[Determination of 21 organophosphate esters and their metabolites in drinking water by automatic solid phase extraction-liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a method for simultaneous determination of 21 organophosphate esters(OPEs) and their metabolites in drinking water by automatic solid phase extraction-liquid chromatography-tandem mass spectrometry. METHODS: The drinking water was purified by automatic solid phase extraction with HLB column, eluted by methanol, determined by liquid chromatography tandem mass spectrometry with ACQUITY UPLC BEH(100 mm×2.1mm, 1.7 µm) column, and quantified by internal standard method. RESULTS: The optimized method could simultaneously detect 21 organophosphate esters and their metabolites in drinking water. The detection limit was 0.01-0.24 ng/L, the quantitation limit was 0.03-0.77 ng/L. The recovery range was 57.6%-121.2% and the relative standard deviation is 1.2%-11.1% when the concentration was 0.8-20 ng/L. Senventeen tap water and 30 packaged drinking water collected by the supermarket were measured. The ΣOPEs range was 16.8-177 ng/L, and the Σdi-OPEs range was 0.328-16.3ng/L, indicating the exposure risk of organophosphates and their metabolites in water. CONCLUSION: The pretreatment of the method is simple, automatic and sensitive, and is suitable for simultaneous high-throughput determination of organophosphate esters and their metabolites in large quantities of drinking water.

[Rapid confirmation method of food poisoning caused by Bacillus cereus cereulide in rice and flour products].

OBJECTIVE: To develop a method for rapid determination of Bacillus cereus cereulide in rice and flour products by ultra-performance liquid chromatography-tandem mass spectrometry, providing emergency measures for food poisoning caused by cereulide. METHODS: Single rice and flour samples were extracted with acetonitrile aqueous solution, salting out, after centrifuged and filmed, the organic phase was directly determined. The complex matrix samples fried rice and noodles were extracted with acetonitrile aqueous solution, cleaned up with HLB column, a ACQUITY UPLC Peptide BEH C_(18) 300Å column(2.1 mm×100 mm, 1.7 µm)was used for liquid chromatography separation, multiple reaction monitoring(MRM) mode was used for detection in electrospray ionization with positive ion mode, and quantified by the solvent standard curve method. RESULTS: At the spiked level of 0.5, 1.0 and 5.0 µg/kg, the recoveries of cereulide in negative steamed rice, steamed bread and noodles samples were 87.4%-98.3%, and the relative standard deviations were 1.4%-4.2%. At the spiking levels of 1.0, 2.0 and 5.0 µg/kg, the recoveries of cereulide in the negative samples such as fried steamed rice and fried noodles were 89.5%-99.3% with the relative standard deviations of 1.1%-7.5%(n=6). The detection limit of cereulide was 0.2-0.3 µg/kg, and the quantification limit was 0.5-1.0 µg/kg. The established method was applied to the detection of the actual samples causing food poisoning in a certain place in Beijing. The content of cereulide in poisoned food samples was 1287-7398 µg/kg, the content of cereulide in two raw materials cold noodles was 0.4 and 9.4 µg/kg. CONCLUSION: The method is simple, rapid, high sensitivity and accurate, and can realize the rapid treatment of food poisoning caused by cereulide.

Human exposure to a mixture of endocrine disruptors and serum levels of thyroid hormones: A cross-sectional study.

Exposure to endocrine disruptors (EDCs) could disrupt thyroid hormone homeostasis. However, human epidemiological studies reported inconsistent observations, and scarce information on the effect of a mixture of chemicals. The aim of the present study was to examine the associations of multiple chemicals with thyroid hormones among adults from China. We measured serum levels of thyroid hormones and urinary levels of 11 EDCs, including six phthalate metabolites, bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS), perchlorate, and thiocyanate among 177 healthy adults without occupational exposure. Associations of multiple urinary analytes with serum thyroid hormones were examined by performing general linear regression analysis and bayesian kernal machine regression analysis. These EDCs were detected in almost all samples. After adjusting for various covariates, we observed only BPF significantly associated with total thyroxin (TT4) (ß=-0.27, 95% confidence interval (CI) [-0.41, -0.14]), total triiodothyronine (TT3) (ß=-0.02 95% CI [-0.03, -0.01]), free T4 (fT4) (ß=-0.02, 95% CI [-0.03, -0.01]), and free T3 (fT3) (ß=-0.04, 95% CI [-0.07, -0.01]), and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) and monoethyl phthalate (MEP) positively associated with TT4 (ß=0.24, 95% CI [0.01, 0.48]) and fT4 (ß=0.02, 95% CI [0.01, 0.04]), respectively. Moreover, we observed significant dose-response relationships between TT4 and the mixture of 11 EDCs, and BPF was the main contributor to the mixture effect, suggesting the priority of potential effect of BPF on disrupting thyroid function under a real scenario of human exposure to multiple EDCs. Our findings supported the hypothesis that human exposure to low levels of EDCs could alter thyroid hormones homeostasis among non-occupational healthy adults.

