An automatic apparatus for determining the crystallisation temperature of liquid pesticide formulations

The report describes an automatic apparatus for determining the crystallisation temperature of liquid pesticide formulations. The results obtained correspond to those obtained by the traditional method of WHO.     

Stability of emulsifiable concentrate pesticide formulations in liquid fertilizers

The stability of some diluted emulsifiable concentrate formulations in clear liquid fertilizers, as affected by the nature and concentration of the salt solutions, was checked by a static test. The time-induced changes in the concentration of the dispersed phase were estimated by visual observations and turbidity measurements. For each formulation a specific relationship between the electrical conductivity of all the fertilizer solutions and the emulsion stability was found. This was valid for a pH range between 4.6–6.3; in alkaline conditions the emulsion stability was relatively lower. A critical electrical conductivity range, above which irreversible destabilization occurred, was observed for each formulation: 100-120 dS m^?1 for fenamiphos, 60-70 dS m^?1 for metolachlor, 30-50 dS m^?1 for chlorpyrifos, and about 45 dS m^?1 for S-ethyl dipropylthiocarbamate (EPTC). The correlation observed between the emulsion stability and the electrical conductivity could be used in a simple and rapid qualitative test to estimate the physical compatibility between emulsifiable concentrate formulations and liquid fertilizers.     

A gravimetric method for determining the relative volatilities of non-aqueous pesticide formulations and spray diluents

A simple gravimetric method was developed for determining the relative volatilities of non-aqueous pesticide formulations and spray diluents, and was compared with the droplet method. The technique involved evaporation of a liquid film from a filter paper surface, and provided greater precision than the droplet method. With both methods, the percentage of mass or volume remaining at time t followed an exponential decay curve, and the coefficients of the equations showed a good correlation between the two methods. The rates of evaporation were consistently lower in the gravimetric method than in the droplet method, and because of this, subtle differences in the relative volatilities of different formulations could be identified by the gravimetric method but not by the droplet method.     

液体农药制剂中烷基酚及其聚氧乙烯醚类助剂的高效液相色谱分析

建立了一种测定6类液体农药制剂中烷基酚（alkylphenols,APs）及其聚氧乙烯醚类（alkylphenol ethoxylates,APEOs）助剂的高效液相色谱-荧光分析方法。乳油、水剂、水乳剂、悬浮剂、可溶液剂和微乳剂样品均经甲醇超声辅助提取,稀释后过聚丙烯膜,采用Poroshell 120 EC-C18（4.6 mm×100 mm,2.7 μm）分离,V（甲醇）:V（乙腈）:V（水）=75.5:6.5:18.0三元流动相等度洗脱,荧光检测器检测,外标法定量。结果表明:在0.05~10或0.1~20 mg/L范围内,APs和APEOs的峰面积与其质量浓度间呈良好线性关系（R2均大于0.999 8）;在添加水平范围内（APs:0.5、2、5 mg/g;APEOs:1、5、25、50 mg/g）,6类液体农药剂型中APs和APEOs的平均回收率为73%~110%,相对标准偏差为0.6%~14.9%,方法的定量限在0.5~1 mg/g。该方法简单、快速、准确,适用于不同液体农药制剂中烷基酚及其聚氧乙烯醚类助剂的测定。     

剂型及表面活性剂对农药药液在植物叶片上铺展行为的影响

为研究不同农药剂型及表面活性剂对药液在亲水和疏水植物叶片表面的持留及铺展行为的影响,通过数码显微镜连续摄像的方法,测试了40种药液液滴在棉花(亲水性)和水稻(疏水性)叶片上的持留及铺展行为。选用5%氯虫苯甲酰胺悬浮剂、25%三唑酮可湿性粉剂和20%三唑酮乳油3种不同剂型的农药,以及Silwet 408、NF100和AgroSpred 730 3种不同表面活性剂,配制不同药液,通过注射器产生液滴并用数码显微镜记录液滴在水稻和棉花叶片上的铺展行为。结果表明:农药剂型对药液表面张力影响不显著,但加入不同表面活性剂却对表面张力影响显著,其对降低表面张力影响的显著程度依次为Silwet 408AgroSpred 730NF100;同种表面活性剂对悬浮剂的影响最大,其次是可湿性粉剂,对乳油的影响最小;加入NF100可增加药液液滴在水稻叶片上的持留能力。结合表面张力结果,证明表面张力并非增强药液持留和铺展能力的唯一因素。     

