杀虫剂雾滴分类及其测量

杀虫剂雾滴分类及其测量河北省卫生防疫站（保定，０７１０００）亢秀敏喷雾器械是害虫防制技术的重要组成部分，优良的喷雾器械能使杀虫剂有最佳的雾滴直径，而雾滴直径与杀虫效果的关系已有定论［２，７．１０］．因此，准确、快速地测量雾滴大小及其分布，是研制，试验...     

高压喷雾技术的初步试验

1雾 雾是一些悬浮在气体(通常指空气)中的小水滴,根据其液滴的大小不同,不同类型的雾具有不同的特点.因而,通常使用术语来定量地描述雾.雾滴大小是以其直径分布范围来划分的,通常的单位是μm,其雾滴划分(表1).     

气相色谱法测定作业场所空气中氢化三联苯

目的:建立作业场所空气中氢化三联苯的采样和测定方法。方法:用活性碳管采样,气相色谱仪测定。结果:方法的检出限为0.3μg/m l,当标准溶液浓度为1~20μg/m l时,相对标准偏差为5.0%~1.4%,相关系数为0.999。测定范围为1~30μg/m l。活性碳管解吸效率为85%~92%。样品在采样管中能稳定7 d。结论:测定的各项指标均符合"作业场所空气中有毒物质监测研究规范"和劳动卫生检测的要求。     

气相色谱—质谱法分析环境空气中甲醇和丙酮

目的建立环境空气中甲醇、丙酮的气相色谱—质谱测定方法。方法环境空气中的甲醇和丙酮经硅胶管采样,甲苯溶剂解吸后,用气相色谱—质谱法分析。采用选择离子扫描方式检测,用甲醇、丙酮的保留时间和特征离子定性,外标法峰面积定量。结果甲醇和丙酮的方法检出限分别为1.2×10-4μg和7.3×10-5μg,测定下限分别为4.0×10-4μg和2.5×10-4μg。按采样体积5 L计,甲醇和丙酮的测量浓度范围分别为0.08 mg/m3~10.0 mg/m3和0.05 mg/m3~10.0 mg/m3,方法的相对标准偏差分别为1.3%~4.2%和1.1%~3.2%,加标回收率分别为91.8%~102.7%和85.3%~100.7%。结论本方法采样方便,测定灵敏、准确,可用于环境空气中甲醇和丙酮的测定。     

工作场所空气中铁的火焰原子吸收光谱测定方法

研究工作场所空气中铁的测定方法。用空气采样器采集粉尘样品,以硝酸和高氯酸为消解液,在280℃消化温度下处理样品,以火焰原子吸收光谱法测定样品的元素铁。结果显示,呼吸性粉尘样品组线性范围为0~2.0μg/ml,相关系数r=0.9993;总粉尘组线性范围为0~16.0μg/ml,相关系数r=0.9988。检出限为0.0267μg/ml,批内精密度测定相对标准偏差为0.472%~1.403%,批间精密度测定相对标准偏差为1.054%~3.588%,加标回收率为98.68%~104.04%。采样效率为95.88%~99.25%。此外,现场采集呼吸性粉尘样品测定,空气中铁的浓度平均为0.057mg/m3;而总粉尘样品测定,空气铁的浓度要高得多,平均浓度3.20mg/m3。该方法简便、快速、灵敏度高,测定结果准确可靠,有较高的实用价值。文章还讨论了采集样品的问题。     

工作场所空气中二甲基甲酰胺和二甲基乙酰胺的气相色谱测定法

目的建立工作场所空气中二甲基甲酰胺(DMF)和二甲基乙酰胺(DMA)的硅胶管采集气相色谱测定方法。方法用硅胶管采集空气中DMF和DMA,无水乙醇解吸后气相色谱法测定。结果 DMF线性范围为0.13～133.3mg/m3,DMA线性范围为0.20～133.3mg/m(3以采集1.5L空气计)。DMF和DMA的相关系数分别为0.9996和0.9995,检出限分别为0.2和0.3μg/ml。DMF平均采样效率为100%,DMA平均采样效率为99%,DMF解吸效率为97%、DMA解吸效率为98%,DMF穿透容量大于2.5mg,DMA穿透容量大于2.4mg,样品在室温或冷藏条件均可保存7d。结论该方法采样方便、检测精密度、准确度高、测定范围宽,适用于工作场所空气中DMF和DMA的测定。     

