Target recognition assisted-primer exchange reaction (Ta-PER) for sensitive analysis of p53 gene and its application in analyzing amatoxin-treated samples.

Sensitive and reliable detection of the p53 gene plays a significant role in precise cancer targeting and in fundamental research. However, the sensitivity of existing p53 gene detection approaches remains to be improved. Herein, we develop a target recognition assisted-primer exchange reaction (Ta-PER) for sensitive analysis of the p53 gene. Ta-PER was initiated by the recognition of a designed dumbbell structure probe by the p53 gene. In Ta-PER, the primer exchange reaction (PER) was combined with molecular beacon-based chain recycling to construct the signal amplification process. Through integrating target recognition with PER-based signal amplification, Ta-PER was established and exhibited a high detection sensitivity, with a limit of detection as low as 56 fM. In addition, the approach was also used to detect the p53 gene in normal HeLa cells and amatoxin-treated HeLa cells. The high level of the p53 gene in amatoxin-treated HeLa cells, which was approximately 1.67 times higher than that in HeLa cell extract, indicated the apoptosis of cells and suggested the promising prospect of the approach.

Simultaneous determination of 11 fluorescent whitening agents in food-contact paper and board by ion-pairing high-performance liquid chromatography with fluorescence detection.

4,4'-Diaminostilbene-2,2'-disulfonic acid based fluorescent whitening agents (DSD-FWAs) are prohibited in food-contact paper and board in many countries. In this work, a reliable high-performance liquid chromatography method was developed for the simultaneous determination of 11 common DSD-FWAs in paper material. Sample preparation and extraction as well as chromatographic separation of multicomponent DSD-FWAs were successfully optimized. DSD-FWAs in prepared samples were ultrasonically extracted with acetonitrile/water/triethylamine (40:60:1, v/v/v), separated on the C(18) column with the mobile phase containing tetrabutylammonium bromide, and then detected by a fluorescence detector. The limits of detection were 0.12-0.24 mg/kg, and the calibration curves showed the linear correlation (R(2) ≥ 0.9994) within the range of 8.0-100 ng/mL, which was equivalent to the range of 0.80-10 mg/kg in the sample. The average recoveries and the RSDs were 81-106% and 2-9% at two fortification levels (1.0 and 5.0 mg/kg) in paper bowls, respectively. The successful determination of 11 DSD-FWAs in food-contact paper and board obtained from local markets indicated that the newly developed method was rapid, accurate, and highly selective.

Simultaneous determination of biotoxins DSP and AZAs in bivalve molluscs and fish by liquid chromatography/tandem mass spectrometry.

RATIONALE: A method has been developed for simultaneous determination of the toxins OA, DTX-1, AZA-1, AZA-2 and AZA-3 in various aquatic products as these can cause diarrhoetic shellfish poisoning (DSP) in humans, an intoxication characterized by vomiting and diarrhea. METHODS: Separation of the toxins was achieved on a C18 column (150 mm × 2.1 mm, 3.5 µm) using an acetonitrile/water gradient with formic acid as an eluent modifier. Electrospray ionisation (ESI) in negative mode was used to generate the molecule related ion [M-H](-), for OA and DTX-1, while ESI in positive mode was used to generate the molecule related ion [M+H](+) for AZAs. Samples were extracted with 80% methanol, followed by partitioning with ethyl acetate, purified on a Poly-Sery MAX cartridge and finally analyzed by LC/ESI-MS/MS in the multiple reaction monitoring (MRM) mode. RESULTS: The limit of detection (LOD) and limit of qualification (LOQ) of the method were in the range of 0.02-0.79 µg/kg and 0.07-2.64 µg/kg in Scomberomorus niphonius, blood clam and oyster, respectively, recoveries of the toxins at three fortification levels ranged from 71.3% to 104.8% with relative standard deviation from 1.0% to 12.5%. The calibration curves were well linear between the LC peak area of the selected ion pair and the concentration of the toxins, with the correlation coefficient over 0.99. CONCLUSIONS: The method was sufficiently sensitive to permit the determination of the toxins DSP and AZA in sea food.

