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Background Liquidambar species are rich sources of essential oils, with applications in cosmetics, perfumes, and pharmaceuticals. Traditionally, the industrial utilization of Liquidambar essential oil has focused on extraction from the resin, while the full potential of their leaf-derived essential oils remains underexplored. This study systematically compares the essential oil composition, sensory characteristics, and aroma profiles of leaves from various Liquidambar species, including hybrid sweetgum, using headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS). A precise internal standard method was conducted to identify progenies exhibiting heterosis in volatile content from a hybrid sweetgum population of 110 full-sib progenies. Results A total of 44 volatile compounds were identified, with monoterpenes ( α -pinene, β -pinene, d-limonene) dominating Liquidambar styraciflua , Liquidambar formosan a and hybrid sweetgum, while Liquidambar orientalis exhibited a unique d-Camphene-rich profile. Hybrid sweetgum progenies exhibiting heterosis in essential oil content were found, with several progenies significantly exceeding the average level. Sensory analysis, combined with odor activity value (OAV) calculations, revealed species-specific aroma profiles: L. styraciflua and hybrid sweetgum were characterized by citrus/herbaceous notes (high d-limonene OAV = 11.07), whereas L. orientalis exhibited pungent camphoraceous tones (d-camphene OAV = 15.9). Multivariate analyses identified eight key volatile compounds with high variable influence on projection (VIP > 1). Conclusions This study highlights the hybrid sweetgum population as a promising genetic resource for high essential oil yield, with seven elite progenies showing industrial potential. The distinct volatile profiles of Liquidambar species, particularly the d-camphene dominance in L. orientalis , underscore genus-wide metabolic diversity.

Modern rectified spirit is distilled ethanol (EtOH) containing only a tiny amount of methanol (MeOH), as opposed to former industrial alcohol, and is frequently used by perpetrators to adulterate or counterfeit Scotch whiskies in Taiwan. As a result, MeOH level presents an obvious discrepancy between adulterated whiskies and authentic Scotch whiskies. In this study, 54 authentic single malt Scotch whisky samples and 30 authentic blended Scotch whisky samples were comparatively analyzed. Instead of various analog internal standards often spiked for GC/MS quantitative analyses, the isotope-labeled internal standard 2H3-MeOH was employed for optimizing the Scotch whisky analysis to achieve a limit of quantitation (LOQ) of 5 ppm for MeOH. The resulting data were further analyzed by a distribution fitting method and showed that the distribution of MeOH levels corresponded to a lognormal distribution for both authentic single malt Scotch whiskies and authentic blended Scotch whiskies. Based on the statistical characteristics of the lognormal distribution, 99.7% of the MeOH concentrations would lie between 13.4 and 44.2 ppm for authentic single malt Scotch whiskies and between 7.87 and 74.9 ppm for authentic blended Scotch whiskies, suggesting that the MeOH level might serve as a marker for the authentication of the seized Scotch whiskies in Taiwan. •2H3-MeOH was used as internal standard (IS) to achieve 5ppm of the limit of quantitation (LOQ).•The distribution of MeOH contents corresponded to lognormal distribution in Scotch Whiskies.•MeOH concentration level could be considered as an exclusionary criterion for the authentication purpose.

A novel internal standard electrochemiluminescence (ECL) sensor has been designed for the detection of ascorbic acid (AA). The adopted dual-emission luminophore (NSGQDs-PEI-luminol-Pt) is composed of nitrogen and sulfur double-doped graphene quantum dots (NSGQDs, as the main luminophore), luminol (as the auxiliary luminophore and internal standard), platinum nanoparticles (Pt NPs, as the co-reaction accelerator), and polyetherimide (PEI, as the linker of NSGQDs and luminol). The results suggest obviously enhanced  ECL intensities by the Förster resonance energy transfer (FRET) between luminol (donor) and NSGQDs (acceptor). In this sensing system, the cathodic ECL intensities of NSGQDs (ECL-1, −1.8 V vs. Ag/AgCl) gradually decrease with increasing concentration of AA, while the anodic ECL intensities of luminol (ECL-2, 0.3 V vs. Ag/AgCl) almost remain essentially constant at a potential window from −2.0 to 0.4 V. The natural logarithm of the ratio between ECL-1 and ECL-2 (ln I (ECL-1/ECL-2) ) shows a good linear relationship with AA concentration ranging from 10 to 360 nM. The regression equation is ln I (ECL-1/ECL-2)  = − 0.0059 c AA  + 3.55 ( R 2  = 0.992) with a limit of detection of 3.3 nM. Such sensor has also been applied for monitoring AA in human serum. The recovery range was 96.5–105.3% and the relative standard deviation was  1.3–3.3%. Graphical abstract

