Gas Chromatography-tandem Mass Spectrometry Research Articles

Altered Steroidome in Women with Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) mainly afflicting young women. Various steroids can influence the onset and development of the disease or, on the contrary, mitigate its course; however, a systematic review of steroidomic changes in MS patients is lacking. Based on the gas chromatography tandem mass spectrometry (GC-MS/MS) platform and, in the case of estradiol, also using immunoassay, this study performed a comprehensive steroidomic analysis in 25 female MS patients aged 39(32, 49) years compared to 15 female age-matched controls aged 38(31, 46) years. A significant trend towards higher ratios of conjugated steroids to their unconjugated counterparts was found in patients, which is of particular interest in terms of the balance between excitatory and inhibitory steroid modulators of ionotropic receptors. Patients showed altered metabolic pathway to cortisol with decreased conversion of pregnenolone to 17-hydroxypregnenolone and 17-hydroxypregnenolone to 17-hydroxyprogesterone and increased conversion of 17-hydroxypregnenolone to dehydroepiandrosterone (DHEA), resulting in lower levels of 17-hydroxyprogesterone, as well as indications of impaired conversion of 11-deoxy-steroids to 11β-hydroxy-steroids but reduced conversion of cortisol to cortisone. Due to over-activation of hypothalamic-pituitary-adrenal axis (HPAA), however, cortisol and cortisone levels were higher in patients with indications of depleted cortisol synthesizing enzymes. Patients showed lower conversion of DHEA to androstenedione, androstenedione to testosterone, androstenedione to estradiol in the major pathway, and testosterone to estradiol in the minor pathway for estradiol synthesis at increased conversion of androstenedione to testosterone. They also showed lower conversion of immunoprotective Δ5 androstanes to their more potent 7α/β-hydroxy metabolites and had lower circulating allopregnanolone and higher ratio 3β-hydroxy-steroids to their neuroprotective 3α-hydroxy-counterparts.

Source identification and human health risk to polychlorinated biphenyls in public parks and playground surface soils, southern zone of Ghana.

Polychlorinated biphenyls (PCBs) constitute a typical example of persistent organic pollutants (POPs) that have been detected globally in most environmental media. Soil serves as a critical reservoir for PCBs. This research is aimed at evaluating the potential exposure and associated health risks posed by soil-laden PCBs to humans during outdoor activities on public playgrounds and parks within the southern zone of Ghana where limited studies have been undertaken. Surface soils collected from 56 sites were processed and analyzed for seven indicator PCBs in soil particle sizes less than 63µm. A multi-residual analytical approach for the simultaneous analysis of PCBs and polycyclic aromatic hydrocarbons (PAHs) via gas chromatography tandem mass spectrometry was utilized. The results indicated that the concentration of PCBs ranged from 0.26 to 24.00µg/kg with an average total concentration of 1.86 ± 3.23µg/kg which is below the environment guideline threshold of 1.3mg/kg stipulated by the Canadian Council of Ministers for residential playgrounds/parkland soils. Multivariate analysis showed that the sources of the PCBs could be attributed predominantly to historical release, atmospheric transfer, and deposition. The excess lifetime cancer risks posed to children and adults are less than 10-6 thereby implying the existence of low carcinogenic health risk to the human populace within the southern zone of Ghana. Thus, the conduct of outdoor activities at the public playgrounds/parks within these highly populated areas poses no significant risk to human health.

Metabolomics Study by Amino and Organic Acid Profiling Analyses in Pre- and Post-Milling Barley Using Gas Chromatography-Tandem Mass Spectrometry