A simple method for simultaneous determination of organophosphate esters and their diester metabolites in dairy products and human milk by using solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry.

Organophosphate esters (OPEs) and their diester metabolites have been frequently found in various environmental matrices and regarded as emerging environmental pollutants, whereas data on their occurrence in foods and human matrices are still limited. In this study, a novel and simple procedure was developed to simultaneously determine 14 OPEs and 6 diester metabolites in dairy products and human milk. After enzymatic hydrolysis by ß-glucuronidase/arylsulfatase, a freeze-dried milk sample was extracted with acetonitrile and purified by solid-phase extraction. Subsequently, all target compounds were determined by HPLC-ESI-MS/MS. Linearity, limits of detection (LODs), recovery, precision, and matrix effects of the proposed methodology were validated, and the parameters of HPLC-ESI-MS/MS were optimized. LODs for OPEs and their diester metabolites were from 0.001 to 0.02 ng/mL, and limits of quantification (LOQs) were 0.01-0.3 ng/mL. Average recoveries at two spiked levels ranged between 67.3 and 121%, with relative standard deviation lower than 20.7%. A test for matrix effects showed that most analytes presented signal suppression, and isotopically labeled ISs were essential for compensating for the matrix effects. Finally, OPEs and their metabolites both showed high detecting frequencies in real samples, which indicated that these emerging pollutants were ubiquitous in foods and the human body, and the impact of the diester metabolites on population exposure must be included in exposure assessment.

[Determination of organophosphorus pesticide residues in milk of cows and sheep by ultra-high-performance liquid chromatography- tandem mass spectrometry combined with passing type purification method].

OBJECTIVE: A method for the rapid determination of dichlorvos, trichlorfon, fenthion, fenthion-sulfone, fenthion-sulfoxide, fenthion-oxon, fenthion-oxon-sulfone, fenthion-oxon-sulfoxide, phoxim, propetamphos, malathion, diazinon and coumaphos 13 common organophosphorus pesticides and their metabolites poison residues in milk of cows and sheep by ultra-high-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) with passing type solid phase extraction(SPE) purification was developed. METHODS: After centrifugation at 4 ℃, the milk was purified by passing type SPE with acetonitrile precipitating protein and determined by UPLC-MS/MS in electrospray positive ion mode(ESI+) and multi-reaction monitoring scanning(MRM), external standard method for quantitative analysis with matrix matching standard curve. RESULTS: The recoveries of 13 target compounds were between 81.5% and 107.5% and relative standard deviation was between 1.24% and 6.23% at three spiked levels of 5, 10, 20 µg/L. The detection limits of 13 target compounds were between 0.015 and 0.15 µg/L, and the quantitative limits were between 0.05 and 0.50 µg/L. No organophosphorus pesticide residues were detected in 20 samples of cows and sheep milk. CONCLUSION: The method has the advantages of good linear independence, low detection limit, high precision and accuracy, and can be used for daily monitoring of milk and related products.

[Clinical features of children and their family members with family clusters of SARS-CoV-2 Omicron variant infection in Shanghai, China: an analysis of 380 cases]. / 上海380例家庭聚集性感染Omicronå˜å¼‚æ ªçš„å„¿ç«¥åŠå ¶å®¶å±žä¸´åºŠç‰¹å¾åˆ†æž.