Phthalic acid esters (PAEs) are emerging pollutants that need to be analyzed precisely. Chromatography-based determination of PAE content in soils are frequently affected by matrix effect, which may limit the quantification of different kinds of PAEs from different types of soil. Here we optimized a QuEChERS protocol combined with gas chromatography-mass spectrometry (GC–MS) for simultaneous determination of 16 PAEs in different soils. PAEs in different type of soils (fluvo-aquic soil, red soil, and black soil) were extracted with acetonitrile followed by GC–MS detection based on quantitative ion internal standard method. All 16 PAEs showed excellent linear relationships with mass peak areas ( R 2  > 0.99). The limits of detection (LOD) and limits of quantitation (LOQ) of all the samples were in the range of 0.91–66.97 µg/kg and 2.7–200.9 µg/kg, respectively. The accurate test at 0.5, 0.1, and 1.0 mg/kg spiking level recorded recovery rate between 80.11% and 100.99% with relative standard deviations (RSDs) ranging from 0.37 to 8.50% in tested matrices. No significant matrix effect was observed for most tested PAEs. This is a simple method with high sensitivity and strong stability, which is suitable and reproducible for quantifying large number of PAEs in different types of soil.

Tritium (3H) is a low-energy β emitter commonly found in environmental water samples, and its routine monitoring requires highly sensitive techniques capable of achieving low detection limits. Liquid scintillation counting (LSC) is the standard method for low-level 3H analysis; however, quenching significantly affects detection efficiency and minimum detectable activity (MDA), and systematic evaluations across different quench levels and measurement approaches remain limited. This study evaluates quench-related uncertainties in low-level 3H measurement using two ultra-low background liquid scintillation counters, Quantulus 1220 and GCT 6220. High- and low-quench conditions were created by varying sample-to-cocktail ratios, and performance was assessed through detection efficiency, minimum detectable activity (MDA), and stability. Under the relative measurement method with limited quench variation, GCT 6220 achieved higher efficiency, lower background, and lower detection limits. Under the internal standard method with broader quench spans, Quantulus 1220 produced smoother efficiency–quench curves and more stable results. Thus, GCT 6220 is advantageous for sensitivity-demanding scenarios, while Quantulus 1220 is better suited for quench-correction applications.