Determination of chloropropanol esters and glycidyl esters in nutritional foods by gas chromatography-tandem mass spectrometry based on acid hydrolysis and solid-phase extraction.

This study presents a method based on acid transesterification and the purification by solid-phase extraction (SPE) coupled with gas chromatography-tandem mass spectrometry for quantifying 3- and 2-monochloropropanediol esters (3-MCPDE, 2-MCPDE) and glycidyl esters (GE) in nutritional foods. The fat was extracted by liquid-liquid extraction with petroleum ether and diethyl ether after the sample was hydrolysed with ammonia. Then the extract was purified by a SPE cartridge filled with the aminopropyl sorbents. It was demonstrated that the optimal elution volume for 3-MCPDE, 2-MCPDE and GE greatly depended on the sample matrix and varied from 6 to 12 mL for four different kinds of food matrices. All three analytes in the sample solution could be fully collected in the first 10-12 mL of eluate. By this way, monoacylglycerols commonly present in the samples were fully removed. Therefore, the overestimation of GE quantification was effectively eliminated. The modified analytical procedure was fully validated in a single laboratory and has been recommended as a Chinese Food Safety National Standard. In addition, two derivatisation agents, heptafluorobutyrylimidazole and phenylboronic acid, were proved to be equivalent in method accuracy and precision for the quantification of three analytes.

[Determination of amanita peptide and tryptamine toxins in wild mushrooms by high performance liquid chromatography-tandem mass spectrometry].

The discovery and identification of mushroom toxins has long been an important area in the fields of toxicology and food safety. Mushrooms are widely favored for their culinary and medicinal value; however, the presence of potentially lethal toxins in some species poses a substantial challenge in ensuring their safe consumption. Therefore, the development of a robust and sensitive analytical method is necessary for accurately identifying the risks associated with mushroom consumption. The study of mushroom toxins, which are characterized by their diversity and substantial variations in chemical structures, present a considerable challenge for achieving precise and high-throughput analysis. To address this issue, the present study employed a robust approach combining a solid-phase extraction (SPE) purification technique with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to establish an analytical method for the detection and quantification of five amatoxins and two tryptamines (psilocybin and bufotenine) present in some mushrooms. Several optimization procedures were undertaken, including optimizing the chromatographic conditions, mass spectrometric parameters, and sample extraction and purification. The procedure involved the extraction of dry mushroom powder with methanol containing 0.3% formic acid, followed by purification using a strong cation exchange cartridge (SCX). The analytes were separated on a T3 chromatographic column (100 mm×2.1 mm, 1.8 µm) using mobile phases of acetonitrile and 5 mmol/L ammonium acetate solution containing 0.1% formic acid. The multiple reaction monitoring (MRM) mode was employed for data acquisition. Amatoxins were quantified using matrix-matched standard calibration curves, whereas isotopic internal standards were used to quantify tryptamine. The results showed that all seven toxins exhibited good linearities (r2>0.99) within the optimized concentration range. The limits of detection (LODs) for bufotenine, psilocybin, and amatoxins were determined as 2.0, 5.0, and 10 µg/kg, respectively, while the limits of quantification (LOQs) were determined as 5.0, 10, and 20 µg/kg, respectively. The LOD and LOQ values further underscore the ability of the method to detect minute quantities of toxins, making it particularly well suited for screening food samples for potential contamination. Using dried shiitake mushroom powder as the matrix, the recoveries of the two tryptamines ranged from 80.6% to 117%, with relative standard deviations (RSDs) ranging from 1.73% to 5.98%, while the recoveries of amatoxins ranged from 71.8% to 115%, with RSDs varying from 2.14% to 9.92% at the three concentration levels. The consistent and satisfactory recoveries of amatoxins and tryptamines demonstrated the ability of this method to accurately quantify the target analytes even in a complex matrix. Comparison with the results of supplementary test method recognized by State Administration for Market Regulation for food (BJS 202008) demonstrated comparable results, indicating no significant differences (p>0.05) in amatoxin contents. The newly developed method is rapid, accurate, precise, meets the required standards, and is suitable for the detection of seven toxins in wild mushrooms. As part of the application of this method, a comprehensive investigation of the distribution of toxins in wild mushrooms from Fujian Province was undertaken. In this study, 59 wild mushroom samples from nine cities were collected in the Fujian province. Species identification was conducted using rDNA-internal transcribed space (rDNA-ITS) molecular barcode technology, which revealed the presence of toxins in the two samples. Notably, one specimen named Amanita fuligineoides contained α-amanitin, ß-amanitin, and phalloidin in quantities of 607, 377, and 69.0 mg/kg, respectively. Additionally, another sample, identified as Tricholomataceae, had a psilocybin concentration of 12.6 mg/kg.

