Direct Chemical Analysis Research Articles

Phosphorous intake in foods and phosphorus status markers in circulation in the Boston Puerto Rican Health Study

Phosphorus (P) additives may be deleterious for health. We measured the P content of key foods, and associations of P intake with biomarkers in the Boston Puerto Rican Health Study (BPRHS). Direct chemical analysis of 92 foods was done with the molybdenum blue spectrophotometric method and inductively coupled plasma mass spectrometry (ICP-MS). A novel algorithm was used to determine bioavailable, natural, and added P. We estimated P intakes from foods in 1323 participants, aged 45–75 y, and associations of these with serum P, fibroblast growth factor 23 (FGF23), parathyroid hormone (PTH), and Klotho. Relationships between intakes and status markers were assessed with Pearson’s correlations and t-tests. Our food analyses generally support P values in the USDA nutrient database, with the exceptions of American and cheddar cheese, which had more P than in the database. Women had higher added P intake than men, and younger participants had higher added P than those older. Total P intake tended to be positively associated with serum P and klotho, and inversely associated with PTH, but relationships were not strong. Puerto Rican adults have high intake of additive P. Culturally sensitive interventions that highlight dietary quality are needed.

Study on Bio-remediation of Oil Contaminated Sand

Abstract: The consumption of oil is getting raised day to day in our country. Its availability is limited to only a few countries. So, it has to be transported from such countries to other parts of the world. Leakage of oil occurs during drilling process and transportation through pipe lines. Due to this leakage the surrounding sand or water gets contaminated. Because of this, contamination sand is getting polluted and its engineering properties are altered. This study is carried out to determine the effects of crude oil contamination on the engineering properties of sea sand and to improve the properties of oil contaminated sea sand by the process Bioremediation. The soil samples are collected from Ganagalla Peta Beach, Andhra Pradesh. The samples are then artificially contaminated using crude oil in varying percentages of 2%, 4%, 6%, 8%, 10% and 12% for 2, 7 and 14 days. Sea sand is considered for this study. The laboratory tests such as direct shear, Standard proctor and chemical analysis was carried for both contaminated and bioremediated sand. As the bioremediation improves the shear strength of the soil, it is carried out for contaminated sand by using bacteria Bacillus amyloliquefaciens as it removing hydrocarbons from the contaminated sand. The Engineering properties of bioremediated sand are compared with contaminated sand

Solvent-free automated thermal desorption-gas chromatography/mass spectrometry for direct screening of hazardous compounds in consumer textiles

The global production of textiles utilizes numerous large-volume chemicals that may remain to some extent in the finished garments. Arylamines, quinolines, and halogenated nitrobenzene compounds are possible mutagens, carcinogens and/or skin sensitizers. For prevention, control of clothing and other textiles must be improved, especially those imported from countries without regulations of textile chemicals. An automated analytical methodology with on-line extraction, separation, and detection would largely simplify screening surveys of hazardous chemicals in textiles. Automated thermal desorption-gas chromatography/mass spectrometry (ATD-GC/MS) was developed and evaluated as a solvent-free, direct chemical analysis for screening of textiles. It requires a minimum of sample handling with a total run time of 38 min including sample desorption, chromatographic separation, and mass spectrometric detection. For most of the studied compounds, method quantification limit (MQL) was below 5 µg/g for 5 mg of textile sample, which is sufficiently low for screening and control of quinoline and arylamines regulated by EU. Several chemicals were detected and quantified when the ATD-GC/MS method was applied in a limited pilot screening of synthetic fiber garments. A number of arylamines were detected, where some of the halogenated dinitroanilines were found in concentrations up to 300 µg/g. This is ten times higher than the concentration limit for similar arylamines listed by the EU REACH regulation. Other chemicals detected in the investigated textiles were several quinolines, benzothiazole, naphthalene, and 3,5-dinitrobromobenzene. Based on the present results, we suggest ATD-GC/MS as a screening method for the control of harmful chemicals in clothing garments and other textiles.Graphical abstract

The resolved chemical composition of the starburst dwarf galaxy CGCG007-025: direct method versus photoionization model fitting

