Physical qualities of a model set of solid, texture-modified food items.

Author : Harrell Le | Published On : 01 Jul 2025

Determination of vitamin D levels in human biological specimens has gained a high relevance over the last decades, essentially because low levels have been associated with several biological disorders. In fact, vitamin D deficiency has become a worldwide health concern covering all ages and genders. The storage of biofluids has to be considered for determination of vitamin D and metabolites in order to fully preserve matrices status. This study attempts to evaluate lyophilization of serum and plasma as a pre-processing step for sample storage prior to quantitative analysis of vitamin D3 and its main hydroxylated metabolites -25(OH)D3, 24,25(OH)2D3 and 1,25(OH)2D3. The protocol including sample lyophilization was characterized in terms of analytical features and compared to the same method, based on SPE-LC-MS/MS, without lyophilization. Sensitivity, precision and accuracy were not affected when we operated with lyophilized serum and plasma and results provided by a set of twenty-four serum samples from DEQAS (Vitamin D External Quality Assessment Scheme) were in agreement with reported concentrations for 25(OH)D3 and 1,25(OH)2D3. A stability study programmed for 9 months allowed ensuring that the concentration of vitamin D3 and metabolites in lyophilized serum and plasma stored at room temperature was not affected during this period. This research has demonstrated that the quantitation of target metabolites is not under the influence of lyophilization. Therefore, including lyophilization prior to analysis could reduce shipment and storage costs, avoid delays of sample processing, and increase the stability of the target analytes due to an effective quenching process.Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main pathogens involved in hospital and community infection. To rapidly and sensitively detect the mecA gene, which is relevant to methicillin-resistant strains, microchip electrophoresis (MCE) integrated with isothermal strand-displacement polymerase reaction (ISDPR) was developed. In the ISDPR signal recycle amplification, the target DNA opened the DNA hairpin structure by specifically binding with the hairpin probe (HP), and then the primer hybridized with the probe and released the target DNA in the presence of Klenow Fragment exo- (KF exo-) polymerase. The released target DNA hybridized with the next HP and then was displaced by the primer again, consequently achieving target recycling and amplification. The amplified products of the HP-cDNA duplex were separated rapidly from other DNAs by MCE. Under optimal conditions, the limit of detection of the target DNA was as low as 12.3 pM (S/N = 3). The proposed ISDPR with MCE method was also successfully applied to detect methicillin-resistant S. aureus, and the experimental results showed that it had some advantages such as being label free, ultrasensitive, rapid and well separated.In this study, a graphene oxide/magnetite (GO-Fe3O4) nanocomposite was synthesized and used as a sorbent in the magnetic solid-phase extraction (MSPE) of gingerols from fresh ginger rhizomes, ginger extracts, commercial tea samples, ginger candies, thermogenic supplements, and tonic water. An MSPE method was developed, and the main influencing parameters in the sample preparation process were investigated. After GO-Fe3O4 based MSPE, 6-gingerol, 8-gingerol, and 10-gingerol were determined by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The whole GO-Fe3O4-MSPE-LC-MS/MS method proved high selectivity and consistent analytical confidence. The limits of detection (LOD) ranged between 2 and 3 μg L-1. Intra-day and inter-day RSDs fluctuated between 1.7 - 13.4% and 0.4-10.9%, respectively. Weighted calibration revealed good linearity within the studied range (5-200 μg L-1) and guaranteed appropriate accuracy (relative residues less then 25%). MSPE with GO-Fe3O4 demonstrated to be a practical, fast, efficient, high-throughput, and environmental-friendly sample preparation technique for determining of gingerols in commercial products, and its hyphenation with LC-MS/MS analysis yield a valuable analytical tool for the confident quality control of commercial ginger-containing products.A nanostructured Ag/Au adhesive film for H2O2 reagentless determination is here proposed. The film has been realised onto ELISA polystyrene microplates. Microwells surface has been initially modified with a gold nanoparticles (AuNPs)/polydopamine thin-film. The pristine AuNPs-decorated film was later functionalized with catechin (Au-CT) allowing a uniform formation of a plasmonic active nanostructured silver network in presence of Ag+. Changes in localized surface plasmon resonance (LSPR) of the silver network upon addition of H2O2 has been used as analytical signal, taking advantage of the etching phenomenon. The Ag/Au nanocomposite-film is characterized by a well-defined (LSPRmax = 405 ± 5 nm), reproducible (intraplate RSD ≤ 9.8%, n = 96; inter-plate RSD ≤ 11.4%, n = 480) and stable LSPR signal. The film's analytical features have been tested for H2O2 and glucose (bio)sensing. Satisfactory analytical performances were obtained both for H2O2 (linear range 1-200 μM, R2 = 0.9992, RSD ≤ 6.3%, LOD = 0.2 μM) and glucose (linear range 2-250 μM, R2 = 0.9998, RSD ≤ 8.9%, LOD = 0.4 μM). As proof of applicability, the determination of the two analytes in soft drinks has been carried out achieving good and reproducible recoveries (84-111%; RSD ≤ 9%). The developed nanostructured film overcomes analytical drawbacks associated with the use of colloidal dispersions in plasmonic assays carried out in solution; the low cost, robustness, ease of use and possibility of coupling enzymatic reactions appears very promising for (bio)sensors based on the detection of H2O2.A rapid, simple and sensitive method was proposed for low-polar acenaphthene analysis by coupling nebulization with dielectric barrier discharge ionization (N-DBDI). check details The sample solution was nebulized followed by heating and converted to be gas-phase analyte molecules prior to DBDI. This boosts the collision efficiency of analyte molecules with reactive species and thus the sensitivity, and the high-velocity gas from nebulization guides ions directed to the MS inlet without deflection. The dependence of sensitivity on the operation parameters was systematically investigated. The LOD and LOQ of acenaphthene were determined to be 0.61 ng/L and 2.05 ng/L, respectively, which were superior approximately 30 folds compared to those obtained by other methods. Parameters, including accuracy, precision, reproducibility and utility, were tested to further evaluate the performance of N-DBDI. Real environmental samples, including river water, initial rainwater and mineral water, were analyzed with good accuracy (93.61-103.