Biodiesel as a carrier for pesticide formulations: a green chemistry approach

Abstract

This article discusses the present status and future scope of biodiesel as a carrier/diluents and alternative source to hazardous volatile organic compounds for liquid pesticide formulations. Development of user and environment-friendly liquid pesticide formulations for sustainable agriculture is the key focus of today’s agrochemical industries. Organic solvents play an important role in ensuring the efficient distribution and delivery of active ingredients (a.i.) during application of liquid pesticide formulations. Presently used petroleum-based solvents have many disadvantages such as low flash points, high volatility, flammability, phytotoxicity, and inhalation problems to users, etc. However, at present it seems that the use of renewable resources, especially plant oils, oils ester (fatty acids alkyl ester) like biodiesel has the capacity to replace the traditional petroleum-based solvents in liquid pesticide formulations with having sustainable characteristics like high flash point, safer storage, transportation and application. Biodiesel which is easily reproducible from waste cooking oil, waste edible oil, animal fat, etc. may be a suitable alternative green solvent for liquid pesticide formulations in the near future.     

Importance of storage stability studies in the development of pesticide formulations

Manufacturers of pesticides must know the shelf life of their products for the most varied storage conditions. Accelerated storage tests at elevated temperatures can never completely substitute long-term tests under practical conditions. Nevertheless, a mathematical evaluation of analysis results can considerably raise the meaningfulness of such accelerated tests since predictions of the anticipated active ingredient decomposition under the many different temperature/time conditions are possible. An example is given to demonstrate that for this purpose only a small number of analytical data are needed. Without the degradation reaction order being determined, a sufficiently accurate estimate of the degradation rate can be made. This is demonstrated by a comparison of calculated and found levels of active ingredient content in a long-term storage test.     

Influence of temperature on physical properties of non-aqueous pesticide formulations and spray diluents: Relevance to u.l.v. applications

The viscosity, surface tension and volatility of a range of ultra-low-volume (ULV) spray diluents and pesticide formulations were measured at 5°C and 20°C. For u.l.v. application of 1.0 to 1.5 litre ha^?1 through conventional boom and nozzle systems or rotary (Micronair) atomisers, it is concluded that the spray medium should have a viscosity of ?30 mPa s at 20°C. The surface tension values covered only a narrow range and showed little temperature dependence. There was no clear optimum and all surface tensions within the range measured would appear to be acceptable for ULV applications. The volatility factor, 1/(A.T_1/2), where A represents the percentage of non-volatile material in the spray mixture and T_1/2, the half-life (minutes) of evaporation, should be <40 times; 10^?5.     

The influence of molasses on the physical properties and sprayability of two pesticide formulations

The effects of molasses on some of the physicochemical properties and on the sprayability of a carbaryl wettable powder (w.p.) and triazophos emulsifiable concentrate (e.c.) were studied in the laboratory and the field. When sprayed in the laboratory on bean leaves, the deposit obtained from either formulation decreased as the percentage of molasses was increased. In an aerial application field trial on cotton, 10% molasses gave a smaller deposit of active ingredient than obtained in the absence of additive, while 20% molasses gave a greater deposit, with either formulation. Molasses had an adverse effect on some properties of the spray mixtures, which resulted in lower deposits when spraying was done at high humidity in the laboratory. This effect was offset when spraying was done at lower humidity in the field, because molasses improved the impaction of droplets by increasing their density and by preventing the complete evaporation of small droplets.     