ABSTRACTThis work focuses on the gas chemical composition of CGCG007-025. This compact dwarf is undergoing a galaxy wide star-forming burst, whose spatial behaviour has been observed by VLT/MUSE. We present a new line measurement library to treat almost 7800 voxels. The direct method chemical analysis is limited to 484 voxels with good detection of the $[\mathrm{S}\, {\small III}]6312\, \mathring{\rm A}$ temperature diagnostic line. The recombination fluxes are corrected for stellar absorption via a population synthesis. Additionally, we discuss a new algorithm to fit photoionization models via neural networks. The eight ionic abundances analysed show a spatial normal distribution with a $\sigma \sim 0.1\, {\rm dex}$, where only half this value can be explained by the uncertainty in the measurements. The oxygen abundance distribution is 12 + log(O/H) = 7.88 ± 0.11. The ${\it T}_{e}[\mathrm{S}\, {\small III}]$ and ne[S ii] are also normally distributed. However, in the central and brightest region, the ne[S ii] is almost thrice the mean galaxy value. This is also reflected in the extinction measurements. The ionization parameter has a distribution of ${\rm log}(U) = -2.52^{0.17}_{0.19}$. The parameter spatial behaviour agrees with the S2+/S+ map. Finally, the discrepancies between the direct method and the photoionization model fitting are discussed. In the latter technique, we find that mixing lines with uneven uncertainty magnitudes can impact the accuracy of the results. In these fittings, we recommend overestimating the minimum flux uncertainty one order below the maximum line flux uncertainty. This provides a better match with the direct method.

Deeper Understanding of Solvent-Based Ambient Ionization Mass Spectrometry: Are Molecular Profiles Primarily Dictated by Extraction Mechanisms?

Solvent-based ambient ionization mass spectrometry (MS) techniques provide a powerful approach for direct chemical analysis and molecular profiling of biological tissues. While molecular profiling of tissues has been widely used for disease diagnosis, little is understood about how the interplay among solvent properties, matrix effects, and ion suppression can influence the detection of biological molecules. Here, we perform a systematic investigation of the extraction processes of lipids using an ambient ionization droplet microsampling platform to investigate how the physicochemical properties of the solvent systems and extraction time influence molecular extraction and detection. Direct molecular profiling and quantitative liquid chromatography-mass spectrometry (LC-MS) of discrete solvent droplets after surface sampling were investigated to provide insights into extraction and ionization mechanisms. The results of this study suggest that intermolecular interactions such as hydrogen bonding play a major role in extraction and detection of lipids using solvent-based ambient ionization techniques. In addition, extraction time was observed to impact the molecular profiles obtained, suggesting optimization of this parameter can be performed to favor detection of specific analytes.

Chemical fingerprinting of phenolic compounds in Finnish berry wines using Fourier transform ion cyclotron resonance mass spectrometry

Chemical fingerprinting of phenolic compounds present in Finnish berry wines was performed using a direct-infusion Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The main aim of this study was to compare the phenolics profiles of wines produced from natural and/or cultivated berries and to demonstrate the feasibility of FT-ICR MS for a direct chemical analysis of the wine samples without chromatographic separation. First, phenolic compounds were recovered from the wine samples by solid-phase extraction (SPE), and the total phenolic content (TPC) was then determined by a Folin-Ciocalteau assay. The TPC of the original berry wines varied from 421 to 2108 mg/L, while the TPC of the extracts was 157–1525 mg/L. Over fifty phenolic compounds were tentatively identified from the wine samples by FT-ICR MS, whose concentrations highly varied depending on the types of berries used in the winemaking process.

Accurately calibrated frequency domain diffuse optical spectroscopy compared against chemical analysis of porcine adipose tissue.

Frequency domain diffuse optical spectroscopy (fdDOS) is a noninvasive technique to estimate tissue composition and hemodynamics. While fdDOS has been established as a valuable modality for clinical research, comparison of fdDOS with direct chemical analysis (CA) methods has yet to be reported. To compare the two approaches, we propose a procedure to confirm accurate calibration by use of liquid emulsion and solid silicone phantoms. Tissue fat (FAT) and water (H2 O) content of two ex vivo porcine tissue samples were optically measured by fdDOS and compared to CA values. We show an average H2 O error (fdDOS minus CA) and SD of 1.9 ± 0.2% and -0.9 ± 0.2% for the two samples. For FAT, we report a mean error of -9.3 ± 1.3% and 0.8 ± 1.3%. We also measured various body sites of a healthy human subject using fdDOS with results suggesting that accurate calibration may improve device sensitivity.