OBJECTIVES: To study the clinical features and prognosis of children and their family members with family clusters of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant infection under the admission mode of parent-child ward. METHODS: A retrospective analysis was performed on the medical data of 190 children and 190 family members with SARS-CoV-2 Omicron variant infection who were admitted to Shanghai Sixth People's Hospital, the designated hospital for coronavirus disease 2019 (COVID-19), April 8 to May 10, 2022. RESULTS: Both the child and adult groups were mainly mild COVID-19, and the proportion of mild cases in the child group was higher than that in the adult group (P<0.05). Respiratory symptoms were the main clinical manifestations in both groups. Compared with the adult group, the child group had higher incidence rates of fever, abdominal pain, diarrhea, and wheezing (P<0.05) and lower incidence rates of nasal obstruction, runny nose, cough, dry throat, throat itching, and throat pain (P<0.05). Compared with the child group, the adult group had higher rates of use of Chinese patent drugs, traditional Chinese medicine decoction, recombinant interferon spray, cough-relieving and phlegm-eliminating drugs, and nirmatrelvir/ritonavir tablets (P<0.05). Compared with the adult group, the child group had a lower vaccination rate of SARS-CoV-2 vaccine (30.5% vs 71.1%, P<0.001) and a shorter duration of positive SARS-CoV-2 nucleic acid (P<0.05). The patients with mild COVID-19 had a shorter duration of positive SARS-CoV-2 nucleic acid than those with common COVID-19 in both groups (P<0.05). The patients with underlying diseases had a longer duration of positive SARS-CoV-2 nucleic acid than those without such diseases in both groups (P<0.05). CONCLUSIONS: Both children and adults with family clusters of SARS-CoV-2 Omicron variant infection manifest mainly mild COVID-19. Despite lower vaccination rate of SARS-CoV-2 vaccine in children, they have rapid disease recovery, with a shorter duration of positive SARS-CoV-2 nucleic acid than adults, under the admission mode of parent-child ward.

Exosomes are involved in total body irradiation-induced intestinal injury in mice.

Ionizing radiation-induced intestinal injury is a catastrophic complication in patients receiving radiotherapy. Circulating exosomes from patients undergoing radiotherapy can mediate communication between cells and facilitate a variety of pathological processes in vivo, but its effects on ionizing radiation-induced intestinal damage are undetermined. In this study we investigated the roles of exosomes during total body irradiation (TBI)-induced intestinal injury in vivo and in vitro. We isolated exosomes from serum of donor mice 24 h after lethal dose (9 Gy) TBI (Exo-IR-24h), then intravenously injected the exosomes into receipt mice, and found that Exo-IR-24h injection not only exacerbated 9 Gy TBI-induced lethality and weight loss, but also promoted crypt-villus structural and functional injury of the small intestine in receipt mice. Moreover, Exo-IR-24h injection significantly enhanced the apoptosis and DNA damage of small intestine in receipt mice following TBI exposure. In murine intestinal epithelial MODE-K cells, treatment with Exo-IR-24h significantly promoted 4 Gy ionizing radiation-induced apoptosis, resulting in decreased cell vitality. We further demonstrated that Exo-IR-24h promoted the IR-induced injury in receipt mice partially through its DNA damage-promoting effects and attenuating Nrf2 antioxidant response in irradiated MODE-K cells. In addition, TBI-related miRNAs and their targets in the exosomes of mice were enriched functionally using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Finally, injection of GW4869 (an inhibitor of exosome biogenesis and release, 1.25 mg·kg-1·d-1, ip, for 5 consecutive days starting 3 days before radiation exposure) was able to rescue mice against 9 Gy TBI-induced lethality and intestinal damage. Collectively, this study reveals that exosomes are involved in TBI-induced intestinal injury in mice and provides a new target to protect patients against irradiation-induced intestinal injury during radiotherapy.

Rapid determination of 13 organophosphorus flame retardants in milk by using modified quick, easy, cheap, effective, rugged, and safe technique, solid-phase extraction, and HPLC-MS/MS.

Organophosphorus flame retardants are a class of widely used plasticizers and flame retardants. In this study, an analytical methodology for the simultaneous determination of 13 organophosphorus flame retardants in milk was developed by using high-performance liquid chromatography-tandem mass spectrometry in combination with a modified quick, easy, cheap, effective, rugged, and safe technique and solid-phase extraction. The experimental parameters of the sample purification procedure and high-performance liquid chromatography-tandem mass spectrometry were optimized. The developed method was validated in terms of linearity, limits of detection, recovery, and precision. The method showed a linear response in the 1-100 ng/mL concentration range and the limits of detection ranged from 0.001 to 0.3 ng/mL. The mean recoveries for most organophosphorus flame retardants were in the ranges of 75.0-115.8% (spiked at 2.5 ng/mL) and 76.7-124.8% (spiked at 25 ng/mL), with relative standard deviations of <13.09%. The developed methodology was successfully applied to the analysis of nine human milk samples and nine commercial cow milk samples. Eleven organophosphorus flame retardants were detected in the human milk samples, with median concentrations that ranged from lower than the limit of detection to 1.47 ng/mL, and only nine organophosphorus flame retardants were detected in cow milk samples, with median levels of <0.32 ng/mL.