Barley (Hordeum vulgare) is a major cereal grain grown in temperate climates globally and provides various nutrients in a peeled form after milling. However, milling causes changes in nutritional composition, including metabolites. Thus, a metabolomics study was conducted to monitor the changes in nutritional composition before and after the milling of Hordeum vulgare seeds (Saechalssal, Hinchalssal, and Yeongbaekchal) focusing on the development and application of new analytical methods for organic acids (OA) and amino acids (AA). Profiling analyses of OAs and AAs were performed using GC-MS/MS. This analytical method showed good linearity (r ≥ 0.995) with limit of detection (0.1 ng, 21.2 ng) and limit of quantitation (0.3 ng, 63.6 ng), respectively. Repeatability varied from 0.1 to 12.4 (% RSD) and accuracy varied from –12.3 to 14.8 (% RE), respectively. Altered levels of 36 metabolites (16 OAs, 20 AAs) were monitored post-milling and compared with pre-milling in the three Hordeum vulgare cultivars. Radar plots of OAs and AAs to corresponding mean levels of each pre-milling group in the three Hordeum vulgare cultivars were easily distinguished from those in each post-milling group. The pre-and post-milling groups of the three Hordeum vulgare cultivars were completely separated by partial least square discriminant analysis, and the lysine, cysteine, glutamic acid, asparagine, 4-hydroxyphenylacetic acid, and citric acid were significantly different. Therefore, this study will be useful for monitoring altered metabolites following milling and discrimination of varieties.

Identification of hypoxene metabolites in urine samples using gas chromatography–tandem mass spectrometry for anti-doping control

Objectives. Hypoxen is a drug which possesses antioxidant and antihypoxic effects. It achieves this by increasing the utilization of oxygen by mitochondria, intensifying oxidative phosphorylation, and as a result, improving tissue respiration. Athletes take it during prolonged exercise, in order to increase efficiency and reduce physical overwork. Since 2023, the World Anti-Doping Agency has included the drug in the monitoring program, in the belief that it can be used to gain a competitive advantage. It is thus a candidate for inclusion in the Prohibited List as a potential regulator of the human metabolism. Currently, there are no studies or scientific publications focusing on the identification of hypoxene in biofluids for the purpose of anti-doping control. The aim of this study is to determine the possible metabolites of the drug and their chromato-mass spectrometric characteristics in urine samples using gas chromatography–tandem mass spectrometry (GC–MS/MS) for doping control screening purposes.Methods. Sample preparation of urine samples was carried out using enzymatic hydrolysis, liquid–liquid extraction and derivatization. The GC–MS/MS method was used for analysis. Screening of hypoxene metabolites was carried out in the mode of total ion current after fragmentation of selected parent ions.Results. Three specific metabolites of hypoxene (m/z 342, 300, and 346, including trimethylsilyl derivatives) were identified in urine samples of volunteers (n = 3). They can act as markers for taking the target antihypoxant, and their possible structural formulas are given. The excretion curves of two metabolites with an m/z of 300 and 346 respectively in urine were studied. The maximum concentration is reached after 8–14 and 1.5–6 h, respectively. It was established, that these metabolites are reliably identified in urine 90 h or more after a single dose of the drug.Conclusions. Possible structures of hypoxene metabolites in urine samples from volunteers were determined for the first time and their chromato-mass spectrometric characteristics were established. The approach developed in this study can be used for screening analysis of hypoxene for the purpose of anti-doping control.

Human Biomonitoring of Serum Polybrominated Diphenyl Ethers by Supported Liquid Extraction and Gas Chromatography Coupled With Tandem Mass Spectrometry.

This study aims to develop and validate a robust analytical method for the quantification of polybrominated diphenyl ethers (PBDEs) in human serum using gas chromatography-tandem mass spectrometry. We compared procedural blanks, recoveries, and operational convenience of liquid-liquid extraction and supported liquid extraction for the determination of serum PBDEs. We evaluated different extraction solvents for their effect on PBDE recoveries. Supported liquid extraction was selected for method validation due to its operational convenience. The method demonstrated satisfactory linearity, sensitivity, and reproducibility, with the range of 0.10-5.00µg/L for most PBDE congeners and 0.20-10.0µg/L for PBDE-154 and PBDE-183, with limits of detection ranging from 2 to 48ng/L, and with matrix effects ranging from 94% to 113%. Quality control assessments indicated that recoveries ranged from 85% to 110% and relative standard deviations of less than 11%. The proposed method was applied to biomonitoring of 111 healthy adults, revealing detectable levels of PBDEs in over 90% of the samples. BDE-47 and BDE-183 were the most prevalent, with mean concentrations of 4.13 and 22.1ng/L, respectively. Detection frequencies ranged from 0.90% for BDE-17 and BDE-85 to 25.2% for BDE-47. Males had higher mean concentrations of BDE-183 than females.