Confined DART-MS for Rapid Chemical Analysis of Electronic Cigarette Aerosols and Spiked Drugs.

A confined direct analysis in a real time mass spectrometry (DART-MS) system and method were developed for coupling directly with commercial electronic cigarettes for rapid analysis without sample preparation. The system consisted of a confining heated glass T-junction, DART ionization source, and Vapur interface to assist aerodynamic transport. Suction generated by positioning the electronic cigarette at the junction inlet allowed for direct chemical analysis of aerosolized electronic liquids from both automatic devices powered by drag and manual button-operated devices, which is unachievable with traditional DART-MS. Parametric analyses for the system investigated Vapur suction flow rate, junction heating, puff duration, and coil power levels. Using this method, rapid chemical analyses of electronic cigarette aerosols from electronic liquids, spiked illicit drugs, and polymeric or plasticizer contaminants were performed in <30 s. The confined DART-MS method provides a streamlined tool for rapid screening of illicit and hazardous chemical profiles emitting from electronic cigarettes.

Single-molecule imaging and kinetic analysis of intermolecular polyoxometalate reactions.

We induce and study reactions of polyoxometalate (POM) molecules, [PW12O40]3− (Keggin) and [P2W18O62]6− (Wells–Dawson), at the single-molecule level. Several identical carbon nanotubes aligned side by side within a bundle provided a platform for spatiotemporally resolved imaging of ca. 100 molecules encapsulated within the nanotubes by transmission electron microscopy (TEM). Due to the entrapment of POM molecules their proximity to one another is effectively controlled, limiting molecular motion in two dimensions but leaving the third dimension available for intermolecular reactions between pairs of neighbouring molecules. By coupling the information gained from high resolution structural and kinetics experiments via the variation of key imaging parameters in the TEM, we shed light on the reaction mechanism. The dissociation of W–O bonds, a key initial step of POM reactions, is revealed to be reversible by the kinetic analysis, followed by an irreversible bonding of POM molecules to their nearest neighbours, leading to a continuous tungsten oxide nanowire, which subsequently transforms into amorphous tungsten-rich clusters due to progressive loss of oxygen atoms. The overall intermolecular reaction can therefore be described as a step-wise reductive polycondensation of POM molecules, via an intermediate state of an oxide nanowire. Kinetic analysis enabled by controlled variation of the electron flux in TEM revealed the reaction to be highly flux-dependent, which leads to reaction rates too fast to follow under the standard TEM imaging conditions. Although this presents a challenge for traditional structural characterisation of POM molecules, we harness this effect by controlling the conditions around the molecules and tuning the imaging parameters in TEM, which combined with theoretical modelling and image simulation, can shed light on the atomistic mechanisms of the reactions of POMs. This approach, based on the direct space and real time chemical reaction analysis by TEM, adds a new method to the arsenal of single-molecule kinetics techniques.

Spectroscopic Identification of Peptide Chemistry in the Caulobacter crescentus Holdfast.

The bacterium Caulobacter crescentus is known to attach irreversibly to underwater surfaces by utilizing an adhesive structure called the holdfast, which exhibits the greatest known adhesive strength of any organism. The very small size of the holdfast (∼400 nm wide and ∼40 nm high) has made direct chemical analysis difficult, and its structure remains poorly understood. In this study, we employ spectroscopic techniques, including attenuated total reflection infrared spectroscopy (ATR-IR) and X-ray photoelectron spectroscopy, to probe holdfast chemistry. The data indicate the presence of a peptide signal within the holdfast polymer. By comparing the ATR-IR spectrum of the holdfast to peptidoglycan spectra from other bacterial species, we demonstrate the similarity of the holdfast chemistry to that of peptidoglycan, suggesting peptide cross-linking may play a role in holdfast architecture. To probe the molecular groups at the interface, surface-sensitive sum frequency generation spectroscopy was used to show that aromatic and hydroxyl groups related to this protein content at the adhesive interface could be playing a crucial role in adhesion. On the basis of these results, we propose a model of the holdfast architecture with similarities to the peptide cross-linking observed in the peptidoglycan polymer of the bacterial cell wall. These results not only provide information about the development of adhesives that could be based on holdfast chemical architecture but also reveal a potentially yet unexplored biosynthetic pathway in holdfast synthesis that has not yet been revealed by genetic approaches, thereby opening up a potentially new avenue of research in holdfast synthesis.

