A study of the pharmacokinetics of clozapine and its metabolites by the dynamics of its distribution in the oral fluid of healthy volunteers.

Clozapine (CLZ) -related accidents or crimes are common in the world. Oral fluid drug detection is a convenient measure of dealing with things like that. There has not been any literature reported detailedly the representation rule of clozapine and its metabolites in oral fluid so far. The study aimed to describe the pharmacokinetics of CLZ and its metabolites N-desmethylclozapine and clozapine-N-oxide in human oral fluid after a single 12.5 mg oral dose of CLZ. Twenty-nine volunteers, including 20 males and 9 females, were recruited, and 2 mL oral fluid was collected from each participant at post-consumption time-points of prior (zero), 0.5, 1.5, 3, 5, 8, 12, 24, 36, 51, 82, and 130 h, respectively. Analytes of interest were extracted with solid-phase extraction and analyzed with liquid chromatography tandem mass spectrometry method. Pharmacokinetic parameters were calculated using the pharmacokinetic software DAS according to the non-compartment model. The maximum concentration, the time of maximum concentration, oral clearance, and the elimination half-life of clozapine were 16.57 ± 9.63 ng/mL, 4.53 ± 3.61 h, 57.65 ± 23.77 L/h and 53.58 ± 52.28 h, respectively. The maximum concentration, the time of maximum concentration, and the elimination half-life of the metabolite N-desmethylclozapine were 3.08 ± 1.19 ng/mL, 9.38 ± 9.33 h and 62.67 ± 82.57 h, respectively; of clozapine-N-oxide were 1.15 ± 0.36 ng/mL, 4.53 ± 2.19 h and 19.15 ± 23.11 h, respectively. It was the first study on the pharmacokinetics of CLZ and its metabolites in the oral fluid of Chinese healthy volunteers, and it provided a basis for the therapeutic drug monitoring and toxicological interpretation in clozapine-related cases.

Nonaqueous Electroextraction with Tunable Selectivity for Direct, Fast, and Exhaustive Enrichment of Per- and Polyfluoroalkyl Acids from Oils and Food Contact Materials.

Widespread concerns have been raised due to the ever-increasing number of novel per- and polyfluoroalkyl acids (PFAAs) and the ever-decreasing level of legacy PFAAs. Most analytical methods for PFAAs suffer from a narrow range of analyzable PFAAs, insufficient sensitivity, poor performance for oil samples, and defective quantification without internal standards or blank matrices. To solve these challenges, a highly selective method for multiple PFAAs from oils and food contact materials (FCMs) was developed based on nonaqueous electroextraction (NE). Through theoretical derivation and experimental investigation, the selectivity of NE was discovered to be tunable, and the range of extractable analytes could be tuned by adjusting the dielectric constant of the sample solution. For PFAAs, the selectivity was attributed to the pKa-based differential migration mechanism, as PFAAs exhibited less variable pKa values in different solvents compared to interference components. The method achieved nonmatrix-matched calibration without internal standards and integration of sample cleanup, selective extraction, and exhaustive enrichment into a fast and convenient operation. The method provided low limits of detection (0.002-0.03 µg·kg-1), satisfactory accuracy (88.0-107.8%), and RSDs (<11.7%). Migration experiments from 33 FCMs to oils were further investigated. PFBS (<0.05-2.34 µg·kg-1) and PFBA (<0.2-0.398 µg·kg-1) were detected from most FCMs. This was the first attempt at PFAA analysis as well as oil sample analysis using an electric field-assisted extraction technique and also the first report on PFAA migration from FCMs into edible oils.

Nonaqueous Miscible Liquid-Liquid Electroextraction for Fast Exhaustive Enrichment of Ultratrace Analytes by an Exponential Transfer and Deceleration Mechanism.

