ABSTRACT
A novel trace analytical method based on solvent sublation (SS) and gas chromatography-mass spectrometry (GC-MS) was developed for the trace determination of twenty-two phthalate esters (PAEs) from plastic beverage packaging. In the solvent sublation section, the effects of solution pH, NaCl concentration, nitrogen flow rate, and sublation time on the sublation efficiency were investigated in detail, and the optimal conditions were obtained. The trace PAEs migrated from plastic beverage packaging to food simulants were separated and concentrated by solvent sublation, and then the trace target compounds in the concentrated solution were analyzed by GC-MS. According to the European Union Regulation, the food simulants including distilled water for the normal beverages and acetic acid solution (3%) for the acetic beverage of yogurt were prepared for migration tests. The trace analysis method showed good linearity, low limits of detection (LODs) of 1.6-183.5 ng/L, and satisfied recoveries (67.3-113.7%).
Subject(s)
Esters/chemistry , Food Packaging , Gas Chromatography-Mass Spectrometry/methods , Phthalic Acids/chemistry , Plastics/chemistry , Beverages/analysis , Solvents/chemistryABSTRACT
Using solvent sublation (SS), a novel pretreatment method for separating and concentrating antioxidants and ultraviolet absorbers from plastic beverage packaging was developed, and these target compounds were quantitatively analyzed by high-performance liquid chromatography (HPLC). In the pretreatment section, the effects of the sublation solvent, solution pH, NaCl concentration, nitrogen flow rate, sublation time, and light condition on the sublation efficiency were investigated in detail and the optimal conditions of the solvent sublation process were selected. The analytical method of SS-HPLC showed good linearity in the range from 0.33 to 667 ng/mL with good presenting regression coefficients (0.9995 ≥ R(2) ≥ 0.9972). Low limits of detection (LODs) of 0.34-1.25 ng/mL and limits of quantification (LOQs) of 1.13-4.15 ng/mL were achieved. The mean recoveries were in the range from 88.73 to 107.65% at 20, 30, and 40 ng/mL spiked levels, and the relative standard deviations (RSDs) were in the range from 2.16 to 10.55%.
Subject(s)
Chromatography, High Pressure Liquid/methods , Food Analysis/methods , Food Packaging , Plastics , Polymers/analysis , Antioxidants/analysis , Benzophenones/analysis , Beverages , Butylated Hydroxytoluene/analogs & derivatives , Butylated Hydroxytoluene/analysis , Chromatography, High Pressure Liquid/instrumentation , Food Analysis/instrumentation , Hydrogen-Ion Concentration , Limit of Detection , Organothiophosphorus Compounds/analysis , Polymers/chemistry , Regression Analysis , Sodium Chloride , Solvents/chemistryABSTRACT
Solvent sublation is a kind of adsorptive bubble separation technique in which the surface-active (or hydrophobic) compounds in aqueous phase are adsorbed on the bubble surfaces of an ascending gas stream and then collected in an organic layer placed on top of the aqueous phase. The technique has many advantages, such as high separation efficiency, high concentration coefficient, low dosage of organic solvent, soft separation process, and simple operation. Thus, this technique has been widely applied in many fields. The present article reviews solvent sublation's theoretical research and some applications in the last 10 years, and gives the development trend in the future.
Subject(s)
Chemical Fractionation/methods , Models, Chemical , Solvents/chemistry , Hydrophobic and Hydrophilic Interactions , KineticsABSTRACT
A novel method is developed for separating and enriching pyrethroid pesticides from vegetables by solvent sublation, and determination of the pyrethroids is performed by high-performance liquid chromatography (HPLC). The effects of organic solvent, pH of the solution, nitrogen flow rate, and sublation time on the sublation efficiency of pyrethroids are investigated in detail, and the optimal conditions of the solvent sublation are selected. The floated product of vegetables in the optimal conditions is determined by HPLC. The limit of detection values range from 1.4 microg/kg (for bifenthrin) to 4.2 microg/kg (for fenpropathin). The recoveries of spiked vegetable samples are from 85.7% to 110.4%, and relative standard deviation values are from 1.70% to 6.19%. The results are satisfactory.
Subject(s)
Chromatography, High Pressure Liquid/methods , Pesticide Residues/analysis , Pyrethrins/analysis , Vegetables/chemistry , Adsorption , Hydrogen-Ion Concentration , Nitriles/analysis , Solvents , UncertaintyABSTRACT
The determination of trace water in gas samples, such as isobutene, chloromethane (polymeric staple gases) and SF6 by a conventional Karl Fischer coulometer is very difficult, because of the adsorption of trace water on the surface of sample pipe, the gasification of the liquefied samples, and the migration of moisture into the measuring cell from the surroundings. To solve these problems, we improved a device for coulometric determination of water by Karl Fischer method. The improved coulometer was used to determine the trace water in isobutene, chloromethane and SF6; RSD was less than 5%, and recoveries ranged from 94.1 to 109.1%, which is adequate for the analysis of industry.
