两种方法测定地表水总氮结果的探讨

本文使用碱性过硫酸钾消解紫外分光光度法(HJ636-2012)和流动注射-盐酸萘乙二胺分光光度法(HJ668-2013)2种方法对地表水总氮进行对比分析测试,结果显示:流动注射-盐酸萘乙二胺分光光度法测定结果小于碱性过硫酸钾消解紫外分光光度法的测定值。同时对该结果进行了原因分析,为地表水总氮测定方法的选择具有参考价值。     

A novel thermal biosensor based on enzyme reaction for pesticides measurement

A novel thermal biosensor based on enzyme reaction for pesticides detection has been developed. This biosensor is a flow injection analysis system and consists of two channels with enzyme reaction column and identical reference column, which is set for eliminating the unspecific heat, The enzyme reaction takes place in the enzyme reaction column at a constant temperature(40℃) realized by a thermoelectric thermostat. Thermosensor based on the thermoelectric module containing 127 serial BiTe-thermocouples is used to monitor the temperature difference between two effluents from enzyme reaction column and reference column. The ability of this biosensor to detect pesticides is demonstrated by the decreased degree of the hydrolytic heat in two types of thermosensor mode. The hydrolytic reaction is inhibited by 36% at 1mg/L DDVP and 50% at 10mg/L DDVP when cell-typed thermosensor is used. The percent inhibition is 30% at 1mg/L DDVP and 42% at 10mg/L DDVP in tube-typed thermosensor mode. The detection for real sample shows that this biosensor can be used for detection of organophosphate pesticides residue.     

Carbon paste electrode modified with chromium thiopental for the potentiometric flow injection analysis of chromium (III)

A chemically modified carbon paste electrode for chromium (III) based on the formation of ion-association complex of chromium with 5-ethyl-6-oxo-5-pentan-2-yl-sulfanyl-pyrimidin-4-olate (thiopental, THP) as electroactive ion-exchanger (Cr-THP) was prepared and investigated. The electrode has a linear dynamic range of 1.7?×?10^?6–1.3?×?10^?2?mol?L^?1, with a Nernstian slope of 19.6?±?0.5?mV per decade and a detection limit of 9.0?×?10^?7?mol?L^?1. It has a fast response time of <15?s and can be used for at least 7 weeks without any considerable divergence in potential. The proposed sensor revealed good selectivity for Cr(III) over a wide variety of mono-, di-, and trivalent cations and could be used in the pH range of 2.3–6.5. The proposed electrode was used in batch measurements and in flow injection analysis. The Cr-CMCPE was successfully applied for the determination of Cr(III) in real samples (wastewater of hot dip galvanizing unit and alloys). The present electrode was also used as an indicator electrode in potentiometric titration of Cr(III). The results were highly satisfactory.     

流动注射法测定水中挥发酚的研究

水中挥发酚是评价水质污染的一个重要指标。对流动注射方法研究的模块进行设计,通过采用单因素法对实验的参数进行优化,考察了泵速、时间、样品环长度、反应管长度、试剂浓度等对测定结果的影响情况;根据质量控制实验,评价该方法的可靠性。最终得到在O-200μg／L的线性范围内,相关系数r〉O．9999,检出限为0．48μg／L,精密度〈2．47％,相对误差〈1．14％,加标回收率在89．5％～105％之间,均获得了较为满意的结果。与国标法相比,该方法具有更高的灵敏度、重现性和准确度。     

土壤中活性铝的流动注射分析

研究了ECR-CTMAB体系测定土壤中活性铝的流动注射分析。结果表明,该方法具有快速、灵敏的特点,进样频率为60个样/时,检出限为0.05μg/ml。用不同提取液提取各地区土壤中活性铝并进行了测定。     

Comparison of regression coefficient and GIS-based methodologies for regional estimates of forest soil carbon stocks

Estimates of forest soil organic carbon (SOC) have applications in carbon science, soil quality studies, carbon sequestration technologies, and carbon trading. Forest SOC has been modeled using a regression coefficient methodology that applies mean SOC densities (mass/area) to broad forest regions. A higher resolution model is based on an approach that employs a geographic information system (GIS) with soil databases and satellite-derived landcover images. Despite this advancement, the regression approach remains the basis of current state and federal level greenhouse gas inventories. Both approaches are analyzed in detail for Wisconsin forest soils from 1983 to 2001, applying rigorous error-fixing algorithms to soil databases. Resulting SOC stock estimates are 20% larger when determined using the GIS method rather than the regression approach. Average annual rates of increase in SOC stocks are 3.6 and 1.0 million metric tons of carbon per year for the GIS and regression approaches respectively.     

流动注射法测定低浓度挥发酚

在监测饮用水、地表水和地下水时流动注射法测定挥发酚显现出明显的优势.