Bio-screening and quantification of methyl paraben in vinegar and coconut juice separated by HPTLC

As a widely used food preservative,methyl paraben was experimentally evidenced with serious hormonelike adverse effects.Herein,a high performance thin-layer chromatography platformed bioluminescent bioautography and image analysis for the selective quantification and confirmation of methyl paraben was proposed and validated in vinegar and coconut juice.First,the detectability of the bioautography to the analyte on different layer materials was estimated,revealing that normal silica gel was the best choice.After that,the liquid of sample extract and working solution were separated to overcome the background noises due to co-extracted matrices.The separation result was then coupled to the optimized bioautography,enabling instant and straightforward screening of the targeted conpound.For accurate quantification,bioluninescent inhibition pattern caused by the analyte was processed by image analysis,giving useful sensitivity(LOD>16 mg/kg),precision(RSD<10.1%)and accuracy(spike-recovery rate 76.9%-112.2%).Finally,the suspected result was confirmed by determining its MS fingerprint,further strengthening the reliability of screening.

A Rapid Separation and Highly Determination of Paraben Species by Ultra-Performance Liquid Chromatography —Electrochemical Detection

In this study, a new technique was developed using rapid ultra-performance liquid chromatography (UPLC)-based separation coupled with electrochemical detection by a boron-doped diamond (BDD) electrode for the detection and quantification of three commonly used parabens (methylparaben (MP), ethylparaben (EP) and propylparaben (PP)). We aimed to reduce the analysis time by using UPLC coupled with a short reverse phase C 18 monolithic column (25 mm×4.6 mm). Operating the monolithic column at low back-pressure resulted in high flow rates. A mobile phaseconsisting of a 25:75 (v/v) ratio of acetonitrile:0.05 Mphosphate buffer (pH 5) at a flow rate of 2.5 mL·min?1 was used to perform the separation. The amperometric detection with the BDD electrode was found to be optimal and reliably reproducible at a detection potential of 1.5 V vs. Ag/AgCl. Under these conditions, the separation of the three targetanalytes (MP, EP and PP) was achieved in 2 min and was linear within a sample concentration range of 0.1 to 50.0 mg·L?1 (r2 values of 0.9970, 0.9994 and 0.9994 for MP, EP and PP, respectively). This method was successfully applied to determine the concentrations of each parabeninsix real samples with therecoveries ranging from of 80.3% - 98.9% for all three parabensfrom samples spiked at 12, 22 and 32 mg·L?1. Therefore, the proposed method can be used as an alternative rapid and selective method for the determination of paraben levels in real samples.

Paraben Content in Adjacent Normal-malignant Breast Tissues from Women with Breast Cancer

Objective Accumulation of estrogenic compounds and other carcinogens in normal breast tissues contributes to unpredictable breast cancer incidence during adolescence and throughout life.To assess the role of parabens in this phenomenon,the paraben content of adjacent normal-malignant breast tissues is measured in women with breast cancer living in Isfahan Province,Iran.Methods Adjacent normal-malignant breast tissue samples were obtained from 53 subjects.The parabens including methyl-paraben(Me PB),ethyl-paraben(Et PB),propyl-paraben(Pr PB),and butylparaben(Bu PB)were extracted from the sample supernatant and then subjected to gas chromatography analysis.Results Some risk factors for breast cancer were stimulated by parabens in adjacent malignant-normal breast tissues among young and middle-aged women with breast cancer.We observed a significant association for dose-response pattern of Me PB[OR=98.34(11.43–185.2),P=0.027]for both ER+and PR+women and Me PB[OR=164.3(CI:112.3–216.3),P<0.001]for HER2+women than women with negative receptors.The risk of 95-fold increase in Me PB dose and 164-fold increase in∑PBs dose were significant for women with hereditary breast cancer in first-degree relatives.Conclusions These results may promote future epidemiology studies and strategies to improve women's lifestyle and consume paraben-free products.

