Determination of total phosphorus and nitrogen in turbid waters by oxidation with alkaline potassium peroxodisulfate and low pressure microwave digestion, autoclave heating or the use of closed vessels in a hot water bath: comparison with Kjeldahl digestion

The evaluation of the use of alkaline peroxodisulfate digestion with low pressure microwave, autoclave or hot water bath heating for the determination of total phosphorus and nitrogen in turbid lake and river waters is described. The efficiency of these digestion procedures were compared to a Kjeldahl digestion procedure with sulphuric acid-potassium sulfate and copper sulfate. The final solution before digestion was 0.045 M in potassium peroxodisulfate and 0.04 M in sodium hydroxide. Procedures were evaluated by the analysis of suspensions of two reference materials, National Institute of Environmental Science, Japan, no. 3 Chlorella and no. 2 pond sediment and natural turbid waters. Best recoveries of phosphorus and nitrogen by microwave heating were obtained when solutions were digested at 95 °C for 40 min. Quantitative recoveries of phosphorus from Chlorella suspensions up to 1000 mg/l were obtained by all three heating procedures, but incomplete recoveries of nitrogen occurred above 20 mg N/l in the digested sample. Good recoveries of phosphorus and nitrogen from suspended sediment suspensions were obtained only from solutions containing <150 mg/l of suspended sediments. Recoveries of phosphorus from phosphorus compounds containing COP and CP bonds added to distilled water were quantitative (94-113%) except for polyphosphates (microwave, 34±8; autoclave, 114±6; water bath, 96±4) and aluminium phosphate (8-23%). Recoveries of nitrogen compounds containing CN bonds added to distilled water were quantitative (94-96%). The analysis of a range of natural turbid water samples by alkaline peroxodisulfate and microwave, autoclave and water bath heating gave similar total phosphorus and nitrogen results. All procedures using alkaline peroxodisulfate underestimate phosphorus concentrations at high suspended sediment concentrations (>150 mg/l) and are only suitable for the analysis of very turbid samples when the turbidity is due to organic matter (algal cells, plant detritus). Underestimation of nitrogen occurs when samples contain more than 20 mg N/l.     

固相萃取-高效液相色谱法测定蔬菜水果中的氨基甲酸酯杀虫剂及其代谢物残留

采用乙腈提取-固相萃取浓缩 高效液相色谱分离 柱后衍生-荧光检测法测定了蔬菜 水果中8种氨基甲酸酯类杀虫剂及其代谢物残留量。采用加标法(添加水平为0.10,0.50mg/kg)测定了氨基甲酸酯杀虫剂及其代谢物的回收率,其平均回收率为70%-120%,相对标准偏差(RSD)小于20%(n=3),最低检出限范围为0.0042-0.0106 mg/kg。该方法的测定结果满足多残留农残的检测要求。     

六味地黄丸的高效液相色谱/电喷雾电离-质谱分析

建立了高效液相色谱/电喷雾电离-质谱定性分析六味地黄丸的方法,通过2级质谱识别了其中的9种化学成分。色谱条件为:Zorbax SB-C18色谱柱;乙腈-水二元高压梯度洗脱;二极管阵列检测器,设定波长254 nm;流速1 mL/min。质谱条件为:Agilent离子阱质谱仪;电喷雾电离(ESI)离子源;负离子检出模式。结果表明,六味地黄丸的总离子流色谱图比紫外色谱图具有更强的特征性,以质谱作为检测器是一种很好的研究中药指纹图谱的方法。     

高效液相色谱法测定丝氨酸:乙醛酸转氨酶的活性

报道了一种用反相高效液相色谱法(HPLC)测定丝氨酸:乙醛酸转氨酶(SGAT,EC2.6.1.45)活性变化的有效方法。将酶初提液与含有L-丝氨酸和乙醛酸的反应体系在30 ℃下反应1 h,反应终止后进行2,4-二硝基氟苯衍生化,通过HPLC测定酶反应前后甘氨酸的衍生化产物量的变化来分析酶的活性。通过流动相组成和浓度梯度的优化,既节省了流动相的用量,也避免了气泡的产生。研究结果表明,该测定方法的准确度和灵敏度比分光光度法和纸色谱分析法高,且简便易行;对于其他转氨酶活性的测定也有一定的参考价值。     