Slight Increases of Phosphorus and Sulfur in Human First Septal Perforator Branches of the Left Anterior Descending Artery with Aging

To elucidate age-related changes of the first septal perforator branch (FSB), the authors investigated age-related changes of elements in the FSBs by direct chemical analysis. In addition, the effects of different arterial sizes and genders on element accumulation were investigated in the FSBs. Sixty-two formalin-fixed adult Thai hearts were used and the FSBs were carefully dissected in the hearts. After the arteries were incinerated with nitric acid and perchloric acid, element contents were determined by inductively coupled plasma-atomic emission spectrometry.

Structure of strongly turbulent premixed n-dodecane–air flames: Direct numerical simulations and chemical explosive mode analysis

Structure of strongly turbulent premixed n-dodecane/air flames with high Karlovitz numbers (Ka) is studied based on three-dimensional (3D) direct numerical simulation (DNS) datasets. Heat release and fuel consumption rates in these flames are observed to be enhanced compared to what can be conventionally described as increases in flame surface area. To explain the cause for the burning rate enhancement, temperature and species mass fractions are first investigated to reveal the overall flame structure. The chemical explosive mode analysis (CEMA) is then employed to identify local combustion modes, including local assisted ignition, auto-ignition, and extinction, each of which is found to play a role in the overall burning rates. The spatial distribution of the local modes is found to be drastically different from that in comparable laminar flames where the local extinction mode is mostly absent. For the high-Ka cases (Ka = 103 and 104), the extinction mode is shown to be comparable to or more important than the auto-ignition mode for heat release and fuel consumption rates. In contrast, the auto-ignition mode plays a more important role in heat release than the extinction mode in laminar and the relatively low-Ka flames (Ka = 102). In addition, two types of mixture pockets are identified by CEMA: pockets of reactants in bulk products and pockets of hot products in bulk reactants. The dynamics of these pockets are strongly affected by the local modes of the spatially adjacent mixtures. While the pockets of reactants in bulk products are almost always consumed by auto-ignition and/or inward flame propagation, the pockets of products in bulk reactants may either grow themselves due to outward flame propagation or contract volumetrically due to local extinction. In contrast to the conventional understanding, local extinction can promote the overall burning process, as it enables mixing of the radicals and sensible energy from the product pockets into the surrounding reactants, thus facilitating their ignition. Clearly, such effects must be considered in order to closely model these flames.

Serial hyphenation of dried spot, reversed phase liquid chromatography, hydrophilic interaction liquid chromatography, and tandem mass spectrometry towards direct chemical profiling of herbal medicine-derived liquid matrices, an application in Cistanche sinensis

Inspired by dried blood spots (DBS), “dried spots of herbal medicines” (DSHM) concept was proposed here. In response to this superior sampling means, a new platform integrating dried spot, serially coupled reversed phase liquid chromatography and hydrophilic interaction liquid chromatography (RPLC-HILIC), and tandem mass spectrometry (MS/MS), was configured for directly, comprehensively chemical profiling of HM-derived liquid matrices. As an important original source of Cistanches Herba (Chinese name: Roucongrong) that is a well-known tonic HM, Cistanche sinensis (Csi) was employed to illustrate and validate the applicability. Dried spots (I.D. 3.0 mm) were prepared by loading 2 μL aliquots of Csi extract onto filter paper. Each dried spot was packed into an in-line filter holder (I.D. 3.0 mm × 4.0 mm) and then inserted behind the auto-sampler of a well-defined instrumentation named RPLC-HILIC–MS/MS. Hybrid ion trap-time of flight MS and hybrid triple quadrupole-linear ion trap MS were deployed in combination for the in-depth MS/MS data acquisition of diverse chemical families, such as phenylethanoid glycosides, lignans, iridoids, amino acids, and so forth. To assist chemical profiling, an in-house chemical library was built by collecting as much prior knowledge as possible. A total of 88 components were detected and tentatively annotated in Csi by matching their multi-stage MS spectra with those of authentic standards and literature data. Collectively, DSHM carried all merits of DBS, and the integrative dried spot-RPLC-HILIC-MS/MS platform was a promising analytical tool for direct chemical analysis and rapid quality evaluation of HMs, in particular those traditional Chinese medicine injections.