An economic comparison of pesticide application regimes for processing tomatoes

In a field experiment aimed at the management of pests, diseases and weeds in tomato agroecosystems using a recommended range of pesticide applications compared with lower chemical input systems, the economics of pesticide use on processing tomatoes in Ohio, USA, was evaluated in 1994 and 1995. The pesticide regimes used included: (i) full-spectrum recommended pesticide use, based on a comprehensive pesticide application schedule including insecticides (carbaryl, endosulfan and esfenvalerate), a fungicide (chlorothalonil) and herbicides (trifluralin and paraquat); (ii) insecticides only, based on applications of the same insecticides and doses used in (i); (iii) fungicides and herbicides only, based on applications of the same fungicides and herbicides used in (i); and (iv) control plots, which received no pesticide applications. All of the costs involved in applying pesticides (chemicals, machinery, labor) were recorded for all treatments for the economic analysis. Overall, the fungicide treatments resulted in higher yields than either the control or the insecticides-only regime, and the profits from the full-spectrum pesticide and fungicide & herbicide regimes were greater than those from the insecticide-only regime and controls in 1994. The yields and profits from all pesticide regimes were substantially less in 1995 than in 1994. http://www.phytoparasitica.org posting Dec. 17, 2002.     

液相微萃取技术在农药残留分析中的应用研究进展

液相微萃取技术(LPME)是一种新型的样品前处理方法,具有快速、简单、廉价、选择性强、准确度高、溶剂消耗量少、环境污染小等优点,方便与各种分析仪器联用。其具有多种模式:单滴液相微萃取(SDME)、中空纤维液相微萃取(HF-LPME)、分散液相微萃取(DLLME)、悬浮固化液微萃取(SFODME)、连续流动微萃取(CFME)、直接悬挂液滴微萃取(DSDME)等,具有很好的研究潜力和应用前景。对液相微萃取技术在农药残留分析中的应用研究进展进行了综述。     

Methods for determining the vapour pressure of active ingredients used in crop protection. Part IV. An improved thermogravimetric determination based on evaporation rate

The vapour pressure of thermally stable substances can be determined easily at ambient pressure using the evaporation rate method. It is possible to measure the evaporation by thermogravimetry in the temperature range from 30°C to 800°C. Vapour pressures as low as 10^?10 Pa (10^?12 mbar) can be determined with excellent reproducibility.     

农药药液物理性质对雾滴空间运行规律的影响模拟研究

研究农药雾滴的空间运行规律及其影响因素,对减少飘移、保护环境及助剂开发都有重要意义。选取2%甲氨基阿维菌素苯甲酸盐(简称甲维盐)乳油,采用Euler-Lagrange离散相模型对雾滴空间运行过程进行数值模拟,分析了农药雾滴的空间运行轨迹。结果表明:黏度和表面张力对雾滴空间运行规律的影响主要作用于喷头出口处的雾化过程,雾化过程的结果决定了后续雾滴空间运行的轨迹和飘移率。药液黏度和表面张力越大,出口处大粒径雾滴所占的比例越高,雾滴的平均粒径和空间运行速率相应增大,在空间运行过程中停留时间缩短,飘移率降低。确定了标准条件下黏度和表面张力调控的适宜范围:黏度在0.001~0.01 Pa·s之间,飘移率为18.77%~12.67%;表面张力在0.042~0.060 N/m之间,飘移率为38.93%~24.40%。针对实际场景,提出了调控药液物理性质的具体方案:通过将2%甲维盐乳油的黏度和表面张力分别增大至0.01 Pa·s和0.060 N/m,可以分别将4 m/s和5 m/s风速条件下的飘移率降低18%和43%,从而有效降低了农药雾滴的飘移损失。     

Exposure risk assessment and evaluation of the best management practice for controlling pesticide runoff from paddy fields. Part 2: model simulation for the herbicide pretilachlor

