Physics Department, Mount Allison University, Sackville, New Brunswick, Canada.
Physics Department, Mount Allison University, Sackville, New Brunswick, Canada.
J Trace Elem Med Biol. 2023 May;77:127136. doi: 10.1016/j.jtemb.2023.127136. Epub 2023 Jan 24.
Novel and emerging biomarkers of zinc status are being developed to help study and address zinc deficiency around the world. Two potential biomarkers, nail and hair, involve the measurement of zinc from easily accessible keratin-based components of the body. Portable X-ray fluorescence (XRF) is a relatively new approach to the assessment of zinc in nail or hair, and has a number of compelling advantages compared with other techniques. The aim of the current study was to test the ability of XRF to measure zinc in keratinized reference materials (RMs) designed to simulate nail and hair.
Four Keratin Matrix RMs were prepared and characterized for numerous trace elements by the New York State Department of Health's Wadsworth Center. The Keratin Matrix RMs consisted of powdered samples of caprine (goat) horns pooled from several animals. Concentrations of zinc, as assessed by inductively coupled plasma mass spectrometry (ICP-MS), were similar to what would be expected from human nail or hair tissues. Repeat measurements of the RMs were made using a portable XRF system. The XRF zinc results were compared with the ICP-MS zinc concentrations. Three different approaches to quantifying the zinc content by XRF were performed: (1) zinc signal to total signal ratio, (2) zinc signal to sulfur signal ratio, and (3) system output zinc concentration.
The portable XRF results from a given RM were found to be consistent across repeat trials under all three approaches to XRF quantitation. Precision, calculated as the relative standard deviation of repeat measurements ranged from an average result of 0.8 % (using the system output zinc concentration method) to 6.1 % (using the zinc signal to sulfur signal ratio method). Measurement of the RMs provided XRF zinc results which scaled well with ICP-MS zinc concentration, particularly when using the XRF zinc to total and system zinc concentration methods. A Bland-Altman plot showed that the XRF system zinc concentration output exceeded the ICP-MS zinc concentration by, on average, 10.2 % ± 1.2 %.
Overall, both accuracy and precision of measurement were found to be promising for portable XRF, provided appropriate conversions to concentration are introduced. The results of this study indicate that portable XRF is an effective and dependable method of assessing zinc concentration in keratinized tissue RMs. This will have implications for the future use of portable XRF to monitor zinc status in humans through measurements of nail and hair.
目前正在开发新的和新兴的锌状态生物标志物，以帮助研究和解决世界各地的锌缺乏问题。两种潜在的生物标志物，指甲和头发，涉及从身体易于获得的角蛋白组成部分测量锌。便携式 X 射线荧光（XRF）是一种评估指甲或头发中锌的新技术，与其他技术相比具有许多优势。本研究的目的是测试 XRF 测量模拟指甲和头发的角蛋白化参考材料（RM）中锌的能力。
纽约州卫生部的瓦兹沃思中心（Wadsworth Center）对四种角蛋白基质 RM 进行了大量痕量元素的制备和特性描述。角蛋白基质 RM 由来自多种动物的山羊角粉末样品组成。通过电感耦合等离子体质谱法（ICP-MS）评估的锌浓度与从人指甲或头发组织中预期的浓度相似。使用便携式 XRF 系统对 RM 进行了重复测量。将 XRF 锌结果与 ICP-MS 锌浓度进行比较。通过三种不同的方法对 XRF 进行定量分析：（1）锌信号与总信号的比值，（2）锌信号与硫信号的比值，以及（3）系统输出锌浓度。
在所有三种 XRF 定量方法下，都发现给定 RM 的便携式 XRF 结果在重复试验中是一致的。精密度，以重复测量的相对标准偏差表示，范围从平均 0.8%（使用系统输出锌浓度方法）到 6.1%（使用锌信号与硫信号比值方法）。对 RM 的测量提供了与 ICP-MS 锌浓度很好地匹配的 XRF 锌结果，特别是当使用 XRF 锌与总锌和系统锌浓度方法时。Bland-Altman 图显示，XRF 系统锌浓度输出平均比 ICP-MS 锌浓度高 10.2%±1.2%。
总体而言，只要引入适当的浓度转换，便携式 XRF 的准确性和精密度都被认为是有希望的。这项研究的结果表明，便携式 XRF 是一种评估角蛋白化组织 RM 中锌浓度的有效可靠方法。这将对未来通过指甲和头发测量来监测人体锌状态的便携式 XRF 的使用产生影响。
