Gas Chromatography With Flame Ionization Detection Research Articles

Epiglottis Cartilage, Costal Cartilage, and Intervertebral Disc Cartilage as Alternative Materials in the Postmortem Diagnosis of Methanol Poisoning.

Alternative materials for postmortem diagnosis in the case of fatal poisonings are much needed when standard materials, such as blood and urine, are unavailable. The study presents a case of fatal mass methanol intoxication resulting from industrial alcohol consumption. The study aimed to determine methanol and formic acid concentrations in epiglottis cartilage, costal cartilage, and intervertebral disc cartilage and to analyze the correlation between their concentrations in cartilage tissues and the femoral blood. Methanol and formic acid concentrations in samples collected from 17 individuals (n = 17) were estimated using gas chromatography with flame ionization detection (GC-FID). Methanol concentration in the costal cartilage correlated with its concentration in the femoral blood (r = 0.871). Similar correlations were found for epiglottis cartilage (r = 0.822) and intervertebral disc cartilage (r = 0.892). Formic acid concentration in the blood correlated only with its concentration in urine (r = 0.784) and the epiglottis (r = 0.538). Cartilage tissue could serve as an alternative material for methanol analyses in postmortem studies. Formic acid, a methanol metabolite, does not meet the requirements for its presence determination in cartilage tissues.

Application of post-column reaction gas chromatography with a single reference gas for offshore air and gas seeped from the seafloor samples.

Ambient air commonly contains carbon dioxide at concentrations greater than 400µmolmol-1 and methane at ~ 2000nmolmol-1; non-methane hydrocarbons are also widespread in the atmosphere at much lower concentrations. For quantification of various carbon-containing compounds in typical analytical instrument, corresponding number of reference materials are required. Therefore, the development of a method that uses a single reference material applicable to air monitoring is desired. Here, we examined a post-column reaction system combined with a gas chromatograph equipped with a flame ionization detector (FID), which involves oxidation and reduction processes after separation. To determine various carbon-containing gases by post-column reaction gas chromatography with FID (GC-r-FID) using a single reference, it is necessary to confirm a good linearity of the response with carbon concentrations originating from various carbon-containing gases. When mixtures of carbon-containing gases at three different concentrations and the calibration curve of the FID response with the concentration converted into methane were used, a single linear calibration curve (correlation coefficient > 0.9999, 18 points) was obtained over four orders of magnitudes (to ~ 5000µmolmol-1 as methane). The applicability of GC-r-FID was confirmed by determining carbon-containing gases in air and gas seeped from the seafloor samples. Because the results were comparable to those obtained by conventional GC-FID and GC-thermal conductivity detector, typically GC-r-FID with a single reference gas should be suitable for air monitoring.

Hybrid volatilomics in cancer diagnosis by HS-GC-FID fingerprinting

Assessing volatile organic compounds (VOCs) as cancer signatures is one of the most promising techniques toward developing non-invasive, simple, and affordable diagnosis. Here, we have evaluated the feasibility of employing static headspace extraction (HS) followed by gas chromatography with flame ionization detector (GC-FID) as a screening tool to discriminate between cancer patients (head and neck—HNC, n = 15; and gastrointestinal cancer—GIC, n = 19) and healthy controls (n = 37) on the basis of a non-target (fingerprinting) analysis of oral fluid and urine. We evaluated the discrimination considering a single bodily fluid and adopting the hybrid approach, in which the oral fluid and urinary VOCs profiles were combined through data fusion. We used supervised orthogonal partial least squares discriminant analysis for classification, and we assessed the prediction power of the models by analyzing the values of goodness of prediction (Q2Y), area under the curve (AUC), sensitivity, and specificity. The individual models HNC urine, HNC oral fluid, and GIC oral fluid successfully discriminated between healthy controls and positive samples (Q2Y = 0.560, 0.525, and 0.559; AUC = 0.814, 0.850, and 0.926; sensitivity = 84.8, 70.2, and 78.6%; and specificity = 82.3; 81.5; 87.5%, respectively), whereas GIC urine was not adequate (Q2Y = 0.292, AUC = 0.694, sensitivity = 66.1%, and specificity = 77.0%). Compared to the respective individual models, Q2Y for the hybrid models increased (0.623 for hybrid HNC and 0.562 for hybrid GIC). However, sensitivity was higher for HNC urine and GIC oral fluid than for hybrid HNC (75.6%) and hybrid GIC (69.8%), respectively. These results suggested that HS-GC-FID fingerprinting is suitable and holds great potential for cancer screening. Additionally, the hybrid approach tends to increase the predictive power if the individual models present suitable quality parameter values. Otherwise, it is more advantageous to use a single body fluid for analysis.

