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After the passage of the Agriculture Improvement Act of 2018 (Farm Bill) that defined hemp as Cannabis sativa L. if it contained ≤0.3 % Δ9-THC on a dry weight basis, forensic laboratories were faced with the challenge of distinguishing marijuana from hemp in seized drug samples. This study reports the results of an interlaboratory validation of a previously developed qualitative decision-point assay for the differentiation of illegal marijuana from legal hemp, utilizing gas chromatography-mass spectrometry (GC–MS) with a 1 % Δ9-THC threshold. The method was validated in terms of selectivity, linearity, carryover, precision, accuracy, extract stability, dilution integrity, and measurement uncertainty. Other elements such as decarboxylation rate and potential for CBD interference were also evaluated. Specificity and positive predictive value were both 100 % using known cannabis reference materials. A total of 8 false negative results were observed among the 280 analyses, resulting in an overall assay sensitivity of 94 % and a negative predictive value of 95 %. The small number of false negative results near the 1 % threshold were attributed to decarboxylation inefficiency in some laboratories. While qualitative in nature, the measurement uncertainty of the assay at the 0.3 % Δ9-THC cutoff (legal threshold) using a 95.45 % confidence interval (k = 2) ranged from 12.2 % to 21.8 % among laboratories (equivalent to 0.3 % ± 0.04 % to 0.07 % Δ9-THC by weight). A one-year retrospective study across three agencies and fifteen laboratories was undertaken. Among the three agencies participating in the original study, 93–96 % of all suspected cannabis seizures yielded results above the administrative threshold of 1 % Δ9-THC (n = 3,288). The interlaboratory method development highlighted differences in performance between sites, ultimately improving the overall robustness of the method. Observations highlight the need for site-specific validation and vigilance. While multi-agency collaborations and interlaboratory validations are valuable, they do not replace the necessity for full, independent, and rigorous validation.

Background

Chemometric analysis is also a powerful tool that can be used in the preliminary stages of analytical methods optimization, but is also efficient in data processing. These new approaches may be the key to the analysis of proteins, carbohydrate, sphignolipids, polyphenols in different food components. Although there are challenges in identifying and annotating those compounds due to the limited availability of analytical standards and structural diversity.

Scope and approach

Chromatograms are a useful tool for learning more about the chemical make-up of the food being tested. This information can occasionally be implicit or presented in a subtle way. Therefore, to extract it, chemometric tools and data mining techniques are needed. A chromatogram's fingerprint allows for the possibility of performing both identity and quality testing on food. This viewpoint aims to offer a current assessment of chromatographic fingerprinting technique in the area of food authentication. Additionally, this methodology's limitations, absence from official analytical methods, and future directions are discussed. Novel techniques have been employed in the past few decades, ranging from high-pressure thin liquid chromatography (HPTLC) to mass spectrometry (MS) and other spectroscopic methods. In the last decade research developments, and the application of analytical methods in qualitative and quantitative studies of food components and their adulterants is reviewed in the present work. High-pressure Thin liquid chromatography (HPTLC) is hyphenated with high resolution mass spectrometry is particularly addressed due to its applicability in the targeted/untargeted metabolomic analysis of all food components.

Key findings and conclusions

In the current study, the HPTLC-MS technique was used to examine food components and food adulteration. The HPTLC-MS hyphenated techniques were found to be an extremely helpful method for the detection of food adulterants as well as the various food components, such as protein, carbohydrates, lipids, essential oils, and flavonoids, which were found to be effective as medicinally.

The existence of extremely toxic mercury contaminants in the environment, even at very low concentrations, poses severe human health issues. Mercury exposure may lead to various diseases, such as prenatal brain damage, cognitive severe, motion disorders, and Minamata diseases. Hence, developing an effective and selective method to detect Hg²⁺ in the environment and biological samples is of great interest. Amongst various Hg²⁺ detection techniques, fluorescent chemosensors offer more convenient procedures, affordable cost, high selectivity, and the capability to perform cell imaging for Hg²⁺ detection. Herein, a novel "turn-on" fluorescent chemosensor, Thiourea-DHP derivative (TUD), highly selective to Hg²⁺, was successfully developed. TUD was synthesized by cyclotrimerization of β-amino acrylate, followed by the thioacylation of the resulting dihydropyridine (DHP) with dimethylamino thiocarbonyl chloride. The Hg²⁺ detection by TUD displayed an astonishing naked-eye blue fluorescence signal under blacklight, exhibiting an LOD of 69 nM or 14 ppb at pH 7.4 in the HEPES buffer. Hg²⁺-induced hydrolytic desulfurization of the low fluorescent TUD to produce the strongly fluorescent urea-DHP (UD) is proposed as a mechanism for this fluorescence enhancement. The formation of UD was confirmed by ¹H NMR, ¹³C NMR, and HRMS. This detecting system of TUD provided excellent percentage recovery (>97 %) for the analysis of Hg²⁺ contaminants in real-environmental water samples. Besides, the TUD probe showed nontoxic properties in living cells towards RAW264.7 murine macrophage cell line even at high concentrations (100 µM). Our proposed TUD probe demonstrated superior sensitivity in pure aqueous media compared to current mercury-desulfurization fluorescent chemosensors. This sensing system proved effective for analysing Hg²⁺ contaminants in real-environmental water samples. Additionally, the nontoxic TUD probe successfully revealed the remarkable biocompatibility for Hg²⁺ detection in living cells.