Duodenal adipose tissue is associated with obesity in baboons (Papio sp): a novel site of ectopic fat deposition in non-human primates.

Ectopic fat is a recognized contributor to insulin resistance and metabolic dysfunction, while the role of fat deposition inside intestinal wall tissue remains understudied. We undertook this study to directly quantify and localize intramural fat deposition in duodenal tissue and determine its association with adiposity. Duodenal tissues were collected from aged (21.2 ± 1.3years, 19.5 ± 3.1kg, n = 39) female baboons (Papio sp.). Fasted blood was collected for metabolic profiling and abdominal circumference (AC) measurements were taken. Primary tissue samples were collected at the major duodenal papilla at necropsy: one full cross section was processed for hematoxylin and eosin staining and evaluated; a second full cross section was processed for direct chemical lipid analysis on which percentage duodenal fat content was calculated. Duodenal fat content obtained by direct tissue quantification showed considerable variability (11.95 ± 6.93%) and was correlated with AC (r = 0.60, p < 0.001), weight (r = 0.38, p = 0.02), leptin (r = 0.63, p < 0.001), adiponectin (r = - 0.32, p < 0.05), and triglyceride (r = 0.41, p = 0.01). The relationship between duodenal fat content and leptin remained after adjusting for body weight and abdominal circumference. Intramural adipocytes were found in duodenal sections from all animals and were localized to the submucosa. Consistent with the variation in tissue fat content, the submucosal adipocytes were non-uniformly distributed in clusters of varying size. Duodenal adipocytes were larger in obese vs. lean animals (106.9 vs. 66.7µm2, p = 0.02). Fat accumulation inside the duodenal wall is strongly associated with adiposity and adiposity related circulating biomarkers in baboons. Duodenal tissue fat represents a novel and potentially metabolically active site of ectopic fat deposition.

Inferring total organic carbon and major element geochemical and mineralogical characteristics of shale core from hyperspectral imagery

Hyperspectral systems that image drill core can capture detail mineralogical information at the millimeter scale and thus have the potential to enable investigators to characterize shale composition and heterogeneity, complementing the direct chemical and x-ray diffraction analysis of core samples and guiding detailed sampling. This method provides insight into petrophysical and geomechanical properties because these properties are significantly correlated to rock composition. We tested this approach on a continuous long core from the shale sequence of the Horn River Group in the Horn River Basin, British Columbia, sampled at a spacing of 1 m (40 in.) and analyzed for geochemical composition. These data enable the calibration of spectral imagery to rock composition and specifically predict total organic carbon (TOC) and the abundance of SiO2, Al2O3, K2O, and CaO. We then imaged nine samples from the Woodford Shale from the Permian Basin, Texas, for a blind test to assess the predictive models. The models were then used to predict TOC and geochemical data over detailed imagery of 300 m (984 ft) of Horn River Group shale core and portray their spatial variability downhole as images and profiles. In its simplest form, hyperspectral imagery can be enhanced to highlight fabric in shale core that otherwise is difficult to visualize because of low brightness. In addition, we show that spectral imagery of shale can also be processed to either convey mineralogical (quartz, clay, and carbonate) or geochemical information. The resulting views can readily be used to guide the selection of samples and may provide tools for scaling reservoir properties from individual plugs to reservoir volumes.

Leaf Spray Mass Spectrometry: A Rapid Ambient Ionization Technique to Directly Assess Metabolites from Plant Tissues.

Plants produce thousands of small molecules that are diverse in their chemical properties. Mass spectrometry (MS) is a powerful technique for analyzing plant metabolites because it provides molecular weights with high sensitivity and specificity. Leaf spray MS is an ambient ionization technique where plant tissue is used for direct chemical analysis via electrospray, eliminating chromatography from the process. This approach to sampling metabolites allows for a wide range of chemical classes to be detected simultaneously from intact plant tissues, minimizing the amount of sample preparation needed. When used with a high-resolution, accurate mass MS, leaf spray MS facilitates the rapid detection of metabolites of interest. It is also possible to collect tandem mass fragmentation data with this technique to facilitate a compound identification. The combination of accurate mass measurements and fragmentation is beneficial in confirming compound identities. The leaf spray MS technique requires only minor modifications to a nanospray ionization source and is a useful tool to further expand the capabilities of a mass spectrometer. Here, fresh leaf tissue from Sceletium tortuosum (Aizoaceae), a traditional medicinal plant from South Africa, is analyzed; numerous mesembrine alkaloids are detected with leaf spray MS.