The Preparation of Covalent Bonding COF-TpBD Coating in Arrayed Nanopores of Stainless Steel Fiber for Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons in Water.

Covalent organic framework (COF)-TpBD was grafted on the arrayed nanopores of stainless steel fiber (SSF) with (3-aminopropyl) triethoxysilane as the cross-linking agent. The prepared SSF bonded with COF-TpBD showed high thermal and chemical stability and excellent repeatability. The prepared SSF bonded with COF-TpBD was also used for the solid-phase microextraction (SPME) of seven kinds of polycyclic aromatic hydrocarbons (PAHs) in actual water samples, followed by gas chromatography with flame ionization detection (GC-FID) determination, which exhibited low limits of detection (LODs), good relative standard deviation (RSD) and high recoveries.

Determination of Polycyclic Aromatic Hydrocarbons in Mate Tea Microencapsulated with Maltodextrin and Lasiodiplodan ((1→6) β–D-Glucan)

The occurrence of polycyclic aromatic hydrocarbons (PAH) in organic mate tea (Ilex paraguariensis) was investigated to evaluate whether the roasting and drying processes under milder temperatures would promote lower PAH levels in the product. Gas Chromatography with Flame Ionization Detector (GC-FID) was used to quantify PAH contents. Different concentrations of PAH were found in all samples of mate tea analyzed, such as acenaphthylene varied between 1.209 and 1.524 µg·g−1; acenaphthene varied between 2.504 and 4.375 µg·g−1; fluorene varied between 1.488 and 1.843 µg·g−1; chrysene ranged between 0.093 and 0.263 µg·g−1; benzo[a]pyrene varied between 0.988 and 3,398 µg·g−1; dibenzo(a,h) anthracene was identified in all the samples, but at concentrations below the limit of quantification. Naphthalene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, benzo[b]fluoranthene, and benzo[k]fluoranthene were identified in the sample used for the extraction of soluble solids that have been encapsulated. The PAH concentration in mate tea samples was above the recommended by European Union legislation for dried herbs and powders of food of plant origin for the preparation of beverages. New yerba mate processing strategies should be studied to minimize PAH contamination and promote healthier products, in addition to government policies for quality control and regulation specifying limit values for the PAHs.

Combining portable NIR spectroscopy and multivariate calibration for the determination of ethanol in fermented alcoholic beverages by a multi-product model

In this study, a multivariate calibration multi-product model was built by combining partial least square regression (PLS) and portable near infrared (NIR) spectroscopy for the determination of ethanol content in fermented alcoholic beverages. Reference values were obtained by gas chromatography with flame ionization detection (GC-FID). Aiming at building a robust model, a great variety of beers, ciders, meads, and wines were incorporated into the model. NIR spectra were recorded between 908 and 1676 nm for 153 alcoholic beverage samples, corresponding to a range from 4.3 to 15.3% (v/v) of alcohol content. PLS model provided accurate results with root mean square errors of calibration (RMSEC) and prediction (RMSEP) of 0.8% and 0.9%, respectively. The developed method was validated through the estimate of proper figures of merit, such as linearity, trueness, precision, analytical sensitivity, bias, and residual prediction deviation (RPD). This method was simple, direct, rapid, of low-cost and environmentally friendly, not consuming reagents or solvents nor generating chemical waste. It could be incorporated in analytical platforms for quality inspection, contributing to provide better transparency in the food supply chain.

First report on quality and purity assessment of sweet almond oil in Brazilian body oils by gas chromatography and mass spectrometry.

