Needle microextraction trap for on-site analysis of airborne volatile compounds at ultra-trace levels in gaseous samples

Needle trap device technique: From fabrication to sampling

Needle Trap Device (NTD) as a novel, versatile, and eco-friendly technique has played an important role in analytical and environmental chemistry. The distinctive role of this interdisciplinary technique can be defended through the sampling and analysis of biological samples and industrial pollutants in gaseous and liquid environments. In recent years, significant efforts have been made to enhance the performance of the needle trap device resulting in the development of novel extraction routes by various packing materials with improved selectivity and enhanced adsorption characteristics. These achievements can lead to the facilitated pre-concentration of desired analytes. This review tries to have a comparative and comprehensive survey of the three important areas of NTD technique: I) Fabrication and preparation procedures of NTDs; II) Sampling techniques of pollutants using NTDs; and III) Employed materials as adsorbents in NTDs. In the packing-material section, the commercial and synthetic adsorbents such as carbon materials, metal-organic frameworks, aerogel, and polymers are considered. Furthermore, the limitations and potential areas for future development of the NTD technique are presented.

Application of a needle trap device packed with a MIP@MOF nano-composite for efficient sampling and determination of airborne diazinon pesticide

In this research, a novel, selective, and efficient porous adsorbent nano-composite comprising a molecularly imprinted polymer and a metal-organic framework (MIP@MOF) was employed for sampling, extraction and analysis of diazinon from the air by a needle trap device (NTD), for the first time. The synthesized MIP@MOF sorbent was characterized by the FT-IR, XRD, FE-SEM, TEM, and EDS techniques. Then, the effective parameters of the sampling (temperature and humidity) and desorption (time and temperature) process were optimized by response surface methodology (RSM). The optimum values of temperature and humidity of the sampling chamber were estimated to be 20 °C and 25.0%, respectively. Also, the highest response during the analyte desorption was obtained at 262 °C and 4.5 minutes. For more details, the performance of the MIP@MOF:NTD method was evaluated by determination of important parameters such as repeatability, reproducibility, the limit of detection (LOD), and the limit of quantification (LOQ), and then compared with the NIOSH 5600 standard method. The values of LOD and LOQ for the targeted analyte were determined to be 0.02 and 0.1 μg m-3, respectively. Also, the repeatability and reproducibility of the proposed method were obtained in the range of (3.9-5.1)% and (5.1-6.4)%, respectively, which proved the acceptable precision of the method. Furthermore, the results of this study exhibited a high correlation coefficient (R 2 = 0.9781) between the proposed method and the recommended NIOSH method. Finally, the proposed procedure was utilized for sampling and determination of the airborne diazinon in real conditions. These results indicated that the proposed MIP@MOF:NTD method can be employed as a fast, simple, environmentally friendly, selective, and effective procedure for sampling and determining diazinon in air.

Optimization of the in-needle extraction device for the direct flow of the liquid sample through the sorbent layer

In-needle extraction was applied for preparation of aqueous samples. This technique was used for direct isolation of analytes from liquid samples which was achieved by forcing the flow of the sample through the sorbent layer: silica or polymer (styrene/divinylbenzene). Specially designed needle was packed with three different sorbents on which the analytes (phenol, p-benzoquinone, 4-chlorophenol, thymol and caffeine) were retained. Acceptable sampling conditions for direct analysis of liquid sample were selected. Experimental data collected from the series of liquid samples analysis made with use of in-needle device showed that the effectiveness of the system depends on various parameters such as breakthrough volume and the sorption capacity, effect of sampling flow rate, solvent effect on elution step, required volume of solvent for elution step. The optimal sampling flow rate was in range of 0.5-2 mL/min, the minimum volume of solvent was at 400 µL level.

Needle-trap device for the sampling and determination of chlorinated volatile compounds

A needle-trap device, with immobilized sorbent inside the syringe, coupled with GC-MS was applied for air sampling and determination of chlorinated volatile organic compounds such as dichloromethane, trichloromethane, and tetrachloromethane. The application of a needle trap packed with combination of three sorbents including Tenax TA, Carbopack X, and Carboxen 1000 resulted in detection limits of few pg for chlorinated volatile compounds and recoveries of 99.2-102.8%. The extraction and desorption parameters were optimized within the study. As a result, the precision determined as RSD was equal to 5.05 and 3.03 and 6.52% for dichloromethane, trichloromethane, and tetrachloromethane, respectively. The storage time for chlorinated compounds up to 48 h and reusability of the needle-trap device were verified. The obtained results have proved the ability of needle traps to compete with other solventless sampling and sample preparation extraction techniques.