Conventional electrical-field-assisted sample preparation (EFASP) methods rely on analyte transfer between immiscible phases and require at least one aqueous phase in contact with the electrode. In this paper, we report a novel nonaqueous miscible liquid-liquid electroextraction (NMLEE) technique that enables fast exhaustive enrichment of ultratrace analytes from a milliliter-level donor in a vial to a microliter-level acceptor in a tube. Miscible nonaqueous solvents are used for the donor and acceptor to overcome common EFASP problems such as high charge or mass transfer resistance, loss of analytes in the membrane phase, water electrolysis, back-extraction, bubble generation, and difficulties in the application of high voltage for fast migration. According to theoretical derivation and experimental verification results, the concentrations of analytes in the donor and their migration velocity in the acceptor both decrease exponentially with time, and the extraction recovery correlates linearly with the current variation. These mechanisms result in efficient enrichment by forming an analyte-enriched zone and allow the extraction progress and recovery to be monitored and estimated based on the current variation. NMLEE was coupled with liquid chromatography-mass spectrometry to analyze 10 amphetamine-type drugs, atropine, nortriptyline, and methadone in blood and urine samples. This method provided low limits of detection (0.003-0.1 ng·mL-1), satisfactory extraction recoveries (89.6-104.1%), and RSDs (<12.3% for intraday and <8.8% for interday), which met the requirements of the ICH guidelines. This study may contribute to the further development of EFASP methods for effective ultratrace analyses in forensic science.

Methamphetamine produces cardiac damage and apoptosis by decreasing melusin.

Methamphetamine (METH) is an amphetamine-type drug that is highly addictive and widely abused. Many studies have shown that METH exposure causes severe damage not only to the nervous system but also to the cardiovascular system. Melusin protein is a mechanotransducer that plays an important role in maintaining normal heart function. However, the role of melusin in METH-induced cardiotoxicity has not yet been reported. We hypothesized that methamphetamine can produce cardiac damage and apoptosis by decreasing the quantity of melusin. To test this hypothesis, we determined the protein expression of melusin and apoptosis markers in METH-treated rats and primary rat cardiomyocytes. We also established a melusin-overexpressing cell model to assess the importance of melusin in maintaining antiapoptotic pathways. To confirm our findings from the in vitro and animal models, we also evaluated the apoptotic index of cardiomyocytes and the protein expression of apoptotic markers in postmortem heart tissues from deceased METH abusers and age-matched control subjects. The results showed that the apoptosis of cardiomyocytes was increased significantly and that the protein expression of melusin was decreased after exposure to METH in primary rat cardiomyocytes, in rats and in humans. METH treatment also decreased the expression of the downstream proteins FAK, IQGAP1, p-AKT, p-GSK3ß, and p-ERK in primary rat cardiomyocytes and in vivo. After overexpression of melusin, the above effects were partially reversed in primary rat cardiomyocytes. We conclude that METH can produce cardiac damage and apoptosis by decreasing melusin, while melusin-activated signaling by phosphorylated AKT, phosphorylated GSK3ß, and ERK may be resistant to methamphetamine-induced myocardial apoptosis.

Simultaneous determination of metabolic and elemental markers in methamphetamine-induced hepatic injury to rats using LC-MS/MS and ICP-MS.

Methamphetamine (METH) is one of the most highly addictive illicit drugs abused all over the world. Much evidence indicates that METH abuse leads to major toxicity, medical consequences, and even severe public health consequences. Existing studies usually focus on the pathomechanism of METH-induced toxicity; therefore, data on metabolites and elements correlating with particular toxicity remain scarce. The objective of the present study is to develop appropriate analytical procedures to identify the differential metabolic and elemental biomarkers on METH-induced hepatic injury to rats. The rats were administrated with METH (15 mg/mL/kg, two times per day) via intraperitoneal (i.p.) injections for four consecutive days. The alanine aminotransferase and aspartate aminotransferase activity levels of in the rat serum of the METH group increase significantly compared with those of the control group, suggesting obvious hepatic injury. The results are further confirmed by the histopathological microscopic observation. A total of 18 small molecular metabolites and 19 elements are selected to perform the simultaneous quantification based on the combination of liquid chromatography coupled with tandem mass spectrometry and inductively coupled plasma mass spectrometry. Sample preparation was optimized to cover all the analytes. Both methods are optimized and validated according to developed guidelines such as limits of detection, limits of quantification, linearity, precision, and recovery. All the obtained data are within the satisfactory range. The normalized data were processed according to the partial least squares discrimination analysis (PLS-DA) model. Five differential metabolic and six elemental markers are identified in rat plasma based on the variable importance in projection (VIP) (> 1) and t test results. Overall, the results obtained in this study demonstrate the developed methods are suitable for simultaneous determination of metabolic and elemental markers in the hepatic injury to rats induced by METH. Graphical abstract.