Breast cancer is the most common cancer and the leading cause of cancer death in women. The majority of deaths from breast cancer do not result from the primary tumor itself but from metastasis to other organs in the body. Here, we report the development of a novel polymeric material that selectively traps breast cancer cells. The cancer cell-capturing polymer was synthesized by grafting L-phenylalanine onto a biocompatible poly(vinyl alcohol) (PVA-Phe). L-phenylalanine exhibits high affinity to L-type amino acid transporter 1 (LAT1), which is overexpressed on various cancer cells. We evaluated cancer cell-selective adhesion ability of PVA-Phe using MCF-7, a human hormone receptor-positive breast cancer model cell expressing LAT1. Our results suggest that LAT1 on cancer cells recognizes the L-phenylalanine and that MCF-7 selectively adheres to the synthesized PVA-Phe. For patients at risk of cancer recurrence, we expect that PVA-Phe synthesized in this study could serve to capture the remaining cancer cells when implanted in the body. Together with an appropriate scaffold that functions to attract cancer cells, PVA-Phe may have the potential to completely prevent cancer recurrence.

The high demand, high cost, and low regulations surrounding high-quality edible oils (HQEO) make them a target for fraudulent actions, particularly adulteration with refined oils. Consequently, the authentication of this kind of oil is of great interest. This work assessed the adulteration degree of five HQEOs: sesame, flaxseed, chia, rapeseed, and extra virgin olive oils, using different chemometric strategies to enhance the detection capability of the analytical methodology. Refined oils used as adulterants were evaluated at low concentrations (2–15 % v/v). Three multidimensional spectroscopic techniques (UV–Visible, near-infrared, and excitation-emission matrix fluorescence) were used, and two data fusion strategies (low- and mid-level) were evaluated. Principal component analysis was applied as an exploratory analysis tool to visualize and interpret the information contained in the dataset. For the adulterant quantification, partial least squares regression analysis was used to build the sensitive predictive models. The results revealed that chemical information enhancement leverages the ability to attain reduced prediction compared to unidimensional signals. In scenarios with low sample variability, conventional unidimensional spectroscopy (UV–Visible or near-infrared) data was shown to be adequate to guarantee predictive efficiency. In contrast, when analysing predictive figures derived from models built using a dataset with high variability, e.g., brands, low-level data fusion approaches enhance predictive efficiency. The results showed that excitation-emission matrix-based or low-level data fusion approaches can be accurately implemented to guarantee the authenticity of edible oils even when a low content of adulterant oil is presented.

A novel optical probe has been successfully developed for the selective detection of Os(VIII) ions. This osmium-sensing platform was intricately designed by incorporating 4-(thiazol-2-yldiazenyl)benzene-1,3-diol (TDBD) as the ionophore within a plasticized PVC membrane, and tributylphosphate (TBP) serving as the plasticizer. Upon exposure to Os(VIII) ions in a 0.5 M HClO₄ acid milieu, the sensing membrane undergoes a distinctive chromatic transition, shifting from a yellow to a pink hue. The preparation of the sensor and the methodology for Os(VIII) determination were meticulously refined to achieve optimal performance. Under these carefully optimized experimental conditions, the proposed optode demonstrated an impressive linear detection range spanning from 2.5 × 10⁻⁹ to 2.5 × 10⁻⁵ M for Os(VIII), alongside remarkable detection and quantification limits of 7.24 × 10⁻¹⁰ and 2.4 × 10⁻⁹ M, respectively. The sensor consistently delivered highly reproducible results, as evidenced by relative standard deviation (RSD) values of 1.45% and 1.30% for Os(VIII) concentrations at 7.5 × 10⁻⁷ and 2.5 × 10⁻⁶ M, respectively, underscoring its precision and reliability. Furthermore, the sensor exhibited a swift response time of 3.0 min, further emphasizing its efficiency. The incorporation of PIMs into the sensor architecture led to a remarkable eight-fold enhancement in its response compared to counterparts lacking PIMs, signifying a significant performance improvement. In assessing potential interference, an investigation into the influence of other ions on Os(III) determination revealed that the prepared sensor displayed exceptional selectivity for Os(VIII) ions, with negligible responses observed in the presence of common ions. Collectively, these experimental findings underscore the sensor's efficacy as an invaluable tool for the precise analysis of osmium content in water samples, aligning it with the rigorous standards of international scientific research.

