不同顆粒大小和金屬種類對於串聯微分電移動度粒徑分析儀與單顆粒感應耦合電漿質譜儀系統傳輸效率的影響

Abstract

單顆粒感應耦合電漿質譜儀(single particle inductively coupled plasma mass spectrometry, spICP-MS) 已被廣泛應用於環境奈米顆粒的研究。然而，實際環境中的奈米顆粒通常為非球形且組成複雜，這可能會影響spICP-MS分析的精準度。已有研究顯示，通過霧化器(atomizer, ATM)、微分電移動度粒徑分析儀(differential mobility analyzer, DMA)及spICP-MS的串聯系統 (ATM-DMA-spICP-MS)，可以獲得更精確的奈米顆粒粒徑量測，同時估算奈米顆粒的濃度。在奈米顆粒濃度的測定中，傳輸效率(transport efficiency, "η" _"n" )，其定義為系統中出流顆粒濃度與進流顆粒數量濃度的比值，的測定極為重要。目前的標準程序中，通常先測定50 nm金標準奈米顆粒的傳輸效率，再假設其他尺寸及種類的奈米顆粒具有相同的傳輸效率，再將此50 nm金標準奈米顆粒的傳輸效率用於這些奈米顆粒濃度的估算。然而，此假設需要加以驗證以確保顆粒數量濃度的準確量化。 本研究採用金標準奈米顆粒(粒徑＝30 nm、50 nm、80 nm及100 nm)、銀標準奈米顆粒(粒徑＝30 nm、50 nm、80 nm及100 nm)以及鉑標準奈米顆粒(粒徑＝50 nm)來探討顆粒尺寸和金屬組成對於獨立spICP-MS和串聯系統傳輸效率的影響。對於獨立spICP-MS而言，所有大於30 nm的金、銀和鉑標準奈米顆粒有相似的傳輸效率，顯示使用50 nm 金標準奈米顆粒所測定的傳輸效率應可以適用於其他尺寸大於30 nm的奈米顆粒。然而，對於串聯系統，實驗結果顯示傳輸效率會隨顆粒尺寸的增加而增加，而且不同金屬奈米顆粒之間存在差異。因此，本研究針對金奈米顆粒和銀奈米顆粒建立了傳輸效率與顆粒直徑之間的相關曲線，此曲線可以用於估算不同尺寸金奈米顆粒和銀奈米顆粒的傳輸效率，可以讓串聯系統更準確地量化環境樣品中金奈米顆粒和銀奈米顆粒的顆粒數量濃度。

Single particle inductively coupled plasma mass spectrometry (spICP-MS) has emerged as a prevalent analytical technique for studying environmental nanoparticles. However, nanoparticles in environmental samples are generally non-spherical and composed of various elements, which influence the precision of spICP-MS analysis. It has been demonstrated that more accurate sizing ability can be achieved by hyphenating the atomizer (ATM), differential mobility analyzer (DMA), and spICP-MS (hyphenated ATM-DMA-spICP-MS). Although the system has been successfully developed, it relies on using a single-sized (typically 50 mm) gold nanoparticle as the reference to determine the transport efficiency ("η" _"n" ), defined as the ratio of effluent particle concentration to influent particle concentration in the system, for particle number concentration estimations. It is generally assumed that the transport efficiency can be applied to nanoparticles with different sizes and metallic compositions. However, this assumption requires verification to ensure accurate quantification of particle number concentration. This study utilized gold standard nanoparticle (AuNPs) (30 nm, 50 nm, 80 nm, 100 nm), silver standard nanoparticle (AgNPs) (30 nm, 50 nm, 80 nm, 100 nm), and platinum standard nanoparticle (PtNPs) (50 nm) to investigate the influences of particle size and metal composition on transport efficiency for stand-alone spICP-MS and the hyphenated system. For stand-alone spICP-MS, a similar transport efficiency was found for these standard nanoparticles with a size > 30 nm, suggesting that the transport efficiency determined using 50 mm AuNPs, as outlined in the spICP-MS manufacture’s user manual, can be used for other nanoparticles with a size greater than 30 nm. In contrast, for the hyphenated system, the transport efficiency generally increased with the particle size and varied among different metallic nanoparticles. The correlations between transport efficiency and particle size were established for AuNPs and AgNPs and can be used to provide a more accurate quantification of particle number concentration of AuNPs and AgNPs in environmental samples using the hyphenated system.