Papers by Muhammad Zain Siddiqui
Foods, 2020
Polyvinyl acetate (PVAc) is used in various adhesive, paint, and transparent tape applications. I... more Polyvinyl acetate (PVAc) is used in various adhesive, paint, and transparent tape applications. It is also used as a food additive in food manufacturing to make chewing gum and fruit and vegetable glazes; however, guidelines on the amount of food additives that is used have not yet been established. In this study, a method was developed for analysis of polyvinyl acetate (PVAc) using high-performance liquid chromatography with an evaporative light scattering detector (HPLC–ELSD) and pyrolyzer–gas chromatography–mass spectrometry (Py–GC–MS). The analytical methods were applied to commercially available chewing gum. In the HPLC–ELSD analysis, the linearity was acceptable (R2 > 0.999), and the limits of detection and quantification were 22.2 and 67.3 µg/mL, respectively. The accuracies of PVAc were 87–115% at spike levels of 200–1000 µg/mL for the intra- and inter-day tests. The contents of PVAc in the chewing gum samples were n.d. (not detected)—13.8 g/kg. The presence of PVAc in ch...
Catalysts, 2018
High-density polyethylene (HDPE) was co-fed into the catalytic pyrolysis (CP) of mandarin peel (M... more High-density polyethylene (HDPE) was co-fed into the catalytic pyrolysis (CP) of mandarin peel (MP) over different microporous catalysts, HY and HZSM-5, with different pore and acid properties. Although the non-catalytic decomposition temperature of MP was not changed during catalytic thermogravimetric analysis over both catalysts, that of HDPE was reduced from 465 °C to 379 °C over HY and to 393 °C over HZSM-5 because of their catalytic effects. When HDPE was co-pyrolyzed with MP over the catalysts, the catalytic decomposition temperatures of HDPE were increased to 402 °C over HY and 408 °C over HZSM-5. The pyrolyzer-gas chromatography/mass spectrometry results showed that the main pyrolyzates of MP and HDPE, which comprised a large amount of oxygenates and aliphatic hydrocarbons with a wide carbon range, were converted efficiently to aromatics using HY and HZSM-5. Although HY can provide easier diffusion of the reactants to the catalyst pore and a larger amount of acid sites than ...
Journal of Analytical Methods in Chemistry, 2013
A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmo... more A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmodic drugs in pharmaceutical parenteral dosage forms (injectable) and in serum has been developed and validated. Mobile phase ingredients consist of Acetonitrile : buffer : sulfuric acid 0.1 M (50 : 50 : 0.3 v/v/v), at flow rate 1.0 mL/min using a HibarμBondapak ODS C18column monitored at dual wavelength of 266 nm and 205 nm for phloroglucinol and trimethylphloroglucinol, respectively. The drugs were subjected to stress conditions of hydrolysis (oxidation, base, acid, and thermal degradation). Oxidation degraded the molecule drastically while there was not so much significant effect of other stress conditions. The calibration curve was linear with a correlation coefficient of 0.9999 and 0.9992 for PG and TMP, respectively. The drug recoveries fall in the range of 98.56% and 101.24% with 10 pg/mL and 33 pg/mL limit of detection and limit of quantification for both phloroglucinol and trimet...
Sustainability, 2021
The pyrolysis of waste electronically heated tobacco (EHT), consisting of tobacco leaves (TL), a ... more The pyrolysis of waste electronically heated tobacco (EHT), consisting of tobacco leaves (TL), a poly-lactic acid (PLA) filter, and a cellulose acetate (CA) filter, was investigated using thermogravimetric (TG) and pyrolyzer–gas chromatography/mass spectrometry (Py-GC/MS) analysis. The pyrolytic properties of waste EHT obtained after smoking were comparable to those of fresh EHT. Although the maximum decomposition temperatures (TmaxS) of waste TL and CA were similar to those of fresh EHT components, the Tmax of waste PLA was slightly higher than that of fresh PLA due to smoldering. The Tmaxs of PLA and CA were lowered when they were co-pyrolyzed with TL due to interactions between pyrolysis intermediates. The apparent activation energies for the non-isothermal pyrolysis of waste EHT components were higher than those of fresh EHT components. Py-GC/MS analysis results indicated that considerable amounts of chemical feedstocks, such as nicotine and limonene from TL, caprolactone and la...
