Date of Award

1-1-2021

Language

English

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College/School/Department

Department of Environmental Health Sciences

Content Description

1 online resource (ix, 102 pages) : illustrations (some color)

Dissertation/Thesis Chair

Patrick J Parsons

Committee Members

Beth Feingold, David Spink

Keywords

Lead poisoning in children, Lead, Atomic absorption spectroscopy, Electrostatic atomization, Blood

Subject Categories

Environmental Health

Abstract

Lead (Pb) is ubiquitous in the environment and exposure can have adverse health effects even at low concentrations, particularly in young children. Blood lead levels (BLLs) are the best indicator of recent Pb exposure. Based upon data from the NHANES, the Centers for Disease Control and Prevention’s (CDC) blood Pb (BPb) reference value, defined as the 97.5th percentile of children 1-5 years old, was lowered from 10 μg/dL to 5 μg/dL in 2012. According to more recent NHANES data, the 97.5th percentile has decreased to 3.5 μg/dL. If the CDC recommends a further lowering of the BPb reference value, many more children will be identified as having elevated BLLs. Electrothermal Atomic Absorption Spectrometry (ETAAS) is an established method for determining Pb in blood and has an estimated detection limit (LOD) of ~1 μg/dL, which presents an analytical challenge for its clinical use, given that the current geometric mean BLL is 0.82 μg/dL. Accuracy and precision may be insufficient to quantitate low BLLs in the 1-5 µg/dL range, which would be essential if the CDC recommends lowering the BPb reference value to 3.5 μg/dL. The principal aim of this study was to improve the previously established method for the determination of Pb in blood using ETAAS, and achieve a lower detection limit to support current screening and diagnostic needs. Different modifiers and calibration strategies were all assessed during method development to yield an improved signal to noise ratio. Proposed method changes include using: a permanent W-Rh modifier; 16 μL injection volume; a 1+9 dilution; and a matrix matched calibration curve ranging from 1 μg/L to 40 μg/L, equivalent to 1 μg/dL to 40 μg/dL. Various blood-based standard reference materials (SRMs) and proficiency testing (PT) samples were used for the method validation study. Human blood samples were analyzed for Pb for validation against an established ICP-MS method. The improved ETAAS method developed achieved a lower LOD of 0.2 μg/dL, with the ability to quantitate BLLs down to 1 μg/dL. Additionally, this method is fit for the purpose of detecting BLLs given the current population levels, with excellent accuracy and precision in the 1- 5 μg/dL range. Results from the SRMs, PT materials and human blood samples were in good agreement with those obtained by ICP-MS, and agreement between two different ETAAS platforms was demonstrated. The proposed improvements provide evidence of an ETAAS method capable of achieving lower LODs with improved accuracy and precision at lower BLLs.

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