[Immuno-affinity chromatographic purification: the study of methods to test citrinin in monascus products by high performance liquid chromatography].

OBJECTIVE: To establish a method to test citrinin (CIT) in monascus products by immuno-affinity chromatography (IAC)-high performance liquid chromatography (HPLC), and to detect the content of CIT in monascus products in Fujian province. METHODS: IAC-HPLC was applied to detect the CIT content in monascus products. The conditions to use HPLC were as follows: C(18) reversed-phase chromatographic column, 150.0 mm×4.6mm×3 µm; mobile phase: the volume ratio of acetonitrile and 0.1% phosphoric acid solution at 65:35; isocratic elution; column temperature: 28°C; flow velocity: 0.8 ml/min; fluorescence detector, excitation wavelength (λ(ex)) was 331 nm and emission wavelength (λ(em)) was 500 nm. The standard curved was established by the linear regression of peak area (Y) to CIT content (X, ng/ml). The accuracy and precision of the method would then be verified. And 32 kinds of monascus products were determined and their color values were compared by this method. RESULT: The standard curve established in this study was Y = 4634.8X-136.42, r = 1.000; whose limits of detection was 20 µg/kg and the limits of qualification was 64 µg/kg. In the range between 200 and 800 µg/kg, the standard recovery rate was 98.9% - 110.0% (n = 3), and the relative standard deviation (RSD) was 0.51% - 1.76%. Out of the 32 samples, CIT was detected from 11 samples of monascus rice, 9 samples of monascus powder and 5 samples of monascus pigments, the content was around 0.212 - 14.500 mg/kg. 4 out of 7 functional monascus samples were detected out CIT, whose content at 0.142 - 0.275 mg/kg. CONCLUSION: The method to detect CIT in monascus products by IAC-HPLC has been established.

Acute mushroom poisoning of Amanita pseudosychnopyramis: A case report from Fujian, China with exact species identification and descriptive study.

Mushroom poisoning is a deeply concerning food safety problem that affects the public in China every year. Although there are statistics on the number of poisonings and incidents, there is a lack of data on the types of toxic mushrooms, clinical manifestations and toxins. A case of wild mushroom poisoning occurred in Xiamen. Descriptive epidemiological investigation, toxins detection, and morphological and phylogenetic identification were immediately performed. The patients exhibited typical neurotoxic symptoms after consuming wild mushrooms, including chills, vertigo, drowsiness, salivation and coma. The average incubation period was 30 min. Treatments that were adopted included fluid infusion, gastric lavage, catharsis, and liver protection treatment. All patients recovered within 10 days. The species was identified as Amanita pseudosychnopyramis, and its contents of muscarine, muscimol and ibotenic acid were 170.3 ± 5.9 mg/kg, 835.4 ± 43.1 mg/kg and 637.9 ± 54.8 mg/kg in dry weight, respectively, as detected by ultrahigh-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). To our knowledge, this is the first report of Amanita pseudosychnopyramis poisoning worldwide.

Determination of zearalenone in botanical dietary supplements, soybeans, grains, and grain products by immunoaffinity column cleanup and liquid chromatography: single-laboratory validation.