工作场所空气中磷酸的采集及测定

目的建立工作场所空气中磷酸的采集及离子色谱测定方法。方法采用超细玻璃纤维滤膜采集样品,用超纯水超声洗脱,经0.22μm滤膜过滤后直接进样,经阴离子色谱柱分离,电导检测器进行测定。结果该方法在1.4~60μg/ml范围内呈线性关系,相关系数为0.999 7,定量下限为1.4μg/ml,最低定量浓度为0.2 mg/m~3(以采样75 L计),精密度为1.9%~4.2%,平均回收率为99.9%,平均采样效率为100.0%,平均洗脱效率为95.2%。结论方法采样效率高,最低检出浓度低,准确度和精密度高,能满足工作场所空气中磷酸的采集及检测要求。     

液相色谱法测定环境空气中的尼古丁

目的建立环境空气中气态尼古丁的液相色谱测定方法。方法被动式采样采集空气中的气态尼古丁,采样后滤膜经超声提取、溶剂萃取、氮吹后,用流动相溶解、C18反相色谱柱分离、紫外检测器检测,以保留时间定性,峰面积定量。结果检出限及测定下限分别为0.05μg/m3、0.16μg/m3;精密度为0.24%～2.62%;实际样品的加标回收率的范围在82.0%～107.2%;样品密封后,在干燥的室温状态下可以保存11天以上。结果该方法适宜于测定公共场所空气中尼古丁的浓度。     

工作场所空气中四溴化碳吸收液采样气相色谱测定方法的研究

目的:建立工作场所空气中四溴化碳吸收液采样气相色谱测定方法。方法:选用无水乙醇作吸收液采集空气中四溴化碳,以毛细管气相色谱(ECD)测定。结果:空气中四溴化碳浓度在0~20 mg/m3(以采集3 L空气样品计,相当于10 ml无水乙醇吸收液采样管中四溴化碳溶液浓度0~6μg/ml)时,线性关系良好(r=0.9997,n=3),回归方程Y=35520.3X-2966.5;方法的检出限为0.086μg/ml(进样1μl,3倍噪声所相当的量);最低检出浓度为0.29 mg/m3(以采集3.0 L空气样品计);相对标准偏差在0.4%~4.0%之间;采样效率92.7%;四溴化碳乙醇溶液封闭严密,4℃冰箱保存6 d稳定。结论:本方法适用于工作场所空气中四溴化碳的浓度测定。     

空气中亚硝酸盐和硝酸盐的离子色谱测定方法的研究

目的:建立空气中亚硝酸盐和硝酸盐的离子色谱测定方法。方法:本文采用超细玻璃纤维滤纸采集空气中亚硝酸盐和硝酸盐,用蒸馏水洗脱过滤后,经色谱柱分离,电导检测器检测,保留时间定性,峰高或峰面积定量。结果:空气中亚硝酸盐和硝酸盐的线性范围分别为0.5~30.0μg/m l和0.5~30.0μg/m l;相关系数分别为0.9997和0.9992;方法的最低检出限分别为0.5μg/m l和0.5μg/m l;若采集300 L空气进行测定,则最低检出浓度分别为0.017 mg/m3和0.017 mg/m3;相对标准偏差分别为0.39%~1.03%和0.45%~1.00%;样品洗脱效率分别为100.4%~103.2%和102.3%~106.8%;采样效率分别为94.8%~100.0%和92.7%~94.6%;样品在室温中至少可保存1周。结论:此法灵敏度高,选择性好,干扰少,是同时检测空气中亚硝酸盐和硝酸盐的好方法。     

Influence of certain dietary fibers on serum and tissue cholesterol levels in rats.