Safety and efficacy of dehydrated ethanol soaking of the operative field in the treatment of spontaneous hepatocellular carcinoma rupture.

BACKGROUND: The aim of our study was to evaluate the clinical safety and value of ethanol surgical field infiltration (ESFI), combined with distilled water peritoneal lavage (DWPL), after hepatectomy in patients with hepatocellular carcinoma (HCC) rupture. METHODS: Rat liver tissue samples were soaked in dehydrated ethanol for different soaking times, and 18 rats were assigned to three groups that underwent different soaking methods of the hepatectomy cut surface. We retrospectively reviewed 45 patients who underwent hepatectomy for treatment of ruptured HCC. Among these, EFSI combined with DWPL was used in 21 patients (DAW group), with only DWPL used in the other 24 patients (DW group). Clinical outcomes were compared between the two groups. RESULTS: For in vitro experiments, the depth of coagulation degeneration and necrosis increased with the duration of soaking. For in vivo experiments, rats in all three groups survived until postoperative day 7 without significant postoperative complication. In patients, the rate of post-operation complication was comparable between the two groups (P = 0.398), with no between-group differences in liver function levels. The incidence of peritoneal dissemination was significantly higher for DW than DAW group (P = 0.037). Kaplan-Meier test identified dehydrated ethanol treatment as a significant factor of disease-free survival (DFS) (P = 0.036). On univariate analysis, dehydrated ethanol treatment was associated with better prognostic outcomes, although it was not retained as an independent factor of patient outcome. CONCLUSIONS: Dehydrated ethanol soaking of the cut surface of the hepatectomy could potentially lower the risk of metastasis and improve the effect of hepatectomy for ruptured HCC as well as showed potential therapeutic value for intraoperative iatrogenic rupture of HCC.

Development and validation of a hydrophilic interaction liquid chromatography-tandem mass spectrometry method for the simultaneous determination of five first-line antituberculosis drugs in plasma.

A new, sensitive and fast method for the simultaneous determination of pyrazinamide, isoniazid, streptomycin, ethambutol, and rifampicin in human plasma was developed and validated. The method required only 100 µL of plasma and one step for sample preparation by protein precipitation. The drugs were separated by using a hydrophilic interaction liquid chromatography (HILIC) column. The mobile phase was methanol and water (0.1% formic acid and 5 mM ammonium acetate, pH 3.0 ± 0.1) in a ratio of 65:35 (v/v), which was eluted at an isocratic flow rate of 0.5 mL/min. Tandem mass spectrometry was performed with a triple-quadrupole tandem mass spectrometer. By use of the HILIC column, the detection was free of ion-pair reagents in the mobile phase, with no significant matrix effects. The total run time was less than 2 min for each sample. The method was validated by evaluating its selectivity, sensitivity, linearity, accuracy, and precision according to US Food and Drug Administration guidelines. The lower limit of quantification was 4.0 ng/mL for pyrazinamide, isoniazid, and rifampicin, 0.5 ng/mL for ethambutol, and 10.0 ng/mL for streptomycin. The intraday precision and interday precision were less than 9%, with the accuracy ranging between -9.3 and 7.3%. The method was successfully applied to therapeutic drug monitoring of 33 patients with tuberculosis after administration of standard antituberculosis drugs. The method has been proved to meet the high-throughput requirements in therapeutic drug monitoring.

Ultrasound-assisted micellar cleanup coupled with large-volume-injection enrichment for the analysis of polar drugs in blood and zebrafish samples.

