Direct determination of phosphite in fertilizers by flow-injection amperometry

A sensor based on graphite electrode modified with palladium-platinum-palladium film is proposed for phosphite determination by flow-injection amperometry. The modified electrode was prepared by a sequential cathodic deposition of Pd, Pt and Pd on a graphite electrode from 0.5% m/v PdCl2 + 28% m/v NH4OH and 2% m/v H2PtCl6 + 10% v/v H2SO4 solutions. After suitable conditioning, the electrode showed catalytic activity for phosphite oxidation when 0. 15 V was applied. The proposed system handles approximately 50 samples per hour (0.0.1 - 0.05 mol L-1 Na-2 HPO3; R-2 = 0.9997), consuming ca. 70 mu L of sample per determination. The limit of detection and amperometric sensibility were 5 X 10(-4) mol L-1 and 1.5 mA L mol(-1), respectively. The proposed method was applied to analysis of fertilizer samples without pre-treatment. Results are in agreement with those obtained by spectrophotometry and titrimetry at 95% confidence level and good recoveries (96-109%) of spiked samples were found. Relative standard deviation (n=12) of a 0.01 mol L-1 Na2HPO3 sample was 2%. The useful lifetime of modified electrode was around 220 determinations. For routine purposes it means that this electrode can be continuously used for 5 hours.

Papel de la industria en el crecimiento argentino: conferencia del Dr. Prebisch, Director Principal a cargo de la Secretaría Ejecutiva de la CEPAL, en la Asociación de Industriales Metalúrgicos

Publicado también en: Prebisch, Raúl: Discursos, declaraciones y documentos 1952-1963, Tomo I; y en: Boletín de la Bolsa de Comercio de Buenos Aires, Buenos Aires, v. 52, No 2685, p. 1791-1798, octubre 22 de 1956

Reports of cases in the Supreme Court of Appeals of Virginia.

Some vols. also contain reports of cases in the General Court of Virginia.

OEuvres de Saint-Simon & d'Enfantin : précédées de deux notices historiques et publiées /

Lib. has reprint: Aalen, O. Zeller, 1963-64.

De la réforme parlementaire et de la réforme électorale.

Mode of access: Internet.

Histoire du gouvernement parlementaire en France : 1814-1848 /

Contiene: Vol.1 - Vol.2 - Vol.3 - Vol.4 - Vol.5 - Vol.6 - Vol.7 - Vol.8 - Vol.9 - Vol.10.

Tobogganning on Parnassus /

Poems.

Tobogganning on Parnassus,/

Poems.

Overset,

"First edition.

[Kraus collection of art auction catalogs.

Miscellaneous catalogs of exhibitions held mostly in Paris and issued by various publishers, from the H. P. Kraus collection.

Les études relatives à l'histoire économique de la France au moyen age

Reprint of 1902 edition.

Coup d'oeil sur l'Espagne.

Mode of access: Internet.

Cours supérieur de grammaire ...

--1. ptie. Grammaire proprement dite.--2. ptie. Haute grammaire.

Essai historique sur l'abbaye de Cluny : suivi de pièces justificatives et de divers fragmens de la correspondance de Pierre-le-Vénérable avec saint Bernard /

Mode of access: Internet.

The coffee planter of Saint Domingo : with an appendix, containing a view of the constitution, government, laws, and state of that colony, previous to the year 1789. To which are added, some hints on the present state of the island, under the British government /

"Appendix": 145 p.