Photofading of Derivatives of Paraben (PHB) by AM1 and PM3 Methods: A Theoretical Study

Calculations of chemical structures and photofading of parabens (PHB—4 hydroxybenzoic acid), which are p-hydroxybenzoic acid alkyl esters were performed. These compounds are used as preservatives for the substances used in cosmetics. The reactivity of these derivatives with an oxidant—singlet oxygen—have been tested with a theoretical method of frontier orbitals. All-valence molecular orbital methods, AM1 and PM3, have been used to calculate frontier electron density for higher occupied HOMO and lower unoccupied LUMO orbitals, which might be sensitive to an electrophilic (with singleton oxygen atom 1O2) or nucleophilic ( superoxide anion radical) attack at a particular atom in a molecule. Using AM1 and PM3, we calculated the reactivity , superdelocalisability and electron density distributions. The obtained superdelocalisability rates allow you to explain the fastness values in different chemical molecules. The structure of parabens (PHB) was optimized by MM+, DM, AM1 or PM3, to achieve constant energy values at a convergence criterion of 0.01 kcal/mol. The performed calculations indicate that the electrophilic oxidation reaction should take place in the aromatic ring in the 2-position to the hydroxyl residue of PHB, whereas the superoxide radical reaction occurs mainly on the alkyl residues of the ester group. The reaction may take place according to superoxide mechanism or 1,2-addition, where the higher superdelocalisability values SN are located on neighboring atoms in aromatic systems.

Simultaneous determination of bisphenols, benzophenones and parabens in human urine by using UHPLC-TQMS

Bisphenols, benzophenones and parabens may alter one or more functions of endocrine system and consequently cause adverse health effects on human. A rapid and sensitive analytical method for the simultaneous determination of six bisphenols, five benzophenones and seven parabens in human urine by using ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry was developed and applied for human urine sample analysis. The eighteen targeted compounds were separated within 11 min. Heated-electrospray ionization was operated with multiple reaction monitoring in negative-ion mode. The limit of detection ranged from 0.01 ng/mL to 0.5 ng/mL.Seven isotope-labeled internal standards were used in the quantitative analysis. After the method was validated for sensitivity, linearity, precision, accuracy and matrix effect, it was applied for the analysis of human urine samples to evaluate the profiles of human exposure. Eight of the targeted analytes were detected in more than 50% urine samples.

Remediation of preservative ethylparaben in water using natural sphalerite:Kinetics and mechanisms

As a typical class of emerging organic contaminants(EOCs), the environmental transformation and abatement of preservative parabens have raised certain environmental concerns. However, the remediation of parabens-contaminated water using natural matrixes(such as, naturally abundant minerals) is not reported extensively in literature. In this study, the transformation kinetics and the mechanism of ethylparaben using natural sphalerite(NS) were investigated. The results show that around 63% of ethylparaben could be absorbed onto NS within 38 hr, whereas the maximum adsorption capacity was 0.45 mg/g under room temperature. High temperature could improve the adsorption performance of ethylparaben using NS. In particular, for the temperature of 313 K, the adsorption turned spontaneous. The well-fitted adsorption kinetics indicated that both the surface adsorption and intra-particle diffusion contribute to the overall adsorption process. The monolayer adsorption on the surface of NS was primarily responsible for the elimination of ethylparaben. The adsorption mechanism showed that hydrophobic partitioning into organic matter could largely govern the adsorption process, rather than the Zn S that was the main component of NS. Furthermore, the ethylparaben adsorbed on the surface of NS was stable, as only less than 2% was desorbed and photochemically degraded under irradiation of simulated sunlight for 5 days. This study revealed that NS might serve as a potential natural remediation agent for some hydrophobic EOCs including parabens, and emphasized the significant role of naturally abundant minerals on the remediation of EOCs-contaminated water bodies.

Fabrication of the Metal-Organic Framework Membrane with Excellent Adsorption Properties for Paraben Based on Micro Fibrillated Cellulose

A kind of novel environmental-friendly composite absorbent material was designed and prepared in this paper.Nanoscale metal-organic frameworks(MOFs)were embedded in the skeleton of cotton micro fibrillated cellulose.By scanning electron microscope(SEM),we observed that a large number of MOFs were attached to the cellulose skeleton.In addition,under the condition of 1800 r/min vortex,the structure of the composite material was stable and was not easily damaged by external forces.The water contact angle test showed that the composite material had excellent hydrophilicity and could be used for the adsorption of pollutants.Then,the material was characterized by energy dispersive X-ray spectroscopy(EDX),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR)and BET adsorption.Through verification,the material had very stable reusability(n=10).The composite material was applied to the solid phase extraction of water samples,such as rain water,toning water and fruit juice,and was quantitatively analyzed by high performance liquid chromatography(HPLC)-UV.This method was then applied to the extraction of four parabens(methyl-,ethyl-,propyl-,and butylparaben)from real samples,yielding limits of detection(LODs)of 0.29-0.58 ng/mL.The linear range was 2-500 ng/mL.The inter-day and intra-day recoveries were 90.7%-106.0%and 87.1%-109.3%,respectively(relative standard deviation<10.8%).

