Confocal Raman microspectroscopy of stratum corneum: a pre-clinical validation study

Skin moisturization is not only important for maintaining skin functional properties but also has great impact on the skin's aesthetic properties. The top layer of the skin, the stratum corneum (SC), plays a key role in protecting and preventing against external aggressions as well as in regulating water flux in and out. Confocal Raman microspectroscopy is the first commercially available technique that provides a non-invasive, in vivo method to determine depth profiles of water concentration in the skin, however, in this case it was applied in an in vitro setting. As the first phase of validating the usefulness of confocal Raman microspectroscopy, we used porcine skin as a surrogate for human skin. Water concentration profiles were obtained using confocal Raman microspectroscopy from isolated pigskin SC and compared with that using the Karl Fischer titration method. The two methods correlated very well with a regression coefficient of 1.07 as well as a correlation coefficient, R(2) = 0.989, which demonstrated the consistency and accuracy of confocal Raman microspectroscopy for water concentration determination. To evaluate the instrument's response to different skin care/cleansing products, a wide range of products were tested to compare their skin moisturization ability. Among those tested were a lotion, commercial soap bar, syndet bar, traditional non-emollient shower gel (water, Sodium Laureth Ether Sulfate (SLES), cocamidopropyl betaine system) and emollient containing shower gel (water, sunflower oil, SLES, cocamidopropyl betaine, glycerin, petrolatum). The results were consistent with what was expected. The water content on skin treated with (A) lotion was significantly higher than the non-treated control; (B) syndet bar-treated skin had a significantly higher water content than soap-based bar-treated sites; (C) non-emollient shower gel washed sites were more moisturized than soap-based bar-treated samples; and (D) emollient shower gel-treated skin was significantly more hydrated than non-emollient shower gel washed skin. The unique and direct quantitative water content information provided by confocal Raman microspectroscopy offers a whole new perspective for fundamental skin moisturization studies and will play an important role in evaluating moisturizing profiles and the hydration potential of products designed for personal care in the cosmetic industry.     

In vivo evaluation in man by two noninvasive methods of the stratum corneum barrier function after physical and chemical modifications

This study investigated the effect of different treatments on skin permeability, in vivo in man, by two noninvasive methods: transepidermal water loss (TEWL) determination measured with an evaporimeter, and Laser Doppler velocimetry (LDV) to measure the lag time before the vasodilatation induced by application of methyl and hexyl nicotinates.
Different treatments were performed on forearms of volunteers: 1. removal of the stratum corneum by stripping, 2. occlusion and hydration of the stratum corneum, 3. application of three surfactants in aqueous solution (Tween 60, sodium dodecyl sulphate and cetyl trimethylammonium bromide).
Increase in TEWL and decrease in lag time before the vasodilating effects of nicotinates measured with LDV after all treatments confirmed the modifications in skin permeability. The variations observed were more or less significant depending on the treatment, the investigative method, and the molecule used for the penetration study. With methyl (hydrophilic) nicotinate, the more TEWL increased, the more lag time decreased. A significant decrease in lag time after hexyl (lipophilic) nicotinate application was observed when there was a very high increase in TEWL. The lipophilic nature of the stratum corneum barrier was confirmed in vivo. Use of these two complementary methods, TEWL and LDV, allows the evaluation in vivo of the effect of different treatments on skin permeability in man.     

基于保留指数原理结合气相色谱-三重四极杆质谱法快速筛查蔬菜中农药残留的方法研究

目的 建立气相色谱-三重四极杆质谱联用法快速筛查蔬菜中农药残留的方法.方法 利用正构烷烃C9-C33标准溶液,结合气相色谱-三重四极杆质谱联用仪及其Smart Database Pesticides数据库建立仪器数据采集方法.选用9种农药为目标物,试样经QuEChERS方法进行萃取净化后,建立质谱多反应监测(multi...     

电感耦合等离子体质谱法测定复配水分保持剂中的18种杂质元素

建立了电感耦合等离子体质谱法测定复配水分保持剂中Cu、Se和Mn等18种杂质元素的检测方法。复配水分保持剂的主要成分为磷酸盐,质谱分析时基体干扰较严重,但经微波消解后,采用以CH4作为反应气的动态反应池模式能较好地消除质谱基体干扰。方法检出限在0.002~0.084μg/g之间,回收率可达82.3%~104.8%。该法在复配水分保持剂多元素同时测定中可获得良好的灵敏度和准确度。      

