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Articles by Sugeng Riyanto
Total Records ( 8 ) for Sugeng Riyanto
  Luthfia Indriyani , Abdul Rohman and Sugeng Riyanto
  The potential application of Differential Scanning Calorimetry (DSC) combined with multivariate calibration was used to verify adulteration of avocado oil from Indonesian avocado cultivars with Refined Bleached Deodorized Palm Superolein (RBDPSO). Avocado oil and adulterant were characterized by significantly different cooling and heating DSC thermal profiles. The addition of RBDPSO makes the shift of overall transitions temperature toward lower temperature, enhancing crystallization, melting enthalpy and developing both process over a narrower temperature range. The change of characteristic exothermic and endothermic event in avocado oil with increasing adulterant was possibly associated with the increase of oleic and stearic acids along the decrease of palmitoleic acid. The multivariate calibration approach was applied to DSC data in order to build the quantitative calibration model for adulterant concentration in a range of 0-50%, (v/v). Partial Least Square Regression (PLSR) and Stepwise Multiple Linear Regression (SMLR) were tested to these mixtures. Generally, both calibration models showed good correlation coefficient (R) with low errors in both calibration and validation sets. But, SMLR model showed better criteria values than PLSR, not only on DSC crystallization profile data but also on heating profiles data. The crystallization models of SMLR and PLSR showed the higher R value (above 0.99) than melting calibration models. The results presented in this study suggest that DSC analysis may be a useful tool for detecting adulteration of avocado oil with RBDPSO. The DSC represent a rapid, environmentally friendly and alternative option for avocado oil quality screening without sample pretreatments.
  Abdul Rohman , Diana Silawati , Sudjadi and Sugeng Riyanto
  The objective of this study is to evaluate the capability of UV-spectrophotometry in combination of multivariate calibration based on Partial Least Square (PLS) regression for simultaneous quantitative analysis and dissolution evaluation of sulfamethoxazole (SUL) and trimethoprim (TRI) in tablet dosage form. The experimental calibration and validation matrixes were constructed with 20 and 10 samples, respectively. The concentration range considered was 1-16 μg mL–1 for both SUL and TRI. The absorbance data of the calibration standards were taken between 200-400 nm. For achieving the best calibration model, the related parameters were evaluated. The optimum number of factors was selected by using the cross-validation method. The evaluation of calibration model is relied on the coefficient of determination (R2) and Root Mean Square Error of Calibration (RMSEC). The coefficient of determination (R2) for the relationship between actual values and predicted values of SUL and TRI was higher than 0.99 indicating good accuracy of the developed method. The RMSEC values obtained were relatively low, namely 0.167% (SUL) and 0.279% (TRI), which indicate acceptable precision of analytical method. The accuracy of developed method was comparable to that of High Performance Liquid Chromatography (HPLC) method. The UV spectrophotometry in combination with PLS calibration model was successfully used for quantitative analysis and dissolution studies of SUL and TRI sulfamethoxazole and trimethoprim in tablet dosage form.
  Abdul Rohman , Yani Ardiyanti , Sudjadi and Sugeng Riyanto
  The method of choice for analysis of drugs in multi-component preparations is chromatographic based technique such as High Performance Liquid Chromatography (HPLC). However, chromatographic method is time consuming and requiring much effort. As a consequence, some simple methods such as UV spectrophotometry are continuously developed, especially in combination with the chemometrics software. The UV-vis spectrophotometry coupled with multivariate calibration of Partial Least Square (PLS) has been developed for quantitative analysis of paracetamol, guaiphenesin and chlopheniramine maleate in the presence of phenylpropanolamine without separation step. The calibration model is prepared by developing a series of sample mixture comprising these drugs in certain proportion. The evaluation of calibration model was based on coefficient of determination (R2) and Root Mean Square Error of Calibration (RMSEC). The result showed that UV spectrophotometry combined with PLS can be used for quantitative analysis of drugs. The coefficient of determination (R2) for the relationship between actual values and predicted values was higher than 0.99 indicating good accuracy. The RMSEC values obtained were relatively low indicating good precision. The accuracy of developed method was compared to that of HPLC. The developed method was successfully used for analysis of paracetamol, guaiphenesin and chlopheniramine maleate in tablet dosage form.
  Abdul Rohman , Liling Triyasmono , Sugeng Riyanto and Lisa Andina
  A simple, rapid and reproducible method for determining the Saponification Value (SV) of Red Fruit Oil (RFO) was developed using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy in combination with multivariate calibration of Partial Least Square (PLS). A calibration model was developed using a series of RFO subjected to several thermal treatments, namely at ambient temperature 28, 100, 150, 180, 200 and 300°C, respectively. Based on the optimization processes, the FTIR spectra of RFO samples were measured in the frequency region of 1145-1168 cm–1 for SV determination. The relationship between actual values of SV as determined using AOCS method and FTIR predicted value as determined with FTIR spectroscopy in combination with PLS calibration model showed a close relationship with coefficient of determination (R2) of 0.998 and the value of Standard Error of Calibration (SEC) was 0.79%. This study concluded that ATR-FTIR spectra can be used to determine SV of RFO. The developed method is simple, rapid with a total analysis time per sample of less than 2 min and environment friendly.
