ALKYLARYLKETONEHOMOLOGOUS SERIES FOR DETERMINATIONOF KOVATS RETENTION INDICES WITH RP-HPLC USING ACETONITRILEIWATER SYSTEM

ABSTRACT Some factors such as the changes of the stationary phase, temperature,pH-value, mobile-phase composition and flow rate play a crucial role in effecting the sensitivity of retention times in high performance liquid chromatography (HPLC) system. Utilizing a retention index system is one of the methods to minimize those effects. Besides the mentioned factors, dead-time influences on determining the retention index as well. In comparison with Gas Chromatography (GC), the retention Index determination method in HPLC is still widely discussed, due to the difficulty of utilizing n-alkane as standard. In addition, the solutes in HPLC interact with the mobile-phase, thus the retention behavior also depend on the mobile-phase.Actually,"It is difficult to use n-alkanes in HPLC as standards in case of some considerable problems, due to they are very non polar but also large retention times which lack of chromophores. Therefore, using n-alkane in routine analysis could be inconvenient. In comparison with n-alkanes, the alkylarylketones homologous series are stable compounds, commercially available and easily detected by a UV detector. This paper introduces Determination of Kovats Retention Index in the HPLC using Alkylarylketone homologous series and then is connected with n-alkane as a frame of reference. Steroids were used as test substance for calculating Kovats retention index values in cetonitrile/watersystem. Keywords: Kovats Retention Index, RP- HPLC, n-alkane, alkylarylketon

Dead time determination and its influence to retention index in GC system using polar capillary column

In this research for the determination of dead timeused a method that is mathematically calculated as iteration and linearization of the polar capillarry column  in  Gas  Chromatography  (GC)  type  DN-Wax,  by  injecting  the  homologous series  of  n-alkanes  (n-pentane  up  to  n-decane)  on  GC  system.  The  dead  time values  obtained  are  then  used  to  determine  the  Kovats  Retention  Index (Retention  Index,  RI).  The  results indicated that the  retention index  had  values of  systematic  error  those  are  more  accurate  than  the  retention  time  (tR), corrected retention time (tR') and retention factor(k'), but the retention index shows  the  value  of  random  error  slightly  larger  than  with  other  retention parameters. In this study  the average values obtained by the iteration method, the  dead  time  was  3.52  minutes  with  a  correlation  coefficient  of  0.9998.Retention  index  values  obtained  are  at  the  confidence  level  92.11%-97.06% with the systematic errors 2.04%-7.89%, while the linearization method showed the average value of the dead time 3.3 minutes witha correlation coefficient of 0.9992,  but  the  value  of  retention  index  values  obtained  show  that  the systematic error is very large.Key words:Dead time, Retention Index, Homologous Series, G

Dead time determination and its influence to retention index in GC system using polar capillary column

In this research for the determination of dead timeused a method that is mathematically calculated as iteration and linearization of the polar capillarry column in Gas Chromatography (GC) type DN-Wax, by injecting the homologous series of n-alkanes (n-pentane up to n-decane) on GC system. The dead time values obtained are then used to determine the Kovats Retention Index (Retention Index, RI). The results indicated that the retention index had values of systematic error those are more accurate than the retention time (tR), corrected retention time (tR') and retention factor(k'), but the retention index shows the value of random error slightly larger than with other retention parameters. In this study the average values obtained by the iteration method, the dead time was 3.52 minutes with a correlation coefficient of 0.9998. Retention index values obtained are at the confidence level 92.11%-97.06% with the systematic errors 2.04%-7.89%, while the linearization method showed the average value of the dead time 3.3 minutes witha correlation coefficient of 0.9992, but the value of retention index values obtained show that the systematic error is very large

ISOLASI ANTIBIOTIK REDUKTIOMISIN DARI BAKTERI TERRESTRIAL Streptomyces sp

Penelitian ini bertujuan melakukan isolasi dan penentuan aktivitas mikrobial senyawa bioaktif reduktiomisin dari bakteri Streptomyces sp. Ank181 daratan (terrestrial). Penelitian ini dilaksanakan di laboratorium kimia organik, Institute of Organic and Biomoleculare Chemistry, University of Goettingen, Germany. Isolat dan subkultur agar bakteri Streptomyces sp. Ank181 diperoleh dari koleksi sampel genus Streptomyces Professor Dr. H. Anke, Institute for Biotechnology and Drug Research, Kaiserslautern, Germany. Struktur reduktiomisin dalam penelitian ini dielusidasi berdasarkan data spektroskopi dan spektrometri massa. Tiga senyawa metabolit sekunder telah berhasil diisolasi dan diidentifikasi dari bakteri tanah genus Streptomyces sp. Ank181, yaitu reduktiomisin, asam 2,3-dihidroksibenzoat, dan asam indole-3-karboksilat. Hasil uji antimikroba menunjukkan bahwa reduktiomisin bersifat bioaktif terhadap bakteri, jamur dan sitotoksik terhadap Artemia salina

