Evaluation and confirmation of an alkylation-gas-liquid chromatographic method for the determination of carbamate and urea herbicides in foods

A method is described for the direct analysis of the urea herbicides linuron, monuron, diuron, chlorbromuron, fluometuron, chloroxuron, and fenuron in cabbage, corn, potatoes, turnip, and wheat at 0.01-1.0 ppm. The samples are extracted with acetone; the filtrate is partitioned with hexane-methylene chloride (1+1) followed by 2 other extractions with methylene chloride. The organic phases are dried and concentrated for column chromatographic cleanup on 2% deactivated Florisil. The column fractions are evaporated just to dryness and redissolved in 10 ml isooctane for high-pressure liquid chromatography on a 25 cm silica gel (5 mum) column. Isopropanol in isooctane is the mobile phase, and compounds are measured by ultraviolet absorption at 254 nm. Recoveries are greater than 80% in most cases. These results are confirmed by alkylation with sodium hydride-methyl iodide in dimethyl sulfoxide to form the methyl products which are analyzed by the same chromatographic system or by gas-liquid chromatography.     

X射线荧光光谱法测定萤石中CaF_2含量不确定度的评定

采用X射线荧光光谱法测定萤石中CaF2含量,分析了分析结果不确定度产生的原因,并建立了数学模型。对测量重复性、标准物质、校准曲线回归、检测条件、试样称量和熔剂中杂质引起的不确定度分量进行评定,计算了合成标准不确定度和扩展不确定度,并给出萤石中CaF2含量测定结果的报告。评定结果表明,校准曲线回归引起的不确定度对总不确定度影响最大。所以,在测定中应特别注意校准曲线的校正和绘制校准曲线所用标准样品的选择。     

原子吸收光谱法测定锌精矿中镉不确定度评定

对锌精矿化学分析方法——火焰原子吸收光谱法测定镉量时的不确定度进行评定。根据分析过程,对其不确定度来源进行量化表述,评定原子吸收光谱法测定锌精矿中镉的不确定度。评估出的不确定度范围,适用于评价不同实验室人员或不同实验室之间测定结果的质量。     

重铬酸钾滴定法测定铁矿石中铁含量不确定度的评估和计算

对重铬酸钾滴定法测定铁矿中铁含量的不确定度的产生原因进行了分析 ,并对一个铁矿样品中铁含量测定结果的不确定度进行了评定     

Pneumonitis secondary to the inhalation of isocyanates. An analysis of 2 cases

We present two patients with diffuse interstitial lung disease attributed to two different forms of presentation of pneumonitis due to inhalation of isocyanates. The first case was acute and accidental and the second was due to longer workplace exposure. In both cases, clinical, radiological and lung function findings as well as results of bronchoalveolar lavage were similar to those of hypersensitivity pneumonitis triggered by organic agents.     

Evaluation of amperometric detector for liquid chromatographic determination of 2-phenylphenol residues in orange rind

A modular component liquid chromatograph has been assembled which has on-stream ultraviolet (UV) and amperometric detectors connected to a dual pen recorder. In this method, the commonly used UV detection technique provides a reference for direct comparisons of results from the amperometric detector. The system has been evaluated and applied to the determination of 2-phenylphenol (2PP) fortified in orange rind. The method is not tedious; before liquid chromatographic analysis, the sample is extracted with methylene chloride and cleaned up on a Florisil column. The method is sensitive to less than 1 ppm 2PP fortified in orange rind; there are no electrically oxidizable interference, from control samples, in the chromatographic region of 2PP. Some background interference does appear from the same samples on the UV chromatogram. Thus, amperometric detection is more specific than UV detection for this application.     

Evaluation of an enzyme linked immunosorbent assay (ELISA) for determination of insulin in dogs

Between 1970 and 1983, 345 patients with ovarian cancer clinical stage I, II, and III were irradiated postoperatively. Five-year NED survival was achieved in 41.7% of patients. The most important prognostic factors were histological grade and clinical stage of cancer. Postoperative external beam radiotherapy appeared to be highly efficient for the patients with microscopic residual disease, giving 70% 5-year survival, and moderately efficient for patients with small, i.e. < or = 3 cm in diameter residual disease, giving 40% 5-year survival. The optimal technique of irradiation appeared to be the irradiation given to the entire abdominal cavity with additional irradiation coned down to the pelvis. External beam radiotherapy was ineffective in patients with gross residual disease, i.e. > 3 cm in diameter, and useless as palliative treatment given to patients with inoperable cancer of the ovary.     