利用保留时间自动调整功能快速建立土壤中15种有机氯农药气相色谱-串联质谱检测方法

目的 通过保留时间自动调整(automatic adjustment of retention time, AART)功能快速简便建立土壤中有机氯的多级反应检测方法。方法 土壤采用QuEChERS方法去除杂质, 选择Rxi-5sil MS色谱柱 (30 m×0.25 mm, 0.25 μm), 柱箱采用程序升温模式, 分流模式进样, 分流比为20:1, 柱流量为1.00 mL/min, 以多反应监测(multiple reaction monitoring, MRM)扫描模式进行检测, 内标法定量。结果 15种有机氯农药方法检出限(S/N=3)范围为1.5~11.0 μg/kg之间; 定量限(S/N=10)在5.0~36.7 μg/kg之间; 3种水平土壤样品添加浓度回收率在66.50%~114.43%之间, 相对标准偏差在1.25%~16.11%之间。结论 利用AART功能创建的土壤中15种有机氯的多级反应检测方法满足实际检测要求, 创建过程快速、简便, 节约研究人员时间和精力, 方法精密度和准确度均满足要求。     

电感耦合等离子体质谱法测定水产品暂养池用水中的重金属元素

目的 建立电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS)检测水产品暂养池水中常见重金属元素(镉、铬、铅、铜,锌、砷等)含量的分析方法.方法 采用电感耦合等离子体质谱法,通过测量质谱的峰面积来测定试样中元素的浓度.结果 该方法能在3 min...     

Characteristic tryptic peptides and gelling properties of porcine skin gelatin affected by thermal action

Thermal action in extraction process had effects on characteristic tryptic peptides identification and gelling properties of porcine gelatin. SDS-PAGE, HPLC-LTQ/Orbitrap high-resolution mass spectrometry, texture analyser and rheometer were used to evaluate collagen depolymerisation degree, characteristic tryptic peptides and gelling properties of gelatins prepared in various thermal actions. Results showed that with increasing temperature and time, depolymerisation degree enlarged, while gel strength, gelling and melting temperature decreased. Mass spectra showed that 47 and 49 common characteristic tryptic peptides were identified in gelatins extracted at 50 °C and 100 °C with various times, respectively. Moreover, 34 common characteristic tryptic peptides were identified in all gelatin samples. Further comparison between this work and our previous investigations yielded 20 common characteristic tryptic peptides, which stably exist in various thermal actions. These common characteristic tryptic peptides may be very helpful for the accurate authentication of porcine gelatin.     

基于多维非稳态导热乘积法的粮粒热物性测定

采用恒温箱结合黄铜短圆柱试样盒形成恒温边界,保证在被测试样中形成多维度热流。运用非稳态导热乘积法结合参数估计法对粮食颗粒导热系数、比热容等进行反演计算。同时考虑在恒温箱上开孔影响恒温箱效果,以及增加试验操作难度,系统采用ZigBee无线数据采集模块实现信号采集与传输。通过对玉米颗粒及稻谷的热物性参数灵敏度分析,发现比热容灵敏度系数较低,针对此,测算系统首先估算出热导率和热扩散率,再对比热容估计结果进行修正。建立试验测试装置,对包括皖稻121在内的4种粮食进行热物性测算,结果与相关文献吻合,同时利用皖稻121的热物性测算结果,理论计算和数值仿真监测点温升随时间变化情况,结果表明,理论计算温升变化趋势与实测温升较为一致,进一步验证了参数估计值的准确性与可靠性。     

From contact angle titration to chemical force microscopy: a new route to assess the pH-dependent character of the stratum corneum

Despite of its complex multicomponent organization and its compact architecture, the Stratum corneum (SC) is not completely impermeable to substances directly applied on the skin surface. A huge number of works have been dedicated to the understanding of the mechanisms involved in substance permeation by exploring deeper layers than the SC itself. Surprisingly, there is a poor interest in studies relating to interactions which may occur in the near-surface region (i.e. approximately 1 nm depth) of the SC. In this work, equilibrium proton-transfer reactions have been used as probes to define in a fundamental point of view the nature of the SC interactions with its environment. Such titration curves are investigated on 'in vitro' SC (isolated SC from abdominal skin tissue) and on 'in vivo' volar forearm (a sebum poor area). The results are discussed in term of work of adhesion and surface pKa values. Because SC can 'reconstruct' under heating, influence of the temperature on titration curves is investigated and the role of the different components is discussed. Different sigmoidal transitions were observed. Two common pKa values (pKa(1) = 4 and pKa(2) = 11.5) were clearly identified in both cases and associated to an acid-base character. By playing with the temperature of 'in vitro' SC, the 'accessibility' of polar functions was increased, thus refining the results by revealing an amphoteric character with an acid-to-base transition at pH 3.5 and two acid transitions at pH = 6.5 and pH = 11.5. Adhesion forces between an Atomic Force Microscopy (AFM) tip and a single isolated corneocyte through buffered liquid media were also investigated to better understand the role of the individual corneocytes.     