Sweet almond oil is a raw material with high-added value used in different products. Then, the aim of this study is to evaluate the quality and purity of 10 body oils based on sweet almond oils currently available in the Brazilian market. Fatty acid composition and triacylglycerol (TAG) profile were determined by gas chromatography with flame ionization detector (GC-FID) and atmospheric solids analysis probe mass spectrometry (ASAP-MS), respectively. The authenticity of samples was assessed using an analytical curve equation. Soybean oil was chosen as the adulterant because it is the cheapest vegetable oil commercialized in Brazil. Hierarchical clustering analysis (HCA) in conjunction with ASAP-MS classified product samples according to the type of vegetable oil (soybean and sweet almond oils). The addition of soybean oil (8.79% to 99.70%) was confirmed in samples. However, only two samples stated in their label the presence of soybean oil as an ingredient. These findings highlight the need for better oversight by regulatory bodies to ensure that consumers acquire high quality and authentic products based on equally high quality and purity of sweet almond oils.

Volatile Compound Abundance Correlations Provide a New Insight into Odor Balances in Sauce-Aroma Baijiu

Sauce-aroma Baijiu (SAB) is one of the most famous Baijius in China; SAB has more than 500 aroma compounds in it. However, the key aroma compound in SAB flavor remains unclear. Volatiles play an important role in SAB aroma and are highly correlated to SAB quality. In the present study, 63 volatile compounds were quantified among 66 SAB samples using gas chromatography with flame ionization detector (GC-FID). The authors analyzed odor contributions and volatile compound correlations in two quality groups of SAB samples. Moreover, an odor activity value (OAV) ratio-based random forest classifier was used to explain the volatile compound relationship differentiations between the two quality groups. Our results proved higher quality SABs had richer aromas and indicated a set of fruity-like ethyl valerate, green- and malt-like isobutyraldehyde and malt-like 3-methylbutyraldehyde and sweet-like furfural, had closer co-abundance correlations in higher quality SABs. These results indicated that the aroma and contributions of volatile compounds in SABs should be analyzed not only with compound odor activity values, but also the correlations between different aroma compounds.

Exploring the Chemical Composition of Bulgarian Lavender Absolute (Lavandula Angustifolia Mill.) by GC/MS and GC-FID.

Lavender (L. angustifolia Mill.) is an important essential oil-bearing and medicinal plant with high commercial value. Lavender scent components can be derived not only as an essential oil but also as lavender concrete or absolute. The development of reliable analytical methods for origin assessment and quality assurance is of significant fundamental importance and high practical interest. Therefore, a comprehensive chemical profiling of seven industrial samples of Bulgarian lavender absolute (L. angustifolia Mill.) was performed by means of gas chromatography-mass spectrometry (GC/MS) and gas chromatography with flame ionization detection (GC-FID). As a result, 111 individual compounds were identified by GC/MS, and their quantitative content was simultaneously determined by GC-FID, representing 94.28-97.43% of the total contents of the lavender absolute. According to our results, the main constituents of lavender absolute (LA) are representatives of the terpene compounds (with the dominating presence of oxygenated monoterpenes, 52.83-80.55%), followed by sesquiterpenes (7.80-15.21%) and triterpenoids (as minor components). Coumarins in various amounts (1.79-14.73%) and aliphatic compounds (hydrocarbons, ketones, esters, etc.) are found, as well. The acyclic monoterpene linalool is the main terpene alcohol and, together with its ester linalyl acetate, are the two main constituents in the LAs. Linalool was found in concentrations of 27.33-38.24% in the LA1-LA6 samples and 20.74% in the LA7 samples. The amount of linalyl acetate was in the range of 26.58 to 37.39% in the LA1-LA6 samples, while, surprisingly, it was not observed in LA7. This study shows that the chemical profile of the studied LAs is close to the lavender essential oil (LO), fulfilling most of the requirements of the International Standard ISO 3515:2002.

