COLLABORATIVE TRIAL AND QUALITY CONTROL IN CHEMICAL ANALYSIS

Abstract                                                             This paper deals with some practical problems related to the quality of analytical chemical data usually met in practice. Special attention is given to the topic of quality control in analytical chemistry, since analytical data is one of the primary information from which some important scientifically based decision are to be made. The present paper starts with brief description on some fundamental aspects associated with quality of analytical data, such as sources of variation of analytical data, criteria for quality of analytical method, quality assurance in chemical analysis. The assessment of quality parameter for analytical method like the use of standard materials as well as standard methods is given. Concerning with the quality control of analytical data, the use of several techniques, such as control samples and control charts, in monitoring analytical data in quality control program are described qualitatively.  In the final part of this paper, some important remarks for the preparation of collaborative trials, including the evaluation of accuracy and reproducibility of analytical method are also given Keywords: collaborative trials, quality control, analytical data Abstract                                                             This paper deals with some practical problems related to the quality of analytical chemical data usually met in practice. Special attention is given to the topic of quality control in analytical chemistry, since analytical data is one of the primary information from which some important scientifically based decision are to be made. The present paper starts with brief description on some fundamental aspects associated with quality of analytical data, such as sources of variation of analytical data, criteria for quality of analytical method, quality assurance in chemical analysis. The assessment of quality parameter for analytical method like the use of standard materials as well as standard methods is given. Concerning with the quality control of analytical data, the use of several techniques, such as control samples and control charts, in monitoring analytical data in quality control program are described qualitatively.  In the final part of this paper, some important remarks for the preparation of collaborative trials, including the evaluation of accuracy and reproducibility of analytical method are also given Keywords: collaborative trials, quality control, analytical dat

Studies on Formation and Thermal Decomposition of Lead Hydride, PbH4

In the present work, some fundamental aspects of the formation of gaseous lead hydride from aqueous solutions containing divalent lead ions (Pb2+) and its application in the atomic absorption spectrometric analysis lead has been investigated. By utilizing a peristaltic pump, an acidic solution of Pb2+ was first oxidized with ammonium peroxodisulphate, NH4S2O8, and followed by reduction with sodium tetrahydroborate, NaBH4. After a gas-liquid separation, the gaseous lead hydride produced was directly swept into an electrically heated open ended quartz tube, located at the light path of an atomic absorption spectrometer in order to have possibilities for specific atomic absorption spectroscopic measurements. The absorbance signals caused by lead atomic absorption could be used proportionally to estimate the density of atomic lead vapor produced in the thermal decomposition under investigation. Results showed that on-line pre-oxidation of the analyte is very important and crucial step in the gaseous hydride generation of lead, and no lead hydride was produced without the involvement of this step. Moreover, it was observed that the use of low major gas flows cannot be applied in quantitative atomic absorption spectrometric determination of lead by this technique. This condition may result in possible losses of the analyte atomic vapor due to metallic condensation

Studies on Formation and Thermal Decomposition of Lead Hydride, PbH4 = Studi tentang Pembentukan dan Dekomposisi Termal Hidrida Timbal PbH4.

In the present work, some fundamental aspects of the formation of gaseous lead hydride from aqueous solutions containing divalent lead ions (Pe) and its application in the atomic absorption spectrometric analysis lead has been investigated. By utilizing a peristaltic pump, an acidic solution of Pb2+ was first oxidized with ammonium peroxodisulphate, NH4S208, and followed by reduction with sodium tetrahydroborate, NaBH4. After a gas-liquid separation, the gaseous lead hydride produced was directly swept into an electrically heated open ended quartz tube, locataed at the light path of an atomic absorption spectrometer in order to have possibilities for specific atomic absorption spectroscopic mesurements. The absorbance signals caused by lead atomic absorption could be used proportionally to estimate the density of atomic lead vapour produced in the thermal decomposition under investigation. Results showed that on-line pre-oxidation of the analyte is very important and crucial step in the gaseous hydride generation of lead, and no lead hydride was produced without the involvement of this step. Moreover, it was observed that the use of low carrier gas flows can not be applied in quantitative atomic absorption spectrometric determination of lead by this technique. This condition may result in possible losses of the analyte atomic vapour due to metalic condenzation

Effect of Aluminium Content in Aluminium Pillared Montmorillonite on Its Surface Acidity Properties

Aluminium pillared montmorillonites from Indonesian natural montmorillonite has been prepared using Al13 Keggin ion pillaring precursor in varied concentrations. Herein we studied their characterization and catalysis application for esterification reaction. X-ray diffraction (XRD), energy dispersive x-ray analysis (EDX), and BET gas sorption analysis were employed to characterize the prepared materials besides the characterization on surface acidity by pyridine and n-butylammine adsorptions and FTIR analysis. The result showed that significant improvement on physicochemical character data was obtained by a pillarization process. Such a process also provided improvements on catalytic activities in esterification reactions. The effect of aluminium content on material characters was discussed in this paper. It was observed from the catalytic activity tests that pillared montmorillonite samples demonstrated higher activity in esterification reaction relative to the raw montmorillonite. It was found that surface profile of materials consist of specific surface area, pore volume and Lewis acidity were significantly affect the catalyst activity

