Summary: The rate of aerobic evolution of 14CO2 from 14C‐glyphosate labelled in the methylphosphonyl carbon, varied 100‐fold within a group of five Hawaiian sugarcane soils. The rate depended inversely on the degree of soil binding, probably associated with the phosphonic acid moiety, and to a less certain extent on soil pH and soil organic matter. After an initial rapid degradation, the rate of 14CO2 evolution in three soils reached a constant at 16–21 days which continued to the 60‐day termination. The other two soils showed a continually decreasing rate throughout. Two soils released over 50% of the labelled carbon in 60 days, a third released 35%, while the remaining soils released 1.2 and 0.8% respectively. Labelled carbon in the soils after 60 days consisted of glyphosate and one metabolite, aminomethyl‐phosphonic acid, with glyphosate predominating in high fixing soils. The 14C could be extracted almost completely with NaOH solution, and remained mainly in solution after acidification.

Atrazine, ametryne, and PCP, all labeled with 14C, were applied to sugarcane and the movement of radioactivity in the plant was followed to determine the fate of their residues. Atrazine-14C and PCP-14C, applied to sugarcane leaf blades, remained at the site of treatment, but with substantial losses of radioactivity. As the leaves naturally abscised, all radioactivity was lost from the plant. applied in nutrient solution to roots of growing plants was absorbed by the roots and did not trans-locate. With time, considerable radioactivity was lost from the roots and solution. Gas chromatography of the root extracts showed that less than 10% of the radioactivity was in the form of PCP. Atrazine-14C and ametryne-14C translocated readily from roots to green leaves with less than 10% of the total recoverable radioactivity in the stalk at any time; radioactive residues were lost from the growing plant as leaves abscised.

Summary. 1. Laboratory methods of evaluating herbicides were developed to determine their relative effectiveness as inhibitors of seed‐germination, seedling growth and juvenile plants under photosynthetic conditions. 2. Chemicals such as dinoseb, PGP and diquat were found to be very toxic to seeds, all of them having an MDso lower than 4 × 10−5 for both radish (Raphanus sativus L.) and Sudan grass (Sorghum sudanense Stapf). 3. Of the chemicals examined, the most toxic to radish seed were dinoseb, PCP, octochlorocyclohexenone, tetrachlorophenol, 2,4‐dinitrophenol, hexachloro‐2,5‐cyclo‐hexadiene‐1‐one and pentabromophenol in that order. Nitrophenols were more toxic to the seeds than the corresponding chloro‐derivatives but pentachloronitrobenzene was inactive. 4. 2,6‐Dichlorobenzonitrile and chlorpropham (CIPC) were found to be especially toxic to Sudan grass seed. 5. 2,4,5‐T, 2,6‐dichlorobenzonitrile and diquat were extremely toxic to germinating cucumber (Cucumis sativus L.) seeds, while the latter two and chlorpropham were very toxic to Sudan grass seedlings. Other herbicides which were quite phytotoxic to plants in this stage are 2,4‐D, 2‐methoxy‐3,6‐dichlorobenzoic acid (cucumber), dinoseb, PGP, EPTC and 2,3,6‐TBA (Sudan grass). 6. Diuron, atrazine, monuron and simazine were found to be quite inactive on the seeds and seedlings tested but extremely phytotoxic to young cucumber plants grown in. the light. Molar concentrations from 10−7 to 10−8, applied only to the roots, were found to be lethal under the conditions employed. Ametryne, prometryne, 2,4,5‐T, JV‐(3,4‐dichlorophenyl)‐N'‐methoxy‐JV'‐methylurea and EPTC were also lethal at this dosage while fenac, 2,4‐D and fenuron were lethal from 10−6 to 10−5 M. 7. In all the tests, 2,4,5‐T was found to be quite effective being especially toxic to germinating cucumber seeds. Evaluation au laboratoire de quelques herbicides Résumé 1. Des méthodes d'évaluation des herbicides au laboratoire ont été créées pour déterminer leur activité comme inhibiteurs de la germination et de la croissance des plantules et des jeunes plantes dans les conditions de la photosynthèse. 2. Des produits tels que le dinoseb, le PCP et le diquat ont été reconnus comme très toxiques pour les semences. Ils présentent tous une DLso inférieure à 4 × 10−5 pour le radis (Raphanus sativus L.) et le Sudan grass (Sorghum sudanense Stapf). 3. De tous les produits examinés, les plus actifs furent, dans l'ordre, le dinoseb, le PCP, l'orthochlorocyclo‐hexanone, le tetrachlorophenol, le 2,4‐dinitrophénol, l'hexachloro2,5‐cyclohexadiène‐l‐one et le pentabromophenol. Les nitrophénols furent plus toxiques pour les semences que les dérivés chlorés correspondants, mais le pentechloronitrobenzène fut inactif. 4. Le 2,6‐dichlorobenzonitrile et le chlorpropham (CIPC) se révélèrent particulièrement toxiques pour les semences de Sudan grass. 5. Le 2,4,5‐T, le 2,6‐dichlorobenzonitrile et le diquat furent extrémement toxiques pour les graines en germination de concombre (Cucumis sativus L.) cependant que les deux dern...

This article details the development of a novel method that overcomes the drawbacks of sandwich ELISA (sELISA) and allows reliable evaluation of simultaneous quantification of the amyloid (Aβ)-peptides, total-Aβ, Aβx-38, Aβx-40, and Aβx-42, in rat brain by optimized sample purification and column-switching liquid chromatographic-tandem mass spectrometry (LC/MS/MS). This method provides accurate analyses of total-Aβ, Aβx-38, Aβx-40, and Aβx-42 with a linear calibration range between 0.05 and 45 ng/mL. Verification for accuracy and precision of biological samples were determined by a standard addition and recovery test, spiked with synthetic Aβ1-38, Aβ1-40, and Aβ1-42 into the rat brain homogenate. This method showed <20% relative error and relative standard deviation, indicating high reproducibility and reliability. The brain concentrations of total-Aβ, Aβx-38, Aβx-40, and Aβx-42 after oral administration of flurbiprofen in rats were measured by this method. Aβx-42 concentrations (4.57 ± 0.69 ng/g) in rats administered flurbiprofen were lower than those in untreated rats (6.48 ± 0.93 ng/g). This was consistent with several reports demonstrating that NSAIDs reduced the generation of Aβ. We report here a method that allows not only the quantification of specific molecular species of Aβ but also simultaneous quantification of total-Aβ, Aβx-38, Aβx-40, and Aβx-42, thus overcoming the drawbacks of sELISA.

No abstract