液相色谱-原子荧光法测定化妆品中硫柳汞和苯基汞

建立了液相色谱(HPLC)-原子荧光(AFS)联用法测定化妆品中硫柳汞和苯基汞含量的方法。样品经超声提取后高速离心,经0.45μm滤膜过滤,HPLC-AFS测定,保留时间定性,外标法定量。该方法硫柳汞在2.5μg/L～50μg/L、苯基汞在62.5μg/L～1250μg/L呈良好的线性关系(R2≥0.998)。在0.075μg、0.15μg、0.225μg 3个添加浓度水平下硫柳汞的回收率为84.7%～101.7%,在1.875μg、3.750μg、5.625μg 3个添加浓度水平下硫柳汞的回收率为84.1%～103.9%,定性重复性为0.30%～0.33%,定量重复性为4.22%～4.96%,硫柳汞的检出限为0.060μg/L,苯基汞的检出限为0.23μg/L(S/N=3)。该方法成本低,分析速度快,精密度好,检出限低,适用于化妆品中硫柳汞和苯基汞的检测。     

MAE-QuEChERS-GC法测定土壤中4种有机氯农药

建立了微波萃取土壤中艾氏剂、七氯、狄氏剂和异狄氏剂4有机氯农药,结合QuEChERS净化和气相色谱定量的分析方法。样品经丙酮-正己烷(V_(丙酮)∶V_(正己烷)=1∶1)提取,从线性、检出限、定量限和精密度等方面考察了方法的性能。4种有机氯的质量浓度在0.005～0.500μg/L范围内与峰面积呈良好的线性关系,相关系数均≥0.998,方法检出限为0.04～0.07μg/kg,样品加标回收率为90%～101%,测定结果的相对标准偏差为1.60%～5.60%(n=6)。该方法操作方便、快速,结果准确、可靠,试剂用量少,缩短了分析时间,适用于土壤中有机氯的测定。     

溴化衍生-液液萃取-气相色谱法检测水中的丙烯酰胺

在pH=1～2条件下,水中的丙烯酰胺与新生溴发生加成反应,生成衍生产物2,3-二溴丙烯酰胺,经乙酸乙酯液液萃取后,通过气相色谱-一微电子捕获检测器检测.结果表明,2,3-二溴丙烯酰胺的线性范围为1～13μg/L,r=0.9936,检出限为1μg/L.单体丙烯酰胺在0.1、0.2、0.4、0.5、1μg/L水平下,回收率为61.6%～112%,RSD为5%～9.49%.     

流动注射光度法测定蔬菜中的亚硝酸盐和硝酸盐

建立了流动注射光度法测定蔬菜中亚硝酸盐和硝酸盐含量的方法。亚硝酸钠的线性范围为20μg/L～1000μg/L,回归方程Y=0.1230x-0.7984,相关系数R:2=0.9999,方法的检出限为0.17mg/kg,相对标准偏差为3.63%,平均回收率为99.02%;硝酸钠的线性范围为20μg/L～5000μg/L,回归方程Y=0.0476x-0.4274,相关系数R:2=0.9999,方法的检出限为25.31 mg/kg,相对标准偏差为1.26%,平均回收率为94.19%。     

气相色谱-质谱法测定水中5种有机磷农药

建立气相色谱-质谱检测地表水中5种有机磷农药残留量的方法,选择离子扫描模式检测,在10～100μg/L范围内呈现良好的线性关系,相关系数大于0.9997,在10μg/L,20μg/L,30μg/L添加水平下,有机磷农药的加标回收率在97.3%～101.4%之间,方法的检出限为5.0μg/L,该方法灵敏度高,分离效果良好,能有效地消除复杂基质带来的干扰,可以作为地表水中有机磷农药残留量的检测和确证方法。     

荧光胺衍生化液相色谱法检测动物肝脏中10种磺胺残留方法探讨

建立动物肝脏中常见的10种磺胺类药物(磺胺胍、磺胺嘧啶、磺胺二甲嘧啶、磺胺甲氧哒嗪、磺胺间甲氧嘧啶、磺胺-5-甲氧嘧啶、磺胺氯哒嗪、磺胺甲恶唑、磺胺二甲氧嘧啶、磺胺喹恶啉)残留量液相色谱同时测定方法。样品通过溶剂提取净化、荧光胺柱前衍生化,用配有荧光检测器的高效液相色谱仪测定,外标法定量。其线性范围分别为2～200μg/L、4～400μg/L、10～1000μg/L,线性相关系数r>0.999;方法检出限(LOD)为2～10μg/kg;其中9种磺胺,在5～100μg/kg的3个添加水平范围内的平均回收率为70.6%～90.2%;相对标准偏差为4.1%～7.6%。     