Multiresidue analysis of 200 pesticides in jasmine (Jasminum sambac (L.) Aiton) flowers

A multiresidue analysis method was established for 200 pesticides in jasmine (Jasminum sambac(L.) Aiton) flowers based on QuEChERS procedure and gas chromatography-tandem mass spectrometry (GC–MS/MS). For better recoveries and purification effects, extraction solvents, extractive salts and purification methods were optimized. The limits of quantification (LOQ) of test pesticides are in the range of 0.01 and 0.1 mg kg−1, most of which were below the maximum residue limits (MRLs) prescribed by EU and China. Recoveries at 0.01, 0.1, 1.0 mg kg−1 were predominantly in the range of 70–120 % (n = 3) with corresponding RSDs lower than 20 %, which suggests satisfactory accuracy. The multiresidue analysis method was applied in monitoring pesticide residues in 8 jasmine flower samples. 50 % of those samples present with 1–2 pesticides residues. This study provides a sensitive and high-throughput method for detection of multi-pesticide residues in jasmine flowers.

Defective porous urchin-like ZnO/NiO microspheres-coated solid-phase microextraction fiber for analysis of trace polychlorinated biphenyls in milk.

Owing to the high lipophilicity of polychlorinated biphenyls (PCB), they easily accumulate in dairy products. Although usually present at very low levels, they pose a serious threat to human health. Therefore, developing a sensitive and reliable method for detecting PCB in dairy products is crucial. Herein, Herein, a metal-organic framework (MOF) material named with bimetallic nodes and double ligands was prepared as a precursor using a one-pot hydrothermal method. Defective porous urchin-like ZnO/NiO, derived from these MOF-based precursors (ZnNi-MOF-NH2) as a sacrificial template, was synthesized via pyrolysis to remove heat-sensitive ligands. To the best of our knowledge, this urchin-like nanostructured ZnO/NiO hybrid was utilized as a solid-phase microextraction (SPME) coating for the first time. Headspace SPME (HS-SPME) was developed for non-contact extraction of PCB in milk prior to gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. Under optimal conditions, the HS-SPME-GC-MS/MS method exhibited a wide linear range (0.01-1000ng·L-1), low limits of detection (0.003-0.025ng·L-1), and high enrichment factors (5714-9906). Additionally, the performance of the ZnO/NiO SPME fiber coating showed no noticeable decrease after 175 uses. The method was applied to trace PCB analysis in milk samples, yielding recoveries of 70.3-114.1%. The ZnO/NiO derived from MOF-based material provides a promising candidate for SPME coatings to extract PCB and other analogs.

Measurement Uncertainty and Validation for Quantification of Marijuana Metabolite: (−)-11-nor-9-Carboxy-Δ9-THC in Human Urine by GC-MS/MS

Background: Since the International Olympic Committee (IOC) was established, sports doping control analyses have revealed a high rate of positive cases for cannabinoids. Cannabinoids were banned in all sports where they were used in competition as per the Prohibited List published annually. Further, it was also included in the threshold drug category. Consequently, developing a reliable method for urine Cannabinoids metabolite quantification plays a pivotal role in sports dope testing. Objective: This work aimed to develop and validate a reliable, cost-effective, robust gas chromatography-tandem mass spectrometry method for detecting (−)-11-nor-9-Carboxy-Δ9- THC component in human urine samples, in compliance with ICH and WADA guidelines. Method: The sample preparation was done by enzymatic hydrolysis for deconjugation, further proceeded with solid phase extraction (SPE), liquid-liquid extraction (LLE), and using an XAD2 column, and N-methyl trimethylsilyl trifluoroacetamide (MSTFA) for derivatization. Results: The linearity was obtained in a range of 50–300 ng/mL, and the correlation coefficient was found to be higher than 0.99. Throughout the entire validation study, the difference in Retention Time (RT) for the analyte, including the Internal Standard (IS), was shown to be less than 1.0%. The quantification limit (LOQ) was calculated at a level of 50 ng/mL in human urine samples for the 3 most abundant ion transitions. The detection limit (LOD) was established at 4 ng/mL. Conclusion: The accuracy, precision, linearity, recovery, quantification limit, and selectivity by GC-MS/MS technique were found acceptable and well satisfactory while following the ICH guidelines. The developed method has been proven to be fit for purpose in accordance with the enforced Guidelines of WADA.