EFFECT OF DIATOMEAOUS EARTH TREATMENT USING HYDROGEN CHLORIDE AND SULFURIC ACID ON KINETICS OF CADMIUM(II) ADSORPTION

In this research, treatment of diatomaceous earth, Sangiran, Central Java using hydrogen chloride (HCl) and sulfuric acid (H2SO4) on kinetics of Cd(II) adsorption in aqueous solution has been carried out. The work was conducted by mixing an amount of grounded diatomaceous earth (200 mesh in size) with HCl or H2SO4 solution in various concentrations for two hours at temperature range of 100 - 150oC. The mixture was then filtered and washed with water until the filtrate pH is approximately 7 and then the residue was dried for four hours at a temperature of 70oC. The product was used as an adsorbent to adsorb Cd(II) in aqueous solution with various concentrations. The Cd(II) adsorbed was determined by analyzing the rest of Cd(II) in the solution using atomic absorption spectrophotometry. The effect of treatment was evaluated from kinetic parameter of adsorption rate constant calculated based on the simple kinetic model. Results showed  that before equilibrium condition reached, adsorpstion of Cd(II) occurred through two steps, i.e. a step tends to follow a reaction of irreversible first order  (step I) followed by reaction of reversible first order (step II). Treatment with acids, either hydrogen chloride or sulfuric acid, decreased adsorption rate constant for the step I from 15.2/min to a range of 6.4 - 9.4/min.  However, increasing concentration of acid (in a range of concentration investigated) did not give significant and constant change of adsorption rate constant. For step II process,  adsorption involved physical interaction with the sufficient low adsorption energy (in a range of 311.3 - 1001 J/mol).     Keywords: adsorption, cdmium, diatomaceous earth, kinetics

EFFECT OF ACID CONCENTRATION ON CHARACTERS OF SILICA GEL SYNTHESIZED FROM SODIUM SILICATE

In this research, synthesis and characterization of silica gel from sodium silicate through sol-gel process using H2SO4, HCl, and citric acid have been investigated. Synthesis was carried out by mixing and stirring  20 mL of H2SO4, HCl or citric acid  at certain concentration with 50 mL of sodium silicate solution (Na2O 0.17 M and SiO2 0.61 M) for one hour and let to form gel.  The gel was washed with distillated water, and dried in an oven at 100 oC. Characterization of silica gel was carried out by determination of acidity, water adsorption capacity, and water content. Identification of functional group and structure were identified using x-ray diffractometer (XRD) and infrared (IR) spectrophotometer, respectively.  Results showed that at a range of investigated concentration (0.6 - 3.0 M) the increase of concentration, formation of gel with H2SO4 tended to be faster, but with HCl and citric acid to be slower. The increase of acid concentration caused water content, water adsorption capacity, and acidity of the silica gel resulted with HCl and citric acid tended to be increased, increased, and increased, but with H2SO4 to be decreased, increased, and decreased, respectively. Based on the IR spectra and XRD data, it could concluded that the synthetic silica gels contained silanol (Si-OH) and siloxane (Si-O-Si) and were amorphous, showing similar pattern to kieselgel G 60 produced by Merck.   Keywords: silica gel, adsorption capacity, sodium silicate, acidit

IMPREGNATION OF 2-MERCAPTOBENZOTHIAZOLE ON DIATOMACEOUS EARTH AND ITS APPLICATION AS MERCURY(II) ADSORBEN IN AQUEOUS MEDIUM

An adsorbent was prepared by impregnating 2-mercaptobenzo-thiazole onto polystirene treated diatomaceous earth support. This adsorbent was then applied to adsorb mercury(II) in aqueous medium. The mercury(II) adsorption characteristics of the adsorbent was studied by the use of the original diatomaceous earth as reference. Interaction of mercury(II) and both of diatomaceous earth as well as MBT-diatomaceous were performed in a aqueous batch system to include the following parameters: (a) medium acidity and (b) mercury(II) adsorption characteristic on MBT-diatomaceous with and without the present of other metal ions. In the present work quantification of mercury(II) adsorption was done by determining the mercury concentration left in the solution after adsorption. A cold vapour-generation atomic absorption spectroscopy technic was used in this determination.The experiment results show, that the adsorption affinity of MBT-diatomaceous is higher than the original diatomaceous earth. The total adsorption energy of mercury(II) for diatomaceous earth (24.702 kJ/mol) and MBT-diatomaceous (46.942 kJ/mol) suggest that the interaction is chemisorption. The mercury(II) maximum adsorption on diatomaceous earth is obtained at pH 6, while similar adsorption on MBT-diatomaceous practically was not influenced by pH changes. The present of other metals, i.e. Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and Zn(II) in solution does not give any appreciable influence to the adsorption affinity of MBT-diatomaceous to mercury(II); the total sum of the mercury(II) adsorbed is constantly high, almost 100 %. Keyword: Impregnation, MBT-diatomaceous, adsorption, mercury(II

