (n = 6) for 85, 88.6, and 89% of compounds in BS, RS, and NAS respectively. At 20 µg/kg, the method performance was satisfactory in each soil for all pesticides. When this validated method was applied to analyse 25 field samples, 6 pesticides were detected in them. In each case, precision (RSD) was <20%. The method sensitivity, accuracy and precision complied with the SANTE/2020/12830 guidelines. The method can be applied for environmental monitoring and risk assessment purposes, thus aiding in regulating pesticide usage in agricultural fields. The limitations and future scope of the study are also discussed.HighlightsA multiresidue method is reported for simultaneous analysis of multi-class pesticides in diverse soilsThe method was validated on 220 pesticides in new alluvial, red lateritic and black soilsSample preparation involved extraction with ethyl acetate and cleanup by a freezing stepThe residues were estimated by gas chromatography tandem mass spectrometry (GC-MS/MS)The method accuracy and precision complied with the EU's SANTE guidelines.

[Determination of three furfural compounds in coffee and coffee products by gas chromatography-tandem mass spectrometry with internal standard isotope].

OBJECTIVE: To establish a method for the determination of three furfural compounds in coffee and its products by gas chromatography-tandem mass spectrometry. METHODS: The samples were extracted with ethanol water(1∶2, V∶V) solution, ultrasonic with 10% Na_2CO_3 solution for 5 min, purified with 100 mg C_(18), 50 mg Srong Cation exchang(SCX), 150 mg anhydrous MgSO_4, separated by HP-INNOWAX capillary column(30 m×0.25 mm, 0.25 µm), detected by gas chromatography-tandem mass spectrometry, and quantified by isotope internal standard method. RESULTS: The correlation coefficients(r) of the three furfural compounds were all greater than 0.999, the limits of detection were 0.004-0.011 mg/kg, and the limits of quantitation were 0.013-0.031 mg/kg. The average recoveries were 86.0%-112% and the relative standard deviations were 4.1%-10.6%(n=6), at 3 supplemental levels in 3 different coffee substrates. Nine samples of coffee beans, instant coffee and coffee drinks were tested, and all three components to be tested were detected. CONCLUSION: The method is simple, rapid, sensitive, with good accuracy and precision. It is suitable for the determination of three furfural compounds in coffee and its products.

Fabrication of magnetic covalent organic framework for efficient extraction and determination of phthalate esters in milk samples.

Using two monomers of 4,4″-diamino-p-terphenyl and 1,3,5-triformylphloroglucinol, a co-precipitation structured magnetic covalent organic framework adsorbent was fabricated. After that, a high efficient vortex-assisted magnetic solid-phase extraction method was developed prior to gas chromatography-tandem mass spectrometry analysis for the determination of phthalate esters in milk samples. The fabricated magnetic adsorbent was facilely fabricated, fully characterized, and exhibited high extraction efficiency, which can be attributed to its larger pore size as well as strong hydrophobic and π-π stacking interactions between adsorbent and phthalate esters. Key parameters affecting extraction efficiency were investigated. Under the optimized conditions, the proposed method possessed good linearity (3.0-1000 µg/L), high sensitivity (0.8-2.1 µg/L for limits of detection), and satisfactory recoveries (76.8-99.2%). The relative standard deviations for intra-day was 3.1-4.5% and inter-day was 3.3-6.1%. This work is suitable for high efficient separation/preconcentration of phthalate esters in milk samples.

Metabolomic analysis of amino acids and organic acids in aging mouse eyes using gas chromatography-tandem mass spectrometry.

This is a metabolomics study for monitoring altered amino acid (AA) and organic acid (OA) metabolism of in eyes from aging an mouse model at 8 and 18 weeks and 18 months. Simultaneous metabolic profiling analysis of OAs and AAs was performed as ethoxycarbonyl/methoxime/tert-butyldimethylsilyl derivatives by gas chromatography-tandem mass spectrometry. A total of 42 metabolites-24 AAs and 18 OAs-were determined and their composition values were normalized to the corresponding mean values of 8-week-old mice as the control group. Then their normalized values were plotted as star graphs, which were distorted and readily distinguishable for each age-related group. Among the 42 metabolites, 18 AAs and 11 OAs were age dependent and significantly different (p < 0.05). Principal component analysis and partial least squares discriminant analysis showed unclear separation between 8- and 18-week-old mice but clear separation between these and 18-month-old mice. In particular, the variable importance in projection scores of 4-hydroxyproline, cis-aconitic acid, glycine, isocitric acid, leucine, pipecolic acid and lysine from partial least-squares-discriminant analysis were higher than 1.3. A heatmap for the classification and visualization of 42 metabolites showed differences in metabolite changes with aging. Altered AA and OA profiles were monitored, which may explain the metabolic disturbance of AA and OA. These findings are related to mitochondrial dysfunctions related to energy metabolism and the impaired antioxidant system in the aging eye. Therefore, the present metabolomics results of the association between physiological states and altered metabolism of AA and OA will be useful for understanding the aging eye and related diseases.

