反相高效液相色法测定水产品中三聚氰胺

采用反相高效液相色谱法(RP-HPLC) 测定了水产品中的三聚氰胺. 色谱柱为Symmetry C18 (5 μm, 4.6 mm×250 mm), 流动相为含有0.01 mol/L庚烷磺酸钠和0.01 mol/L柠檬酸的乙腈(1+4)水溶液, 检测器为紫外检测器, 检测波长240 nm. 线性范围为1～50 μg/mL, 相关系数为0.9998, 最低检出限为0.24 μg/mL, 样品平均加标回收率为78.8%～96.1%, 相对标准偏差为3.7%～6.4%. 方法可用于水产品中三聚氰胺的测定.     

柱后加碱脉冲积分安培检测-离子色谱法测定水产品中十种生物胺

建立了利用淋洗液自动发生梯度淋洗的离子交换色谱法同时测定水产品中酪胺、5-羟色胺、腐胺、尸胺、组胺、庚二胺、苯乙胺、亚精胺、精胺、色胺等10种生物胺的方法。样品经处理后用Ionpac CS17分离柱和Ionpac CG17型保护柱分离,以EG40自动淋洗液发生器生成的5.0～55 mmol/L的MSA为淋洗液梯度洗脱,脉冲积分安培检测器检测。对梯度进行优化,10种生物胺都能基线分离,并且浓度和峰面积在一定范围内呈良好的线性关系。检出限在0.04 mg/kg以下,回收率在91.2%～102.5%之间,样品的RSD(n=6)小于5%。方法可用于水产品的检测。     

超高效液相色谱-串联质谱法同时测定水产调味品中的罗丹明B、结晶紫和孔雀石绿

1引言罗丹明B常被违法用于调味品的染色,孔雀石绿和结晶紫因具有消毒和杀菌作用而常被违法应用于水产品养殖中。三者结构类似,都具有高毒、高残留和致癌、致畸、致突变等特点,色谱分离较难,且由于食品基质复杂,对质谱检测影响较大。目前,单独检测3种物质的方法分别有高效液相色谱法[1]、气相色谱-质谱法[2]、液相色谱-质谱法[3]和液相色谱-     

微波消化-氢化物原子荧光法测定水产品中的铅

采用微波消化技术溶解水产品,以氢化物－原子荧光法测定铅,讨论并确定了最佳测定条件,结果表明,铅的测定线性范围为0－100ng/mL,方法的相对标准偏差为1．2％－5．3％,回收率为94．8％－103．5％。该方法简便、快速,用于水产品中铅的测定,获得令人满意的结果。     

微波消解石墨炉原子吸收光谱法测定水产品中痕量铍

采用微波制样技术,用石墨炉原子吸收光谱法测定水产品中痕量铍。方法的线性范围为0-10μg·L-1,检出限为0．076 ng·g-1,相对标准偏差为2．7％,回收率为97．0％。方法准确、快速、简便,并与常压消解法的结果比较,基本一致,已用于水产品中痕量铍的测定。     

Trace enrichment of metal ions in aquatic environments by Saccharomyces cerevisiae

Sorption properties of baker’s yeast cells, characterised as Saccharomyces cerevisiae were evaluated for trace enrichment of metal ions: Cd²⁺, Cr³⁺, Cr⁶⁺, Cu²⁺, Pb²⁺ and Zn²⁺ from aqueous environments. Metal concentration was determined by flame atomic absorption spectrometry (FAAS). Parameters affecting metal uptake such as solution pH, incubation time, amount of yeast biomass and effect of glucose concentration (energy source) were optimised. Further studies were carried out to evaluate the effects on metal uptake after treating yeast with glucose as well as with an organic solvent. The results showed that trace enrichment of the metals under study with yeast, depends upon the amount of yeast biomass, pH and incubation time. Treatment of yeast cells with 10-20 mM glucose concentration enhanced metal uptake with exception to Cr⁶⁺, whose metal enrichment capacity decreased at glucose concentration of 60 mM. Of the investigated organic solvents THF and DMSO showed the highest and lowest capacity, respectively, to enhance metal uptake by yeast cells. Trace enrichment of metal ions from stream water, dam water, treated wastewater from a sewage plant and wastewater from an electroplating plant achieved enrichment factors (EF) varying from 1 to 98, without pre-treatment of the sample. pH adjustment further enhanced the EF for all samples. The results from these studies demonstrate that yeast is a viable trace metal enrichment media that can be used freely suspended in solution to achieve very high EF in aquatic environments.     