Multi-class, multi-residue analysis of pesticide residues in fishery products using LC and GC-MS/MS

Pesticide residues in agricultural products and the environment have been studied extensively over the years. Through the excessive or illegal use of pesticides, residues enter the surrounding environment and are absorbed by animals. Livestock and fishery products are subject to pesticide residue regulation, which includes the establishment of maximum residue limits. However, currently, fishery products are regulated only for ethoxyquin, neglecting the potential for bioaccumulation. This study aims to develop a method for the multi-class, multi-residue analysis of pesticide residues in fishery products—flatfish, eel, shrimp, and Manila clam—based on the QuEChERS method. A total of 327 compounds, including 263 pesticides and their metabolites, were identified using liquid chromatography and gas chromatography–tandem mass spectrometry. The method can quantify 263 pesticide residues in flatfish, 265 in eel, 264 in shrimp, and 263 in Manila clam, respectively. Additionally, the method can be applied to quantify 244 pesticide residues in seaweed. The method proves effective and useful for monitoring both food safety and environmental contamination.

Determination of some indicator polychlorinated biphenyls (I-PCBs) in foods by gas chromatography tandem mass spectrometry (GC-MS/MS)

Polychlorinated biphenyls (PCBs) are toxic chemicals that persist in the environment and can accumulate in the food chain. The study was conducted with the aim of developing a method to determine the content of 6 I-PCBs compounds by gas chromatography-mass spectrometry (GC-MS/MS) combined with Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) technique for sample treatment. The sample was extracted with acetonitrile (ACN) solvent and cleaned with PSA adsorbent. The cleaned extract was analyzed on a GCMS/MS system with a DB-5MS column (30 m × 0.25 mm × 0.25 µm). The method had good specificity, the linear range was established in the range of 1.5-40 ng/g, the correlation coefficient R2 > 0.999. The method recovery was 74.5-102.7% and the relative standard deviation (RSD%) ranged from 0.9-6.20% for milk and meat samples. The method's limit of detection (LOD) and limit of quantification (LOQ) for 6 I-PCBs were 0.5 ng/g and 1.5 ng/g, respectively. The method was applied to analyze the content of 6 I-PCBs in 40 food samples (meat and meat products, milk and dairy products) randomly purchased in Hanoi. The results showed that in all 40 analyzed samples, 1 powdered milk sample detected PCB-28 and PCB- 101, the total content of I-PCBs was 13.0 ng/g fat lower than the European regulations.

Development of the headspace gas chromatography-tandem mass spectrometry method for ethylene oxide and ethylene chlorohydrin residue in medical devices.