The carbonation of ultramafic rocks, including tailings from ultramafic-hosted ore deposits, can be used to remove CO2 from the atmosphere and store it safely within minerals over geologic timescales. Quantitative X-ray diffraction (XRD) using Rietveld refinements can be employed to estimate the amount of carbon sequestered by carbonate minerals that form as a result of weathering of ultramafic rocks. However, the presence of structurally disordered phases such as serpentine minerals, which are common in ultramafic ore bodies such as at the Woodsreef chrysotile mine (New South Wales, Australia), results in samples that cannot be analyzed using typical Rietveld refinement strategies. Previous investigations of carbon sequestration at Woodsreef and other ultramafic mine sites typically used modified Rietveld refinement methods that apply structureless pattern fitting for disordered phases; however, no detailed comparison of the accuracy (or precision) of these methods for carbon accounting has yet been attempted, making it difficult to determine the most appropriate analysis method. Such an analysis would need to test whether some methods more accurately quantify the abundances of certain minerals, such as pyroaurite [Mg6Fe23+(CO3)(OH)16·4H2O] and other hydrotalcite group minerals, which suffer from severe preferred orientation and may play an important role in carbon sequestration at some mines. Here, we assess and compare the accuracy, and to a lesser extent the precision, of three different non-traditional Rietveld refinement methods for carbon accounting: (1) the PONKCS method, (2) the combined use of a Pawley fit for serpentine minerals and an internal standard (Pawley/internal standard method), and (3) the combined use of PONKCS and Pawley/internal standard methods. We examine which of these approaches represents the most accurate way to quantify the abundances of serpentine, pyroaurite, and other carbonate-bearing phases in a given sample. We demonstrate that by combining the PONKCS and Pawley/internal standard methods it is possible to quantify the abundances of disordered phases in a sample and to obtain an estimate of the amorphous content and any unaccounted intensity in an XRD pattern. Eight artificial tailings samples with known mineralogical compositions were prepared to reflect the natural variation found within the tailings at the Woodsreef chrysotile mine. Rietveld refinement results for the three methods were compared with the known compositions of each sample to calculate absolute and relative error values and to evaluate the accuracy of the three methods, including whether they produce systematic under- or overestimates of mineral abundance. Estimated standard deviations were also calculated during refinements; these values, which are a measure of precision, were not strongly affected by the choice of refinement method. The abundance of serpentine minerals is, however, systematically overestimated when using the PONKCS and Pawley/internal standard methods, and the abundances of minor phases (<10 wt%) are systematically underestimated using all three methods. Refined abundances for pyroaurite were found to be increasingly susceptible to error with increasing abundance, with an underestimation of 6.6 wt% absolute (60.6% relative) for a sample containing 10.9 wt% pyroaurite. These significant errors are due to difficulties in mitigating preferred orientation of hydrotalcite minerals during sample preparation as well as modeling its effects on XRD patterns. The abundances of hydromagnesite [Mg5(CO3)4(OH)2·4H2O], another important host for atmospheric CO2 during weathering of ultramafic rocks, was consistently underestimated by all three methods, with the highest underestimation being 3.7 wt% absolute (or 25.0% relative) for a sample containing 15.0 wt% hydromagnesite. Overall, the Pawley/internal standard method produced more accurate results than the PONKCS method, with an average bias per refinement of 6.7 wt%, compared with 10.3 wt% using PONKCS and 12.9 wt% for the combined PONKCS-Pawley/internal standard method. Furthermore, the values for the refined abundance of hydromagnesite obtained from refinements using the Pawley/internal standard method were significantly more accurate than those for refinements done with the PONKCS method, with relative errors typically <25% for hydromagnesite abundances between 5 and 15 wt%. The simpler and faster sample preparation makes the PONKCS method well-suited for rapid carbon accounting, for instance in the field using a portable XRD; however, the superior accuracy gained when using an internal standard make the Pawley/internal standard method the preferable means of undertaking a detailed laboratory-based study. As all three methods displayed an underestimation of carbonate phases, applying these methods to natural samples will likely produce an underestimate of hydromagnesite and hydrotalcite group mineral abundances. As such, crystallographic accounting strategies that use modified Rietveld refinement methods produce a conservative estimate of the carbon sequestered in minerals.

Staphylococcus aureus (S. aureus) is one of the most common pathogens for nosocomial and community infections, which is closely related to the occurrence of pyogenic and toxic diseases in human beings. In the current study, a lab-built microchip capillary electrophoresis (microchip CE) system was employed for the rapid determination of S. aureus, while a simple-to-use space domain internal standard (SDIS) method was carried out for the reliable quantitative analysis. The precision, accuracy, and reliability of SDIS were investigated in detail. Noted that these properties could be elevated in SDIS compared with traditional IS method. Remarkably, the PCR products of S. aureusnuc gene could be identified and quantitated within 80 s. The theoretical detection limit could achieve a value of 0.066 ng/μL, determined by the using SDIS method. The current work may provide a promising detection strategy for the high-speed and highly efficient analysis of pathogens in the fields of food safety and clinical diagnosis.