Evaluation of yeast strains as possible agents for trace enrichment of metal ions in aquatic environments

Sorption properties of six yeast strains were evaluated for trace enrichment of metal ions; Cd²⁺, Cr³⁺, Cr⁶⁺, Cu²⁺, Pb²⁺, and Zn²⁺ from aqueous environments. Metal concentration was determined by flame atomic absorption spectrometry (FAAS). The results showed that trace enrichment of the metals under study with yeast, was dependent on the pH and available metal ions. Enrichment time of 30 min gave an optimum metal uptake. The presence of Na⁺, K⁺, and Ca²⁺ suppressed the uptake of Pb by less than 5%, but suppressed the uptake of Zn by between 15 and 25%. Mg²⁺, Cu⁺, Cu²⁺, Cr³⁺ Cr⁶⁺, Cd²⁺, and Zn²⁺ suppressed the uptake of Pb by between 25 and 35%, and that of Zn by between 15 and 25%. For both Pb and Zn, Cd had the highest suppression of 35 and 30%, respectively for baker's yeast (Saccharomyces cerevisiae). Baker's yeast achieved enrichment factors (EF) of 23, 4, 100, and 1 for dam water, stream water, treated wastewater, and industrial effluent samples for Cu, Pb, Zn, and Cr, respectively. The recoveries of optimised Cd and Cr samples spiked with 2 μg ml⁻¹ of the metal could reach up to 90%, but never exceeded 66% for 10 μg ml⁻¹ samples. For Cu and Pb, the recoveries generally increased independent of concentration, however they were not as high as those for Zn, which exceeded 90% for all the samples spiked with 10 μg ml⁻¹ of the metal. S. cerevisiae PR 61/3 had the highest EF for Cr as compared to the other yeast strains. S. cerevisiae PRI 60/78 was the only yeast strain which was able to enrich Cd in all the samples. Baker's yeast had the highest EFs for Cu and Zn as compared to the other yeast strains without pH adjustment of the water samples. Candida tropicalis attained the highest EFs for Pb as compared to the other yeast strains. The results indicate that all the yeast strains used had a high affinity for Zn based on the EF values achieved. The results from these studies demonstrate that yeast is a viable trace metal enrichment agent that can be used freely suspended in solution to enrich metal ions at relatively low concentrations. This has ramifications on the traditional methods of sampling, sample collection, and transportation from remote sampling sites.     

Applicability of the polyphenylene oxide film dosimeter to high UV exposures in aquatic environments

Previous research has proven that the Poly (2,6-dimethyl-1, 4-phenylene oxide) (PPO) dosimeter is capable of receiving both in-air and underwater UV exposures that are significantly greater than those of the more commonly used polysulphone dosimeter, within a range of accuracy close to what would be expected of dosimetric measurements made in-air provided that the necessary calibrations are completed correctly by factoring in different atmospheric column ozone levels, SZA ranges, varying water turbidity and DOM levels. However, there is yet to be an investigation detailing the performance of the PPO dosimeter and its ability to measure UV in an actual field environment over an extended period of time. This research aims to bridge this gap in the knowledge by presenting a measurement campaign carried out in two real world aquatic environments and a simulated sea water environment using a batch of PPO dosimeters set at different depths and aligned to a range of different angles and geographical directions by means of attachment to a custom built dosimeter submersible float (DSF) unit over the space of a year at a sub-tropical location. Results obtained from this measurement campaign were used to compute a K_d value for the sea water in each particular season. These K_d values where found to be in close agreement to standalone K_d values derived from results taken using a standard calibrated spectrometer in the same sea water.     

Modeling a swimming fish with an initial boundary value problem: Unsteady maneuvers of an elastic plate with internal force generation

In order to model unsteady maneuvers in swimming fish, we develop an initial-boundary value problem for a fourth-order hyperbolic partial differential equation in which the fish's body is treated as an inhomogeneous elastic plate. The model is derived from the three-dimensional equations of elastic dynamics, and is essentially a simple variant of the classical Kirchhoff model for a dynamic plate. The model incorporates body forces generating moment to simulate muscle force generation in fish. The initial-boundary value problem is reduced to a beam model in one spatial dimension and formulated computationally using finite differences. Interaction with the surrounding water is represented by nonlinear viscous damping. Two example applications using simple but physically reasonable physiological parameters are presented and interpreted. One models the acceleration from rest to steady swimming, the other a rapid turn from rest.     

高效液相色谱-串联质谱内标法同时测定水产品中15种喹酮类药物残留量

建立了水产品中15种喹诺酮类药物(QNs)残留量的高效液相色谱-串联质谱(HPLC-MS/MS)测定方法。以氘代试剂为内标,样品经酸性乙腈萃取后,用正己烷脱脂,旋转蒸发浓缩,采用HPLC-MS/MS选择反应监测(SRM)正离子模式测定,内标法定量。可同时对水产品中的15种QNs进行定性和定量测定。15种QNs的检出限(S/N=3)为1.0μg/kg,定量限(S/N=10)为2.0μg/kg;在10.0～200.0ng/mL时峰强度与质量浓度的线性关系良好(r0.99)。方法的平均回收率范围为66%～121%。该法简便快捷,分析成本低,在一定程度上实现了药物残留的快速检测。