Ethylene oxide (EO) sterilization is commonly employed for the sterilization of medical devices and has a very high market share. However, EO and its metabolite ethylene chlorohydrin (ECH) are toxic to humans. In compliance with the classification and residue limits of medical devices defined by ISO 10993-7, our study established two extraction methods for the testing of EO and ECH. The first method involves simulated-use extraction using water as the extraction solvent. While the second, exhaustive extraction, directly extracts sample through headspace sampling analysis. Gas chromatography-tandem mass spectrometry in multiple reaction monitoring mode was utilized, requiring only 16 min. Then, the developed method was applied to assess 10 commercially available medical devices sterilized by EO. In simulated-use extraction, calibration curves were evaluated in the range of 1-100 and 5-500 μg for EO and ECH, respectively (r > 0.999). Inter-day recoveries ranged from 85.0% to 95.2% and from 94.8% to 102.4%. In exhaustive extraction, calibration curves spanned 0.5-50 and 2-200 μg for EO and ECH, respectively (r > 0.999). Inter-day recoveries ranged from 101.6% to 102.1% for EO and from 98.1% to 102.2% for ECH. After analysis of the 10 commercially available medical devices, two cotton swabs were found to have ECH of 35.1 and 28.4μg per device, and four medical devices were found to have EO with concentration below the limit of quantification. Meanwhile, we found that the EO internal standard (propylene oxide) recommended by ISO 10993-7 had interference problems with other similar substances and was not suitable as an internal standard for EO. This study offers a sensitive and straightforward analytical approach to EO and ECH residues in a variety of medical devices. In addition, the results show that the EO or ECH content of these types of medical devices in our study falls below the regulatory limits, therefore instilling confidence among consumers regarding their safe use.

Exploration of Nutraceutical Potentials of Isorhapontigenin, Oxyresveratrol and Pterostilbene: A Metabolomic Approach

Resveratrol (trans-3,5,4′-trihydroxystilbene, RES) is one of the most well-known natural products with numerous health benefits. To explore the nutraceutical potentials of some dietary RES derivatives including isorhapontigenin (trans-3,5,4′-trihydroxy-3′-methoxystilbene, ISO), oxyresveratrol (trans-3,5,2′,4′-tetrahydroxystilbene, OXY) and pterostilbene (trans-3,5-dimethoxy-4′-hydroxystilbene, PTS), their impacts on metabolism and health were assessed in Sprague Dawley rats after a two-week daily oral administration at the dose of 100 µmol/kg/day. Non-targeted metabolomic analyses were carried out with the liver, heart, brain and plasma samples using gas chromatography–tandem mass spectrometry (GC-MS/MS). Notable in vivo health benefits were observed, as the rats received ISO, PTS or RES showed less body weight gain; the rats received OXY or RES displayed healthier fasting blood glucose levels; while all of the tested stilbenes exhibited cholesterol-lowering effects. Additionally, many important metabolic pathways such as glycolysis, pentose phosphate pathway, tricarboxylic acid cycle and fatty acid oxidation were found to be modulated by the tested stilbenes. Besides the reaffirmation of the well-known beneficial effects of RES in diabetes, obesity, cardiovascular disease and Alzheimer’s disease, the metabolomic analyses also suggest the anti-diabetic, cardio-, hepato- and neuro-protective activities of ISO; the anti-diabetic, cardio-, hepato- and neuro-protective effects of OXY; and the anti-aging, anti-inflammatory, cardio-, hepato- and neuro-protective potential of PTS. Interestingly, although these stilbenes share a similar structure, their biological activities appear to be distinct. In conclusion, similarly to RES, ISO, OXY and PTS have emerged as promising candidates for further nutraceutical development.

Maternal Diet during Pregnancy Alters the Metabolites in Relation to Metabolic and Neurodegenerative Diseases in Young Adult Offspring

Maternal nutrition during the critical period of pregnancy increases the susceptibility of offspring to the development of diseases later in life. This study aimed to analyze metabolite profiles to investigate the effect of maternal diet during pregnancy on changes in offspring plasma metabolites and to identify correlations with metabolic parameters. Pregnant Sprague-Dawley rats were exposed to under- and overnutrition compared to controls, and their offspring were fed a standard diet after birth. Plasma metabolism was profiled in offspring at 16 weeks of age using liquid chromatography–mass spectrometry (LC-MS/MS) and gas chromatography–tandem mass spectrometry (GC-MS/MS). We analyzed 80 metabolites to identify distinct metabolites and metabolic and neurodegenerative disease-associated metabolites that were sex-differentially altered in each group compared to controls (p < 0.05, VIP score > 1.0). Specifically, changes in 3-indolepropionic acid, anthranilic acid, linoleic acid, and arachidonic acid, which are involved in tryptophan and linoleic acid metabolism, were observed in male offspring and correlated with plasma leptin levels in male offspring. Our results suggest that fatty acids involved in tryptophan and linoleic acid metabolism, which are altered by the maternal diet during pregnancy, may lead to an increased risk of metabolic and neurodegenerative diseases in the early life of male offspring.