In Situ Multi-Modal Approach for Electrode-Electrolyte Interfacial Chemistryand Electrode and Electrolyte Aging Behavior Studies

Increasing demands for cost-effective electric vehicles and electrochemical energy storage systems require advanced secondary batteries with higher energy density, longer lifetime, and enhanced safety. Increase of the battery operating voltage is one realistic strategy to extend the energy density, but it is accompanied by irreversible structural changes to the electrodes and parasitic reactions within an electrode-electrolyte interphase resulting in capacity fading and subsequent battery failure. Therefore, a fundamental understanding of underlying electrochemical mechanisms in the electrodes during battery cycling is critical for the development of next-generation secondary batteries.Based on our previous studies utilizing in situ surface-enhanced Raman spectroscopy to monitor the evolution of the Si-electrolyte interphase1 and in situ ATR-FTIR to investigate the voltage dependent electrolyte solution structure changes at the interface, transition metal redox chemistry, and cathode/electrolyte interfacial layer evolution,2 recently we updated the in situATR-FTIR with a newly designed ‘full-cell’ that enables us to analyze the interfacial reactions and interactions on the surfaces of both electrodes that directly influence battery performance, lifetime, and safety. Specifically, we focus on transition metal complex formation and its effect on solid-electrolyte interphase (SEI) formation and evolution on the anode due to transition metal dissolution and crosstalk of Mn-rich cathodes at high voltages (≥4.4 V).In addition, using our multi-modal characterization—a combination of in situ gas chromatography with flame ionization detection (GC-FID) and in situ ATR-FTIR—(electro)chemical degradation of the electrolyte is correlated with gas evolution in the battery. For example, GC-FID measures increasing amounts of ethylene gas until the end the first charging cycle of a LiNiO2//Graphite cell with Gen2 electrolyte (LiPF6 in ethylene carbonate (EC):ethyl methyl carbonate (EMC), 3:7 wt.%). Concurrently, in situ ATR-FTIR shows decreasing concentration of EC solvent, as calculated from the FTIR intensity of EC vibrational absorption. Ethylene is a known by-product of ethylene carbonate electrochemical reduction and is produced during SEI formation.3 Quantifying multiphase reactions occurring during battery operation is critical to understanding and mitigating battery degradation pathways, and developing next-generation battery materials systems.

Monitoring hydrocarbon levels during bioremediation by enhanced bio-stimulants using GC-FID

The efficacy of bio-stimulants on the remediation of hydrocarbon polluted soil was assessed using Gas Chromatography with Flame Ionization Detector (GC-FID). The enhanced bio-stimulants were discarded melon pulps, discarded breadfruit pulps and poultry droppings. These were applied to the polluted soil in the ratio of 1:5; the blend was observed for sixty days. Inferring from the chromatographs, the carbon compounds present in the polluted and remediated soils ranged from C12 – C40 with varying concentrations; C12 to C19 were dominant, C9 to C11 were residual with negligible concentrations. The total petroleum hydrocarbon (TPH) of polluted soil was 42,229.73 mg/kg, and the remediated soils were: biodegraded melon pulp - 23,786.3 mg/kg, biodegraded breadfruit pulp - 15,322.82 mg/kg, and chicken droppings, - 7,314.29 mg/kg. The results indicated that TPH of the polluted soil was reduced by 43.67% in sample remediated with biodegraded melon pulp, 63.71% in sample remediated with biodegraded breadfruit pulp, and 82.67% in sample remediated with chicken droppings. Therefore, a decreasing order of the effectiveness of the bio-stimulants is thus: chicken droppings > biodegraded breadfruit pulp > biodegraded melon pulp. The higher remediation potential of poultry droppings is attributable to high nitrogenous content. The study showed that the aforementioned bio-stimulants are effective in remediation of petroleum polluted soil. GC-FID detected the hydrocarbon present and their concentrations in the polluted and remediated soils. GC-FID is preferred to other analytical techniques due to its precision in identification and quantification of hydrocarbon fractions.

DLLμE/GC-MS as a Powerful Analytical Approach to Establish the Volatilomic Composition of Different Whiskeys