PENENTUAN WAKTU MATI MEMANFAATKAN DERET HOMOLOG ALKILPARABEN PADA RP-HPLC DALAM SISTEM PELARUT METANOL/AIR

Penelitian ini dalam rangka pengembangan dan aplikasi metode penentuan waktu mati (t0) pada Kromatografi Cair dari yang telah pernah dan berhasil diterapkan di GC. Waktu mati merupakan parameter yang sangat penting untuk penentuan parameter lain seperti Faktor kapasitas (k’), retensi relative (tR’) dan indeks retensi kovats (IR), sehingga didapat hasil berupa data base yang bisa diterapkan dalam intrumentasi GC dan RP-HPLC. Penentuan waktu mati dengan menggunakan dua metode yaitu metode iterasi dan metode linearisasi, sehingga didapat nilai indeks retensi kovats dari senyawa uji pada sistem RP-HPLC dengan menggunakan deret homolog alkilparaben. Hasil penelitian menunjukkan deret homolog alkilparaban terbukti dapat digunakan untuk penentuan indeks retensi Kovats  dalam RP-HPLC dengan koefisien korelasi yang sangat baik  terutama pada sistem pelarut MeHO/H2O (90:10)

PENENTUAN WAKTU MATI MEMANFAATKAN DERET HOMOLOG ALKILPARABEN PADA RP-HPLC DALAM SISTEM PELARUT METANOL/AIR

Penelitian ini dalam rangka pengembangan dan aplikasi metode penentuan waktu mati (t0) pada Kromatografi Cair dari yang telah pernah dan berhasil diterapkan di GC. Waktu mati merupakan parameter yang sangat penting untuk penentuan parameter lain seperti Faktor kapasitas (k’), retensi relative (tR’) dan indeks retensi kovats (IR), sehingga didapat hasil berupa data base yang bisa diterapkan dalam intrumentasi GC dan RP-HPLC. Penentuan waktu mati dengan menggunakan dua metode yaitu metode iterasi dan metode linearisasi, sehingga didapat nilai indeks retensi kovats dari senyawa uji pada sistem RP-HPLC dengan menggunakan deret homolog alkilparaben. Hasil penelitian menunjukkan deret homolog alkilparaban terbukti dapat digunakan untuk penentuan indeks retensi Kovats  dalam RP-HPLC dengan koefisien korelasi yang sangat baik  terutama pada sistem pelarut MeHO/H2O (90:10).

Hydrogen Desorption Properties of MgH2 + 10 wt% SiO2 + 5 wt% Ni Prepared by Planetary Ball Milling

MgH2 is a very hopeful material for application as hydrogen storage material in the solid form. This is due to its reversibility and its ability to store large amounts of hydrogen, which is 7.6 wt%. However, this material still has weaknesses, namely high operating temperature and slow kinetic reactions. Various attempts have been made to overcome this weakness, including downsizing and adding catalyst. In this study, double catalyst was used, namely natural silica extracted from rice husk ash and nickel nano powder, with a composition of MgH2 + 10 wt% SiO2 + 5 wt% Ni. The purpose of this research was to study the effect of downsizing and using these catalysts to the thermodynamic and kinetic properties of the hydrogen storage material MgH2. Samples were prepared by using High Energy Ball Milling (HEBM), with variations in milling time of 1, 5, 10, and 15 hours. The X-ray Diffraction (XRD) pattern showed the presence of an impurity phase in the samples milled for 10 and 15 hours. It also showed a reduction in grain size with increasing milling time. However, agglomeration has occurred in the samples milled for 15 hours. From the Scanning Electron Microscope (SEM) results can be seen that the sample with longer milling time, were homogeneously distribute. Thermal investigation showed that the lowest desorption temperature was achieved in samples with milling time of 5 and 10 hours, namely 287 °C and 288 °C. This study shows that natural silica catalyst plays a role in improving the thermodynamic characteristics of MgH2, while Ni plays a role in improving the kinetic characteristics of MgH2. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

AKTIVITAS BEBERAPA SENYAWA TURUNAN BENZOPIRAN (CHROMONES) DAN BENZOFURANON (COUMARANONES) TERHADAP Steinernema feltiae (The Activities of Benzopyran (Chromones) and Benzofuranones (Coumaranones) Derivatives against Steinernema feltiae)

This study was purposed to inquire the activities of benzopyran (chromones) and benzofuranones (coumaranones) derivatives against Steinernema feltiae (S. feltiae). The toxicity assay against S. feltiae showed that benzopyran derivatives 2, 3, 4, 6, and 9 have the highest activity on S. feltiae with viabilities percentage of 50%. The compound 9 demostrated the highest activity with LD 50 and LD values, 7.2 and 52.2 μM, respectively. The activities of compound 7 and 10 showed the lowest toxicity. Interestingly, the activity of benzofuranone derivatives showed significant activities against S. feltiae. Compare to benzopyran derivatives, the benzofuranone derivatives has the highest toxicity, in particular compound 13 with LD 5.45 μM. The nematicidal assay showed that benzofuranones (coumaranones) derivatives revealed higher activities than benzopyran (chromones) derivatives.Key words: chromones, benzopyran, coumaranones, benzofuranone, and Steinernema feltia

PENGARUH KOMBINASI EKSTRAK PETROLEUM ETER BAWANG PUTIH (Allium sativum Linn) DENGAN VITAMIN C TERHADAP AKTIVITAS Candida albicans

Garlic (Allium sativum) contains organosulfur compound that plays an important role as an antibacterial and antifungal activities. Ascorbic acid or vitamine C also has been show has a good activity as an antioxidant and as an antifungal. The aims of the research is to determine the effect of the combination of petroleum ether garlic extract with vitamin C against Candida albicans. Zone of inhibition testing done by Kirby-Bauer method. The results showed that the combination of petroleum ether garlic extract with vitamin C in concentration of 50% did not show an activity significantly. Meanwhile, the activity of petroleum ether garlic extract alone at concentration of 50 and 75% showed activities towards Candida albicans with a diameter of inhibition zone are 19.46 and 27.46 mm respectively.