Effect of gamma irradiation on the degradation rate of various pesticides and active ingredients in dandelion

The levels of 37 pesticides in dandelion were analyzed using gas chromatography-tandem mass spectrometry (GC–MS/MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The dandelion samples were treated with different irradiation doses, pH levels, moisture contents, and initial concentrations. Additionally, the respective contents of chicoric, chlorogenic, and caffeic acids in the dandelion samples were determined using high-performance liquid chromatography (HPLC) with DAD detector. The results showed that the pesticide degradation rate was positively correlated with the irradiation dose and negatively correlated with pesticide concentration. The degradation of most pesticides followed first-order kinetics. The pesticide degradation rate initially decreased and subsequently increased with an increase in the pH. Irradiation below 8 kGy had an insignificant effect on the three active ingredients of dandelion. The chicoric acid content decreased with an increase in water content and pH, whereas the caffeic acid content increased.

Gas Chromatography Tandem Mass Spectrometry (GC-MS/MS) for High-Throughput Screening of Pesticides in Rice Samples Collected in Bangladesh and Saudi Arabia

Gas Chromatography Tandem Mass Spectrometry (GC-MS/MS) with modified QuEChERS sample preparation has been applied to the high-throughput screening of pesticide residuals in rice collected from Bangladesh and Saudi Arabia markets. Both countries consume high volumes of rice, which is a fundamental food for their populations. We report optimized sample preparation and mass spectrometry analysis protocols, which can be rapidly deployed in analytical laboratories. The screening of four groups (organophosphorus, synthetic pyrethroid, organonitrogen, and organochlorine) of a total of 115 pesticides can be performed within ~10 min using a matrix-matched calibration. For most compounds, the limits of detection and quantification (LOD/LOQ) are well below the maximum residue levels (MRLs) of the main regulators. The method generally demonstrates acceptable recovery values (91 compounds 75–125% and 10 compounds 30–75%). Out of 55 rice samples analyzed, 16 samples (29%) contained pesticide residues above LOQ. Four samples contained chlorpyrifos with concentrations ranging from 21.3 to 71.9 µg/kg, ten samples contained tebuconazole (34.7–69.0 µg/kg), and three samples contained pirimiphos methyl (10.7–20.7 µg/kg). The concentrations of the pesticide residues detected in these samples are well below MRL of FAO/WHO (chlorpyrifos, 500 µg/kg; tebuconazole, 1500 µg/kg; pirimiphos methyl, 7000 µg/kg).

Implementation of gas chromatography tandem mass spectrometry for the analysis of six high boiling point polyhydric alcohols in cosmetics and toothpaste based on precolumn derivatization

Based on precolumn derivatization, an analytical method has been developed for the determination of six high boiling point polyhydric alcohols (HBPAs, b.p. > 300 ℃) in cosmetics and toothpaste, including erythritol, xylitol, Pro-Xylane-S, inositol, mannitol, and sorbitol. The water dispersion and oil in water samples were extracted by distilled water. The water in oil sample was firstly pre-dispersed with acetone, and then extracted by distilled water. The extract was concentrated to dry under nitrogen, and derivatized with acetic anhydride under the dispersion and catalysis of anhydrous pyridine. The derivatives were detected by gas chromatography-tandem mass spectrometry in the selected reaction monitoring mode, and quantified using arabinitol as internal standard. The experimental conditions such as the selection of columns, extraction procedures, and derivative conditions were optimized. This method was properly validated under the optimized conditions, and obtained excellent analytical features. Specifically, the correlation coefficients in the range of 0.02 ∼ 0.5 mg/L all exceed 0.992. The method limits of detection and quantification were 0.25 and 0.8 mg/kg, respectively. The average recoveries in toothpaste, cosmetics with oil in water and water in oil were 81.8 ∼ 107.1 %, with the relative standard deviation were 3.1 ∼ 7.2 %. The established method was successfully applied to commercial samples of different matrices, showing the advantages of simplicity, sensitivity, and good reproducibility, and can be used for the determination of HBPAs in cosmetics and toothpaste. The proposed methodology solves the problem that there is no detection method for HBPAs in cosmetics.

