[Rapid determination of 10 fat-soluble vitamins in health foods by ultra performance convergence chromatography].

Fat-soluble vitamins are important efficacy indicators in health foods because they are essential for human physiological functions. The existing method for the simultaneous determination of fat-soluble vitamins has various problems, such as limited determination components, complex sample, pretreatment process, and high requirements for personnel operating ability. Therefore, establishing a fast, simple, and accurate method that can detect various common fat-soluble vitamins at the same time is necessary. In this study, a method for the simultaneous determination of 10 commonly used fat-soluble vitamins such as vitamin A acetate (VA acetate), vitamin A palmitate (VA palmitate), vitamin E acetate (VE acetate), vitamin K1 (VK1), α-tocopherol, ß-tocopherol, γ-tocopherol, δ-tocopherol, vitamin D2(VD2) and vitamin D3 (VD3) in health foods was established by ultra performance convergence chromatography (UPC2). First, the contents of about 1.0 g of capsule samples were accurately weighed. A grinder was used to grind tablet samples into powder. The powder mixture was then precisely weighed at 2.0 g. Both substances were placed in 50 mL brown stopper tubes. The test tube was then filled with 20 mL 75% dimethylsulfoxide (DMSO) aqueous solution for demulsification. The tubes were then sonicated before being extracted with n-hexane. The centrifuged supernatant was added to vials for detection. Viridis HSS C18 SB column (100 mm×3.0 mm, 1.8 µm) was applied and CO2 was used as the mobile phase A. After comparing the influence of acetonitrile, methanol, and their mixture on chromatographic peak separation, acetonitrile-methanol (85∶15, v/v) was used as the mobile phase B. The injection volume was 1 µL. Using simulator software, the optimal chromatographic conditions were obtained after a set of three-factor orthogonal experiments of flow rate, gradient slope, and column temperature. The flow rate and column temperature were both set at 1.9 mL/min and 30 ℃. Furthermore, the maximum absorption wavelength of these 10 fat-soluble vitamins was selected for detection. Ten vitamins were baseline separated after 7 min of gradient elution. The limits of detection (LODs) and quantification (LOQs) of capsule samples were 0.4-60 µg/g and 2-150 µg/g, respectively, whereas the results for tablet samples were 0.2-30 µg/g and 0.8-75 µg/g. The linear ranges of the 10 fat-soluble vitamins were 0.1-100 µg/mL. The recoveries of spiked samples ranged from 96.5% to 113.9%, with RSD values less than 4%. Precision, stability, and repeatability RSD values were all less than 2%. By comparison, the determination results of this method were basically consistent with the existing national food safety standards. This method is simple, rapid, sensitive, and accurate, and it can meet the detection requirements of the 10 fat-soluble vitamins in health foods. Simultaneously, this method lays the foundation for the rapid and simultaneous detection of fat-soluble vitamins in existing health foods.

Three-Dimensional Printed Microdevice to Enhance Headspace Microextraction for Enrichment of Histamine in Milk.

In this work, a three-dimensional (3D) printed microdevice was designed to fix a drop of extractant that was applied to the enrichment of the most toxic biogenic amine, histamine, by headspace single-drop microextraction (HS-SDME). Concomitantly, based on the hybridization chain reaction of the histamine aptamer isothermal nucleic acid amplification strategy, a new fluorescence sensing method was developed to realize the highly sensitive detection of histamine. This is the first application of a 3D-printed microdevice to realize the HS-SDME process, which, among other advantages, effectively solves the problem of unstable and variable drop volumes that can plague traditional SDME and ensures the accuracy and repeatability of the extraction process. The calibration linear range of this SDME-fluorescence method was from 10 pM to 5 µM (R2 > 0.98), and the limit of detection was as low as 3 pM. In addition, the method was successfully demonstrated to determine histamine spiked in milk, with recoveries of between 93% and 104%, and relative standard deviations of less than 5%. The method established in this study has important practical significance for food safety monitoring and human health and provides new ideas and solutions for the design and application of biosensors.

Ultrahigh-Performance Supercritical Fluid Chromatography and Detection of Multiple Biogenic Amines in Gentamicin Sulfate: Method Development Using Computer-Assisted Modeling.

In order to solve the problem of difficult separation of various biogenic amines (BAs), which have similar structures or very different polarities, in gentamicin, by conventional liquid chromatography, a new ultrahigh-performance supercritical fluid chromatography (UHPSFC) method was developed. In this method, 10 BAs were derivatized precolumn using dansyl chloride and separated using a UHPSFC system. By computational simulation, complete separation of 10 BAs was successfully achieved. Detection was performed using a photodiode array (PDA) and single-quadrupole mass spectrometry (MS) together with electrospray ionization (ESI). A wide linear range (10-2500 ng/mL) was achieved, with the limits of detection (LODs) between 1.2 and 10.0 ng/mL and the limits of quantification (LOQs) between 5.0 and 25.0 ng/mL. Apart from high sensitivity, this UHPSFC-PDA/ESI-MS detection method also displayed high accuracy, the matrix effect was reduced by an appreciable extent, and the recovery rates of the 10 BAs were between 84.1 and 117.1%. For comparison, high-performance liquid chromatography-tandem mass spectrometry (MS/MS) was also used for the detection of underivatized BAs in gentamicin, showing good linearity and high sensitivity (LODs from 0.05 to 1.00 ng/mL and LOQs from 1.00 to 12.50 ng/mL) for all BAs except for spermine and spermidine. Although single-quadrupole MS is inferior to MS/MS in terms of sensitivity, the UHPSFC method could detect more BAs. It also achieved the quantification limits required for impurity determination, demonstrating a potential strategy to offer a map overview of possible BA presence in fermentation antibiotics.