| Manganese, as an essential trace element, is a cofactor in numerous enzymes that aid in bone growth, cholesterol synthesis, and carbohydrate metabolism. Manganese can become toxic with overexposure, potentially leading to neurodegenerative effects and the disease manganism. Manganese concentrations in blood and urine have been widely used in monitoring current exposure and now there is interest in using manganese concentrations in teeth for monitoring historical exposure, especially in utero and in early childhood.;The primary objective of this study was to develop, validate, and compare methods for the determination of manganese in blood and urine using graphite furnace atomic absorption spectrometry (GFAAS), quadrupole-based (Q-) inductively coupled plasma mass spectrometry (ICP-MS), and sector field (SF-) ICP-MS. A secondary goal was to investigate the determination of manganese in tooth specimens using laser ablation (LA-) coupled to ICP-MS. From this comprehensive work, the measurement traceability of manganese in blood, urine, and teeth was characterized; a thorough understanding of the mass spectrometry behind the measurement of manganese was achieved; and the current interlaboratory performance for blood and urine manganese was evaluated.;Experiments showed that GFAAS is a suitable technique for determining manganese in blood and urine, but for Q-ICP-MS, the use of a reaction/collision gas is necessary to attenuate polyatomic interferences and abundance sensitivity (blood). The use of medium resolution mode in SF-ICP-MS is necessary to avoid these interferences. For manganese in teeth, several methods of calibration for LA-ICP-MS were explored, but accurate quantification still remains a challenge for this technique. Matrix-matched calibrations are required for blood, urine, and teeth in ICP-MS. Using the New York State Department of Health (NYS DOH) Trace Elements Proficiency Testing (PT) Program, interlaboratory performance for blood and urine manganese was summarized as ±4 μg/L or ±20% (above 20 μg/L) and ±1.5 μg/L or ±20% (above 7.5 μg/L), respectively.;In conclusion, blood manganese can be used as a biomarker of exposure after careful optimization of analytical techniques. Urine manganese is less useful as concentrations are generally near detection limits. Tooth manganese is an information-rich biomarker, but more work is needed to improve its quantification. |