热解吸-电喷雾-原位串联质谱法快速筛查10种蔬菜中214种农药残留

目的 建立热解吸-电喷雾-原位串联质谱法快速筛查蔬菜中214种农药残留的分析方法。方法 蔬菜样品经取样探针刮取后,接入热解析电喷雾离子源,经质谱检测分析。通过比较不同电喷雾溶液和稀释溶剂对仪器检出限的影响,同时探究不同进样方式所产生的溶剂效应从而优化仪器条件,提高检测方法的灵敏度和准确度。结果 以甲醇溶液(甲醇:水=1:1,V:V)为电喷雾溶液,乙腈为稀释溶剂,采用溶剂挥干后的进样方式,建立了214种农药及农药代谢产物数据库。应用建立的筛查方法对市售的100批次蔬菜样品进行筛查分析,筛查出8种农药化合物残留。对检出的目标物采用超高效液相色谱-质谱法定量分析,结果表明,这8种化合物检测结果均为阳性,但均未超过其最大残留限量(maximum residue limit, MRL) 0.2 mg/kg。结论 该方法缩减了前处理时间,兼具了高效、高通量、高灵敏度及低成本等优点,能够为食品安全监管提供有力的技术支撑,保障食品安全和消费者健康。     

电感耦合等离子体质谱法测定白酒中铅的前处理方法

目的探讨不同前处理方法对使用电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS)测定白酒中铅含量检测结果准确性的影响。方法采用直接酸化稀释法、蒸干乙醇酸化稀释法和微波消解法分别对3份白酒样品及质控白酒样品进行前处理,使用10μg/L铋溶液作为在线内标,使用ICP-MS得到标准工作曲线后,测定白酒中的铅含量,并进行回收率实验。结果标准物质和加标回收率情况表明直接酸化稀释法处理的白酒样品铅平均含量偏低一些,但与其他2种方法相比差异不显著(P 0.05)。3种前处理方法对质控样品测定结果都在允许误差范围内。直接酸化稀释法存在一定的基体影响,蒸干乙醇酸化稀释法和微波消解法稳定性更好。结论蒸干乙醇酸化稀释法简化了白酒样品的前处理过程,减少了硝酸的用量,结果可靠,可在今后的检测工作中进行使用。     

热分解-电化学法测定印染废水中的总氮

为解决总氮测量方法(HJ 636—2012)存在的问题,建立了热分解-电化学法并应用于检测印染废水。结果表明,热分解-电化学法的检测范围为0～200.00 mg/L,检出限为0.025 mg/L,测量印染废水水样的相对标准偏差为3.0%～4.1%,加标回收率为98.9%～101.5%。与HJ 636—2012方法比较,热分解-电化学法具有测量简便快捷、干扰因素少、检测范围广和灵敏度高等优点。     

Water content of roasted coffee: impact on grinding behaviour,extraction, and aroma retention

Normal and long time roasting trials were carried out on industrial scale. Different amounts of water were applied during quenching, resulting in water contents in the range of 2.3–8.8 g/100 g wb. Coffees were ground immediately after cooling, and after equilibration times of 6 and 24 h. Particle size distribution of ground coffees, percolation time, and extraction properties were investigated on an espresso coffee machine. Coffees ground after 24 h resting time were subjected to storage trials to determine aroma stability as influenced by water content. Coffees with high moisture content exhibited coarser particles upon grinding, and equilibration time prior to grinding was needed for coffees with high water content to improve grinding results. Coffees with low water content did not exhibit this time dependency prior to grinding. Coffees with low water content were extracted more effectively than high moisture coffees, and percolation was slower. During open and closed storage, evolution of hexanal and sulfides was highly sensitive to water content. However, differences in evolution of other aroma compounds were found during closed storage only, where moisture content had a negative impact on aroma stability of the coffees subjected to investigation.     