A novel ultrasound-assisted micellar cleanup strategy (UAMC) coupled with large volume injection (LVI) high performance liquid chromatography (HPLC) method was proposed and successfully applied to the analysis of cefathiamidine in complex biological samples such as whole blood, plasma, serum and even zebrafish, a challenging positive real sample. Based on the micelle-biomacromolecule interaction, the phase-separation feature of surfactant micelles and ultrasound cavitation, UAMC possessed an impressive matrix cleanup capability and could rapidly reach distribution equilibrium (approximately 2 min), which enabled simultaneous sample cleanup and analyte extraction within 8 min. Due to the high cleanup efficiency of UAMC, large volume of pretreated samples could be injected for analysis without peak broadening, impurity interference and column degradation. Thus, online analyte enrichment could be automatically performed to significantly improve method sensitivity by the column-switching LVI-HPLC system, a commercial HPLC system with small modifications. The UAMC-LVI-HPLC method creatively integrated sample cleanup, analyte extraction and on-column enrichment into simple operation. In addition, the UAMC-LVI-HPLC method enabled non-matrix-matched analysis of cefathiamidine in complex biological samples. This feature was helpful to address the problems caused by conventional matrix-matched or internal standard calibration methods, such as matrix bias, increased workload, limited availability of suitable blank matrices and the use of expensive internal standards. The method had low limits of detections (e.g., 0.0051 mg/L and 0.038 µg/g), wide linear ranges (0.030-100 mg/L and 0.15-489 µg/g), good linear correlation (R2 = 0.9999), satisfactory accuracy (97.6-109.7%) and excellent intra- and interday precision (0.5-4.9%). Thus, UAMC-LVI-HPLC is expected to be a promising candidate for bioanalysis in therapeutic drug monitoring or pharmacokinetic and toxicology studies in the future.

Analysis of the essential oils of Coriandrum sativum Using GC-MS coupled with chemometric resolution methods.

The essential oils extracted from Coriandrum sativum L. were analyzed by GC-MS coupled with chemometric resolution methods. Through the chemometric resolution methods, peak clusters were uniquely resolved into the pure chromatographic profiles and mass spectra of each component. Qualitative analysis was performed by comparing the pure mass spectra with those in the NIST 05 mass spectral library. Quantitative analysis was performed using the total volume integration method. A total of 118 constituents were detected, of which 104 were identified, accounting for 97.27% of the total content. The results indicate that GC-MS combined with chemometric resolution methods can greatly enhance the capability of separation and the reliability of qualitative and quantitative results. The combined method is an economical and accurate approach for the rapid analysis of the complex essential oil samples in Coriandrum sativum L.

Phase solubility diagrams and energy surface calculations support the solubility enhancement with low hygroscopicity of Bergenin: 4-Aminobenzamide (1: 1) cocrystal.

Herein, we reported a new bergenin: 4-aminobenzamide (BGN-4AM) cocrystal with significantly enhanced solubility and low hygroscopicity probed from two aspects such as phase solubility diagrams and theoretical calculations. Compared with anhydrous BGN, BGN-4AM solubilities in water and different buffer solutions (pH = 1.2, 4.5, 6.8) increase significantly. It is noted that BGN-4AM solubility in pH = 6.8 buffer solution presents 32.7 times higher than anhydrous BGN. Interestingly, BGN-4AM (0.31 ± 0.07%) showcases lower hygroscopicity than anhydrous BGN (9.31 ± 0.16%). The predicted and experimental solubilities agree with each other when considering solubility product (Ksp) and solution binding constant (K11) in phase solubility diagrams, indicating the solution complexes formation occurs. Further crystal surface-water interactions and Bravais, Friedel, Donnay-Harker (BFDH) analyses based on Density Functional Theory with dispersion correction (DFT-d) methods support the enhanced solubility. The water probe demonstrates an average interaction energy of -6.48 kcal/mol on the 002 plane of BGN-4AM, and only -5.47 kcal/mol on the 011 plane of BGN monohydrate. The lower lattice energy of BGN-4AM guarantees its lower hygroscopicity than BGN monohydrate. BGN-4AM with enhanced solubility and low hygroscopicity can be a potential candidate for further formulation development.

Bioaccessibility and bioavailability adjusted dietary exposure of cadmium for local residents from a high-level environmental cadmium region.