[Determination of furan in canned foods and packaged beverages by headspace gas chromatography-mass spectrometry].

OBJECTIVE: A headspace gas chromatography-mass spectrometry(HS-GC-MS) method for the analysis of furan in canned foods and packaged beverages was established. METHODS: The furan was extracted from the samples by headspace method. D_4-furan was used as internal standard and separated on a HP-Plot Q(30 m×0.32 mm, 20 µm) column. The results were qualitative and quantitative by gas chromatography-mass spectrometry. RESULTS: The linear range of this method was 2.0-200.0 ng, and the regression equation of the working curve was y=1.14x +0.116(r~2=0.999). The recoveries were 86.3%-96.2% with the relative standard deviations(RSDs) less than 10%(n=6). The limit of quantification of furan was 1.0 ng. Through the detection of 59 samples, it was found that the common canned food and hard packaged drinks were commonly contaminated with furan, and the concentration of furan in coffee, milk tea, canned fish and other products were relatively high, with a maximum value of 153.99 ng. CONCLUSION: The method is simple, rapid, accurate and reliable, and could be used for the detection of furan in the two kinds of food.

[Determination of α_2-agonists in animal food by ultra high performance liquid chromatography -tandem mass spectrometry].

OBJECTIVE: To establish an analytical method for determination of 6 kinds of α_2-agonists in animal foods by ultra high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). METHODS: The samples of animal food were enzymatic hydrolysis by ß-glucosidase/arylsulfatase, purified by MCX column. The separation was performed on a Dikma leapsil C_(18) column(2. 1 mm×100 mm, 2. 7 µm), then the target compound were detected by ultra high performance liquid chromatography-tandem mass spectrometry with electron spray ionization(ESI) positive ion scan in mode of multiple reaction monitoring(MRM) and quantified by matrix matched external standard method. RESULTS: At the spiked level of 1, 2 and 4 µg/kg, the recoveries of each compound were in the range of 70. 4%-111. 2% with the relative standard deviations of 2. 3%-18. 8%. The qualitative limits of detections were 0. 06-0. 3 µg/kg and the quantitative limits were 0. 2-1. 0 µg/kg for the 6 targets compounds. By using the established method, the target compound in 30 samples including pork, pig liver, pig kidney, beef and mutton were detected, and no excessive veterinary drug residue were detected. CONCLUSION: The established method is simple, rapid, high sensitivity and good stability, with a wide variety and a certain development. It can provide more convenient and fast detection method support for the daily monitoring of veterinary drug residues in animal food.

[Determination of 20 kinds of ß-receptor blockers in animal foods by ultra high performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish an analytical method for determination of 20 kinds of ß-receptor blockers residues in animal foods by ultra high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). METHODS: The samples of animal foods were enzymatic hydrolysis by trichloroacetic acid(TCA), purified by MCX column. The separation was performed on a Waters ACQUITYTM BEH C_(18 )column(100 mm×2. 1 mm, 1. 7 µm), then the target compounds were detected by UPLC-MS/MS with ESI positive ion scan in mode of multiple reaction monitoring(MRM) and quantified by matrix matched external standard method. RESULTS: At the spiked level of 1, 2 and 4 µg/kg, the recoveries of each compound were in the range of 61. 9%-119. 1% with the relative standard deviations of 1. 5%-28. 4%(n=6). The qualitative limits of detections were 0. 01-0. 15 µg/kg and the quantitative limits were 0. 03-0. 50 µg/kg for the 20 targets compounds. By using the established method, the target compounds in 30 animal foods were detected, and no excessive veterinary drug residue were detected. CONCLUSION: The established method is simple, rapid, high sensitivity and good stability, with a wide variety and a certain development. It can provide more convenient and fast detection method support for the daily monitoring of veterinary drug residues in animal foods.