BACKGROUND: Monitoring studies revealed high concentrations of pesticides in the drainage canal of paddy fields. It is important to have a way to predict these concentrations in different management scenarios as an assessment tool. A simulation model for predicting the pesticide concentration in a paddy block (PCPF‐B) was evaluated and then used to assess the effect of water management practices for controlling pesticide runoff from paddy fields. RESULTS: The PCPF‐B model achieved an acceptable performance. The model was applied to a constrained probabilistic approach using the Monte Carlo technique to evaluate the best management practices for reducing runoff of pretilachlor into the canal. The probabilistic model predictions using actual data of pesticide use and hydrological data in the canal showed that the water holding period (WHP) and the excess water storage depth (EWSD) effectively reduced the loss and concentration of pretilachlor from paddy fields to the drainage canal. The WHP also reduced the timespan of pesticide exposure in the drainage canal. CONCLUSIONS: It is recommended that: (1) the WHP be applied for as long as possible, but for at least 7 days, depending on the pesticide and field conditions; (2) an EWSD greater than 2 cm be maintained to store substantial rainfall in order to prevent paddy runoff, especially during the WHP. Copyright © 2010 Society of Chemical Industry     

Exposure risk assessment and evaluation of the best management practice for controlling pesticide runoff from paddy fields. Part 1: Paddy watershed monitoring

Rice pesticide concentrations in surface water along with hydrological balance and water management conditions were investigated in a paddy watershed of about 100 ha at the Sakura river basin in Tsukuba, Japan, for 3 years from April 2002. Monitoring on different hydrological scales ranging from a paddy plot up to a watershed determined the importance of water management associated with rainfall events and the cyclic irrigation for reducing pesticide discharge into aquatic environments. Surface drainage significantly increased as a response to rainfall events greater than about 1.5 cm day(-1). A total of 16 herbicides were detected in the stream water and their peak concentrations mostly occurred from early to mid-May following the pesticide application period. Two water management factors influencing the pesticide runoff from paddy fields were defined: excess water storage capacity (EWSC) and water holding period (WHP). Uncertainty analyses of pesticide discharge from a paddy plot for dymron (daimuron) and imazosulfuron (IMS) were performed using Monte Carlo simulation (MCS) with prescribed probability of rainfall and water management practice from observations over a period of 3 years. Application of an intermittent irrigation scheme with shallow water depth practice and high drainage gate to maintain the EWSC > 2 cm and increasing WHP from the current Japanese Agricultural Chemicals Regulation law of 3-4 days to at least 10 days were recommended for reducing the pesticide runoff from paddy fields in a monsoon region such as in Japan. The combination of good water management in field plots and small-scale water cycling is the best management practice for controlling pesticide discharge from paddy watersheds.     

An assessment of the consequences of the controlled release of pesticides from granular formulations

The value of an analytical approach to the assessment of the advantages resulting from the use of controlled release granular formulations of pesticides is discussed. The methods are illustrated by considering the concentration-time profiles resulting from the application of such formulations to water and to soils. The importance of the particular environment in which these formulations are used and of the dynamic nature of the pest population is emphasised. It is concluded that relatively simple controlled release granular formulations could give improvements in the performance of pesticides compared with conventional formulations but that the practicality of producing such formulations with a sufficiently large range of release rate constants is uncertain. Equally their use under field conditions might be subject to practical difficulties.     

Effects of temperature and humidity on the contact angle of pesticide droplets on rice leaf surfaces

The effects of external factors such as temperature, humidity, pesticide formulation, and pesticide concentration on the contact angle of pesticide droplets on rice leaf surfaces were analyzed. The experiments showed that there were significant differences in the contact angles of droplets on the leaf surfaces under different temperatures and humidity. As the ambient temperature increased, the contact angle first decreased and then increased, reaching a minimum value at 25°C. With a gradual increase in humidity, the contact angle significantly increased and reached a maximum at 100% humidity. Finally, it was concluded that both the formulation and concentration of the pesticide had a significant effect on the contact angle of droplets on rice leaf surfaces. The experiments also illustrated that the effects of the pesticide formulation and concentration on the contact angle were more significant than those of temperature and humidity.     

从农药登记试验看我国施药技术方面的问题

解决我国施药技术落后问题应从植保技术人员自身做起,从田间药效试验入手,进行科学设计,规范试验过程,严格控制喷洒的均匀一致性,减少雾滴分布差异,避免人为误差,确保试验数据的准确可靠。通过发挥田间药效试验的示范作用,引导农民改变错误施药习惯和观念,推动科学合理施药技术的普及。