The critical health risks caused by cadmium (Cd) via dietary exposure are commonly assessed by detecting Cd concentrations in foods. Differently, in this study, the bioaccessibility and bioavailability of Cd in major local harvests were introduced to assess the dietary exposure of local residents from a high-level environmental Cd region. The results indicated that certain Cd was released into the digestive juice after in vitro digestion with a bioaccessibility of 20-63% for rice and 3-32% for leafy vegetables, and the released portion was partially absorbed by Caco-2 cells with a bioavailability of 2-21% for rice and 0.2-13% for leafy vegetables. The results obtained from the toxicokinetic model revealed that the predicted urinary Cd values from the estimated daily intake (EDI) of Cd, which accounted for bioaccessibility and bioavailability, were consistent with the actual measured values, and the EDIs were considerably lower than the acceptable daily intake. This suggests that the bioaccessibility and bioavailability adjusted dietary Cd exposure should be more precise. The key issues addressed in our study implores that a potential health risk cannot be neglected in people with high consumption of rice from high-level zone.

Simultaneous determination of ropivacaine, bupivacaine and dexamethasone in biodegradable PLGA microspheres by high performance liquid chromatography.

A simple and rapid high-performance liquid chromatography method coupled with UV detector was developed and validated for the simultaneous determination of ropivacaine, bupivacaine and dexamethasone in biodegradable poly(lactic-co-glycolic acid) (PLGA) microspheres within 11 min. Chromatographic separation was performed on a XDB-C(18) column using a mobile phase comprised of acetonitrile-NaH(2)PO(4) buffer (pH 3.5, 30 mM) (30:70, v/v) with a flow rate gradient program. The method was in good linearity (r>0.999) over the range of 0.025-40.0 microg/ml for ropivacaine and bupivacaine, and 0.05-40 microg/ml for dexamethasone. The method was proved to be precise with intra- and inter-day precision less than 3.0% and 6.0% for all drugs and accurate with intra- and inter-day accuracy between -8.0% to 4.5% and between -5.0% to 5.5% for all drugs. The assay was rapid, simple and easy to apply. Therefore, it was very suitable for routine determination and quality control of ropivacaine, bupivacaine and dexamethasone in PLGA microspheres.

[Determination of streptomycin in honey determined by hydrophilic interaction chromatography combined with tandem mass spectrometry].

OBJECTIVE: To establish a method for the determination of streptomycin in honey by determined hydrophilic interaction chromatography combined with tandem mass spectrometry (HILIC-MS/MS). METHODS: A hilic column was used, and the mobile phase was consisted of acetonitrile (5 mmol/L ammonium acetate and 0.1% formic acid, 60:40). Samples were extracted by the cation-exchange SPE cartridge. The extraction samples were then identified and quantitated by HILIC-ESI-MS/MS. RESULTS: Linear calibration curves were obtained at the concentration ranges from 10. 5 microg/kg to 105 microg/kg (the correlation coefficients were above 0.99). The limit of detection was 1.05 microg/kg. The average recoveries for streptomycin spiked in honey ranged from 71.3 to 82.5% and their relative standard were between 3.4% and 8.2%. CONCLUSION: The method for determination of streptomycin in honey could be simple, sensitive and accurate.

A simple, versatile, and automated pulse-diffusion-focusing strategy for sensitive milliliter-level-injection HILIC-MS/MS analysis of hydrophilic toxins.

The measurement of trace hydrophilic toxins in complex aqueous-rich matrices is a daunting challenge. To address this analytical bottleneck, pulse diffusion focusing (PDF), a novel sample injection technique for hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS), was developed. Theoretical and experimental investigations of the mechanism and key parameters revealed that the pulse-injection approach, assisted by solvent diffusion, efficiently solved the volume overload problem. This milliliter-level-injection HILIC-MS/MS technique was reported for the first time herein, and provided a significant enhancement in sensitivity compared to the conventional injection method, in addition to being an efficient approach to address the solvent incompatibility of off-line sample preparation and HILIC. The automated PDF-HILIC-MS/MS system was obtained by slightly modifying a commercial LC-MS/MS instrument in an easy and economical manner. The efficiency of the system was demonstrated through the detection of trace tetrodotoxin contents in plasma and urine samples. Low limits of detection (i.e., 0.65 and 2.2 ng·mL-1) were obtained using the simplified sample preparation method. The recoveries were in the range 91-113.3 % with intra-day and inter-day precisions of ≤9.6 %. Further experimental results proved the method to be versatile for various hydrophilic toxins.

Micelle-dominated distribution strategy for non-matrix matched calibration without an internal standard: "Extract-and-shoot" approach for analyzing hydrophilic targets in blood and cell samples.