[Determination of L-carnitine, choline, taurine in infant formula milk powder by ultrafiltration tube cleaning and ultra-performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a method for simultaneous determination of L-carnitine, choline, taurin in infant by ultrafiltration tube cleaning and ultraperformance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). METHODS: The sample was dissolved in water and acid hydrolyzed, then adjusted pH with a sodium hydroxide solution. After ultrafiltration tube cleaning and centrifugation, the sample solution was separated on an amide column ACQUITY UPLC BEH Amide(2. 1 mm × 100 mm, 1. 7 µm) and detected by MS/MS under multiple reaction monitoring(MRM) mode. The quantification was performed by the internal standard calibration method. RESULTS: The linear ranges were 1. 00-500 µg/L for L-carnitine and choline, 10-1000 µg/L for taurine with correlation coefficients of 0. 999. The mean recoveries were 89. 7%-107. 4% with relative standard deviations(RSD, n = 6) were2. 6%-8. 1%. The detection limits of the method were 0. 812 mg/kg for choline, 0. 623 mg/kg for L-carnitine and 9. 34 mg/kg for taurine, respectively. CONCLUSION: This method is simple, accurate, reproducible and sensitivity.

[Determination of ochratoxin A and ochratoxin alpha in wine by ultra-performance liquid chromatography tandem mass spectrometry].

OBJECTIVE: To establish a method for determination of ochratoxin A and ochratoxin alpha in wine by ultra-performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS) based on isotopic internal standard method. METHODS: The wine sample was adjusted to pH 9. 0 by 5% ammonia and concentrated by a MAX solid phase extraction cartridge. The UPLC separation was performed on a ACQUITY BEH C_(18) column(100 mm×2. 1 mm, 1. 7 µm)with a isocratic elution program of acetonitrile and 5 mmol/L ammonium acetate as the mobile phase. Electrospray ionization was applied and operated in the positive ion mode. The concentration of wine was quantified by isotope internal standard. RESULTS: The calibration curves were linear in the concentration range of 1. 0-50. 0 µg/L, the coefficients of correlation were 0. 9996 and 0. 9993, respectively. The limits of detection(LODs) of both were 0. 10 µg/kg, and the limits of quantitative were 0. 35 µg/kg. The average recoveries at the spiked levels of 0. 35, 2. 00 and 10. 00 mg/kg were 88. 6%-108. 0%, and the relative standard deviations(RSDs) were 2. 1%-9. 2%, respectively. CONCLUSION: This method is simple, sensitive, accurate and reliable, which is suitable for the determination of ochratoxin A and ochratoxin alpha in wine.

[Determination of 5 kinds of fish anesthetics residues in fish by ultra-high performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: A method for the simultaneous determination of 5 kinds of fish anesthetics residues in fish has been developed by ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). Eugenol, methyl-eugenol, methyl-isoeugenol, acetyl-isoeugenol and tricaine methanesulfonate(MS-222) were concerned. METHODS: After homogenization fish samples were extracted by acetonitrile-water(80↿0, V/V), purified by Oasis PRiME HLB solid-phase extraction column. Then after centrifuged and concentrated, the samples were separated by Waters ACQUITY UPLC BEH Phenyl column(2. 1 mm×100 mm, 1. 7 µm). The detection was confirmed and quantified by mass spectrum of triple quadrupole in the multiple reaction monitoring(MRM) mode. RESULTS: The calibration curves showed good linearity in each range with correlation coefficients greater than 0. 995. Three levels spiked recovery experiments were carried out using blank fish mud extraction as substrate, the recoveries ranged from 72. 6% to 106. 0%, the relative standard deviations(RSDs) ranged from 2. 2% to 20. 1%(n=6). The qualitative limits of detections(S/N>3) were 0. 14-0. 30 µg/kg and the quantitative limits(S/N>10) were 0. 5-1. 0 µg/kg. CONSLUSION: The method is simple and easy to operate, with less organic reagent, high sensitivity and good stability. The isomers of methyl eugenol and methyl isoeugenol were successfully separated. It is suitable for the detection of 5 kinds of fish anesthetics in fish.

The oncoprotein HBXIP promotes human breast cancer growth through down-regulating p53 via miR-18b/MDM2 and pAKT/MDM2 pathways.

