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|Development of simple green chemical analysis for Ethanol, Carbaryl and Protein Assays in food and agricultural product samples
|การพัฒนาการวิเคราะห์ทางเคมีแบบสะอาดอย่างง่าย เพื่อการหาปริมาณเอทานอล คาร์บาริลและโปรตีน ในตัวอย่างอาหารและผลิตภัณฑ์ทางการเกษตร
|Chiang Mai : Graduate School, Chiang Mai University
|Simple and green chemical analysis methodologies were developed for the determination of ethanol, carbaryl and protein in food and agricultural product samples. These methods include: 1) downscaling system with a simple pretreatment for the assay of ethanol contents in alcoholic beverages, 2) green sample preparation and analysis for cost-effective and precise assay of carbaryl in vegetable samples and 3) downscaling Kjeldahl digestion with downscaling analytical device for determination of protein in food samples. A rapid, simple and field-portable cotton sensor analytical device based on membraneless gas diffusion method was developed for the quantitative analysis of ethanol in alcoholic beverage samples. The proposed device consisted of well plate as donor chamber and a K2Cr2O7 immobilized cotton pad as an acceptor sensor. The solution handling leads to operation in micro-liter volume scales. The simple preparation involved membraneless gas diffusion for separate ethanol from sample matrix, which ethanol vapor to diffuse through into K2Cr2O7 immobilized cotton pad. The detection step involved the reaction of ethanol with K2Cr2O7 on cotton. The change of color due to the reaction leads to the monitoring of the ethanol contents by smartphone-based digital imaging. Under the optimum condition of the proposed method, a linear calibration graph was obtained in the concentration range of 1 - 14% (v/v). The limit of detection (LOD) and limit of quantification (LOQ) were 0.4 and 1.4% (v/v) respectively. The relative standard deviations were in range of 2.4 - 4.5% and 2.8 - 5.1% for repeatability (n = 10) and reproducibility (n = 5), respectively. Good recoveries between 83 to 113% were obtained. The proposed method can be successfully applied to determination of ethanol in alcoholic beverage samples. The results were found to be in good agreement between the proposed method and gas chromatography with flame ionization detector (GC-FID) method. This was verified by the student's t-test which showed no significant difference at 99% confidence level. Carbaryl is a carbamate insecticide and parasiticide. The determination of carbaryl in vegetable samples is necessary to protect consumer health. A simple and reliable spectrophotometric method was developed for determination of carbaryl in vegetable samples. In this part, an ultrasound-assisted QuEChERS and ultrasound-assisted cloud point were presented for a sample preparation and preconcentration of target substance. The spectrophotometric analysis is based on a derivatized reaction of 1-naphthol metabolite of carbaryl with 4-aminoantipyrine using peroxidase enzyme, extracted from jackfruit latex, as a catalyst in the present of hydrogen peroxide. The red colored product was preconcentrated using ultrasound-assisted cloud point extraction prior to measure at 500 nm. The calibration curve of carbaryl standard of proposed method was 0.025- 0.20 mg L-1. The limit of detection and limit of quantification were 0.9 and 24 ug L-1 (or 0.045 mg kg-1 and 1.2 mg kg-1), respectively. The relative standard deviations of 0.13 mg L-1 carbaryl standard were 5.15% and 7.24% for repeatability and reproducibility, respectively. The developed method was applied for the determination of carbaryl in vegetable samples available in the markets. The results from the developed method were compared with high-performance liquid chromatography with a reverse phase system and a UV detector. The results obtained by the two methods were not significantly different at 99% confidence level. A simple and low-cost miniaturized device with downscaling Kjeldahl digestion was developed for the determination of protein in food samples. The miniaturized device was designed and fabricated by sticker-plastic sheet. The solution handling leads with operator in micro-liter volume scales. The proposed method is based on the complexation reaction between ammonium-nitrogen after digestion with Nessler's reagent, resulting in a yellowish-brown colloidal product then was detected by smartphone-based digital imaging for quantitative analysis. Downscaling Kjeldahl digestion deployed homemade iron block. A linear calibration graph was obtained in the concentration range of 5 - 60 mg L-1 ammonium-nitrogen. Limits of detection and quantification were 2.8 and 7.6 mg L-1, respectively. The relative standard deviations of 20 mg L-1 ammonium- nitrogen standard were 6.7% and 8.8% for repeatability and reproducibility, respectively. The developed method was successfully applied to the analysis of protein in food samples. The results from the proposed method was compared with conventional Kjeldahl method, which is one of the most commonly used for protein analysis. The results obtained by two methods were not significantly different at 95% confidence level.
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