Determination of Benzo[a]pyrene in Edible Oil by High Performance Liquid Chromatography-Fluorescence Detector (HPLC-FL)

In this study, an optimized high performance liquid chromatography-fluorescence detector (HPLC-FL) method for the determination of benzo[a]pyrene in edible oil was established. HPLC was performed with Thermo Fisher Scientific C18 column (250 mm×4.6 mm, 5 μm) as the chromatographic column and acetonitrile and water as the mobile phase, and the excitation wavelength and emission wavelength of fluorescence detector were 286 and 430 nm, respectively. The response was high, and the linear range was 0.5-10.0 ng/ml. The lowest limit of detection was 0.11 ng/ml, and the average recovery was 92.5%. This method is suitable for quantitative analysis of benzo[a]pyrene content in edible oil.

Determination of Veterinary Drug Residues in Animal-derived Foods by Liquid Chromatography-Mass Spectrometry

[Objectives]This study was conducted to establish a rapid and effective method for simultaneous extraction of 54 kinds of veterinary drug residues in animal-derived food, including sulfonamides, quinolones, tetracyclines, malachite greens, penicillins, nitroimidazoles, tranquilizers and macrolides, by HPLC-MS. [Methods] The samples were extracted with 80% acetonitrile water(containing 0.1% formic acid), combined with QuEChERS extraction technology and C18 and PSA purification, analyzed by high performance liquid chromatography-mass spectrometry, and quantified by external standard method. The target substances were analyzed on ZORBAX Eclipse C18 chromatographic column using 0.2% formic acid water and 0.2% methanol as mobile phases. The gradient elution mode was used for chromatographic separation and multiple reaction detection. [Results] In the linear range of 0.5-50.0 ng/ml, the linear relationship of the 54 kinds of veterinary drug residues was good, with correlation coefficients(r~2) greater than 0.995, and the detection limits ranged from 0.30 to 1.00 μg/kg. The results showed that the recovery ranged from 75.4% to 118.2% when different matrixes were added for recovery. [Conclusions] This method is simple, efficient, accurate, stable, and highly operable. It is applicable to simultaneous batch screening of veterinary drug residues in animal-derived food, and has high practical application value.

Influences of various grazing systems on community biomass of a desert grassland in Inner Mongolia,China

This study investigated the effects of various grazing systems, including continuous grazing, rotational grazing, and no-grazing systems, on the community biomass in the Stipa breviflora Griseb desert grassland during the grazing seasons in 2005, 2006, and 2007, based on study sites established in 1999. We found that the seasonal dynamics of the aboveground biomass were quite similar among the three treatments, which reached peak values in period from August to September during each study year. The continuous grazing system reduced the aboveground biomass from 2005 to 2007 under drought conditions, and the rotational grazing and no-grazing systems maintained more aboveground biomass than the continuous grazing system did. The belowground biomass declined with the increase of soil depth among the three treatments, and in the surface 20-cm soil layer it accounted for more than 60% of the total biomass. The belowground biomass was found to be highly correlated with soil depth under rotational grazing. The total belowground biomass within the 0--100-cm soil layer for rotational grazing was sig- nificantly higher than for continuous grazing and no-grazing, and had 15,775 kg/ha more biomass. Our results demonstrate that conservative rotational grazing can alleviate grassland deterioration by reserving more aboveground and belowground biomass than the continuous grazing system does.

Determination of Sodium Pentachlorophenoxide Residues in Animal-derived Foods by Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS)

[Objectives]This study was conducted to establish an ultra-high performance liquid chromatography-tandem mass spectrometry for the rapid extraction of sodium pentachlorophenoxide from animal-derived food.[Methods]The samples were extracted with an acetonitrile water solution(8∶2),0.1 mol/L hydrochloric acid and a purification extraction bag with shaking.Centrifugation was performed to obtain supernatants,which were added to purification tubes containing PSA and C_(18) for purification,and then filtered with membranes for determination.Each test solution was separated by a ZORBAX Eclipse plus C_(18) column with acetonitrile and 5 mmol/L ammonium acetate as mobile phases,and determined with electrospray ionization and multiple reaction monitoring.[Results]The method had good linearity in the concentration range of 1.0-50 ng/ml,and the correlation coefficient was 0.9997.The limit of detection was 0.25μg/kg and the limit of quantification was 0.75μg/kg.The recovery was between 87.4%and 112.5%,and the RSD%was between 0.5%and 10.0%.[Conclusions]The method has simple operation and high sensitivity,and is suitable for trace detection of sodium pentachlorophenoxide in large quantities of animal-derived food.

Pre-column Derivatization-High Performance Liquid Chromatography for the Detection of Monensin in Livestock and Poultry Meat

[Objectives]A method for the detection of monensin in poultry and livestock meat by pre-column derivatization-high performance liquid chromatography was established.[Methods]The sample was extracted with chloroform,derivatized with trichloroacetic acid and 2,4-dinitrophenylhydrazine,and centrifuged to obtain a purified solution.A C18 chromatographic column(4.6 mm×150 mm,5μm)was used for separation with(1.5%)acetic acid water∶methanol(volume ratio)=1∶9 as the mobile phase using a DAD detector for detection,and the external standard method was adopted for peak area quantification.[Results]Monensin had good linearity in the concentration range of 5.00-200 mg/L,with the linear correlation coefficient r 2>0.999;the detection limit was 5.00 mg/kg;the relative standard deviation was smaller than 10%;and the recoveries of standard addition experiment were in the range of 75%-110%.[Conclusions]The method has the advantages of simple pretreatment operation,good derivatization effect and fast detection speed,and is suitable for detecting monensin in poultry and livestock meat.