Mammalian hepatitis B X-interacting protein (HBXIP) is an 18-kDa protein that regulates a large number of transcription factors such as TF-IID, E2F1, SP1, STAT3, c-Myc, and LXR by serving as an oncogenic transcription coactivator and plays an important role in the development of breast cancer. We previously showed that HBXIP as an oncoprotein could enhance the promoter activity of MDM2 through coactivating p53, promoting the MDM2 transcription in breast cancer. In this study we investigated the molecular mechanisms underlying the modulation of MDM2/p53 interaction by HBXIP in human breast cancer MCF-7 cells in vitro and in vivo. We showed that HBXIP could up-regulate MDM2 through inducing DNA methylation of miR-18b, thus suppressing the miR-18b expression, leading to the attenuation of p53 in breast cancer cells. In addition, HBXIP could promote the phosphorylation of MDM2 by increasing the level of pAKT and bind to pMDM2, subsequently enhancing the interaction between MDM2 and p53 for the down-regulation of p53 in breast cancer cells. In MCF-7 breast cancer xenograft nude mice, we also observed that overexpression of HBXIP promoted breast cancer growth through the miR-18b/MDM2 and pAKT/MDM2 pathways. In conclusion, oncoprotein HBXIP suppresses miR-18b to elevate MDM2 and activates pAKT to phosphorylate MDM2 for enhancing the interaction between MDM2 and p53, leading to p53 degradation in promotion of breast cancer growth. Our findings shed light on a novel mechanism of p53 down-regulation during the development of breast cancer.

[Detection method of phthalate esters and their metabolites in blood].

OBJECTIVE: A method for determination of phthalate esters and their metabolites in blood by using SPE-ultra performance liquid chromatography tandem mass spectrometry. METHODS: A stable isotope detection method been developed for the determination of 20 kinds of phthalate esters and 6 kinds of phthalate esters metabolites in blood by ultra-performance liquid chromatography-mass spectrometry( UPLC-MS) coupled with SPE column purification. Blood samples were diluted with acetate buffer( pH5. 2), enzymatic hydrolyzed by ß-glucuronidase for 12 h, then purified with HLB column. An ACQUITYBEH Phenyl column( 2. 1 mm ×100 mm, 1. 7 µm) was used for separation by the gradient elution with acetonitrile and aqueous solution containing 0. 02% formic acid as the mobile phases. In the present study, an electrospray ionization( ESI) source was used, and the internal standard method was used for quantitation. RESULTS: The linear ranges of the 26 analytes were from 1. 0- 20. 0 µg/L, the coefficients of correlation were greater than 0. 995. The limits of detection( LODs) of the 26 analytes were all lower than1. 0 µg/L. Recoveries studies were carried out using serum samples fortified with the 26 analytes at the levels of 2. 5, 5. 0 and 10. 0 µg/L, recoveries were obtained in the range of63. 0%- 97. 7% with relative standard deviations( RSDs) from 1. 9% to 19. 1%. CONCLUSION: The established method is accurate and highly sensitive, and can be used for the qualitative and quantitative analysis of the residues of the phthalate esters and their metabolites in the blood samples.

[Rapid detection of 8 veterinary drug residues in chicken by QuEChERS-ultra performance liquid chromatography tandem mass spectrometry].

OBJECTIVE: To develop a method for determination of 8 veterinary drug residues in chicken matrix by Qu ECh ERS-ultra performance liquid chromatography tandem mass spectrometry. METHODS: Chicken samples were extracted with acid acetonitrile, salting out, and then the organic phase were cleaned up by C18 and PSA. A Waters ACQUITYTM BEH C18column( 100 mm × 2. 1 mm × 1. 7 µm) was used for LC separation, ESI positive ion scan was used with multiple reaction monitoring( MRM)mode and quantified by matrix-matched external standard method. RESULTS: At the spiked level of 1, 2 and 4 µg / kg, the recoveries of each compound were in the range of 81. 2%- 94. 1% with the relative standard deviations of 4. 2%- 14. 3%. The qualitative limits of detections were 0. 1- 0. 2 µg / kg and the quantitative limits were 0. 2- 0. 5 µg / kg for the 8 targets compounds. The established method was applied to the detection of the 8targets compounds in 30 chicken samples, and none of the 8 veterinary drugs exceeded the residue limits. CONCLUSION: The method is simple, rapid, high sensitivity and good stability, with a wide variety and a certain development. It can be used for the daily monitoring of the veterinary drug residues in chicken.

[Determination of 4 kinds of plant growth regulator in bean sprout by solid phase extraction column coupled with ultra-high performance liquid chromatography].