微波消解-原子吸收光谱法测定山西老陈醋中微量元素

以山西老陈醋为原料,微波消解法处理样品,采用原子吸收光谱法对Zn、Fe、K、Ca、Mg 5种微量元素含量进行测定。通过混酸体系、混酸体积比、样液与消解液体积比和消解时间单因素试验,利用正交试验确定微波消解处理样品的最佳条件。结果表明,在以HNO3-H2O2为消解试剂的混酸体系中,Zn、Fe、K、Ca四种微量元素最佳消解条件为混酸体积比7∶1,样液与消解液体积比1∶4,消解时间为20 min;微量元素Mg最佳消解条件为混酸体积比7∶1,样液与消解液体积比1∶4,消解时间为25 min,在此条件下,测得样品回收率在95.0%～106.0%,精密度试验结果相对标准偏差为0.42%～1.13%。优化后的微波消解法具有反应快、消解彻底、精密度好、准确度高等特点,为进一步研究和分析山西老陈醋的营养价值提供参考。     

Analysis of thermal properties of multilayered fabrics by full factorial and Taguchi method

The present paper reports the thermal and evaporative resistances of multilayered fabric ensembles meant for cold weather conditions. A three-layered structure was used to simulate the multilayered fabric ensemble. Knitted, through air-bonded nonwoven and coated fabrics were used as inner, middle and outer layer fabrics, respectively. Inner and middle layer fabrics were varied in mass per unit area in three different levels. Three different coated fabrics, namely, polyester polymer-coated fabric and two different polytetrafluoroethylene-coated fabrics which vary in pore size and porosity were used in outer layer. Taguchi’s L₉ orthogonal array, meant for three variables and three levels were used to form nine different multilayered fabric ensembles. Signal to noise ratio was studied to predict and optimize the thermal properties of multilayered fabric ensembles. Full factorial design was used to study the effectiveness of predicting thermal properties of multilayered fabrics using Taguchi’s approach. Regression equations were developed and contour plots were drawn to analyse the effect of chosen parameters on thermal properties of fabrics. In both the methods, the percentage contributions of each factor for thermal and evaporative resistances of multilayered fabrics were studied using sum of squares method. It was found that the Taguchi’s method reduces the number of experiments significantly and predicts the thermal properties of multilayered fabrics with good prediction performance. Mass per unit area of inner layer was found to have no significant effect on thermal and evaporative resistances of multilayered fabric ensembles. Mass per unit area of through air-bonded nonwoven fabric was found to be the most significant parameter in determining the thermal resistance of multilayered fabrics. Mass per unit area of middle layer and pore size of coated fabrics were found to contribute almost equal level in deciding the evaporative resistance of multilayered fabrics.     

QuEChERS-高效液相色谱-串联质谱法快速测定鸡肉中氟虫腈及其代谢物

建立一种QuEChERS-高效液相色谱-串联质谱法,快速测定鸡肉中氟虫腈及其3种代谢产物(氟甲腈、氟虫腈砜及氟虫腈亚砜)的方法。鸡肉样品经乙腈分散,DisQuE提取管提取和DisQuE净化管净化后,采用液相色谱-串联质谱定量测定,选择性多反应监测模式检测。在0.5~20ng/mL线性范围内,氟虫腈及其代谢产物的回归方程均呈良好的线性关系,R2>0.999,在添加水平为1.0、5.0、10.0μg/kg时,平均回收率为75.2%~89.9%,相对标准偏差(RSD)为0.8%~9.2%,方法检出限为0.5μg/kg,定量限为1.0μg/kg。该方法简便快捷,灵敏度和准确度均较高,精密度较好,适用于鸡肉中氟虫腈及其代谢产物残留量的检测。     

超高效液相色谱-串联质谱法同时测定罗非鱼养殖淡水中的9种喹诺酮类药物含量

目的建立超高效液相色谱-串联质谱联用法(ultraperformanceliquidchromatography-tandemmass spectrometry, UPLC-MS/MS)测定罗非鱼养殖淡水中9种喹诺酮类药物的分析方法。方法探究优化色谱条件、固相萃取柱条件、洗脱液比例和体积等对回收率产生影响的主要因素。样液制成0.1 mol/L Na2EDTA-Mcllvaine缓冲溶液后调节pH为4.0、采用聚合物固相萃取柱进行净化,吹干浓缩、溶解过滤后,经乙腈和乙酸铵-甲酸水溶液梯度洗脱、色谱柱Poroshell 120 EC-C18(50 mm×2.1 mm, 2.7μm)分离、超高效液相色谱-串联质谱仪测定, 8种化合物内标法定量, 1种化合物外标法定量。结果 9种目标物的检出限为0.02～0.2 ng/L,平均回收率为80.1%～110.3%,相对标准偏差(relative standard deviation, RSD)均小于10%。结论本方法经济、简便、稳定、准确性高,能满足实际罗非鱼养殖淡水中9种喹诺酮类药物含量测定的要求。