Dosage polarographique des résidus d'acétate de triphénylétain (Bresten) sur les légumes

Abstract

Nous avons mis au point une méthode de dosage des résidus de Brestan (acétate de triphénylétain) qui restent fixés sur les légumes aprés un traitement anticryptogamique des cultures. Elle consiste á extraire le Brestan au moyen d'un solvant organique, á minéraliser l‵extrait obtenu et é doser polarographiquement l'étain.

Physical basis of atomic absorption spectrometry. II. Influence of temperature gradients on spatial distribution of neutral atoms in the long pathlength cell

“…Thus, the long absorption path, achieved by passing a hydrogen-air flame through a 90 cm long Vycor or an alundum tube, yields, e.g., from 10 to 100 times greater sensitivity for zinc and cadmium than that obtained with conventional devices. Such increases in sensitivity, apparently in direct proportion to the length of the cell (7), suggested a relationship similar to that expressed by the Beer-Lambert law in molecular absorption spectrometry. However, the effect of pathlength and the limit of detection varied considerably for different elements.…”

“…At a distance of about 40 cm, cadmium absorption reaches a maximum and remains constant thereafter, up to 100 cm from the burner. This apparently accounts for the remarkable detection sensitivity for this element in the long pathlength system (7). In contrast, calcium atoms absorb maximally about 3 cm from the burner head but absorption ceases beyond 20 cm.…”

“…Use of long absorption cells in atomic absorption spectrometry remarkably lowers the detection limit for certain elements (7). Thus, the long absorption path, achieved by passing a hydrogen-air flame through a 90 cm long Vycor or an alundum tube, yields, e.g., from 10 to 100 times greater sensitivity for zinc and cadmium than that obtained with conventional devices.…”

“…Burner. The platinum burner is the only component of the present system which differs from that used previously (7).…”

“…It is placed at the entrance of the cell, leaving only a narrow gap (2 mm), and reducing substantially the amount of entrained air (7,6). Flame conditions are controlled easily, permitting studies of atomic absorption along the cell path under stable conditions.…”