OBJECTIVE: A method for the determination of 6-benzylaminopurine( 6-BAP), isopentennyladenine( z-IP), 4-fluorophenoxyacetic acid( 4-FPA), 4-chlorophenoxyacetic acid( 4-CPA) in bean sprout was developed using solid phase extraction column with ultra-high performance liquid chromatography. METHODS: The sample was extracted by acetonitrile,dehydrated by salt,then centrifugation,and purified by PXC/PWA solid phase extraction column. The chromatographic analysis was carried out on C18 chromatographic column( 100 mm ×2. 1 mm,1. 8 µm),acetonitrile and sodium dihydrogen phosphate for gradient elution,diode array detector for detection,and quantified with external standard method. RESULTS: The calibration curves showed good linearity in the range of 0. 25-25 µg/mL( 6-BAP and z-IP) and 0. 50-50 µg/mL( 4-FPA and 4-CPA) with correlation coefficients greater than 0. 999. Three levels spiked recoveries were carried out using blank bean sprout extraction as substrate,the recoveries ranged from70. 0% to 96. 4%,and the relative standard deviations( RSDs) ranged from 2. 84% to12. 10%( n = 6). The qualitative limits of detections were 0. 0082-0. 075 mg/kg and the quantitative limits were 0. 027-0. 25 mg/kg for the 4 PGRs. CONCLUSION: The method is simple and easy to operate using solid phase extraction column coupled,simultaneous determination of 4 PGRs by ultra-high performance liquid chromatography,can ensure the corresponding accuracy,sensitivity and precision.

Simultaneous Determination of Multiple Intracellular Primary Metabolites by Ultrahigh Performance Liquid Chromatography Coupled with a Q Exactive HF Mass Spectrometer.

In this study, we established an ultrahigh-performance liquid chromatography-Q Exactive HF MS (UHPLC-HF MS) method for the simultaneous determination of 25 targeted metabolites relating to a broad coverage of central metabolic pathways, such as glycolysis pathway, tricarboxylic acid cycle (TCA), serine biosynthesis pathway (SSP), glutaminolysis pathway, and closely related biosynthetic reactions. A Shodex Asahipak NH2P-50 2D column was used to separate the targeted compounds, and Full MS + PRM detection using an electrospray ionization source in negative mode was employed. The method also integrated a sample purification step by passing through a Waters Sirocco 96 plate to remove protein impurities, ensuring the better resolution and sensitivity of the proposed method. The calibration curves of the method showed good linearity within the range of 1-10 000 µg L-1 with the correlation coefficient no less than 0.99. The method can be used for routine quantification of primary metabolites in a wide variety of cell extract samples. With the help of the method, for the first time, we successfully separate the isomers of 3-phosphoglycerate (3-PG) and 2-phosphoglycerate (2-PG), which lay the groundwork for the accurate quantification of metabolites of the tumor cells, the study of PGAM1 inhibitors, and the development of neotype anticancer drugs.

[Determination of 3-hydroxyisovaleryl carnitine in plasma and urinary excretion by ultra-performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS ) method was developed for the determination of 3-hydroxyisovaleryl carnitine in plasma and urinary excretion. METHODS: Plasma and urinary excretion samples were centrifugated with high speed at 3000 x g for 10 minutes, and the MCX solid phase extraction column was used to filter and purify the liquid samples. The following procedures were elution, wash-out, redissolve, detection. The chromatographic separation was achieved on a Waters Acquity UPLC BEH C18 column (2.1 mm x 50 mm, 1.7 microm), with a mobile phase composed of 0.1% formic acid in water-methanol with gradient elution. Analyte quantification was performed in the positive electrospray ionization mode and multiple monitoring. The quantification and qualification were performed using the internal standard of 3-hydroxyisovaleryl carnitine, then the evaluation for accuracy and precision were followed. RESULTS: The linear range of 3-hydroxyisovaleryl carnitine were 0.1-20.0 microg/L in the plasma and 5.0-200 microg/L in urine, with both the linear correlation coefficient above 0. 99. Moreover, in three standard levels, rate of recovery in plasma and urine ranged from 78.6% to 115.6%. The RSD of six parallel determination for the 3HIA-carnitine in plasma and urine were 4.80% and 5.70% respectively. The detection and quantification limits for plasma and urine were 0.04 microg/L, 0.1 microg/L and 0.03 microg/L, 0.08 microg/L, respectively. CONCLUSION: The sample preparation method is simple and fast, and the method can be used to analyze 3-hydroxyisovaleryl carnitine in plasma and urinary excretion efficiently and sensitively.