气相色谱-质谱法测定动物组织及饲料中克伦特罗

在研究各种分析克伦特罗的方法基础上,建立了合理、可靠、可操作性的气相色谱质谱联用测定克伦特罗的方法。试样用0.1mol/L高氯酸溶液提取,提取液用异丙醇乙酸乙酯(1∶9,体积比)萃取,萃取液浓缩后用SCX离子交换固相小柱净化,φ=3%浓氨水甲醇溶液洗脱、浓缩干,经N,O双三甲基硅基三氟乙酰胺衍生后,进行分析检测。采用选择离子模式检测(m/z86、243、262、277),衍生物的峰面积与样品质量浓度在5.00～1000μg/L呈良好的线性关系,相关系数大于0.999,方法最低检出限达1μg/kg(或1μg/L)。猪肝试样和尿样在1、10和100μg/kg(或μg/L)三水平加标平均回收率分别在73.4%～96.8%和84.4%～92.2%,变异系数在7.0%～16%和6.0%～11%;猪肉和饲料加标平均回收率分别为81.5%和70.6%,变异系数为5.8%和4.5%。     

顶空气相色谱-质谱法测定地表水中的异丙苯

建立了顶空气相色谱-质谱检测地表水中异丙苯残留量的方法,选择性离子扫描模式检测,在10～100μg/L范围内呈现良好的线性关系,相关系数为0.9995,在30和50μg/L添加水平下,异丙苯的加标回收率在97.9%～100.6%之间,方法的检出限为2.0μg/L,该方法灵敏度高,分离效果良好,能有效地消除复杂基质带来的干扰,可以作为地表水中异丙苯残留量的检测和确证方法。     

双道原子荧光法同时测定云母钛珠光颜料中痕量砷和汞

采用混合酸(6mL盐酸,2mL硝酸和5mL氢氟酸)消解云母珠光颜料样品,在消解液中加入硫脲溶液后,以双道原子荧光法同时测定了样品中痕量砷和汞。砷和汞的线性范围分别为0.5～10μg/L和0.1～2.0μg/L,相关系数为0.9993和0.9997,检出限为0.0215μg/L和0.0035μg/L。两个水平加标回收率测试结果为84.4～102.5%。实际样品中砷和汞的含量分别为1.4777mg/kg和0.0162mg/kg,对实际样品平行测定7次,荧光强度的相对标准偏差分别为4.28%和5.84%。两元素同时测定可以提高分析效率,节省化学试剂,测量效果令人满意。     

静态顶空气相色谱-质谱法测定盐酸沃尼妙林中有机溶剂残留量

建立了测定盐酸沃尼妙林中丙酮、乙酸乙酯、甲基叔丁基醚残留的静态顶空气相色谱-质谱联用方法。将样品和参照品溶于水,在顶空瓶中加热进样,对于不同溶剂,该方法的回收率范围为85.38%～110.15%,相对标准偏差为1.98%～3.64%。丙酮、乙酸乙酯、甲基叔丁基醚残留的最低检出限分别为0.02、0.01、0.002μg/g。通过对实际样品的检测,证明该方法简单、灵敏、可靠,适用于盐酸沃尼妙林中有机溶剂残留的分析。     

Freeze-substitution: the addition of water to polar solvents enhances the retention of structure and acts at temperatures around –60°C

High‐pressure freezing followed by freeze substitution and plastic embedding is becoming a more widely used method for TEM sample preparation. Here, we have investigated the influence of solvents, fixative concentrations and water content in the substitution medium on the sample quality of high‐pressure frozen, freeze‐substituted and plastic embedded mammalian cell culture monolayers. We found that the visibility of structural details was optimal with acetone and that extraction increased with both increasing and decreasing solvent polarity. Interestingly, the addition of water to polar solvents increased the sample quality, while being destructive when added to apolar solvents. The positive effect of water addition is saturable in acetone and ethanol at 5%(v/v), but even addition of up to 20% water has no negative effect on the sample structure. Therefore, a medium based on acetone containing fixatives and 5% water is most optimal for the substitution of mammalian cell cultures. In addition, our results suggest that the presence of water is critical for the retention of structure at temperatures around –60°C.     

质子转移反应质谱法测量呼气丙酮的影响因素分析

丙酮是人体呼出气体中含量最高的挥发性有机物之一,它与糖尿病、肺癌等疾病有着一定的关系。本研究通过注射法配制了不同二氧化碳浓度和湿度下的丙酮混合气体,应用质子转移反应质谱（PTR-MS）法对Tedlar采样袋中的丙酮混合气体进行浓度检测,研究二氧化碳浓度、气体湿度、氧气离子浓度和一氧化氮离子浓度等因素对丙酮浓度测量结果的影响,并推导出修正公式。结果表明：二氧化碳浓度和气体湿度的增加不会对丙酮离子的计数值产生明显影响,但会增加水合氢离子团簇离子的含量;氧气离子浓度的增加会提高丙酮碎片离子的含量;一氧化氮离子的测量浓度很低,对丙酮测量结果的影响可以忽略不计;以上各影响因素在使用修正公式后,可以有效地抑制影响,优化实验结果。     