ADSORPTION OF Mg(II) AND Ca(II) ON DISULFONATO-SILICA HYBRID

Adsorption of Mg(II) and Ca(II) on disulfonato-silica hybrid (DSSH) in the aqueous solution has been studied. The hybrid was synthesized by sol-gel process with sodium silicate solution from rice hull ash, chloroprophyltrimethoxysilane (CTS) and 4-amino-5-hydroxy-naphtalene-2,7-disulfonic acid monosodium salt (ANSNa) as silica source, cross linker and active group, respectively. Sodium silicate solution was reacted with CTS and ANSNa that were added dropwise. Adsorption of magnesium and calcium ions on DSSH was carried out in a batch system. Solution pH significantly affected magnesium and calcium adsorption and the optimum condition was obtained at pH = 6. The synthesized DSSH showed a high adsorption capacity of 0.0844 mmol/g and 0.1442 mmol/g for Mg(II) and Ca(II), respectively. The adsorption isotherm obtained with Langmuir isotherm model gives the negative values of ΔG°, i.e. -23.334 kJ/mol and -22.757 kJ/mol for Mg(II) and Ca(II), respectively, indicating the spontaneous process of adsorption. Kinetic studies showed that the adsorption of Mg(II) and Ca(II) ions onto HDSS follows the pseudo-second-order kinetics

SYNTHESIS OF 1,9-BIS [1-PHENYL-3-METHYL-5-HYDROXY-4-PYRAZOLYL] 1,9 NONANEDIONE AND ITS APPLICATION FOR THE EXTRACTION OF COBALT ( II), NICKEL (II), AND CADMIUM (II)

Synthesis of 1,9-bis [1-phenyl-3-methyl-5-hydroxy-4- pyrazolol)-1,9-nonanedione (HL-7-LH) and its application for the extraction of cobalt (II), nickel (II), and cadmium (II) have been carried out. The HL-7-LH were prepared by treating a dioxane solution of 1-phenyl-3-methyl-5-pyrazolone (H2PMP) containing calcium hydroxide catalyst with azelaoyl dichloride [ClCO(CH2)7C0C1l Purification of the HL-7-LH obtained were done by mean recrystallization in etanoltoluena (9:1) at 70°C. Characterization of the HL-7-LH were done by infrared and nuclear magnetic resonance spectroscopic techniques. The application of the HL-7-LH as extractant in the extraction of cobalt, nickel, and cadmium were performed in chloroform and dichloromethane. It was observed that the effectivity of the extraction increases as the extractant concentration and pH increases. Results show that cobalt, nickel, and cadmium extraction in chloroform wereobtained with the extraction constants (log Keks) = -5,37, -5,44, -5,22 and at dichloromethane were -5,19, - 5,24, and -5,08.Key Word : Synthesis, effectivity of the extraction, the extraction constant

A Kinetic Study of Aluminium(III) and Chromium(III) Adsorption by Silica Gel <i>Chaetoceros calcitrans</i> Biomass Immobilized on Silica Gel

The kinetics of aluminium(III) and chromium(III) adsorption in an adsorbent prepared by immobilization of Chaetoceros calcitrans biomass on silica ge has been investigated. The functional groups which were probable involved in the adsorption processes also identified. Experimentally, the adsorption was conducted by coloumn and batch method. In this work atomic adsorption spectrophotometric techniques was applied indirectly to determine of the metal ion adsorpted, and infra red spectroscopic technique was used for the identification of functional groups present in the adsorbent. The study included two parts of experiment, i.e. 1) the determination of rate of adsorption and 2) the determination of capacity and energy of adsorption. Results showed that the AI(III) and Cr(III) adsorption data fit quiet well with non linear kinetics model proposed by Langmuir-Hinshelwood giving a first order rate constant, (k1) of 8.65.10-3 min-1 for AI(III) and 9.92.10-4 min' for Cr(III) when the immobilized biomass used as the adsorbent in agreement with the activation energy calculation giving values of 1.184 kcal/mole for Al(111) and 1.877 kcal/mole for Cr (Ill). It was concluded that the adsorption of Al(III) and Cr(III) on Chaetoceros calcitrans immobilized and free Chaetoceros calcitrans adsorbents, may be classified as chemical adsorption, involving entalphi of adsorption in the range of 6-17 kcal/mole. And the infra red spectroscopic data indicated that the functional groups i.e.: carboxylate (-COO), hydroxyl (-OH) silanol (SI-OH), siloksil (SI-O-Si) and amine (NH2) are present in free Chaetoceros calcitrans biomass and silanol (Si-OH), siloksil (Si-O-Si), hydroxyl (-OH)and C-H metilene (-CH2) are present in immobilized biomass Chatoceros calcitrans, while only siloksil (Si-O-Si) and silanol (Si-OH) in silica gel