The analysis of trace hydrophilic targets in complex aqueous-rich matrices is considerably challenging, generally requiring matrix-matched calibration, internal standard, or time-and-labor-intensive sample preparation. To address this analytical bottleneck, a non-matrix-matched calibration strategy without using internal standard was reported for the first time to analyze complicated biosamples such as whole blood, plasma, serum, and cell samples. This strategy, termed micelle-dominated distribution, also aimed at realizing the simple "extract-and-shoot" analytical process for such complex matrices. The micelle-matrix interaction was found to efficiently eliminate the matrix effect by dominating phase separation and analyte distribution between the extraction and matrix phases. Thus, calibration linear curves prepared in water were applicable to the analysis of all the above-mentioned sample types. Rapid distribution equilibrium within 4 min was achieved. This strategy could tolerate direct large volume injection, thereby providing two-order-of-magnitude enhancement in the sensitivity of ion-pair chromatography. The analytical method integrated cell rupture, matrix cleanup, analyte extraction, and on-column preconcentration into a fast and high-throughput operation. The successful application to the determination of exogenous pesticides and endogenous glutathione exhibited low limits of detection (0.0085-0.015 µg mL-1 for pesticides; 0.52 µg mL-1 for glutathione), wide linear ranges (0.028-50 µg mL-1 and 0.049-50 µg mL-1 for pesticides; 1.7-1000 µg mL-1 for glutathione), good linearies (R2 = 0.9994-0.9999), excellent accuracy (recoveries of 91.3-105.2%), and good precision (0.7-6.2% at the levels of 0.028 (or 0.049), 0.1, 0.5, and 50 µg mL-1 for pesticides; 0.5-8.7% at 1.7, 500, and 1000 µg mL-1 for glutathione).

[Study on the chemical constituents of Sarcandra glabra by HPLC-ESI-MS/MS].

OBJECTIVE: To study and compare the main chemical constituents of Sarcandra glabra and qingrexiaoyanning capsules which were extracted by acetic ether. METHODS: The sample solution were analyzed by a Zorbax C18 column with a gradient mobile phase composed of acetonitrile and 0.1% formic acid solution. Both UV and mass spectrometry detector were used simutaneously, full-scan detection mode was evaluated for the identification of all LC peaks. RESULTS: We analyzed the mass spectrum of every LC peak and identified 26 molecular mass from the ion chromatogram of Sarcandra glabra extraction and 16 molecular mass from the extractions of qingrexiaoyanning capsule. 5 compounds were identified. CONCLUSION: High performance liquid chromatography-mass/mass spectrometry has special advantages on analyzing the chemical constituents of traditional Chinese medicine.

Investigation of Trace Element Content in the Seeds, Pulp, and Peel of Mashui Oranges Using Microwave Digestion and ICP-MS Analysis.

Fresh Mashui orange samples were pretreated with microwave digestion using an HNO3-H2O2 system. The levels of Mg, K, Ca, Fe, Mn, Cu, Zn, As, Cd, and Pb in the seeds, pulp, and peel were then determined using inductively coupled plasma mass spectrometry (ICP-MS) combined with collision cell technology (CCT) and kinetic energy discrimination (KED). The standard curve coefficient of determinations of the ten tested elements were between 0.9995 and 0.9999. The instrument detection limit was between 0.112 ng/L and 3.05 ng/mL. The method detection limit was between 0.0281 and 763 ng/g. The average recovery rate was between 85.0 and 117%. The current results showed that Mashui oranges are rich in three elements, namely Mg, K, and Ca. The concentrations of K and Ca were significantly higher than that of Mg in the peel. The content of K was the highest in the seeds. Fe, Mn, Cu, and Zn had the second highest concentrations, and Fe was the highest in the seeds, while Cu was the lowest in the peel. As, Cd, and Pb (hazardous elements) had the lowest concentrations of all the tested elements.

Determination of Aflatoxins in Edible Oils from China and Ethiopia Using Immunoaffinity Column and HPLC-MS/MS.