Trace-level analysis of polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons in human plasma or serum by dispersive liquid-liquid microextraction and gas chromatography-tandem mass spectrometry.

A method to determine 8 polychlorinated biphenyls (PCBs), 23 organochlorine pesticides (OCPs) and 16 polycyclic aromatic hydrocarbons (PAHs) was described using dispersive liquid-liquid microextraction (DLLME) of a small amount of plasma or serum sample and gas chromatography-tandem mass spectrometry (GC-MS/MS). The appropriate selection of the extraction solvent and dispersing solvent contributes to a high extraction yield and a clean extract. To verify the developed method, the interference, linearity of the calibration curve, detection limit, precision and accuracy were evaluated. The calibration curves were linear by 2-3 orders of magnitude with correlation coefficients above 0.997 in all cases. The LODs of PCBs, OCPs and PAHs were measured in the ranges of 0.0006-0.0029, 0.001-0.029 and 0.0002-0.012 ng/mL. The intraday precision achieved by this method was 2.19-10.3% (PCBs), 1.65-14.3% (OCPs) and 0.91-12.8% (PAHs), and the intraday accuracy 1.56-7.37% (PCBs), 2.34-19.6% (OCPs) and 1.49-15.7% (PAHs). The advantage of this method is that the analysis of PCBs, OCPs, and PAHs can be performed in a single chromatographic run, and the low detection limit enables monitoring of target substances in low exposure general public samples, and the analysis procedure is relatively simple and fast.

Multiresidue Pesticide Analysis in Tea Using GC-MS/MS to Determine 12 Pesticide Residues (GB 2763-2021).

Pesticides are widely used on tea plants, and pesticide residues are of significant concern to consumers. The National Food Safety Standard Maximum Residue Limits for Pesticides in Food (GB 2763-2021) was recently amended. However, detection methods for pesticides newly added to the list of residues in beverages have not yet been established. For that reason, this study developed a solid-phase extraction (SPE) and gas chromatography-tandem mass spectrometry (GC-MS/MS) method for determining the residues of 12 pesticides, including four newly added, in black and green tea. Sample preparation processes (sample extraction, SPE clean-up, elution solvent, and elution volume) were optimized to monitor these residues reliably. Multiple reaction monitoring (MRM) was used for GC-MS/MS electron impact (EI) mode determination. Finally, satisfactory recoveries (70.7-113.0% for green tea and 72.0-99.1% for black tea) were achieved at three concentrations (10 µg/kg, 20 µg/kg, and 100 µg/kg). The LOQs were 0.04-8.69 µg/kg, and the LODs were 0.01-3.14 µg/kg. This study provides a reliable and sensitive workflow for determining 12 pesticide residues in tea, filling a gap in the newly revised National Standards.

Quantitative analysis and contamination profiles of PCBs, OCPs, and PAHs in black-tailed gull eggs in the Republic of Korea.

The simultaneous determination of 8 polychlorinated biphenyls (PCBs), 23 organic chlorine pesticides (OCPs), and 35 polycyclic aromatic hydrocarbons (PAHs) in black-tailed gull eggs was described using ultrasound-assisted extraction and gas chromatography-tandem mass spectrometry (GC-MS/MS). The ranges of the lower limits of detection for PCBs, OCPs, and PAHs were 0.006-0.029, 0.01-0.10, and 0.01-0.20 µg kg-1, respectively. The intraday precision was in the range of 0.650-12.9% and the intraday accuracy was in the range of 86.6-113%. When the proposed method was used to analyze the target compounds in gull eggs collected from six sites in the Republic of Korea, the analytical results demonstrated concentration ranges of 113.32-394.07 µg kg-1 for total PCBs, 422.92-1082.09 µg kg-1 for total OCPs, and 134.50-231.27 µg kg-1 for total PAHs in the samples. The PCA results for PAHs and OCPs were well differentiated by sampling site, whereas those for PCBs differed little by sampling site. There were more pyrogenic PAHs in the West Sea and the South Sea with many industrial areas than in the East Sea with few industrial areas. Differences in the OCP patterns of samples from the West Sea close to China were considered to be related to the use of DDT in China until recently. PCBs were accumulated in the samples regardless of region, so there was no significant difference in the PCB patterns between the samples obtained from the three Seas.

Shrimp count size: GC/MS-based metabolomics approach and quantitative descriptive analysis (QDA) reveal the importance of size in white leg shrimp (Litopenaeus vannamei).