Cryo-FIB-SEM-EDSを用いた流体包有物の個別化学組成分析：キルギス共和国マクバル岩体の超高圧変成岩の例

Cryo-FIB-SEM-EDSを用いた流体包有物の個別化学組成分析：キルギス共和国マクバル岩体の超高圧変成岩の例

An improved method for PCR-based detection and routine monitoring of geosmin-producing cyanobacterial blooms

Production of taste and odour (T/O) compounds, principally geosmin, by complex cyanobacterial blooms is a major water quality issue globally. Control of these cyanobacteria imposes a significant cost on water producing and dependent industries, and requires routine monitoring and management. Classic monitoring methods, including microscopy and direct chemical analysis, lack sensitivity, are laborious, expensive or cannot reliably identify the source of geosmin production. Polymerase Chain Reaction (PCR) based tools targeting the geosmin synthase gene (geoA) provide a novel tool for routine monitoring. However, geoA is variable at the nucleotide level and potential geosmin producers represent a broad taxonomic distribution, such that multiple PCR primers with distinct amplification protocols are needed to target all potential sources of this important T/O compound. Development of novel primers is hindered by a lack of sequence data and limited field and laboratory data on geosmin producers prevents prioritizing taxa for PCR testing. Here we performed a genetic screen of 253 bloom samples from Victoria, Australia using each existing PCR protocol targeting geoA. We detected Dolichospermum ucrainicum as the major geosmin producer (87% of sequenced samples) along with 3 unknown geoA sequence types. Using these data, we designed a novel, short amplicon, PCR protocol utilising a single standardised primer pair, capable of amplifying all geoA positive samples in our study, as well as a Nostoc punctiforme positive control. This single protocol geoA PCR can further be tested on other geosmin producers and will simplify routine monitoring of T/O producing cyanobacteria.

Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics.

Endogenous volatile organic compounds (VOCs) such as acetone in exhaled human breath are associated with metabolic conditions in the bloodstream. Development of compact, rapid detectors of exhaled breath chemical composition in clinical settings is challenging due to the small sample size that can be collected during a single exhalation as well as spectroscopic interference by the abundance of water. In this paper, we show that the activity of a catalytic polymer membrane (Nafion 117) toward the heterogeneous condensation reaction of immobilized resorcinol reagent with gas-phase acetone can be preserved even at 100% ambient relative humidity through the incorporation of organic acids such as vanillic or tiglic. The reaction produces a colored flavan product that permits highly selective and sensitive correlation to acetone concentration in exhaled breath. Such behavior suggests solvent displacement, analogous to homogeneous liquid-phase systems. However, unlike classic acid-base equilibria, the extent of optode water resistance is shown to increase with the pKa of the imbibed organic acid while peak signal intensity of the imbibed acid undergoes a bathochromic shift to longer wavelengths. These observations are consistent with competition between organic acid deprotonation by water in a mixed solvent system on the one hand and immobilization on the other. Finally, we demonstrate how when applied to the direct chemical analysis of acetone in exhaled human breath, the approach yields excellent correlation to blood glucose in diabetics.

Food Composition Databases: Considerations about Complex Food Matrices.

Nowadays, many countries have their own national Food Composition Databases, whose continuous updating allows the inclusion of a large number of foods, reflecting the food habits of the population and the growing number of foods on the market in the best way possible. Therefore, particular attention should be directed to the study not only of individual foods or food components but also of the nutritional characteristics of dishes, meals and diets, as they are really consumed. Recently, a reviewed sensitivity in Europe towards the implementation of standardized procedures for generating reliable composition data for composite dishes has been carried out. Although direct chemical analysis is the most accurate method to determine food composition, the nutrient content of complex matrices and composite dishes is often calculated from the nutrient contents of the individual ingredients, considering the different thermal treatments and using some preparation factors. In this context, this paper aims to give an updated picture on Food Composition Databases; in particular, their application regarding complex matrices is examined together with the need to optimize their calculated nutritional values. Results obtained by this calculation should almost always be observed as approximations.