Pectin, carragheenan, agar gum arabic, cellulose and wheat bran were each fed to rats at a level of 5 to 7% to examine their effect on serum, liver and tissue cholesterol levels. Diets (casein-sucrose diet containing 10-15% soybean oil, or skim milk-wheat flour diet containing 10-15% soybean oil) supplemented with either 0, 0.2, or 0.5% cholesterol were used to test the possibly dietary interactions. Among the fibers tested, pectin displayed the most hypocholesterolemic effect. In some experiments, pectin lowered the level of cholesterol in the serum, liver, and aorta, but it elevated body cholesterol levels. Carragheenan was inconsistent in lowering serum cholesterol levels and tended to increase liver and carcass cholesterol levels. These results probably suggest that pectin and carragheenan can affect the distribution of cholesterol within the body. Gum arabic and agar did not lower serum cholesterol levels and in one case gum arabic elevated them. Furthermore, in some experiments they elevated liver body cholesterol levels. It appears that feeding of gum arabic and agar probably resulted in an expansion of the whole body cholesterol pool. Feeding of wheat bran or cellulose had no significant effect on either serum or liver cholesterol levels. The study indicates that the effect of dietary fiber is dependent on the composition of the diet. Furthermore, while some fibers such as pectin may exhibit a hypocholesterolemic effect in rats, other fibers such as gum arabic and agar may actually elevate serum or tissue cholesterol levels.     

A change in human faecal flora in response to inclusion of gum arabic in the diet

1. Gum arabic is a water-soluble polysaccharide resistant to human gut enzymes and thus can be described as dietary fibre. 2. Using a most-probable-number technique, estimates were made of total anaerobes and of gum-arabic fermenters in the faeces of a volunteer during a control period and during addition of 10 g gum arabic/d to the diet. Using an enrichment technique, the principal bacteria able to utilize gum arabic as the only carbohydrate source were isolated and characterized. 3. Faecal samples were analysed for undegraded gum arabic and, following acid-hydrolysis, for total sugars. 4. The proportion of the faecal flora able to degrade the gum arabic polymer rose from an initial level of 6.5% to more than 50% during gum-arabic ingestion, and subsequently returned to the control level after ingestion ceased. The principal gum-arabic fermenters were species of Bacteroides and Bifidobacterium. 5. Undegraded gum arabic was not detected in any faecal sample nor were there significant differences in the level of total sugars in acid-hydrolysed faeces between gum arabic and control periods. 6. The results presented indicate a direct and rapid change in faecal flora in response to a specific change in the diet of a human volunteer.     

An experimental design to study colonic fibre fermentation in the rat: the duration of feeding

1. The time-course of metabolic adaptation by rats to diets containing either wheat bran or gum arabic was studied during a 12-week period. 2. Stool weight was increased with wheat bran but not with gum arabic, and had stabilized after 4 weeks. 3. Bacterial mass as measured by diaminopimelic acid content had stabilized by week 4. Bacterial mass increased on feeding gum arabic but was unchanged with wheat bran. 4. There was increased caecal short-chain fatty acid, hydrogen and methane production with gum arabic but not with wheat bran. The change in caecal metabolic activity was slow to stabilize (8-12 weeks at least). 5. The faecal excretion of bile acids increased twofold with the wheat-bran-supplemented diet compared with the gum-arabic-supplemented and unsupplemented diets. Relatively greater amounts of muricholic acids were present in the caeca and faeces of gum-arabic-fed rats compared with the other groups.     

Fluctuating asymmetry and exposure to pyrethroid insecticides in Triatoma infestans populations in northeastern Argentina

Fluctuating asymmetry (FA), a phenotypic marker used as indicator of developmental stress or instability, is sometimes associated with insecticide application and resistance. Here we investigated the occurrence and amount of wing size and wing shape FA in Triatoma infestans females and males collected before and 4 months after a community-wide pyrethroid spraying campaign in a well-defined rural area of Pampa del Indio, Argentina. Moderate levels of pyrethroid resistance were previously confirmed for this area, and postspraying house infestation was mainly attributed to this condition. In the absence of insecticide-based selective pressures over the previous 12 years, we hypothesized that 1- if postspraying triatomines were mostly survivors to insecticide spraying (pyrethroid resistant), they would have higher levels of FA than prespraying triatomines. 2- if postspraying triatomines have a selective advantage, they would have lower FA levels than their prespraying counterparts, whereas if postspraying infestation was positively associated with immigrants not exposed to the insecticide, prespraying and postspraying triatomines would display similar FA levels. For 243 adult T. infestans collected at identified sites before insecticide spraying and 112 collected 4 months postspraying, wing size and wing shape asymmetry was estimated from landmark configurations of left and right sides of each individual. At population level, wing size and shape FA significantly decreased in both females and males after spraying. Males displayed greater wing size and shape FA than females. However, at a single peridomestic site that was persistently infested after spraying, FA declined similarly in females whereas the reverse pattern occurred in males. Our results suggest differential survival of adults with more symmetric wings. This pattern may be related to a selective advantage of survivors to insecticide spraying, which may be mediated or not by their pyrethroid-resistant status or to lower triatomine densities after insecticide spraying and the concomitant increase in feeding success.     