利用溶质-溶剂模型预测晶体成核的难易

成核作为结晶的初始阶段,直接影响着晶体产品的结构、手性、纯度、晶型和粒径分布等性质。但由于成核具有随机性,通过实验成核不仅耗时耗力而且很难洞悉分子间的相互作用。本文选择结构相似的对羟基苯甲酸乙酯(EP)、对羟基苯甲酸丙酯(PP)和对羟基苯甲酸丁酯(BP)为模型物质,计算了EP、PP和BP在四种不同的有机溶剂(乙醇、乙酸乙酯、丙酮、乙腈)中单个溶质分子和单个溶剂分子的结合能。不论是EP、PP还是BP与各溶剂的相互作用大小都服从乙醇>乙酸乙酯>丙酮>乙腈。因此,可以预测EP、PP和BP在乙醇中成核最慢,在乙酸乙酯和丙酮中成核较慢,在乙腈中成核最快。当溶剂相同的时候,EP最难成核,其次是PP,BP容易成核,预测的结果与实验结果一致。本研究证明利用溶质-溶剂(1∶1)模型可以预测成核的难易,进而有利于筛选溶剂,提高实验效率。

β分子筛负载SO_(4)^(2-)/Fe_(2)O_(3)催化合成尼泊金丁酯

以实验室自制的β分子筛负载SO_(4)^(2-)/Fe_(2)O_(3)固体酸作催化剂,不加有毒带水剂,催化合成了尼泊金丁酯.考查了催化剂用量、醇酸摩尔比、反应时间等对尼泊金丁酯的酯化率的影响.结果表明,β分子筛负载SO_(4)^(2-)/Fe_(2)O_(3)固体酸具有超强酸性,对尼泊金丁酯具有较好的催化性能,适宜的反应条件为:n酸∶n醇=1.0∶1.2,催化剂用量为对羟基苯甲酸的10%,反应时间3 h,对羟基苯甲酸的转化率达92%以上.

对羟基苯甲酸酯类防腐剂的环境和人体暴露研究进展

对羟基苯甲酸酯(parabens,PBs)作为一类防腐剂,因其具有独特的理化性质而被广泛应用于食品、药品和个人护理品中.但随着科学技术的发展和研究的不断深入,PBs被证明在一定程度上具有与持久性有机污染物相类似的“持久性、生物富集性和生物毒性”,是潜在的内分泌干扰物.近年来此类防腐剂已经在世界范围内的环境介质和人体样本中被广泛检出,且检出浓度呈逐年上升趋势,引发国内外高度关注.本文分别从环境外暴露和人体内暴露两个方面,对国内外最新的PBs暴露相关研究成果进行归纳和总结,为开展PBs人体暴露和健康风险评估研究提供参考及思路.

超高效液相色谱-串联质谱法测定烟用水基胶中14种杀菌剂

建立超高效液相色谱-串联质谱同时快速测定烟用水基胶中溴硝醇、尼泊金酯、山梨酸、苯甲酸及异噻唑啉酮的方法。烟用水基胶经水分散后,用甲醇萃取,离心后取上层清液过0.22μm有机滤膜,再稀释20倍后上机测定。选取ACQUITY BEH C_(18)(100 mm×2.1 mm,1.7μm)色谱柱,以水和甲醇为流动相分离,分别在电喷雾正负离子模式下和多反应监测(MRM)模式下检测。结果表明,所有待测物在各自的质量浓度范围内线性良好,相关系数均大于0.998,其中6种尼泊金酯(尼泊金甲酯、尼泊金乙酯、尼泊金丙酯、尼泊金异丙酯、尼泊金丁酯、尼泊金异丁酯)、5-氯-2-甲基-4-异噻唑啉-3-酮、2-正辛基-4-异噻唑啉-3-酮、4,5-二氯-N-辛基-4-异噻唑啉-3-酮的线性范围为0.25~10 ng/L;溴硝醇、2-甲基-4-异噻唑啉-3酮、1,2-苯并异噻唑-3-酮的线性范围为2.5~100 ng/L;山梨酸、苯甲酸的线性范围为25~1000 ng/L。线性相关系数均不小于0.998。方法的定量限为0.03~2.69μg/g。低、中、高3个浓度水平下,14种目标化合物在烟用水基胶中平均回收率为76.4%~125.4%,相对标准偏差为1.7%~12.2%(n=6)。该方法的精密度、准确度符合测定要求。该方法操作简单,准确灵敏,重复性好,适用于烟用水基胶中溴硝醇、尼泊金酯等杀菌剂的同时检测。