Journal of Analytical and Applied Pyrolysis
Science of The Total Environment
Journal of Analytical and Applied Pyrolysis
Catalysts
The thermal and catalytic pyrolysis of two kinds of Tetra Pak waste (TP-1 and TP-2) over three di... more The thermal and catalytic pyrolysis of two kinds of Tetra Pak waste (TP-1 and TP-2) over three different acidic catalysts—HZSM-5(SiO2/Al2O3, 30), HBeta (38), and Al-MCM-41(20)—were investigated in this study. Tetra Pak (TP) wastes consist of composite material comprising kraft paper, polyethylene (PE) film, and aluminum foil. Thermal decomposition behaviors during the pyrolysis of TPs were monitored using a thermogravimetric (TG) analyzer and tandem micro reactor-gas chromatography/mass spectrometry (TMR-GC/MS). Neither the interaction between the non-catalytic pyrolysis intermediates of kraft paper and PE, nor the effect of aluminum foil have been monitored during the non-catalytic TG analysis of TPs. The maximum decomposition temperatures of PE in TP-1 shifted from 465 °C to 432 °C by HBeta(38), 439 °C by HZSM-5(30), and 449 °C by Al-MCM-41(20), respectively. The results of the TMR-GC/MS analysis indicate that the non-catalytic pyrolysis of TPs results in the formation of large am...
Journal of Analytical and Applied Pyrolysis
Energy Conversion and Management
Journal of Cleaner Production
A stability indicating, accurate, specific, precise, and simple reverse phase high performance li... more A stability indicating, accurate, specific, precise, and simple reverse phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated for the simultaneous determination of Phloroglucinol (PGD) and Trimethylphloroglucinol (TMP) in bulk, pharmaceutical dosage forms of tablet and in body fluid. Methanol: Buffer: Sulfuric Acid 0.1mol/l (60:40:03) was the mobile phase at flow rate 1.0 ml/min using a Symmetry C18 column monitored at 234nm. The APIs were subjected to stress conditions of hydrolysis (acid, base, oxidation, and thermal degradation). Maximum degradation was observed in acid and 35% H2O2 while found stable in the other stress conditions. The calibration curve was linear with a correlation coefficient of more than 0.9995 for both drugs. The averages of the absolute and relative recoveries were found to be 100.154% and 99.993% for Phloroglucinol and Trimethylphloroglucinol respectively, with 30pg/ml LOD and with 300pg/ml LOQ. The developed meth...
Journal of Analytical Methods in Chemistry, Oct 28, 2013
A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmo... more A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmodic drugs in pharmaceutical parenteral dosage forms (injectable) and in serum has been developed and validated. Mobile phase ingredients consist of Acetonitrile : buffer : sulfuric acid 0.1 M (50 : 50 : 0.3 v/v/v), at flow rate 1.0 mL/min using a Hibar μBondapak ODS C18 column monitored at dual wavelength of 266 nm and 205 nm for phloroglucinol and trimethylphloroglucinol, respectively. The drugs were subjected to stress conditions of hydrolysis (oxidation, base, acid, and thermal degradation). Oxidation degraded the molecule drastically while there was not so much significant effect of other stress conditions. The calibration curve was linear with a correlation coefficient of 0.9999 and 0.9992 for PG and TMP, respectively. The drug recoveries fall in the range of 98.56% and 101.24% with 10 pg/mL and 33 pg/mL limit of detection and limit of quantification for both phloroglucinol and trim...
Method validation is a key element in the establishment of reference methods and within the asses... more Method validation is a key element in the establishment of reference methods and within the assessment of a laboratory's competence in generating dependable analytical records. Validation has been placed within the context of the procedure, generating chemical data. Analytical method validation, thinking about the maximum relevant processes for checking the best parameters of analytical methods, using numerous relevant overall performance indicators inclusive of selectivity, specificity, accuracy, precision, linearity, range, limit of detection (LOD), limit of quantification (LOQ), ruggedness, and robustness are severely discussed in an effort to prevent their misguided utilization and ensure scientific correctness and consistency among publications.
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Papers by Muhammad Zain Siddiqui