Gum arabic establishes prebiotic functionality in healthy human volunteers in a dose-dependent manner

The present study was undertaken to determine the prebiotic efficacy of gum arabic upon consumption by man for up to 4 weeks and, if any, to establish the dose-effect relationship. Human healthy volunteers consumed various daily doses (5, 10, 20, 40 g) of gum arabic (EmulGold) in water for up to 4 weeks. Daily consumption of water was taken as the negative control and that of 10 g inulin as the positive control. At 0, 1, 2 and 4 weeks quantification of bacterial numbers in stool samples was performed via real time-PCR techniques and questionnaires were filled in to account for potential drawbacks. The genera of Bifidobacteria and Lactobacilli were taken as potentially beneficial bacteria and those of Bacteroides, Clostridium difficile and Enterococci as potentially non-beneficial, this distinction was dependent on the issue of these numbers being or becoming out of balance in the host. Compared with the negative control the numbers of Bifidobacteria and Lactobacilli 4 weeks after consumption were significantly higher for gum arabic: the optimal dose being around 10 g. Moreover, at this dose the numbers of Bifidobacteria, Lactobacilli and Bacteroides were significantly higher for gum arabic than for inulin. No significant drawback was encountered during the study. It is concluded that gum arabic establishes prebiotic efficacy, at least as good as inulin. The optimal daily dose was found to be 10 g.     

Evaluation of certain food additives. Seventy-first report of the Joint FAO/WHO Expert Committee on Food Additives

This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, with a view to recommending acceptable daily intakes (ADIs) and to preparing specifications for identity and purity. The first part of the report contains a general discussion of the principles governing the toxicological evaluation and assessment of intake of food additives. A summary follows of the Committee's evaluations of technical, toxicological and intake data for certain food additives: branching glycosyltransferase from Rhodothermus obamensis expressed in Bacillus subtilis, cassia gum, cyclamic acid and its salts (dietary exposure assessment), cyclotetraglucose and cyclotetraglucose syrup, ferrous ammonium phosphate, glycerol ester of gum rosin, glycerol ester of tall oil rosin, lycopene from all sources, lycopene extract from tomato, mineral oil (low and medium viscosity) class II and class III, octenyl succinic acid modified gum arabic, sodium hydrogen sulfate and sucrose oligoesters type I and type II. Specifications for the following food additives were revised: diacetyltartaric acid and fatty acid esters of glycerol, ethyl lauroyl arginate, glycerol ester of wood rosin, nisin preparation, nitrous oxide, pectins, starch sodium octenyl succinate, tannic acid, titanium dioxide and triethyl citrate. Annexed to the report are tables summarizing the Committee's recommendations for intakes and toxicological evaluations of the food additives considered.     

The effect of dietary fibre sources on aflatoxicosis in the weanling male rat

1. Two experiments with male weanling rats were conducted in which they received individually and restrictedly either a basal semi-purified diet containing starch as the principal carbohydrate or the same diet to which mixed aflatoxins were added in quantities providing from 0.13 to 0.4 mg aflatoxin B1/kg diet. Various natural ingredients, or semi-purified sources of dietary fibre were substituted for a portion of the starch in the basal diet containing aflatoxin. The diets were fed for 13-14 weeks after which the rats were given ad lib. a commercial rodent diet until they were killed at 109 weeks of age. 2. Two further experiments were conducted in which twenty-four rats in each experiment received the basal diet plus aflatoxin, or diets in which a portion of the starch was replaced by gum arabic or by wheat offal. After 13 or more weeks the absorption, retention and excretion of 14C-labelled aflatoxin B1 was measured in each rat. 3. The addition of gum arabic or wheat bran to the diet decreased the effects of the toxin in the first two experiments, but as measured by several characteristics, only wheat bran provided an effect which persisted during the period when neither it nor the toxin was given. The effects included an apparent reduction in tumour incidence. The change in the content of starch in the basal diet, occurring as a consequence of adding the test ingredients is also considered to be an associated cause of the effects observed. 4. In comparison to starch, wheat offal increased the total 14C in the faeces and the proportion of the total found during the first 48 h after dosing. Rats receiving starch excreted more 14C in their urine and retained more 14C in their livers. The differences between gum arabic and starch were not significant as measured by 14C excretion and retention. Liver size as a proportion of carcass weight was less in rats receiving wheat offal or gum arabic, and rats receiving wheat offal had a lower incidence of fat-loaded hepatocytes. 5. The interaction of dietary toxins, or drugs, with the ingredient composition of diet may affect animal response even when the diets are adequate and similar in nutrient composition. This may be of significance both in drug-safety studies and in animal production.     