高效液相色谱法拆分盐酸哌醋甲酯的主要代谢产物盐酸哌醋甲酸

首次发展了一种新型快速的采用高效液相色谱直接拆分血液中手性药物盐酸哌醋甲酯(methylphenidate,MPH)的主要代谢产物盐酸哌醋甲酸(ritalinic acid, RA)的方法。实验中采用α1-酸性糖蛋白手性分离柱,以0.4%(体积分数)的醋酸水溶液(含体积分数0.1%的DMOA,pH 3.4)为流动相,成功地对体外试验中RA的含量进行了分析,结果表明在人和狗的血浆中d-MPH的代谢速度明显的快于l-MPH。     

反相高效液相色谱法测定血浆中的辅酶Q10

建立了一种检测血浆中辅酶Q10含量的高效液相色谱法。血浆经甲醇脱脂蛋白后,以正己烷萃取,萃取液依次经硅胶柱净化、C18柱固相萃取,再进行高效液相色谱分析。色谱柱为Hypersil ODS2柱(5 μm,150 mm×4.6 mm i.d.),以异丙醇-甲醇(体积比为45∶55)溶液作流动相,辅酶Q9作内标,检测波长为275 nm。在0.1-50.0 mg/L质量浓度范围内,辅酶Q10与辅酶Q9的峰面积比与相应CoQ10的质量浓度呈良好的线性关系(r2=0.999),血浆中辅酶Q10的检测限为0.03 mg     

反相液相色谱质谱法分离鉴定3,4,6,7,9,10-6H-3,3,6,6-四甲基-9-对硝基苯基吖啶-1,8二酮

应用反相高效液相色谱法，分离和鉴定3，4，6，7，9，10－6H－3，3，6，6－四甲基－9－对硝基苯基吖啶－1，8－二酮（化合物Ⅰ），分离系统包括Zorbax SB C18及苯基柱，紫外检测器检测波长为285nm，等比和线性梯度淋洗，液相色谱－质谱联用和光导二极和列检测系统被用来鉴定主要化合物及其它杂质，此方法可达到分离效果好，灵敏度高。     

高能量密度材料1,3,3-三硝基氮杂环丁烷研究进展

介绍了新型高能量密度材料1，3，3－三硝基氮杂环丁烷（TNAZ）的合成，物理性能，爆轰性能，安全性，热分解机理及其应用研究的进展， 并对其应用前景进行了展望。     

Pressure-induced metastable phase transition in orthoenstatite (MgSiO3) at room temperature: a Raman spectroscopic study

Phase behavior of a synthetic orthoenstatite in a diamond-anvil cell has been studied up to ∼22 GPa by using Raman spectroscopy at room temperature. Under quasi-hydrostatic conditions, orthoenstatite undergoes a reversible phase transformation at an apparent transition pressure of ∼10 GPa for compression and ∼9.5 GPa for decompression. The 3d transition-metal cations, e.g., Fe²⁺ and Ni²⁺, show only a minor effect on the transition pressure within 10 wt% of addition. All the Raman frequencies in both orthoenstatite and its high-pressure phase increase monotonically with increasing pressure. The amount of forward or backward transition is fixed at a given pressure and forms a hysteresis loop in the transition %-pressure plan. The type for the present metastable phase transition is inferred to be of first order and the high-pressure polymorph may be the intermediate between orthoenstatite and the high-pressure clinoenstatite (i.e., the high-P C2/c phase). A mechanism based on Mnyukh's edgewise model of interface motion has been suggested to account for the observed phenomena.     

高效液相色谱-质谱法测定大豆中磺酰脲类除草剂多残留量的研究

建立了高效液相色谱-质谱联用(HPLC-US)选择离子监测(SIR)同时检测大豆中10种磺酰脲类除草剂多残留量的方法。样品经乙腈提取,正己烷液-液分配,弗罗里硅土填充柱净化,然后采用HPLC-ESI( )-MS测定。对液-质分离、样品前处理条件进行了详细的研究和优化。10种磺酰脲类除草剂在25-1000μg/L范围内线性良好,相关系数为0．9996-0．9997。在0．02-1．0mg／kg浓度范围内,平均加标回收率在72．1％-98．8％之间,相对标准偏差为0．90％-7．74％。该方法简便、快速、灵敏,净化效果较好,可同时满足进、出口大豆中多种除草剂残留量的检验工作需要。