Preliminary risk assessment of exposure to 3-monochloropropanediol and glycidyl fatty acid esters from infant formula and baby food products on the Saudi market

3-Monochloropropanediol fatty acid esters (3-MCPDE) and glycidyl esters (GE) are well-identified processing-induced chemical toxicants detected in infant formula and baby foods worldwide. We analysed the levels of 3-MCPDE and GE in infant formula and baby food products available in Saudi Arabia, followed by a dietary risk assessment for exposure to these contaminants in infants and young children from birth to 3 years. Eighty-five commercial infant formulas (n = 35) and baby foods (n = 50) available for consumption by infants and babies purchased from the Saudi market during 2022 were analysed for these contaminants using gas chromatography-tandem mass spectrometry. 3-MCPDE and GE were detected in 100 and 80% of the samples, with a mean concentration of 57 µg/kg (range: 2–285 µg/kg) and 30 µg/kg (range: not detected–217 µg/kg), respectively. The highest concentration was found in milk-based formula for infants 0–6 months (285 µg/kg) and the lowest was found in fruit purees (2 µg/kg). Preliminary exposure and risk assessment showed increased exposure to 3-MCPDE for infants exclusively fed infant formula with exposure declining with age due to the introduction of solid foods. GE exposure levels reached 0.8 µg/kg body weight per day, which declined over time with margin of exposure values below 25,000. These results indicate that the levels of 3-MCPDE and GE in infant formula may pose potential risks to infants exclusively fed formula; therefore, adopting EU regulations should reduce the presence of these processing contaminants in essential infant foods.

A-316 A quantitative gas chromatography tandem mass spectrometry method for metabolic profiling of urine organic acids and acylglycines

Abstract Background The analysis of urine organic acids (UOA) and acylglycines (UAG) are an essential investigation for the diagnosis inborn errors of metabolism (IEMs). The vast majority of methods for these analytes use gas chromatography mass spectrometry (GC-MS) and are only qualitative. Gas chromatography tandem mass spectrometry (GC-MS/MS) offers greater sensitivity and selectivity and enables the combination of qualitative screening with quantitative analysis. We describe the development and validation results of a quantitative GC-MS/MS method. Methods Urine creatinine concentrations were measured (CobasPro, Roche Diagnostics) and normalized to 1.25 mmol/L. After internal standard addition, each urine specimen, calibration standard and QC were incubated with a hydroxylamine solution followed by a liquid-liquid extraction. Further sample concentration permitted the isolated UOA and UAG to be derivatized using N,O-bis(trimethylsilyl)trifluoroacetamine (BSTFA) with 1% chlorotrimethylsilane (TMCS) prior to injection. GC-MS/MS analysis was performed using a GC-MS-TQ8050 triple quadrupole system (Shimadzu) with a 30 m DB-5MS (Agilent J&W) capillary column (0.25 mm, ID of 0.25 µm). Split injection mode was deployed with an initial column temperature of 70°C. The mass spectrometer was operated in electron ionization (EI) and multiple reaction monitoring (MRM) modes. Results The optimal temperature gradient for high-resolution UOA and UAG separations was derived and their respective retention times determined. MS/MS detection parameters were optimized to permit the identification of precursor and production ions for all (N=36) derivatized analytes. Total analysis time was 33.8 min per injection. This method permits the measurement of 11 samples in one batch and is highly linear for all analytes (R^2 >0.99 and average slope 1.04). The limit of quantification (LOQ) was established and ranged from <0.05 to 2.1 µmol/mmol creatinine. Intra- and inter-day imprecision (CV%) was determined using matrix-matched abnormal and normal QC. Intra-day imprecision (N=10) ranged from 1.3% (2-ketoglutaric acid) to 9.7% (3-hydroxybutyric acid). Inter-day imprecision (N=30 over 15 days) ranged from 2.2% (ethylmalonic acid and methylmalonic acid) to 20.5% (3-hydroxy-3-methylglutaric acid). The method had an average accuracy of 113±14% for analytes included in the ERNDiM quantitative organic acids (urine) external quality assurance program. For analytes not included in this proficiency testing, the method showed good agreement when compared to a national reference laboratory, with average Deming correlation coefficients and regression slopes being 0.9944 and 1.1, respectively. No interferences were detected when monitoring the analyte quantifier and qualifier ion ratios in patient urine. Conclusions The devised GC-MS/MS protocol permits the unbiased identification and quantification of UOA and UAG used to investigate IEMs. The method has acceptable sensitivity, specificity, precision and accuracy for clinical routine clinical testing.