GC/MS研究茶叶中拟除虫菊酯类农药残留的提取方法

针对茶叶中拟除虫菊酯类农药残留的提取方法进行研究,比较了加水浸泡对农残提取的影响。结果表明,加水浸泡的样品农残提取率反而降低,通过对样品净化淋洗剂种类和体积的优化选择,总结出一套简便实用的前处理方法。茶叶不用水浸泡,直接用50 mL V（丙酮）∶V（正己烷） =1∶1的溶液超声提取,提取液过活性炭柱,浓缩后再过Florisil柱,用15 mL V（正己烷）∶V（乙酸乙酯）=2∶1的溶液淋洗,浓缩后用GC/MS法测定。回收率为81%~120%,RSD为2.2%~7.8%,检测限为0.002~0.01 mg•kg^-1。     

测定矿泉水中的氯离子和硫酸根离子

建立用单柱阴离子色谱测定矿泉水中的氯离子和硫酸根离子的方法。采用NJSA-4A阴离子交换柱、0.35mmol/L NaCO_3和0.05mmol/L NaHCO_3混合溶液为流动相、电导检测器在13min内完成矿泉水中Cl~-和SO_4~(2-)的测定。该法具有良好的线性相关性和重复性(相对标准偏差小于1.92%),回收率为96.6%～100.4%。方法简便实用,用于实际样品分析,所得结果令人满意。     

Influence of fluids on the abrasion of silicon by diamond

Silicon wafers ((100) p-type) were abraded at room temperature in the presence of acetone, absolute ethanol and water by a pyramid diamond, and the resulting groove depth was measured as a function of the normal force on the diamond and the adsorbed fluids, all other experimental conditions being held constant. The rates of increase in groove depth (the depths of the groove(s)) are in the ratio 1:2:3 for water, absolute ethanol and acetone respectively for a constant normal force. The groove depth rate is lower when the normal force is decreased. The abraded surfaces were examined by scanning electron microscopy. At a constant normal force, the silicon abraded in the presence of water was chipped, as expected for a classical brittle material, while the surfaces abraded in the other two fluids showed ductile ploughing as the main mechanism for silicon removal.     

Application of ring method to measure surface tensions of liquids in high magnetic field

The high-magnetic-field tensiometer (HMFT) has been developed to measure surface tensions of liquids in high magnetic field based on the ring method. The HMFT was composed of three parts: weighing system, liquid circulatory system, and supporting system. Some improvements for the conventional tensiometer were made in order to overcome the magnetic effects. The surface tension of acetone was measured using the HMFT. The results showed that the surface tension of acetone linearly varied with the magnetic field intensity and increased by 0.69 mN m(-1) or 2.9% in the magnetic field of 10 T. The HMFT could better determine the surface tension of liquids with and without the magnetic field and it provided a simple and practical way to measure the surface tension of liquids at room temperature in a high magnetic field.     

MEASUREMENT OF RADIATION INDUCED LOCALIZED ABSORPTION IN CHROMATOGRAPHIC ELUENTS BY MEANS OF THE CO LASER AND THE PZT PYROELECTRIC DETECTOR

Abstract

Combined use of the CO laser and PZT piezoelectric detector is proposed as a sensitive and specific detector for gas chromatography. The feasibility of this detection scheme is demonstrated for a model mixture containing varying proportions of acetone in water. After separation on a GC column, spectra of both constituents were recorded in the 1600 cm^?1 to 1900 cm^?1 range that encompasses the characteristic frequency of C=O bond in acetone. Reasonably high sensitivity (mass concentration limit is 1.2x10^?8 g acetone) and a good degree (factor 530) of spectral discrimination was achieved by a proper selection of analytical wavelengths.     

Note: characterization of CaF2/acetone bandpass photon detector with Kr filter gas

A modified design of a CaF(2)/acetone bandpass photon detector that uses Kr as a filter gas to tune the energy resolution is presented. Our design combines two standard single window detector tubes to build the Kr filter gas chamber. Synchrotron radiation has been used to determine the energy resolution of the detector, as a function of Kr pressure. The improvement in the detector energy resolution by 250 meV compared to the CaF(2)/acetone detector is better than that reported earlier. Substantial variation in the shape of the CaF(2)/acetone detector response functions is observed for different acetone pressure (≤3 mbar), and anode voltage (≤800 V). Our analysis reveals that the changes in the shape of the detector response function are associated to different regions of the detector operation.     

甲基化处理气相色谱-质谱法同时检测大米中12种酸性除草剂

实验采用丙酮酸性水溶液(150∶20,体积比)提取试样中农药残留物,提取液用乙酸乙酯液液分配、凝胶渗透色谱仪(GPC)净化后,用重氮甲烷乙醚溶液衍生化,用气相色谱-质谱(GC/MS)选择离子监测模式(SIM)内标法(IS)测定,分离色谱柱为DB-5MS。10种农药的回收率≥80%;相对标准偏差≤10%;最低检测限0.01~0.05 mg/kg。