Elemental Bio-imaging Facility, University of Technology, Sydney, Broadway, New South Wales, Australia.
Anal Chem. 2012 Aug 7;84(15):6707-14. doi: 10.1021/ac301156f. Epub 2012 Jul 9.
Imaging of trace metal distribution in tissue sections by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is typically performed using spatial resolutions of 30 μm(2) and above. Higher resolution imaging is desirable for many biological applications in order to approach the dimensions of a single cell. The limiting factor for increasing resolution is sensitivity, where signal-to-noise ratios are poor due to inherent background spectral interferences and reduced sample volume with decreasing laser beam diameter. Several prominent spectral interferences are present for a number of biologically relevant isotopes, including the (40)Ar(16)O(+) spectral interference on (56)Fe(+). We examined if H(2) as a reaction gas could improve the analytical performance of imaging experiments for a range of masses with spectral interferences. At low (<1 mL min(-1)) H(2) flow rates, greater spectral interference due to H(+) adducts was observed for (55)Mn, (57)Fe, and (59)Co. At higher flow rates of up to 3 mL H(2) per minute, the spectral interferences were reduced leading to improvement in limits of analysis for masses with O- and N-based polyatomic interferences. Enhanced sensitivity with the reaction cell allowed construction of high resolution (6 μm(2)) imaging of (56)Fe in the mouse brain that approached the dimensions of single cells.
采用激光烧蚀-电感耦合等离子体质谱法（LA-ICP-MS）对组织切片中的痕量金属分布进行成像，通常使用 30μm(2)及以上的空间分辨率进行。对于许多生物学应用，更高的分辨率成像更可取，以便接近单个细胞的尺寸。提高分辨率的限制因素是灵敏度，由于固有背景光谱干扰和激光束直径减小导致的样品体积减少，信噪比较差。对于许多与生物学相关的同位素，包括 (56)Fe(+)上的 (40)Ar(16)O(+)光谱干扰，存在几个突出的光谱干扰。我们研究了在存在光谱干扰的情况下，作为反应气体的 H(2)是否可以改善一系列质量的成像实验的分析性能。在低(<1 mL min(-1))H(2)流速下，(55)Mn、(57)Fe 和 (59)Co 的 H(+)加合物引起更大的光谱干扰。在高达 3 mL H(2)/分钟的更高流速下，光谱干扰减少，导致具有 O 和 N 基多原子干扰的质量的分析极限得到改善。反应池的增强灵敏度允许构建接近单个细胞尺寸的小鼠大脑中 (56)Fe 的高分辨率（6μm(2)）成像。