原子吸收光谱法测定低合金钢中锰含量的不确定度评定

根据国家标准检验方法 ,结合实验室的日常分析实际情况和具体条件 ,对原子吸收光谱法测定低合金钢中锰含量进行测量不确定度评定。分析并识别不确定度的来源、量化每个不确定度分量 ,并且确定最大不确定度分量为溶液浓度分量 ,从而合成标准不确定度以及形成该方法扩展不确定度的表达 ,为质量控制提供有效、可靠、可溯源的测量数据     

硅铝合金中硫含量测定结果的不确定度评定

采用红外吸收法测定硅铝合金中的微量硫,对硫测定结果的不确定度进行了评估.评估后认为,按此方法测定硫,称量和标液定容不是影响硫测定不确定度的主要因素.     

X射线荧光光谱法测定高铝耐火材料中氧化铝的测量不确定度评定

本文对X射线荧光光谱法(XRF)测定高铝耐火材料中Al2O3的测量不确定度来源进行了详细的分析,对XRF法测定高铝耐火材料中Al2O3结果的测量不确定度进行了仔细的评定,最终给出了扩展不确定度。     

重铬酸钾滴定法测定地质样品中氧化亚铁结果的不确定度评定

对滴定法测定地质样品中氧化亚铁含量的不确定度来源进行了详细分析,对测定过程中的主要不确定度分量进行了合理评定,包括样品和标准物质重铬酸钾的称量引入的不确定度,重铬酸钾的纯度引入的不确定度,容量瓶和滴定管的体积引入的不确定度,相关元素的摩尔质量引入的不确定度以及测量的重复性引入的不确定度。最后合成标准不确定度乘以95%置信概率下的扩展因子2获得测量结果的扩展不确定度。     

红外吸收法测定焦炭中硫的不确定度评定

采用红外吸收法测定焦炭中硫,并对一个焦炭中硫的不确定度进行了评定,给出评定结果,求出测定结果的扩展不确定度。     

硅钼蓝分光光度法测定钢样中硅量的不确定度评定

对硅钼蓝光度法测定钢样中硅量不确定度的产生原因进行了分析,并对一个钢样中硅含量测定结果的不确定度进行了评定。     

Evaluation of alternative methods to prepare porcine adipocytes for measurement with an electronic particle number and size determination apparatus

Experimental investigations with mammalian adipose tissue require a determination of adipocyte number as a basis for expression of metabolic and growth data. Determination of cell size is also important in adipose tissue because the fivefold or greater variation in adipocyte diameter in most growing and adult mammals precludes simple determination of cell number to interpret the biological observations. There are two approaches to determine adipocyte size and number: microscopic methods and electronic particle counter methods. Microscopic methods use embedded sections, frozen sections, or isolated cells, whereas electronic particle number and size instrumental methods use adipocytes released from fixed tissue fragments or adipocytes fixed after isolation. The advantage of the electronic approach is that it evaluates thousands of particles, although the standard fixative, osmium, is quite toxic. Consequently, we evaluated a number of alternative fixation methods to prepare isolated porcine adipocytes for number and size determination by electronic instrumentation. Fixation in 3, 4, or 5% glutaraldehyde or in 4% formaldehyde were not acceptable procedures for porcine adipocytes. The 4% glutaraldehyde fixation procedure was acceptable for isolated rat adipocytes (Stewart and Kaplan, 1993); porcine adipocytes seem to be much more susceptible to breakage using these procedures than rat adipocytes. We also added urea or Triton X-100 to glutaraldehyde- and osmium-fixed cells to decrease clumping and adhesion of individual cells; none of these additions was beneficial. Ability to store samples would improve the logistics for these time-consuming analyses. Samples of osmium-fixed adipocytes were stored in osmium, in .9% NaCl (saline) after removal of osmium, in 8 M urea after osmium removal with saline, or in .01% Triton X-100 after osmium removal with saline. Storage in urea or Triton was inappropriate because of irreversible clumping of individual cells. Storage in osmium was acceptable for at least 30 d. and storage in saline was marginally acceptable. The variability of the size determination process for osmium-fixed adipocytes was evaluated.     

X射线荧光光谱法测定烧结矿中TFe的不确定度评定

采用X射线荧光光谱法测定烧结矿中TFe,应用现代统计学理论对其分析结果不确定度的产生原因进行分析,同时对烧结矿中TFe含量测定结果的不确定度进行了评定,确定了分析结果的置信区间。     

红外吸收法测定钢中硫的不确定度评定

利用EMIA-820V碳硫分析仪测定钢样中的硫含量,从测定过程入手分析不确定度产生的原因,并得出了评定不确定度的简便方法.