Judul: Potensi metode penambahan standar titik-H untuk penentuan simultan kromium (III) dan kromium (VI):
Abstrak: Metode penambahan standar titik-H (HPSAM) telah dicoba untuk penentuan simultan Cr(III) dan Cr(VI). Campuran pereaksi kromogenik dari 2- hidroksibenzaldiminoglisina (HBIG) dan kuersetin dalam larutan miselar setiltrimetilamonium bromida digunakan untuk penentuan simultan kedua ion di atas. Metode yang digunakan didasarkan pada perbedaan absorbans dari kompleks yang terbentuk yaitu Cr(VI)-kuersetin pada dua panjang gelombang yang berbeda (558 dan 577 nm) dengan absorbans untuk Cr(III)-2-hidroksibenzaldiminoglisina konstan. Hasil dari menggunakan HPSAM pada contoh sintetik menunjukkan bahwa Cr(III) dan Cr(VI) tidak dapat ditentukan secara simultan dengan kondisi kompromi analisis yang telah ditentukan. Hal ini karena Cr(III) yang tidak terdeteksi dan persentase simpangan baku relatif Cr(VI) lebih besar dari 5%. Walaupun demikian HPSAM masih memiliki potensi untuk penentuan simultan Cr(III) dan Cr(VI) karena pada beberapa ulangan pengukuran yang dicoba, konsentrasi Cr(VI) yang ditemukan mendekati konsentrasi yang dibuat secara teoretis.
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Judul: Penentuan kadar Fe(III) dan Cr(VI) secara simultan dengan menggunakan teknik spektroskopi
Abstrak: Cr (VI) and Fe (III) are a metal that have a potency cause environmental and drinking water pollution. One of the analytical techniques that can be used to determine Fe (III) and Cr (VI) simultaneously is to use a combination of spectrophotometric method with multivariate calibration. Multivariate calibration used is partial least square (PLS) multi-component analysis technique. Modelling carried out on a solution of Fe (III) and Cr (VI) in 24 variations with quercetin as a chromogenic reagent and CTAB as a complex stabilizer. Modeling results show the optimum solution of the sample was the variation of concentration ratio of Fe: Cr at 10 ppm: 1 ppm, quercetin at 2.95x10-5 M, CTAB 1.35x10-3 M, and reaction time was 45 minutes. Validation of the model is done by using samples of unknown concentration and show a good results only in optimum conditions
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Judul: Biology and ecology of the buffalo fly, haematobia exigua de meijere (diptera:muscidae)
Abstrak: The life history of the buffalo fly was observed at room temperature of 27°-29.5°C and at a relative humidity of 48-68 percent. The eggs hatched after 17-22 hours, with an average of 18 hours. First instar larvae measured 1.25 + 0.16 mm long and 0.27 + 0.037 mm wide. reach the second larval stage. It took 6-12 hours to the second instar larvae measured 2.676 +0.187 mm long and 0.353 +0.028 mm wide. The second instar took about 12-24 hours to reach the third larval stage. The third instar measured 6.833 + 0.189 mm long and 0.919 + 0.051 mm wide. It took about 2-3 days for the third instar to become pupae. Duration of the pupal stage was about 5-7 days before the adults emerged. Under laboratory condition, the buffalo fly completed its life cycle in 9.5 to 10.5 days, whereas under field condition it took 9-14 days with an average of 10.5 days. The growth ratio which was based on the measurements of the cephalo-pharyngeal skeleton of each instar was 1.797. The preoviposition period was 8-12 days and mating usually occurred on the 6th or 7th day. The longevity of the male was 29 days, whereas it was 32 days in the female. The range of egg production under laboratory condition was between 20-139 per female fly. The belly and hind legs of the carabao were the most preferred habitat either during cloudy and cool dry or shiny and warm day. When the weather was clear and the carabao was in the shade, the flies tended to be more distributed particularly on the shoulder, dewlap, back and horns. The carabaos had relatively fewer Musca sp. and Stomoxys calcitrans than cattle; never the less carabaos had a higher infestation of buffalo fly than cattle. Oviposition occured either during the day or night but the buffalo flies were more active during the night than in the day time. The effect of various lengths of exposure time of manure in relation to the oviposition was profound. observed, the maximum number of the buffalo flies was occurred when the dung was exposed for 30 minutes. With increasing time of exposure the number and variety of insects also increase. It was evident that Sepsidae and psychodidae were the most dominant insects emerging from the dung. The number of buffalo flies also increased with increasing
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