The volatilomic fingerprint of nine different whiskeys was established using a rapid and sensitive analytical approach based on dispersive liquid–liquid microextraction (DLLμE) followed by gas chromatography mass spectrometry detection (GC-MS) and gas chromatography with flame ionization detection (GC-FID). The influence of the extractor solvent on the extraction efficiency of volatile compounds (VOCs) was evaluated by DLLμE/GC-MS. The highest amounts of VOCs were obtained using 5 mL of sample, dichloromethane as the extractor solvent, and acetone as the disperser solvent. The proposed method showed no matrix effect, good linearity (R2 ≥ 0.993) in the assessed concentration range, recovery (ranging from 70 to 99%, precision (RSD ≤ 15%) and sensitivity (low limits of detection and quantification). A total of 37 VOCs belonging to different biosynthetic pathways including alcohols, esters, acids, carbonyl compounds, furanic compounds and volatile phenols were identified and quantified using DLLμE/GC-MS and DLLμE/GC-FID, respectively. Alcohols (3-methylbutan-1-ol, propan-1-ol), esters (ethyl decanoate, ethyl octanoate, ethyl hexanoate), and acids (decanoic acid, octanoic acid, hexanoic acid) were the most abundant chemical families. The multivariate statistical analysis allowed for the discrimination of whiskeys based on their volatilomic fingerprint, namely octanoic acid, 2-furfural, ethyl octanoate, ethyl hexanoate, acetic acid, ethyl dodecanoate, butan-1-ol, and ethyl decanoate.

Removal of COD and Ammoniacal-Nitrogen from Industrial Wastewater using Adsorption with Plantain Husk Adsorbent

The rate of depletion of ground/surface water has increased due to the weakness in the existing laws, contamination of the ground water and excess usage of water that produce increased quantity of wastewater. In this study, wastewater from Dangote Fertilizer Limited (DFL) was treated using adsorption method of treatment with consideration of the factors (pH, temperature and contact time) that impedes the efficiency of the method. Plantain husk, which is an agricultural waste, was used as adsorbent in the adsorption process. Response Surface Methodology (RSM) was used to determine the experimental number of runs after which it gives the optimum conditions of those parameters considered. The plantain husk was characterized using Gas chromatograph with Flame Ionization detector (GC-FID). The results obtained in the study revealed that utilization of the plantain husk as adsorbent in adsorption process for the removal of COD and Ammoniacal nitrogen from industrial wastewater will yield a high percentage removal (values). Ammoniacal nitrogen removal with plantain husk adsorbent was about 93% maximum and as pH increased to 7.5 (alkaline), a slight decrease in the Ammoniacal nitrogen removal percentage to about 92% could be attained. Furthermore, percentage removal of COD from the wastewater of about 83% maximum could be obtained. Effect of temperature on COD removal is a direct correlation as increase in temperature could lead to the decrease in COD removal. It can be concluded that the interaction between contact time and pH as compared to other interactions has an overall positive effect in the adsorption process of Ammoniacal nitrogen removal from wastewater. Being an agricultural waste and environmentally friendly materials, adsorbent from plantain husk should be considered for treatment of industrial waste water for removal of COD and ammoniacal nitrogen.

An evaluation of qH NMR: A complementary approach to GC-FID for quantification of Thymol and trans-Anethole in essential oils and supplements

Sweet fennel (Foeniculum vulgare Mill. var. dulce) and thyme (Zataria multiflora Boiss.) are regarded as the important supplies for pharmaceutical, food, cosmetic, and perfume industries. The major components trans-anethole and thymol are represented in fennel and thyme, respectively. The essential oils (EOs) content and the value of their related constituents should be given in strict quality control due to the storage conditions, source, and adulterations. In this study, we compared the validation of quantitative 1H NMR (qH NMR) method with the gas chromatography with flame ionization detection (GC-FID) to quantify the trans-anethole and thymol in fennel and thyme EOs and their related supplements. The current results showed that the quantification of trans-anethole and thymol by qH NMR method was successfully achieved from their EOs and supplements. All the validation parameters including linearity, robustness, repeatability, and stability were authenticated for thymol and trans-anethole quantification. Similar results were obtained in both qH NMR and conventional GC-FID methods. Therefore, according to the measured values, the qH NMR method was adequate to determine the constituents of the EOs, with the results being roughly comparable to those obtained by GC-FID, with the advantage of being simple, repeatable, rapid (8–10 min, while for GC-FID 55 min) and essential for quality control of commercial samples.

Physicochemical Characteristics of Bambara Groundnut Speciality Malts and Extract.