  Luthfia Indriyani , Abdul Rohman and Sugeng Riyanto
  A study was carried out to determine the physico-chemical characteristics of avocado oil derived from three Indonesian avocado cultivars, namely Bantul (MAB), Purwokerto (MAP) and Garut (MAG). The extraction of avocado oil from avocado fruit was carried out using solvent extraction method. The avocado oil obtained from all samples had a green yellowish color. The iodine value of MAG is 88.7 g I2/100 g oil, slightly higher than MAB (87.0 g I2/100 g oil) and MAP (77.09 g I2/100 g oil) indicated that MAG contains more unsaturated fatty acid. The saponification values of avocado oil were 193.1 mg KOH/g oil for MAB, 198.4 mg KOH/g oil for MAP and 153.17 mg KOH/g oil for MAG, respectively. The peroxide values of MAB, MAP and MAP were 166.1, 124.7 and 14.9 meq kg–1 oil, respectively. The Conjugated Dienes (CDs) and Conjugated Trienes (CTs) value of MAB, MAP and MAG were significantly different in the specific absorptivity range value from 2.6-3.7. The MAG had lowest CDs and CTs value. The anisidine value for avocado oil samples ranged from 10.59-11.36. There were no significant differences in the anisidine value among avocado oil samples. Avocado oil samples had high amounts of total unsaturated fatty acids, i.e., MAB (55.7%), MAP (62.8%) and MAG (68.9%), respectively. Thermal analysis by Differential Scanning Calorimetry (DSC) showed that avocado oil from three different cultivar had different melting and crystallization profile. Principal component analysis was used to classify each sample based on their DSC parameters. The results showed that by using the melting and crystallization profiles the discrimination of three avocado oils was very clear.
  Abdul Rohman , Fajar A. Lumakso and Sugeng Riyanto
  The falsification of high price edible oils such as avocado oil become a serious problem in the oil trade. Simple and rapid methods for identifying and discriminating authentic Avocado Oil (AO) from its adulterants are increasing demand. This current work proposes the use of combination of mid infrared spectroscopy technique with Partial Least Square-Discriminant Analysis (PLS-DA) as direct and rapid tool to discriminate authentic AO from the adulterants of Soybean Oil (SO) and Grape Seed Oil (GSO) in binary and ternary mixture. Discrimination was carried out using the chemometrics approach, namely PLS-DA based on the infrared spectral data. The selected frequency used for authentication of AO was 1500-750 cm–1. Special spectral treatment of smoothing and offset correction was implemented to reduce the noise and background spectral. Furthermore, the high accuracy and clear discrimination were obtained with 100% correctness for binary mixture analysis and 93.3% for ternary mixture.
  Yohanes Martono , Sugeng Riyanto , Sudibyo Martono and Abdul Rohman
  Background and Objective: Simulated stevia beverages contain major diterpene glycoside, stevioside and rebaudioside A from Stevia rebaudiana . Methodology: The objective of this study was to develop FTIR spectroscopy in combination with multivariate analysis of Partial Least Square (PLS) regression for determination of stevioside and rebaudioside A in simulated stevia beverages. The PLS calibration was optimized by selecting wave number region capable provided the highest coefficient determination, R2 and lowest Root Mean Square Error Calibration (RMSEC). Results: Finally, the combined wave number range of 1161-2773 and 868-1041 cm–1 using Multiplicative Scattering Correction (MSC) followed by offset correction transformation spectra was chosen for stevioside determination with R2 and RMSEC value of 0.9954 and 3.40%, respectively. Meanwhile, selected wave number region at 791-1839 cm–1 without spectra transformation revealed optimal PLS regression for rebaudioside A determination with R2 and RMSEC of 0.9820 and 2.91%, respectively. Conclusion: The FTIR spectroscopy in combination with multivariate analysis of PLS regression could be used an alternative method for determining stevioside and rebaudioside A in simulated stevia beverages.
  Irma Antasionasti , Sugeng Riyanto and Abdul Rohman
  Background: Synthetic-based antioxidants are suspected to cause toxic or mutagenic effects toward human health, therefore, the demand for natural antioxidants increased. One of the natural antioxidant sources is Avocado Peel (AP). Objective: The objective of this study is to determine antioxidant activities of the extract, fractions and isolates from AP using in vitro method of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) radical scavenging, reducing power of iron (III) as well as total phenolic and flavonoid contents. Materials and Methods: Ethyl acetate fraction of AP is fractionated using vacuum liquid chromatography and gravitation column chromatography methods. To identify the chemical structure of the active compound of antioxidants in AP, FTIR spectroscopy and gas chromatography-mass spectrometry (GC-MS) are used. Results: Among extracts evaluated, methanol extract has the strongest antioxidant activity. Further fractionation of methanolic extract showed that fraction 8 is the most active fraction with IC50 values of 4.221±0.137 mg mL–1 (DPPH assay) and 0.855±0.013 mg mL–1 (ABTS assay), with reducing power of iron (III) of 723.067±18.849 mg ascorbic acid g–1 fraction. Phenolics contents contributed 37, 40.78 and 47.45%, compared with the contribution of flavonoids compounds of 26.71, 19.25 and 34.62% for DPPH radical scavenging, ABTS radical scavenging and reducing power of iron (III) to iron (II), respectively. Isolation of the fraction 8 of methanol extract indicated the presence of 1,2,4-trihidroksiheptadek-12,16-diyne and isolation of the ethyl acetate extract indicated the presence of 1,2,4-trihidroksiheptadek-16-yne-18-ene. Conclusion: The AP is potential to be used as food supplement due to its antioxidant activities.
 
 
 
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