使用衝擊採樣瓶和單粒子感應耦合電漿質譜儀 (sp-ICPMS)檢測環境空氣中二氧化鈦奈米微粒之可行性研究

Abstract

二氧化鈦奈米微粒(TiO2 NPs)是世界上使用最廣泛的奈米材料之一，其應用範圍從半導體產業、環境整潔到商業產品等。先前的研究指出，二氧化鈦奈米微粒可能對人產生氧化壓力、發炎或細胞凋亡等毒性作用。隨著二氧化鈦奈米微粒在各個領域的使用普及性，人們暴露到二氧化鈦奈米微粒的風險也隨之而提升，並且可能對健康產生不利影響。然而，目前為止較少有研究探討環境空氣中二氧化鈦奈米微粒的濃度和粒徑分佈，而且既有的標準採樣分析方法需要耗費較長的時間和成本。因此，快速採樣分析環境空氣中的二氧化鈦奈米微粒是一項挑戰性的議題。本研究目的旨在嘗試和評估新的環境空氣中二氧化鈦奈米微粒之採樣分析方法，並以此方法量測環境空氣中二氧化鈦奈米微粒質量濃度、數目濃度和粒徑大小。 本研究以Sigma-Aldrich的二氧化鈦奈米微粒粉末(< 100 nm)作為標準品，使用三個25 mL衝擊採樣瓶搭配高流量泵和單粒子感應耦合電漿質譜儀(sp-ICPMS)採樣分析二氧化鈦奈米微粒，並以掃描式電移動度微粒分徑器(SMPS)量測結果作為黃金標準，來評估使用衝擊採樣瓶和sp-ICPMS採樣分析環境空氣中二氧化鈦奈米微粒之可行性。衝擊採樣瓶和高流量泵的採樣條件設定為：採樣流率2 Lpm、採樣時間2 min和捕集液體積20 mL。 研究結果顯示，sp-ICPMS分析二氧化鈦奈米微粒的準確度和儀器穩定性皆在80 % - 120 %的範圍內。SMPS量測二氧化鈦奈米微粒之平均質量濃度、平均數目濃度和平均粒徑大小分別為0.35μg/m3、612.05顆/cm3和28.56 nm。至於sp-ICPMS分析儲存14天後經超音波震盪處理的二氧化鈦奈米微粒樣本之平均質量濃度與平均數目濃度分別為3.70μg/m3和261.79顆/cm3，平均粒徑為33.3 nm，與SMPS量測結果最為接近。 本研究認為在粒徑大小方面，sp-ICPMS與SMPS的量測結果較有相似性，至於質量濃度和數目濃度方面，需要更進一步探討兩種分析儀器之間的相關性。此外，本研究發現超音波震盪處理有助於二氧化鈦奈米微粒在二次去離子水中的粒徑穩定性。同時，本研究也觀察到儲存天數的長短對於二氧化鈦奈米微粒之質量濃度、數目濃度和粒徑大小的變化沒有明顯的影響。本研究為量測環境空氣中二氧化鈦奈米微粒提供了一種新的嘗試，也為未來建立二氧化鈦奈米微粒的採樣和分析方法提供了參考。

Titanium dioxide nanoparticles (TiO2 NPs) are among the most widely used nanomaterials globally, with applications spanning from the semiconductor industry and environmental cleanup to commercial products. Previous studies have indicated that TiO2 NPs may induce oxidative stress, inflammation, or apoptosis in humans. As the prevalence of TiO2 NPs in various fields increases, the risk of exposure to these particles also rises, potentially leading to adverse health effects. However, few studies have investigated the concentration and size distribution of TiO2 NPs in ambient air, and existing standard sampling and analysis methods are often time-consuming and costly. Consequently, the rapid sampling and analysis of TiO2 NPs in ambient air remains a challenging issue. This study aims to attempt and evaluate novel sampling and analysis methods for TiO2 NPs in ambient air, measuring their mass concentration, number concentration, and size. In this study, Sigma-Aldrich titanium dioxide nanopowder (< 100 nm) was used as the standard. Three 25 mL impingers, combined with a high-flow pump and single-particle inductively coupled plasma mass spectrometry (sp-ICPMS), were used to sample and analyze TiO2 NPs. The measurements obtained with the scanning mobility particle sizer (SMPS) served as the gold standard to evaluate the feasibility of using impingers and sp-ICPMS for sampling and analyzing TiO2 NPs in ambient air. The sampling conditions for the impingers and high-flow pump were set as follows: sampling flow rate of 2 Lpm, sampling time of 2 minutes, and a collection liquid volume of 20 mL. The results showed that the accuracy and instrument stability of sp-ICPMS for analyzing TiO2 NPs were within the range of 80 % - 120 %. The SMPS measurements of TiO2 NPs indicated an average mass concentration of 0.35 μg/m³, an average number concentration of 612.1 particles/cm³, and an average particle size of 28.6 nm. For the sp-ICPMS analysis of TiO2 NP samples treated with ultrasonic agitation after 14 days of storage, the average mass concentration and number concentration were 3.70 μg/m³ and 261.8 particles/cm³, respectively, with an average particle size of 33.3 nm, closely matching the SMPS measurements. The findings of this study suggest that sp-ICPMS and SMPS provide similar results regarding particle size, but further investigation is needed to understand the correlation between the two instruments concerning mass concentration and number concentration. Additionally, the study found that ultrasonic agitation helps maintain the size stability of TiO2 NPs in deionized water. No significant effect of storage duration on the mass concentration, number concentration, or size of TiO2 NPs was observed. This study offers a novel approach to measuring TiO2 NPs in ambient air and provides a reference for future development of sampling and analysis methods for TiO2 NPs.