超高效液相色谱法测定口腔护理产品中异噻唑啉酮类含量

采用超高效液相色谱法测定口腔护理产品中异噻唑啉酮类含量。通过HyperSep反相C8/苯磺酸离子交换器(HyperSep C8/BSAIE),Sep-Pak C18吸附剂的固相萃取(SPE)及超高效液相色谱/二极管阵列检测器(UPLC/DAD)用于同时测定口腔护理产品中甲基异噻唑啉酮(MI)和甲基氯异噻唑啉酮(MCI)。结果发现,HyperSep C8/BSAIE和UPLC/DAD的洗脱溶剂为混合物(乙腈和甲醇体积比2∶1),较佳检测波长为255 nm;该方法具有良好的线性范围(0.005~10μg/mL),测定系数(R^(2),0.997~0.999),检测限(LOD,0.001~0.002μg/g);在检测低(0.07μg/mL)、中(3μg/mL)和高(15μg/mL)质量浓度的标准混合物时,相对标准偏差RSD<3%。共研究了12个口腔护理样品,MI含量为nd~0.89μg/g,MCI含量为nd~0.62μg/g。根据样品的类型,回收率在95.33%~101.43%之间。

气相色谱-质谱法测定化妆品中苯甲酸酯类和对羟基苯甲酸酯类16种防腐剂

建立了测定化妆品中苯甲酸酯类和对羟基苯甲酸酯类防腐剂的气相色谱-质谱(GC-MS)方法。样品经饱和氯化钠和乙酸乙酯提取,离心后取上清液用乙腈定容。提取液经HP-5ms毛细管色谱柱(30 m×250μm×0.25μm)分离,采用选择离子监测模式(SIM)扫描测定,外标法定量。16种防腐剂在相应的线性范围内线性关系良好,其中苯甲酸酯类的检出限和定量限分别为0.3μg/g和1μg/g,对羟基苯甲酸酯类的检出限和定量限分别为0.6μg/g和2μg/g。实验选取了3种基质在两个水平下验证方法的回收率和精密度,16种防腐剂的加标回收率为85.4%~113.8%,相对标准偏差(RSD,n=6)≤10.9%。检测的50批婴幼儿类化妆品中对羟基苯甲酸甲酯和对羟基苯甲酸丙酯的使用频率最高,分别为50%和36%,添加量均符合规定。

对羟基苯甲酸酯对好氧颗粒污泥基本特性的影响

研究采取好氧颗粒污泥(AGS)工艺处理含有对羟基苯甲酸酯(PBs)的废水,在长期运行过程中,AGS工艺在稳定去除COD、氨氮、磷酸的同时,可以高效去除PBs,去除率达到88%以上。在微生物理化性质分析中发现,PBs长期影响下AGS的形态结构变得不规则和松散,同时AGS的粒径增速降低。PBs刺激了污泥中EPS(胞外聚合物)的分泌来应对PBs,同时在PBs长期影响下AGS中EPS的化学结构发生变化,试验组AGS中LB-EPS与对照组相比缺少了芳香族蛋白质,而这种物质与颗粒的稳定性相关。微生物群落分析发现PBs对于颗粒污泥中各种菌纲和菌属的相对丰度产生了影响,并且微生物的多样性有所升高。Meganema和Rhodocyclaceae是R2中的优势菌属,且相对丰度均远高于R1中的丰度,表明可能其对于PBs具有抗性。Meganema的富集影响了颗粒的稳定性,而Rhodocyclaceae的高丰度可能在对PBs的去除上发挥重要作用。

响应面法优化水葫芦生物炭吸附尼泊金乙酯工艺研究

以水葫芦为原材料,柠檬酸改性制备生物炭对尼泊金乙酯(EP)的吸附。通过Box-Behnken Design实验,使用吸附剂添加量、pH值、EP初始浓度和反应时间这四个变量对尼泊金乙酯去除率的影响进行模拟优化。实验结果表明:水葫芦生物炭(WB)与柠檬酸改性水葫芦生物炭(CA-WB)在各单因素实验中对EP溶液去除影响的大小顺序为:吸附剂添加量>EP浓度>pH>反应时间。WB吸附EP的最佳反应条件为:pH为1.12、反应时间为3.28 h、EP初始浓度为18.4 g/L和WB添加量为3.86 g/L,此时WB对EP的去除率为81.04%,实际条件下验证EP去除率为85.12%,与预测值误差为4.79%;CA-WB吸附EP的最佳反应条件为:pH为2.8、反应时间为3.23 h、EP初始浓度为14.7 mg/L和CA-WB添加量为3.73 g/L,此时CA-WB对EP的去除率为96.00%,实际条件下验证EP去除率为93.24%,与预测值误差为2.96%。

