The antioxidant activity (AA), total phenolic content (TPC), and total flavonoid content (TFC) of selected Indonesian Zingiberaceae herbs were determined. An optimization extraction procedure was conducted by using Taguchi L16 orthogonal array. Four chemical assays were applied, including 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity assay, H2O2 scavenging activity assay, Folin–Ciocalteau (F–C) assay, and NaNO2-AlCl3-NaOH assay, which revealed remarkable differences in AA, TPC, and TFC. The result indicated the diversity of AA composition among the herbs, and C. longa exhibited the highest AA. HPLC-PAD analysis revealed that curcumin was present in five high antioxidant herbs, and the highest amount was in C. longa. Pearson correlation analysis indicated that the identified TPC and TFC were significant contributors to AA, and curcumin was likely the main contributing antioxidant compound. Our approach concluded that C. longa is the greatest source of natural antioxidants among 12 Indonesian indigenous Zingiberaceae herbs. The use of a mixed-method approach to augment the findings of solitary methods might facilitate future researchers to uncover deeper and hidden meanings.
AbstrakPenelitian ini mempelajari pengaruh variasi waktu penguapan terhadap kinerja membran selulosa asetat. Pada proses ultrafiltrasi, selulosa asetat dibuat dengan menambahkan polietilen glikol (PEG) sebagai agen pembentuk pori membran dan meningkatkan nilai fluks membran. Pembuatan membran selulosa asetat dilakukan dengan metode inversi fasa. Variasi waktu penguapan yang digunakan selama 0, 1, 3, dan 5 menit. Membran selulosa asetat yang terbentuk dikarakterisasi meliputi uji porositas, fluks dan rejeksi. Hasil penelitian menunjukkan waktu penguapan selama 5 menit menghasilkan membran yang lebih rapat. Hasil pengukuran porositas, fluks dan rejeksi terhadap dekstran 500 kDa berturut-turut sebagai berikut: 53,35%; 4,078 (L/jam.m 2 ) dan 92,917%. PENDAHULUANMembran ultrafiltrasi merupakan salah satu jenis membran dengan gaya dorong tekanan yang digunakan untuk memisahkan makromolekul dan koloid dari larutannya. Membran ultrafiltrasi mempunyai struktur asimetrik dengan lapisan atas lebih rapat (ukuran pori lebih kecil) dan porositas permukaan lebih rendah dibanding lapisan bawah, sehingga ketahanan hidrodinamiknya lebih tinggi. Ukuran molekul yang dapat ditahan oleh membran ultrafiltrasi berkisar antara 10 3 -10 8 Dalton [1].Proses pembuatan membran ultrafiltrasi sering kali menggunakan teknik inversi fasa, yaitu suatu proses pengubahan bentuk polimer dari fasa cair menjadi padatan dengan kondisi terkendali. Membran dapat dibuat dari berbagai material seperti selulosa asetat (CA), polisulfon, polieter sulfon, dan poliamida [2]. Pemilihan material membran menjadi penting karena berhubungan dengan pemilihan jenis pelarut dan nonpelarut yang digunakan. Material membran ultrafiltrasi yang berkembang saat ini adalah membran selulosa asetat.Pembuatan membran selulosa asetat biasanya dilakukan dengan penambahan aditif yang dimaksudkan untuk mengatur viskositas larutan polimer, memperbanyak jumlah pori yang terbentuk atau untuk merubah sifat polimer dari hidropobik menjadi hidrofilik. Aditif yang dapat ditambahkan ke dalam proses pembuatan membran selulosa asetat antara lain polivinil klorida, dimetil ftalat, monosodium glutamat dan polietilen glikol. Penambahan polietilen glikol (PEG) sebagai aditif dapat meningkatkan laju permeasi membran Parameter lain yang dapat mempengaruhi proses pembentukan struktur membran yang dihasilkan adalah waktu penguapan pelarut. Waktu penguapan pelarut secara jelas mengindikasikan bahwa semakin lama waktu penguapan akan mempertebal permukaan membran dan menurunkan fluks air tetapi meningkatkan selektivitas membran [6]. Pembuatan membran selulosa asetat dengan waktu penguapan 3 menit dengan komposisi 22% selulosa asetat, 15% aseton, 60% dimetil sulfoksida (DMSO), dan 3% dimetil ftalat (DMP) menghasilkan membran ultrafiltrasi dengan nilai fluks 2,2438 L/jam.m 2 dan rejeksi terhadap dekstran 100-200 kDa sebesar 91,15% [7].BERKALA SAINSTEK 2017, V (1): 7-10
Preliminary study of preparation reference material for trigonelline determination in green coffee beans have been performed by HPTLC method. Physical characterization performed on green coffee beans include the determination of moisture content, ash content and metal content. Water content values obtained on average 6.4% (%RSD 4.8) and ash content 3.9% (%RSD 16.2). Metal determination (Cu, Zn, Fe) with atomic absorption spectrometry method found Cu 9.4 (mg/kg), Zn 12,0 (mg/kg) and Fe 64.0 (mg /kg). Sonication as extraction method using methanol solvent for 30 minutes and separation method HPTLC on aluminum plates coated with silica gel 60 F254. Eluent used was mixture of n-propanol: methanol: water (4:1:4, v/v/v) with elution length 8 cm. Linear regression obtained in concentration range 200-1200 ng spot -1 with R 2 = 0.9857. Detection limits obtained 140.7 ng and 468.9 ng for quantitation limit. Repeatability was achieved from 800 ng spot -1 (% RSD 13.8).
Hydrogen sulfide (H2S) is a toxic, corrosive, and flammable gas. The presence of H2S gas can be reduced by a permeation method using PTFE (Polytetrafluoroethylene) membranes and PVDF (polyvinylidene fluoride) membranes. This H2S gas passed through the membrane and was then captured by the SAOB (Sulfide Anhydride Oxidant Buffer) in S2- species form. A visible spectrophotometer was applied for the analysis of passed H2S gas. Using a PTFE membrane, the optimum flow rate was obtained at 14.71 mL/min, with a mass flux of 0.825 kg/m2.hour, permeability coefficient of 0.696 kg/m2.hour.bar, and percent removal of H2S gas was 88.14%. The optimum flow rate for the SAOB was obtained at a rate of 0.30 mL/min with a mass flux of 0.843 kg/m2.hour and a percent removal of H2S gas of 89.98%. Based on the results obtained on the PVDF membrane, the mass flux produced in the optimization of H2S gas is 0.742 kg/cm2.hour, and the optimization of the SAOB solution is 0.754 kg/cm2.hour. The resulting permeability coefficient value is 0.741 kg/cm2.hour. The results indicate that this study can remove H2S gas at the optimum H2S gas flow rate of 4.76 mL/minute of 94.89% and the optimum SAOB flow rate of 0.3 mL/minute of 95.66%
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