Evaluating the detection of barbiturates in dried blood spots: A comparative analysis using gas chromatography-mass spectrometry, gas chromatography-tandem mass spectrometry, and liquid chromatography-tandem mass spectrometry with different extraction methods

Rapid and accurate characterization and quantitation of blood barbiturates and their combination drugs are very important for the clinical treatment of acute barbiturate poisoning. A comparison of dried blood spot (DBS) and traditional liquid-liquid extraction (LLE) in the pre-treatment stage, as well as a comparison of gas chromatography-mass spectrometry (GC–MS), gas chromatography-tandem mass spectrometry (GC–MS/MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS) as instrumental analysis methods, revealed differences in the analysis results of barbiturates and their combination drugs under different conditions. Based on these findings, we introduce a DBS-GC–MS/MS method. The developed and validated method showed good selectivity, sensitivity (LOD: 0.1 μg mL−1, LOQ: 0.2 μg mL−1), linearity (R2>0.9992), trueness (<15 %, except for carbamazepine, at 29.4 %), and precision (<15 %). Recovery was also good for most target compounds, but significant matrix effects were evident. Compared with the LLE method, the DBS method has the benefits of easy sample collection, storage, and transport, as well as simple pre-treatment and reduced reagent and energy consumption. Compared to LC-MS/MS, GC–MS/MS requires no switching between positive and negative ion modes and uses the MRM detection mode, meaning that more information about the sample compounds can be obtained in less analysis time. Using actual sample analysis, we have demonstrated the advantages of the DBS-GC–MS/MS method for the qualitative and quantitative analysis of barbiturates and poisoning events due to combinations of these drugs. Comparison of the three instruments and the two treatment methods revealed their analysis characteristics. From the perspective of practical application, the broad practical value and advantages of DBS should be embraced in more applications, and future analytical laboratory development should continue to recognize GC–MS/MS as a useful supplement to LC-MS/MS.

Infant and Toddler Health Risks Associated with Pesticide Residue Exposure Through Fruit- and Vegetable-Based Baby Food

This research specifically delves into the potential health risks associated with pesticide residues in fruit- and vegetable-based foods for Turkish infants and toddlers.A total of 36 baby food samples were analyzed using a validated method covering 355 pesticide residues, employing liquid chromatography-tandem mass spectrometry (LCMS/ MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). Notably, 72.2% of the samples revealed no pesticide residues, while 10 samples exceeded the Maximum Residue Limits (MRLs) stipulated by the EU Directives. Specifically,pyriproxyfen had the greatest average concentration in pear fruits (0.573mg/kg). Notably, both pyrimethanil and pyriproxyfen were the most frequently detected analytes in all positive samples. The study further simulated a population, considering age-specific energy requirements for infants and toddlers. Pyriproxyfen demonstrated the highest average exposure (1.58±2.20μg/kg bw/day) across all age groups. Notably, for 6-month-old infants, the toxicological contribution as a percentage of the ADI for pesticides remained below 14.73%. It emphasizes the necessity for regulatory measures to ensure the safety of foods intended for infants and toddlers in the Turkish market. These findings support ongoing efforts to uphold pesticide levels within acceptable safety limits.