Background: Aflatoxin (AF) ingestion through contaminated foodstuffs causes at least 250000 deaths every year from hepatocellular carcinoma in China and sub-Saharan Africa. Objective: The main objective of the study was to determine the aflatoxin levels of oils in South Gondar, Ethiopia, and oils purchased from retail markets in Guangzhou, China. Methods: We used a rapid, sensitive, and selective HPLC-tandem mass spectrometry (MS/MS) method for the determination of aflatoxins in edible oils from China and Ethiopia using immunoaffinity column cleaning. Results: The level of contamination for Ethiopian oils ranged between 0.07 and 145.59 µg/kg for total aflatoxins. Of the 27 edible oil samples from Guangzhou, China, the total concentration of aflatoxins (AFB1 + AFB2 + AFG1 + AFG2) ranged between 0.03 and 2.23 µg/kg. Conclusions: The study concluded that the peanut oils from Ethiopia were contaminated with aflatoxins higher than the allowable limit set by many countries while the oils from China were safe for human consumption. Highlights: We first describe an HPLC-MS/MS method for the determination of aflatoxins in 48 edible oil samples from China and Ethiopia using immunoaffinity column cleaning. This is the first preliminary study done on Ethiopian edible oils, giving policy-makers and future researchers baseline data. It is also used to assess the aflatoxin levels of the Chinese edible oils from Guangzhou. Therefore, conducting a comparative study points out the severity of the problem and helps to formulate a new national standard for policy-makers, making this study imperative.

[Analysis of methamphetamine and amphetamine chiral enantiomers in hair by high performance liquid chromatography-tandem mass spectrometry].

A chiral separation method was developed for the analysis of methamphetamine (METH) and amphetamine (AM) in hair by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The samples were extracted using methanol by ultrasonication in a high-temperature water bath. The chromatographic separation was performed on a SUPELCO Astec CHIROIOTIC® V2 column with the mobile phase of methanol-20 mmol/L ammonium acetate aqueous solution containing 0.1% (v/v) formic acid (99:1, v/v). All the compounds showed linear relationship in the range of 15-300 ng/mg (r>0.99). The limits of detection (LODs) of METH and AM were 0.1 ng/mg and 0.15 ng/mg, respectively. The limits of quantification (LOQs) of METH and AM were 0.4 ng/mg and 0.5 ng/mg, respectively. The inter-day precisions were all ≤ 6.8%, and the intra-day precisions were all ≤ 11.4%. Fifty drug abuse samples were determined by this method. Up to 70% of the cases were determined as S-(+)-METH and S-(+)-AM, while 18% of the cases were S-(+)-METH, S-(+)-AM, R-(-)-METH and R-(-)-AM. The proposed method is rapid, simple, and provides technical support and a scientific basis for the chiral analysis in actual hair samples for forensic toxicant identification.

"Inverse" cloud point extraction coupled with large volume injection ion-pair chromatography: A green route integrating extraction, challenging sample cleanup and on-column concentration into fast simple operation.

The efficient isolation of trace hydrophilic compounds from complicated aqueous-rich samples remains a daunting challenge. Herein, to address the analytical bottleneck, a novel inverse cloud-point extraction (ICPE) strategy was proposed based on the extraction principle opposite to that used in traditional CPE. Then, an original large-volume injection ion-pair chromatography (LVI-IPC) method was developed and systematically investigated based on the retention mechanism of the dynamic ion-exchange model. The combined ICPE-LVI-IPC method integrated extraction, challenging sample cleanup, and (on-column) concentration in a fast, simple phase-separation and injection operation. This method was successfully applied to the determination of melamine in dairy samples, including milk, yogurt and milk powder. The organic-solvent-free and sorbent-free sample preparation process could be accomplished within 11 min, requiring only 1.2 mL of water solution per sample. As an efficient on-column concentration strategy, LVI significantly improved the sensitivity. The obtained limit of detection of 0.0028 mg kg-1 was far below the limits established by the Codex Alimentarius Commission. Good recoveries were obtained from samples spiked at four concentration levels (92.6-95.8%), with satisfactory intraday and interday precisions of 1.9-3.9% and 1.6-5.2%, respectively. Further evaluation of the accuracy, by analyzing a certified milk reference material gave a small relative error of 2.2%. Comparisons with a variety of efficient methods showed the superiority of the proposed method in terms of sensitivity, speed, sample and solvent consumption, practicability, and throughput.