复配防腐剂在怪味鸡丝中的应用研究

探讨怪味鸡丝包装方式对鸡丝品质的影响,研究复配防腐剂对怪味鸡丝的防腐效果。运用现代感官分析和仪器分析对分装和混装鸡丝进行检测,分析表明:在4℃条件下储存,混装鸡丝较分装鸡丝而言,其储藏期略短,但质构特性稍强;两种鸡丝在挥发性成分和含量上都有所差异,造成口感、香味的差异。综合各项指标,选择产品混装为后续实验条件。在怪味鸡丝中添加防腐剂,利用菌落总数、pH、酸价和过氧化值四类指标分析单一防腐效果。结果表明:单一防腐剂最适添加量分别为:对羟苯甲酸乙酯0.18 g/kg;苯甲酸钠0.81 g/kg;聚赖氨酸0.1 g/kg。依据单一防腐效果两两复配,选出最优的复配组合。复配防腐剂的实验结果表明:最佳复配方案为:苯甲酸钠0.455 g/kg(以配制食醋带入)、聚赖氨酸0.12 g/kg(以白煮肉带入)。

固相萃取-高效液相色谱法测定水产调味品中7种对羟基苯甲酸酯类防腐剂

建立了固相萃取-高效液相色谱法同时测定蚝油、虾油、鱼露中的7种对羟基苯甲酸酯类防腐剂(对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯、对羟基苯甲酸异丙酯、对羟基苯甲酸异丁酯、对羟基苯甲酸庚酯)。样品分别用甲醇和20%甲醇水溶液超声提取,离心后经MAX固相萃取小柱富集、净化。使用Chromcore 120 C18色谱柱(150 mm×4.6 mm,3.0μm)分离,以乙腈-5 mmol/L乙酸铵水溶液为流动相(初始流动相体积比30∶70),梯度洗脱,流速0.7 mL/min,以二极管阵列检测器检测,检测波长254 nm,柱温35℃。7种对羟基苯甲酸酯类防腐剂在0.5~50.0 mg/L内具有良好的线性关系,相关系数均大于0.9999,检出限为0.2~0.4 mg/kg,定量限为0.5~1.3 mg/kg。选用蚝油、虾油、鱼露3种样品在3个加标水平下做加标回收试验,7种防腐剂在3种样品中的回收率较好,分别为91.0%~102%、95.5%~106%、95.0%~105%,相对标准偏差≤6.97%。利用该研究建立的检测方法对135个实际样品进行风险筛查,发现某酱油、醋、酱腌菜等存在对羟基苯甲酸甲酯、对羟基苯甲酸乙酯等。该方法操作简单,结果准确,重复性好,干扰少,灵敏度高,可作为测定水产调味品蚝油、虾油、鱼露中7种对羟基苯甲酸酯的有效检测方法。

QuEChERS净化-气相色谱/三重四极杆质谱法测定酱油中6种对羟基苯甲酸酯类

试验建立了QuEChERS净化-气相色谱/三重四极杆质谱仪检测酱油中6种对羟基苯甲酸酯类含量的方法。样品经盐酸酸化、乙腈提取、QuEChERS净化,用气相色谱/三重四极杆质谱仪检测,外标法定量。本方法实验条件下,对羟基苯甲酸酯类在0.02~5.0 mg/L范围内呈良好线性关系,相关系数r2≥0.9991;样品中加标回收率为78.3%~101.3%,相对标准偏差介于1.5%~4.2%,对羟基苯甲酸酯类的检出限为0.01 mg/kg。该方法操作简便,重现性好,且准确度、灵敏度高。

钴改性秸秆生物炭对尼泊金乙酯的吸附研究

以小麦秸秆为原料,通过浸渍法制备改性生物炭,对其采用XRD、SEM进行表征分析,研究钴改性生物炭对尼泊金乙酯(EP)的吸附性能。讨论了改性生物炭的用量、尼泊金乙酯的初始浓度,反应时间及反应温度对EP溶液的吸附影响。实验结果表明:改性生物炭对EP的吸附主要以化学吸附为主;在一定范围内,改性生物炭对EP的吸附效率随生物炭用量的增加而增加;反应温度对改性生物炭吸附EP的影响较大,在EP浓度为30 mg/L、生物炭添加量为5 g/L、温度为45℃条件下吸附4 h时EP最大去除率为95.5%。