Compositional analysis of polysaccharides is crucial in many applications of analytical chemistry, and typically involves hydrolysis as initial step, to break glycosidic bonds and release individual monosaccharide units. We developed a new method for the microwave-assisted acid hydrolysis of polysaccharides, here applied for determining the composition of the polysaccharide fraction within the lignocellulosic matrix of Pinus sylvestris. The optimisation of reaction conditions was carried out using a GC–MS method after a double-step sugar derivatization process.

Under the optimized conditions, specifically, employing 2 M TFA, 40 min, and 120 °C, a high depolymerisation yield was achieved with minimal degradation. Furthermore, the amount of polysaccharides detected in pine wood aligns with the results in existing literature, substantiating the determined chemical composition.

The synergy of microwave-assisted acid hydrolysis and full factorial design not only facilitated the determination of the optimal hydrolysis conditions but also enabled the assessment of the parameters influencing the polysaccharide hydrolysis process and their relationships. This approach made it feasible to achieve maximum hydrolysis efficiency while minimizing analyte degradation, employing a method that reduces environmental impact through the use of microwave energy. This strategy effectively reduced the required reaction temperature, time, and reagent quantities.

Microwaves are electromagnetic waves which move at the speed of light. Samples directly exposed to this phenomenon are heated faster than conventional conduction heating methods. This is exploited in acid assisted digestion where a food sample in a suitable acid matrix can be completely destroyed leaving a clear solution of measurable elements. In pressurised systems the temperature can be rapidly increased far above the conventional boiling point of the solvent and the closed microwave vessel environment is ideal for volatile elements.

There is a constant aspiration to achieve lower levels of detection and advances in instrument capabilities with specialised plasma based techniques for the identification and quantification of individual elements at ultra-trace levels have evolved. To realise this; sample preparation, digestion efficiency and sample introduction need to be optimised. Exogenous inputs such as preparation environment, reagent grade, the analyst and apparatus cleaning steps all have the potential to leave an elemental footprint on the sample and therefore contribute to the uncertainty of the analytical result. Knowledge of sample composition and subsequent interaction with microwaves and plasma are an important consideration for complete digestion without which the result is not accurate.

This work presents, for the first time, an exploitation of an argentometric Mohr's method for iodide detection using diameter-based measurement on laminated paper-based analytical device (LPAD). Our LPAD is simplified fabricated with no required hydrophobic barrier for patterning a detection flow channel. In the absence of a flow channel, the liquid is imbibed radially into the filter paper outward from the small center inlet hole. This imbibition leads to the measurement of diameter after the formation of the precipitation product. For LPAD, a rectangular piece of Whatman filter paper is cut and positioned between a top laminating sheet, which has a hole punched for inlet, and a bottom laminating sheet. The central inlet hole enables access to the liquid on the paper. For iodide analysis, silver nitrate is dispensed first, followed by the iodide standard/sample. This process leads to the formation of pale-yellow silver iodide solids on the paper. The chromate indicator solution is subsequently loaded to the paper. The color of the chromate solution imparts a tint to the circular band of silver iodide solids, resulting in an intense yellow color. When the silver iodide precipitates are stained, the chromate solution typically serves as an indicator, chemically reacting to an excess silver nitrate solution moistened on paper. This reaction generates an outer reddish-brown ring of silver chromate. The distinct color contrast between the intense yellow (tinted silver iodide) and reddish-brown (silver chromate) allows for clear observation of the measurement boundary, facilitating diameter-based measurements of the circular band of silver iodide. We demonstrate the applicability in analysis of pharmaceutical KI tablets. The quantitative results obtained from diameter-based measurement LPAD show good agreement with those obtained from the potentiometric method. Our hydrophobic barrier-free LPAD is rapid, cost-effective, low liquid consumption and applicable for onsite analysis.

Ensuring accurate and precise measurements of analytes is crucial in gravimetric analysis but can be jeopardized by overlooking analyte in the filtrate, washing solutions, residue during analytical procedure, and weighing form of analyte. To address this issue, a stoichiometric approach for the purity determination of high-purity BeO was developed using gravimetric analysis. This method involved the systematic stoichiometric evaluation of the stepwise conversion of the different weighing forms of Be. The initial BeO sample underwent sequential conversion to the Be complex with N-benzoyl-N-phenyl hydroxylamine, BeO, and BeSO₄; each was evaluated for stoichiometry via gravimetric analysis. The amounts of Be in the filtrate and washing solution, and their loss during sample preparation were measured using inductively coupled plasma-optical emission spectrometry (ICP-OES). Additionally, the sulfate content in the BeSO₄ precipitate was determined by the gravimetric analysis of BaSO₄ to validate the stoichiometry of the precipitate. The observed mass ratios of different Be weighing forms were compared with the theoretical values at each conversion step. The composition of the final converted BeSO_4, i.e., the observed mass ratio of BaSO₄/BeSO₄, was comparable to the theoretical composition. The purity of the initial BeO sample was determined to be 100.03 % ± 0.17 % (k=2). The measured purity was successfully validated by comparing it with that of NIST SRM 3105a Be standard solution using ICP-OES.