Detection of trace chlorine pollutants in recycled pulp using gas chromatography-tandem mass spectrometry with response surface-optimized carbon structure online catalysis.

RATIONALE: Chlorinated aromatics and alkanes are widely used for their flame retardancy, but they need to be monitored when used in recycled pulp. This paper reports the use of palladium acetate/activated carbon (Pa/Ac) activated by nitric acid as an online catalyst to determine chlorinated aromatics and chlorinated alkanes in recycled paper products using gas chromatography-tandem mass spectrometry (GC-MS/MS), which significantly improves the sensitivity of the method and remarkably lowers the detection limits. METHODS: The Pa/Ac catalyst was prepared using a self-made catalytic device and used as key to the online catalytic conversion of target chlorinated aromatic hydrocarbons and chlorinated alkanes for GC-MS/MS analysis. The response surface model was used to optimize catalytic conditions. Then GC-MS/MS in the multireaction monitoring mode with online catalysis was applied for the analysis of polychlorinated biphenyls, polychlorinated terphenyls, polychlorinated naphthalene, and chlorinated paraffins (CP) in recycled paper products. RESULTS: Compared with traditional methods, the Pa/Ac catalyst can transform chlorinated aromatic hydrocarbons into aromatic hydrocarbons through dechlorination hydrogenation, thus lowering the detection limit of the GC-MS/MS method significantly. It can transform paraffin chloride into the corresponding alkane to better distinguish short-chain, medium-chain, or long-chain CPs. Online catalytic conversion significantly improved the sensitivity and reproducibility (88.7%-113.1%) of the method. Tissue samples with various concentration levels of chlorinated aromatics and chlorinated alkanes were tested. The linearity range of the reduced target compounds in the reduction product solution was 0.02-1.00 µg/ml (R2  > 0.995). The quantitative detection limit was 0.03-0.05 µg/kg, and relative standard deviation was less than 6.9%. CONCLUSION: This study was the first to introduce the Pa/Ac catalytic device as an online catalytic unit in the determination of chlorinated aromatics and chlorinated alkanes using the GC-MS/MS method. The target compounds were converted into alkanes and aromatic hydrocarbons with unchanged carbon structures, and the method could achieve a low detection limit with no need for high-end methods such as GC-chemical ionization ion source (CI)-MS or high-resolution mass spectrometry. These methods are suitable for the determination of chlorine pollutants in recycled paper and its raw materials.

Potential safety concerns of volatile constituents released from coffee-ground-blended single-use biodegradable drinking straws: A chemical space perspective.

Incorporating spent coffee grounds into single-use drinking straws for enhanced biodegradability also raises safety concerns due to increased chemical complexity. Here, volatile organic compounds (VOCs) present in coffee ground straws (CGS), polylactic acid straws (PLAS), and polypropylene straws (PPS) were characterized using headspace - solid-phase microextraction and migration assays, by which 430 and 153 VOCs of 10 chemical categories were identified by gas chromatography - mass spectrometry, respectively. Further, the VOCs were assessed for potential genetic toxicity by quantitative structure-activity relationship profiling and estimated daily intake (EDI) calculation, revealing that the VOCs identified in the CGS generally triggered the most structural alerts of genetic toxicity, and the EDIs of 37.9% of which exceeded the threshold of 0.15 µg person-1 d-1, also outnumbering that of the PLAS and PPS. Finally, 14 VOCs were prioritized due to their definite hazards, and generally higher EDIs or detection frequencies in the CGS. Meanwhile, the probability of producing safer CGS was also illustrated. Moreover, it was uncovered by chemical space that the VOCs with higher risk potentials tended to gather in the region defined by the molecular descriptor related to electronegativity or octanol/water partition coefficient. Our results provided valuable references to improve the chemical safety of the CGS, to promote consumer health, and to advance the sustainable development of food contact materials.

Aluminum Foil Lattice Method for Characterizing Performance of Bath-Type Ultrasonic-Assisted Extraction Equipment.

Background: Bath-type ultrasonic-assisted extraction (UAE) has been developed as one of the most important sample pretreatment methods, especially for batch-sample pretreatment. So far, however, requirements for the performance of bath-type UAE equipment have not been standardized, nor has a suitable evaluation method that can be used to judge the feasibility of ultrasonic equipment for extraction been presented in the available regulations or standards. Objective: A simple and efficient method that can be used to evaluate the performance of bath-type UAE equipment is necessary to be proposed and established. Methods: First, distribution of a sound field in ultrasonic equipment was measured by acoustimeter and the dyeing method, through which influencing factors including frequency, preheating time, and output power of the equipment, as well as the horizontal and vertical position for locating the sample in the equipment, were investigated, and optimized parameters for extraction were achieved. Then, through the aluminum foil lattice method, by calculating the perforated rate of the aluminum foil, cavitation intensity of the ultrasonic equipment can be quantitatively determined. Results: With the optimized working conditions and by selecting appropriate parameters for the aluminum foil, perforated holes formed on the foil displayed a good pattern. Further validation experiments indicated conformity between the established method and the actual extraction effect of the ultrasonic equipment, proposing a suitable requirement for the cavitation effect of the bath-type UAE equipment. Conclusions: The aluminum foil lattice method has been proved to be simple, convenient, inexpensive, and reliable for quickly evaluating the extraction performance of bath-type UAE equipment.

A robust method for determining water-extractable alkylphenol polyethoxylates in textile products by reaction-based headspace gas chromatography.

Alkylphenol polyethoxylates (APEO), surfactants used in the production of textiles, have the potential to move from the fabric to the skin of the person wearing the clothes, posing an inherent risk of adverse health consequences. Therefore, the textile industry needs a fast, robust method for determining aqueous extractable APEO in fabrics. The currently-favored HPLC methods are limited by the presence of a mixture of analytes (due to the molecular weight distribution) and a lack of analytical standards for quantifying results. As a result, it has not been possible to reach consensus on a standard method for the determination of APEO in textiles. This paper addresses these limitations through the use of reaction-based head space-gas chromatography (HS-GC). Specifically, water is used to simulate body sweat and extract APEO. HI is then used to react the ethoxylate chains to depolymerize the chains into iodoethane that is quantified through HS-GC, providing an estimate of the average amount of APEO in the clothing. Data are presented to justify the optimal operating conditions; i.e., water extraction at 60°C for 1h and reaction with a specified amount of HI in the headspace vial at 135°C for 4h. The results show that the HS-GC method has good precision (RSD<10%) and good accuracy (recoveries from 95 to 106%) for the quantification of APEO content in textile and related materials. As such, the method should be a strong candidate to become a standard method for such determinations.