Speciality malts and their extracts have physicochemical characteristics such as colour, flavour, and aroma sorted for in food production. Speciality malts used in food production are mostly produced from cereal grains. Hence, this study aimed to produce speciality malts from Bambara groundnut (BGN) seeds and analyse their physicochemical characteristics and metabolites. The base, toasted, caramel, and roasted malt were produced by drying at different temperatures and times. Syrups were produced isothermally from the speciality malts. The speciality malts and syrups were assessed for colour, pH, protein, α and β-amylases, total polyphenols, antioxidants, and metabolite profiling. The BGN speciality malts were assayed for fatty acid methyl esters (FAME), hydrocarbons, sugar alcohols, sugars, acids, amino acids, and volatile components using capillary gas chromatography-mass spectrometry (GC-MS) and gas chromatography with flame ionisation detection (GC-FID). The colours of the speciality malts and syrups were significantly (p = 0.000) different. The protein content of the BGN speciality malts was significantly different (p = 0.000), while the protein content of the syrups was not significantly different. The amylase activities of the BGN speciality malt decreased with the change in kilning temperatures and time. The α- and β-amylase activities for the specialty malts were 1.01, 0.21, 0.29, 0.15 CU/g and 0.11, 0.10, 0.10, 0.06 BU/g. The total polyphenols and antioxidant activities differed for all BGN speciality malts. There were twenty-nine volatiles detected in the BGN speciality malts. Fifteen amino acids consisted of seven essential amino acids, and eight non-essential amino acids were detected in the speciality malts. Fatty acid methyl esters (FAME) identified were palmitoleic, oleic, linolelaidic, linoleic, and arachidic acid. The sugars, organic acids, and sugar alcohols consisted of lactic acid, fructose, sucrose, and myo-inositol. The BGN speciality malts exhibited good physicochemical characteristics and metabolites that can make them useful as household and industrial ingredients for food production, which could be beneficial to consumers.

Synergistic Effect of Cloves (Syzygium aromaticum), Thyme (Thymus vulgaris) and Lemon (Citrus limon) Blended Essential Oils Optimized by Mixture Design for Improving the Antioxidant Activity

Background: Combining various essential oils (EOs) for developing pharmaceutical formulations has been the focus of attention in recent years. Objectives: This study aimed to determine the antioxidant effect of the combination of three Eos obtained from clove (Syzygium aromaticum L.), lemon peel (Citrus limon L.), and thyme (Thymus vulgaris L.) by using mixture design. Methods: The EOs of lemon peel (EOL), clove (EOC), and thyme (EOT) as well as their combination were analyzed using a gas chromatograph with flame ionization detector (GC/FID). The antioxidant activities of the EOs from EOL, EOC, and EOT as well as their combination were measured adopting DPPH assay. The construction and statistical analysis of the experiment were designed using the NemrodW (LPRAI, version 2000) software. Results: EOL, EOC, and EOT were found capable of neutralizing DPPH radical. EOC was distinguished by its strongest antiradical activity with IC50=15.02±0.02 µg/mL. EOT had an IC50=29.20±0.12 µg/mL while EOL had 188.69±0.95 µg/mL. The positive standard BHT was detected to be IC50=24±0.02 µg/ mL. The optimal, combinative mixture of essential oils may have been determined based on these isoresponse curves which allowed fixing the ideal combinations of ingredient in terms of quantity to obtain an EO mixture possessing appreciable and optimal antioxidant characteristics. The predicted antioxidant properties determined by the mixing plan model were retained and the experiments were carried out respecting the contents of proposed ingredients of 25.7% EOT, 32.3% EOL, and 41.9% EOC equivalent to 15.42 mg, 19.38 mg and 25.14 mg, respectively. This resulted in arriving at an essential oil mixture with an experimental IC50=11.023±0.145 µg/mL which was similar to those of the predicted antioxidant properties with an order of 10.907±0.212 µg/mL and a non-significant difference of P<0.05, based on which the validity of the proposed mixing plan model was determined. The combined EO was also found to be rich in eugenol (32.35±1.13%), thymol (25.49±0.03%), and limonene (21.30±0.02%). Conclusion: Statistical planning and the development of utility profiles for mixtures of essential oils may have been used to predict the optimal composition as well as to determine their antioxidant profile.