Investigation of Cognition Status of Menopausal Hormone Therapy in Medical Institutions Staff

Objective:To investigate the cognition,application and commendation of menopausal hormone therapy(MHT)among medical institution staff with different professional background.Methods:Female staff aged 40-60 years in 4 tertiary hospitals were randomly selected.The participants'characteristics and the information of cognition,application and recommendation of MHT were collected by questionnaire.Results:A total of 341 people participated in this study,the cognition rate of MHT was 37%and the recommendation rate was 44%.For people with indications of MHT,the utilization rate is 15%,and 84.6%of them have used MHT for less than 3 years.84.6%of those who did not use MHT considered menopause is not a disease and there was no need to use medication.Compared with nurses,doctors know more about MHT(P<0.01),and MHT recommendation rate of doctors was higher than that of nurses(P<0.01).The cognition of MHT were analyzed in menopause group,irregular menstruation group and regular menstruation group,there was no difference was found among these three groups(P>0.05).Conclusion:Strengthening the training of MHT related knowledge in medical institutions,will be helpful to improve the cognition and utilization rate of medical institutions and promote the whole society to study and use MHT.

Clinical Efficacy of Dienogest and Levonorgestrel-Releasing Intrauterine System in the Treatment of Adenomyosis

Objective:To compare the clinical efficacy and adverse reactions of dienogest and levonorgestrel-releasing intrauterine system in the treatment of adenomyosis.Methods:A total of 60 cases of adenomyosis admitted to Dezhou Women and Children’s Hospital from January 2020 to October 2021 were selected and randomly divided into two groups(Group A and Group B),which were initiated on dienogest and levonorgestrel-releasing intrauterine system,respectively.The therapeutic effects and adverse reactions of the two groups were analyzed.Results:After 6 months of treatment,the uterine volume in the LNG-IUS group reduced slightly compared with that before treatment,with no statistical significance(p>0.05),while that in the DNG group increased slightly compared with that before treatment,with no statistical significance(p>0.05).After 6 months of treatment,the hemoglobin of patients in both groups increased compared with that before treatment;there was no significant difference in the DNG group(p>0.05),but there was significant difference in the LNG-IUS group(p<0.01).After 6 months of treatment,the VAS scores of the two groups were significantly lower than those before treatment(p<0.01);the serum CA125 level in both groups decreased significantly compared with that before treatment(p<0.01).Conclusion:Mirena(levonorgestrel-releasing intrauterine system)has better therapeutic effect on adenomyosis and fewer adverse reactions than deinogest.

Analysis on the Factors Related to the Accidental Pregnancy in 98 Teenage Girls

Objective:To understand the general information of adolescent girls with unplanned pregnancy and the information about abortion and reproductive health knowledge,analyze the influencing factors of unplanned pregnancy and explore the preventive measures.Methods:Using epidemiological investigation method,the adolescent females(age<19 years old)who volunteered requested pain deprivation in our hospital from January 2018 to December 2019 were examined by questionnaire with informed consultation,and the results were analyzed.Results:After screening,98 valid questionnaires were received.The average age of girls were 16.81 years old,and the youngest was 13 years old.Employed girls accounted for 54.0%,students for 23.5%and unemployed people for 22.5%.Non-eamers accounted for 38.8%,and those with monthly income less than 3,000 yuan accounted for 86.8%.78.6 of those aged 16-18 had sex for the first time.The age of first sexual intercourse<15 years old accounted for 21.4%・The first abortion patients accounted for 84.7%,repeated abortion accounted for 15.3%.years old accounted for 19.05%.First abortion in the age<15 There was no statistical difference between the reproductive health knowledge mastery score and the family economic status,parents*12*5 occupation,parents'marital status,parents5 sex education(P>0.05).The score of reproductive health knowledge was statistically different from that of school sex education and hospital sex education(P<0.05).Conclusions:The primary cause of unintended pregnancy is the lack of knowledge of contraception and reproductive health.Schools and hospitals are effective in sex education for adolescent girls.Relevant government departments,schools,families and hospitals should pay more attention to sex education and strengthen efforts to improve the quality of education,so as to further reduce the harm caused by accidental pregnancy of adolescent girls.

Managed grassland alters soil N dynamics and N2O emissions in temperate steppe

Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen（N） dynamics and nitrous oxide（N2O） emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N2O emissions by field experiments in Hulunber in northern China. Soil（0-10 cm）, nitrate（NO3-）,ammonium（NH4＋）, and microbial N were measured in plots in a temperate steppe（Leymus chinensis grassland） and two managed grasslands（Medicago sativa and Bromus inermis grasslands） in 2011 and 2012. The results showed conversion of L. chinensis grassland to M.sativa or B. inermis grasslands decreased concentrations of NO3--N, but did not change NH4-N . Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M.sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa（i.e., a legume grass） increased N2O emissions by 26.2%, while the conversion to the B. inermis（i.e., a non-legume grass） reduced N2O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO3-＋-N and NH4-N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N2O emissions.