A reliable and sensitive isotope-labelled internal standard method for simultaneous determination of chlorantraniliprole and cyantraniliprole in fruits (apple and grape), vegetables (cucumber and tomato) and cereals (rice and wheat) using ultra-high-performance liquid chromatography–tandem mass spectrometry was developed. Isotope-labelled internal standards were effective in compensating for the loss in the pretreatment and overcoming the matrix effect. The analytes were extracted with acetonitrile and cleaned up with different kinds of sorbents. The determination of the target compounds was achieved in less than 4 min using a T3 column combined with an electrospray ionization source in positive mode. The overall average relative recoveries in all matrices at three spiking levels (10, 20 and 50 μg kg -1 ) ranged from 95.5 to 106.2 %, with all relative standard deviations being less than 14.4 % for all analytes. The limits of detection did not exceed 0.085 μg kg -1 and the limits of quantification were below 0.28 μg kg -1 in all matrices. The method was demonstrated to be convenient and accurate for the routine monitoring of chlorantraniliprole and cyantraniliprole in fruits, vegetables and cereals.

The method for the determination of 16 priority polycyclic aromatic hydrocarbons (PAHs) in plant leaves has been studied extensively, yet the quantitativemethod for measuring non-priority PAHs in plant leaves is limited. A method for the simultaneous determination of 31 polycyclic aromatic hydrocarbons (PAHs) in plant leaves was established using an ultrasonic extraction–gas chromatography–mass spectrometry–internal standard method. The samples of plant leaves were extracted with ultrasonic extraction and purified with solid-phase extraction columns. The PAHs were separated by using gas chromatography–mass spectrometry equipped with a DB-EUPAH capillary column (20 m × 0.18 mm × 0.14 μm) with a selective ion monitoring (SIM) detection mode, and quantified with an internal standard. The method had good linearity in the range of 0.005~1.0 μg/mL with correlation coefficients greater than 0.99, and the method detection limit and maximum quantitative detection limit were in the ranges of 0.2~0.7 μg/kg and 0.8~2.8 μg/kg, respectively. The method was verified with spiked recovery experiments. The average spiked recovery ranged from 71.0% to 97.6% and relative standard deviations (n = 6) were less than 14%. Herein, we established a quantitativemethod for the simultaneous determination of priority and non-priority PAHs in plant leaves using GC–MS. The method is highly sensitive and qualitatively accurate, and it is suitable for the determination of PAHs in plant leaves.

In this study, we evaluated the extraction effect of three different extractants, namely hexane + ether (v/v = 3:1), acetonitrile and ethyl acetate, on polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs) in placenta detected and analysed by triple quadrupole gas chromatography–mass spectrometry (GC-MS/MS). The results showed that n-hexane + ether (v/v = 3:1) had the highest extraction efficiency. Under the optimal conditions, the limits of detection (LOD) for the 10 PAHs were 0.003–0.0167 μg/L with relative standard deviations (RSD) of 1.4–5.48% and detection rates of 68.19–107.05%, and the correlation coefficients were (R2, 0.9982–0.9999). The LODs for the nine PAEs were 0.0015–3.5714 μg/L and the correlation coefficients were (R2, 0.9982–0.9999). The limits of detection (S/N = 3) for the nine PAHs were 0.0015–0.5714 μg/L with relative standard deviations (RSD) of 3.15–8.37%, and the detection rates were 80.45–112.59% with correlations of (R2, 0.9972–0.9998). The method was applied to the analysis of PAHs and phthalates in placenta samples from pregnant women. The method’s accuracy and applicability were demonstrated. In comparison with other methods for the detection of PAEs and PAHs, the method proposed in this paper has a wider linear range, lower minimum detection limit and comparable recovery with good correlation. This paper is dedicated to providing another method for improving the performance of extracting solid tissues.