Fertilization using sewage sludge in unfertile tropical soils increased wood production in Eucalyptus plantations.

Fertilization of Eucalyptus plantations using sewage sludge on unfertile tropical soils represents an alternative to using mineral N and P fertilizers. A 44-month field experiment was conducted to study the effects of increasing application of sludge, and its interactions with mineral N and P fertilizers, on wood volume. Four rates of sludge (0, 8, 15 and 23 Mg ha-1, dry base), N (0, 47, 95 and 142 kg ha-1) and P (0, 28, 56 and 84 kg ha-1 of P2O5) were combined in a 4 × 4 × 4 factorial scheme in a totally randomized block design. Response surface and age-shift modeling was used to establish an initial recommendation for mineral fertilization of the Eucalyptus plantations treated with sludge and to analyze the implications of increased growth on the duration of the forest cycle in a tropical climate. The results showed that from 8 to 44 months after planting, the sludge application (with or without N and P) yielded a statistically larger wood volume (P < 0.05), compared to application of N and P fertilizers only. The response surface modeling showed the following outcomes: i) application of sludge based on N criterion reduced the need for N and P fertilizers by 100%; and ii) an increase in wood volume by 7% could be achieved, compared to NPK fertilizers only, if 2/3 of the recommended P was applied. The cultivation time to produce 150 m3 ha-1 of wood volume was 45 months for the control and was reduced by two, three, four, or five months, respectively, through application of recommended P, sludge dose, sludge plus one third of P, and sludge plus two thirds of P. On the whole, sewage sludge could represent an excellent unconventional N and P fertilizer source for wood production on unfertile tropical soils.

Determination of mono-, di-, and oligosaccharides by capillary electrophoresis with capacitively coupled contactless conductivity detection.

Saccharides and chitooligosaccharides can be separated in electrophoretic conditions by raising the pH of the medium, which renders the corresponding alcoholate forms. These anionic species can be separated and detected with capacitively coupled contactless conductivity detection as negative peaks because of their low mobilities when compared to the hydroxyl mobility, which is the main co-ion in the background electrolyte. Three methods for different matrixes are presented in this chapter.

Determination of caffeine in coffee products by dynamic complexation with 3,4-dimethoxycinnamate and separation by CZE.

A method based on the formation of pi-complexes with chlorogenate-like species was proposed for the determination of caffeine in regular (nondecaffeinated) and decaffeinated coffee. Both caffeate and 3,4-dimethoxycinnamate were able to transform caffeine--a neutral species in aqueous solutions--into an anionic species. The usage of 3,4-dimethoxycinnamate in the running electrolyte is advantageous, because of its greater chemical stability and the improved resolution of the peaks of caffeine, theobromine, and theophylline. Negative peaks were registered with a capacitively coupled contactless conductivity detector when solutions of these alkylxanthines were analyzed with a BGE composed of 20 mmol/L 3,4-dimethoxycinnamic acid and pH adjusted to 8.5 with Tris. This behavior was expected, because the complex is larger and thus should move slower than the free anion. Caffeine was determined in ground and instant coffee with precision and accuracy that meet Brazilian norms about such products. The LOD was estimated as 33 mg/L, which corresponds to 0.8 and 0.3 mg of caffeine per gram of dry instant coffee and ground coffee, respectively. For the case of decaffeinated coffee, ten times preconcentration with dichloromethane was carried out to allow the quantitation of caffeine, which should not exceed the concentration of 1 mg/g in dry matter.