The accuracy, repeatability, and reproducibility characteristics of a method for measuring levels of zearalenone (ZON) in botanical root products, soybeans, grains, and grain products were determined by an AOAC single-laboratory validation procedure. Replicates of 10 test portions of each powdered root product (black cohosh, ginger, ginseng), brown rice flour, brown rice grain, oat flour, rice bran, soybeans, and wheat flour at each spiking level (ZON at 0, 50, 100, and 200 microg/kg) were analyzed on 3 separate days. Test samples were extracted with methanol-water (75 + 25, v/v). The extracts were centrifuged or filtered, diluted with phosphate-buffered saline (PBS) containing 0.5% Tween 20, and filtered; the filtrates were applied to an immunoaffinity column containing antibodies specific for ZON. After the column was washed with methanol-PBS (15 + 85, v/v) containing 0.5% Tween 20 and then with water, the toxin was eluted from the column with methanol, and the eluate was diluted with water. The eluate containing the toxin was then subjected to RPLC with fluorescence detection. All commodities that were found to contain ZON at < 10 microg/kg were used for the recovery study. The average within-day and between-days recoveries of ZON added at levels of 50-200 microg/kg ranged from 82 to 88% and from 81 to 84%, respectively, for all test commodities. The total average of within- and between-day SD and RSDr values for all test commodities ranged from 2.5 to 7.3 microg/kg and from 4.6 to 6.2%, respectively. HorRat values were <1.3 for all matrixes examined. The tested method was found to be acceptable for the matrixes examined.

Variability and profiles of lipophilic marine toxins in shellfish from southeastern China in 2017-2020.

A total of 1338 samples were analyzed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to study the toxin profiles of lipophilic marine toxins in bivalve mollusks collected from the southeast coast of China from 2017 to 2020. The most abundant toxin was HomoYTX, followed progressively by YTX and PTX2. Low proportions of OA, DTX-1, and DTX-2 were found. No AZA1, AZA2, and AZA3 were quantified above limit of quantitation (LOQ). The highest concentrations of HomoYTX, YTX, PTX2, OA, DTX-1, and DTX-2 were 429, 98.0, 40.3, 33.0, 22.6, and 26.5 µg/kg, respectively. Mussels (Mytilus galloprovincialis, Perna viridis), scallop (Chlamys farreri) and clam (Atrina pectinate) accumulated higher toxin levels than clams (Sinonovaculla Constricta, Ruditapes philippinarum), oyster (Crassostrea gigas) and scallop (Arca granosa). Homo YTX and PTX2 levels reached the maximum in July and June, respectively, and the OA-group peaked in August. The results provide a reliable basis for monitoring marine toxins and protecting the health of aquatic consumers.

Toxin and toxicity identification of mangrove horseshoe crab Carcinoscorpius rotundicauda collected from South China.

The presence of paralytic shellfish poisoning (PSP), diarrhetic Shellfish Poisoning (DSP), tetrodotoxin (TTX) and its analogues (11-oxoTTX, 4.9-anhydro-11-oxoTTX, 4.9-anhydroTTX, 5-deoxyTTX, 5.11-dideoxyTTX, 5.6.11-trideoxyTTX and 4.9-anhydro-5.6.11-trideoxy TTX) were initially investigated in Carcinoscorpius rotundicauda collected from south China with Liquid chromatography-tandem mass spectrometry (LC-MS-MS) and mouse bioassay. The TTX toxicity was 10.8 ±â€¯3.9 MU/g muscle, 6.3 ±â€¯0.6 MU/g viscera and 6.3 ±â€¯0.6 MU/g eggs in mean value. Merely dcGTX2 and dcSTX were detected in ten Specimens, ranging from 0.01 to 0.77 µg/g. Analyses suggested that these Carcinoscorpius rotundicauda contain TTX and its analogues as the major toxin and PSPs as the minor, respectively. Besides, no DSPs were found.

Determination of 3-chloropropane-1,2-diol in liquid hydrolyzed vegetable proteins and soy sauce by solid-phase microextraction and gas chromatography/mass spectrometry.

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography/mass spectrometry (GC/MS) method was developed to determine 3-chloropropane-1,2-diol (3-MCPD) in hydrolyzed vegetable protein and Chinese soy sauce. The 3-MCPD was firstly derivativized with phenylboronic acid in aqueous solution at 90 degrees C for 10 min, then extracted by HS-SPME and finally detected with GC/MS, parameters related to both the derivative reaction and the HS-SPME process were optimized. The proposed method has a linear range of 0.0194-394 microg g(-1), a detection limit of 3.87 ng g(-1) (S/N = 3), and a precision of RSD = 7.5% (n = 5). Seventeen real samples, including four HVPs and thirteen soy sauce samples, were analyzed to examine the feasibility of the proposed procedure; with a concentration of 3-MCPD and acceptable recoveries at 0.71 microg g(-1) spiked levels were obtained. Being simpler, faster and more environmentally benign than the existing methods, this method is accurate and suitable for routine analysis.