INTRODUCTION: "Count size" is a term used to represent the number of shrimps in one pound or kilogram that applies globally in the shrimp industry. Based on shrimp body weight, count sizes range over the smallest (> 70) up to the largest size (U15) of shrimp. Large shrimps are considered highly palatable; therefore, they are priced higher than the small shrimps. However, the pricing of shrimp has not been based on scientific findings since there have been no studies reporting the correlation between shrimp quality and shrimp size. OBJECTIVE: In this study, we aimed to investigate the importance of shrimp size in terms of metabolite profile and sensory properties. METHODS: Nine groups of Litopenaeus vannamei, categorized based on their body weight similarity, were collected from various sampling sites regardless of the difference in days of culture (count size 16/20, 21/25, 26/30, 41/50, and 51/60). Gas chromatography/mass spectrometry (GC/MS)-based metabolomics analysis was employed to characterize their metabolite profiles. Furthermore, a robust PLS regression model was constructed to predict the shrimp size using metabolome data. Following this, the difference in sensory attributes among commercial shrimp count sizes 21/25-41/50 was confirmed using quantitative descriptive analysis (QDA). RESULTS: Small shrimp (> 70-51/60) had higher accumulation of proteinogenic and non-proteinogenic amino acids, sugars, and organic acids compared to large shrimps (41/50-16/20). The QDA of commercial count sizes (21/25-41/50) performed by trained panelists showed that sweetness, juiciness, crispness, and red color attributes increased with an increase in shrimp size. Based on the PLS model, proline as a sweet-tasting metabolite also showed an increased level along with the shrimp size. CONCLUSIONS: These findings demonstrate the importance of shrimp count size with regard to shrimp quality.

[Determination of fipronil and its metabolites in eggs using dispersive- solid phase extraction and gas chromatography-tandem mass spectrometry].

OBJECTIVE: To develop a method for determination of fipronil and its metabolites in eggs by gas chromatography-tandem mass spectrometry(GC-MS/MS)cleaned with dispersive-solid phase extraction(D-SPE). METHODS: Orthogonal array design with OA16(4~4) matrices was used to optimize the efficiency of D-SPE. The targets were extracted from samples with acetonitrile, and followed by D-SPE cleanup. The extracts were analyzed by GC-MS/MS, and quantified by internal standard method with matrix correction. RESULTS: The calibration curves showed good linearity in the range of 1.0-250.0 µg/L. The correlation coefficients were larger than 0.99.The average recoveries spiked in eggs at the levels of 2 µg/kg, 4 µg/kg and 20 µg/kg were between 87.1% and 125.0%(n=6), and the relative standard deviations were less than 10%. The limits of determination were between 0.1 and 0.4 µg/kg, and the limits of quantitation were between 0.3 and 1.2 µg/kg. CONCLUSION: The method possesses low background, high sensitivity. It can be applied to determine the residues of fipronil and its metabolites in eggs.

Metabolomic analysis of organic acids, amino acids, and fatty acids in plasma of Hanwoo beef on a high-protein diet.

INTRODUCTION: Ketoacidosis of metabolic disease showed in beef cattle although body weight was increased by high-grain diets (HGDs). However, few studies have examined for health status related with metabolic disease of ketoacidosis following high-protein diet (HPD). OBJECTIVES: Metabolomic analysis was performed for the monitoring of health status associated with metabolic disease of ketoacidosis in the plasma of Hanwoo heifers following a HPD. METHODS: Hanwoo heifers of 24 months with 459 ± 42 kg weight were used under a 2 × 2 crossover design. The plasma was collected from control (n = 5) and HPD group (n = 5) on day 21 following diet adaptation for 20 days. Metabolic profiling analysis of organic acids (OAs), amino acids (AAs) and fatty acids (FAs) by gas chromatography-tandem mass spectrometry combined with star pattern analysis was performed in plasma. Levels of OAs, AAs and FAs were evaluated by Mann-Whitney test, PCA and PLS-DA. RESULTS: In HPD group, ketoacidosis as metabolic disease was monitored by elevated acetoacetic acid and 3-hydroxybutyric acid. In addition, the elevation of ketogenic AAs, reduction of medium chain FAs and OAs with energy metabolism in TCA cycle were monitored in HPD group. Star graphic pattern was characteristic and readily distinguished between control and HPD groups. In PLS-DA, two groups were separated with VIP score of top-ranked 10 FAs as important metabolites for discrimination. CONCLUSION: Elevation of ketone body including ketogenic AAs and reduced energy metabolism of FAs and OAs may useful for evaluation of health states associated with ketoacidosis from metabolic event by HPD in beef cattle.