A Review of Techniques for the Determination of Total Petroleum Hydrocarbons in Soils

The Total Petroleum Hydrocarbon (TPH) is the total of different types of hydrocarbons in the crude oil mixture. It includes volatile petroleum hydrocarbons and extractable petroleum hydrocarbons. The TPH determination techniques are primarily grouped into spectroscopic (ultraviolet spectroscopy, raman spectroscopy, fluorescence spectroscopy, infrared spectroscopy) and non- spectroscopic (gravimetric, immunoassay, gas chromatography with mass spectrometric detection (GC/MSD), gas chromatography with flame ionization detection (GC-FID)) techniques. Solvent and the sample characteristics determine the efficiency of the techniques. This paper compares spectroscopic (fourier transform infrared spectroscopy and ultraviolet spectroscopy) and non-spectroscopic (gravimetric and gas chromatography) methods in the determination of TPH in soil. Spectroscopic and non-spectroscopic techniques are efficient, but the paper recommends spectroscopic techniques because the techniques are efficient with small operational time, and are safer in occupational health and safety issues. In addition their results are accurate and reliable.

Determination of n-3 index and arachidonic acid/eicosapentaenoic acid ratio in dried blood spot by gas chromatography.

Background: Clinical and epidemiological studies suggest that analysis of the polyunsaturated fatty acids (PUFAs) is essential to evaluate nutritional requirements and disease risk. We describe a simple, sensitiveand non-invasive method for estimating the n-3 index and arachidonic acid (AA)/eicosapentaenoic acid (EPA) ratio in dried blood spots (DBSs). Experimental: After obtaining DBSs on a spot card, PUFAs were transesterified (direct, acidic transesterification) and subsequently extracted with n-hexane. Gas chromatography withflame ionization detection (GC-FID) was used to analyze the extracted PUFAs, and then n-3 index and AA/EPA ratio were calculated. Method validation showed satisfactory precision and linearity. Conclusion: This analysis is simple and reliable to estimate PUFA status, and it was successfully applied to samples from 20 subjects, demonstrating its applicability.

Migration of mineral oil aromatic hydrocarbon (MOAH) from hot melt adhesives used in food packaging materials

This article studies the migration of MOAH from hot melt adhesives used in multilayer laminates into food simulants. First, the initial concentration of a group of compounds selected as MOAH markers in several adhesives was determined by headspace solid phase microextraction coupled to gas chromatography mass spectrometry (HS-SPME-GC-MS), using the previously optimised method. Then, the migration of the MOAH fraction and MOAH markers from the laminates was studied. The MOAH fraction was analysed by gas chromatography with flame ionisation detection (GC-FID), and the MOAH markers were analysed by HS-SPME-GC-MS. Twelve MOAH markers were detected, and their initial concentrations were between 0.46 and 33.8 μg g-1. Only eight were identified after migration, ranging between 0.62 and 21.33 μg dm-2, with a migration percentage of 12–75%. The fraction of MOAH that migrated eluted mainly in the C16-C25 range and reached concentrations of 19.65 μg dm-2 from the laminate.

Characterization of the Fatty Acid and Elemental Composition of Human Milk with Chemometric Processing to Determine the Nutritional Value

Breast milk represents the best food for growth and healthy development of new-borns and infants. Exclusive breast feeding is recommended for the first 6 months of life. The composition of human milk changes throughout the lactation period. The aim of this preliminary study was to evaluate the variations in fatty acid composition and elemental concentrations of breast milk during the first 6 months of lactation. Fatty acid methyl esters were prepared by standard methods, separated, and quantified by gas chromatography with flame ionization detection (GC-FID). An inductively coupled plasma mass spectrometry (ICP-MS) method was used to determine 16 elements in breast milk after acid microwave digestion. The mean concentrations of essential elements and potentially toxic elements were as follows: 410.3 mg/L (Na), 53.5 mg/L (Mg), 118.4 mg/L (P), 516 mg/L (K), 326.4 mg/L (Ca), 0.5 mg/L (Fe), 0.4 mg/L (Cu), 1.5 mg/L (Zn), 0.2 mg/L (Cr), 0.02 mg/L (Ni), 3.5 µg/L (Li), 5.0 µg/L (Mn), 0.6 µg/L (Co), 7.7 µg/L (As), and 1.5 µg/L (Pb). Analysis of variance (ANOVA), linear discriminant analysis (LDA) and Pearson’s correlation analysis was applied to evaluate correlations among the lactation stages as a function of fatty acid and elemental contents and to identify the best discriminant markers.