[Development of the determination methods of fatty acid esters of chloropropanediols in fat-rich foods].

Fatty acid esters of chloropropanediols are a kinds of newly emerged food contaminants, especially 3-monochloropropane-1,2-diol (3-MCPD) esters that have been detected in many foodstuffs such as infant formula and edible oils at relatively high levels. Based on the Tolerable Dose Intake (TDI) of 3-MCPD, the intake of 3-MCPD from 3-MCPD esters may cause the health risk to human beings. The researches for the analysis of 3-MCPD esters have been carried out in some institutes abroad, but there were only a few in China. This paper reviews the methods for the determination of 3-MCPD esters in fat-rich foods, including the extraction, hydrolysis, the derivatization of 3-MCPD esters, the total amount of 3-MCPD esters and the amounts of monoesters and diesters of 3-MCPD.

Determination of paralytic shellfish poisoning toxins by HILIC-MS/MS coupled with dispersive solid phase extraction.

This paper describes the use of QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) for the extraction, cleanup and detection of 10 paralytic shellfish toxins (PSP) in sea food by HILIC-MS/MS with positive ESI. Matrix matched calibration standards were used to compensate for matrix effects. The toxins were extracted with acetonitrile/water (90:10, v/v) containing 0.1% formic acid and cleaned by HLB and GCB sorbents. Qualitative and quantitative detection for the analytes were carried out under the multiple reaction monitoring (MRM) in positive ionization mode after chromatography separation on a TSK-gel Amide-80® column (150 mm×2.0 mm×3 µm). Studies at three fortification levels for the toxins in the range of 8.1-225.5 µg/kg gave mean recoveries from 71.3% to 104.6% with relative standard deviation (RSD) ≤ 15.8%. The limit of detection (LOD) was below the recommended regulatory limit of 170 µgSTX(equ.)/kg and the proposed method fully meets the needs of daily monitoring.

Comparison of QuEChERS sample preparation methods for the analysis of pesticide residues in fruits and vegetables.

This article describes the comparison of different versions of an easy, rapid and low-cost sample preparation approach for the determination of pesticide residues in fruits and vegetables by concurrent use of gas and liquid chromatography (GC and LC) coupled to mass spectrometry (MS) for detection. The sample preparation approach is known as QuEChERS, which stands for "quick, easy, cheap, effective, rugged and safe". The three compared versions were based on the original unbuffered method, which was first published in 2003, and two interlaboratory validated versions: AOAC Official Method 2007.01, which uses acetate buffering, and European Committee for Standardization (CEN) Standard Method EN 15662, which calls for citrate buffering. LC-MS/MS and GC-MS analyses using each method were tested from 50 to 1000ng/g in apple-blueberry sauce, peas and limes spiked with 32 representative pesticides. As expected, the results were excellent (overall average of 98% recoveries with 10% RSD) using all 3 versions, except the unbuffered method gave somewhat lower recoveries for the few pH-dependent pesticides. The different methods worked equally well for all matrices tested with equivalent amounts of matrix co-extractives measured, matrix effects on quantification and chemical noise from matrix in the chromatographic backgrounds. The acetate-buffered version gave higher and more consistent recoveries for pymetrozine than the other versions in all 3 matrices and for thiabendazole in limes. None of the versions consistently worked well for chlorothalonil, folpet or tolylfluanid in peas, but the acetate-buffered method gave better results for screening of those pesticides. Also, due to the recent shortage in acetonitrile (MeCN), ethyl acetate (EtOAc) was evaluated as a substitute solvent in the acetate-buffered QuEChERS version, but it generally led to less clean extracts and lower recoveries of pymetrozine, thiabendazole, acephate, methamidophos, omethoate and dimethoate. In summary, the acetate-buffered version of QuEChERS using MeCN exhibited advantages compared to the other tested methods in the study.