Plasma enteroglucagon and small bowel cytokinetics in rats fed soluble nonstarch polysaccharides

The influence of dietary fiber on plasma glucagon and enteroglucagon (EG) and on ileal crypt cell production rate (CCPR) was assessed in the rat. A fiber-free semisynthetic diet and diets containing insoluble cellulose, Na-carboxymethylcellulose (CMC), guar gum, pectin, gum arabic, methylcellulose (MC), and hydroxypropylmethylcellulose (HPMC) at 10 g/100 g were fed for 14 d. Animals given soluble polysaccharides had plasma EG levels significantly higher than animals given insoluble cellulose, but only those fed the most viscous gums showed evidence of increased mucosal cell proliferation in the distal ileum. It was concluded that viscous nonfermentable polysaccharide gums stimulate the release of EG in the rat by slowing the absorption of nutrient, whereas the nonviscous polysaccharide gum arabic, or its breakdown products, probably directly stimulate mucosal endocrine cells. The failure of gum arabic to stimulate CCPR despite increased plasma EG indicated that EG alone is not a sufficient stimulus for increased mucosal cell proliferation.     

Collection and determination of COUNTER (terbufos) insecticide in air

A method has been developed and validated for the personal monitoring of COUNTER, O-O-diethyl-S-[(tert-butylthio)methyl]phosphorodithioate, terbufos, in air. COUNTER insecticide vapor is collected on standard NIOSH-type charcoal tubes at 150 mL/min for an 8-hour sampling period. When COUNTER insecticide exists as a dust as well as a vapor, a sampling train consisting of a mixed cellulose ester filter followed by a standard charcoal tube is used. The collected material in each case is desorbed with toluene and analyzed by gas chromatography using a nitrogen-phosphorus detector. Average collection efficiencies of 91.9% were obtained for the charcoal tube, and filter-tube sampling train systems. The sample generation system, collection medium, and analytical methodology are discussed.     

Evaluation of certain food additives and contaminants

This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, with a view to recommending acceptable daily intakes (ADIs) and to preparing specifications for identity and purity. The Committee also evaluated the risk posed by two food contaminants, with the aim of deriving tolerable intakes where appropriate and advising on risk management options for the purpose of public health protection. The first part of the report contains a general discussion of the principles governing the toxicological evaluation of and assessment of dietary exposure to food additives and contaminants. A summary follows of the Committee's evaluations of technical, toxicological and dietary exposure data for certain food additives (aluminium-containing food additives, Benzoe Tonkinensis, glycerol ester of gum rosin, glycerol ester of tall oil rosin, glycerol ester of wood rosin, octenyl succinic acid modified gum arabic, polydimethyl siloxane, Ponceau 4R, pullulan, pullulanase from Bacillus deromificans expressed in Bacillus licheniformis, Quinoline Yellow and Sunset Yellow FCF) and two food contaminants (cyanogenic glycosides and fumonisins). Specifications for the following food additives were revised: aluminium lakes of colouring matters; beta-apo-8'-carotenal; beta-apo-8'-carotenoic acid ethyl ester; beta-carotene, synthetic; hydroxypropyl methyl cellulose; magnesium silicate, synthetic; modified starches; nitrous oxide; sodium carboxymethyl cellulose; and sucrose monoesters of lauric, palmitic or stearic acid. Annexed to the report are tables summarizing the Committee's recommendations for dietary exposures to and toxicological evaluations of the food additives and contaminants considered.