Reactions of first-row transition metal ions with propargyl alcohol in the gas phase

Assessing the stability of Cd, Mn, Pb, Se, and total Hg in whole human blood by ICP-DRC-MS as a function of temperature and time

BACKGROUND

Comprehensive information on the effect of time and temperature storage on the measurement of elements in human, whole blood (WB) by inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS) is lacking, particularly for Mn and Se.

METHODS

Human WB was spiked at 3 concentration levels, dispensed, and then stored at 5 different temperatures: -70 °C, -20 °C, 4 °C, 23 °C, and 37 °C. At 3 and 5 weeks, and at 2, 4, 6, 8, 10, 12, 36 months, samples were analyzed for Pb, Cd, Mn, Se and total Hg, using ICP-DRC-MS. We used a multiple linear regression model including time and temperature as covariates to fit the data with the measurement value as the outcome. We used an equivalence test using ratios to determine if results from the test storage conditions, warmer temperature and longer time, were comparable to the reference storage condition of 3 weeks storage time at -70 °C.

RESULTS

Model estimates for all elements in human WB samples stored in polypropylene cryovials at -70 °C were equivalent to estimates from samples stored at 37 °C for up to 2 months, 23 °C up to 10 months, and -20 °C and 4 °C for up to 36 months. Model estimates for samples stored for 3 weeks at -70 °C were equivalent to estimates from samples stored for 2 months at -20 °C, 4 °C, 23 °C and 37 °C; 10 months at -20 °C, 4 °C, and 23 °C; and 36 months at -20 °C and 4 °C. This equivalence was true for all elements and pools except for the low concentration blood pool for Cd.

CONCLUSIONS

Storage temperatures of -20 °C and 4 °C are equivalent to -70 °C for stability of Cd, Mn, Pb, Se, and Hg in human whole blood for at least 36 months when blood is stored in sealed polypropylene vials. Increasing the sample storage temperature from -70 °C to -20 °C or 4 °C can lead to large energy savings. The best analytical results are obtained when storage time at higher temperature conditions (e.g. 23 °C and 37 °C) is minimized because recovery of Se and Hg is reduced. Blood samples stored in polypropylene cryovials also lose volume over time and develop clots at higher temperature conditions (e.g., 23 °C and 37 °C), making them unacceptable for elemental testing after 10 months and 2 months, respectively.

Thermochemistry, bonding, and reactivity of Ni+ and Ni2+ in the gas phase

In this review, we present a general overview on the studies carried out on Ni(+-)- and Ni(2+)-containing systems in the gas phase since 1996. We have focused our attention in the determination of binding energies in parallel with an analysis of the structure and bonding of the complexes formed by the interaction of Ni(+) with one ligand, or in clusters where this metal ion binds several identical or different ligands. Solvation of Ni(2+) by different ligands is also discussed, together with the theoretical information available of doubly charged Ni-containing species. The final section of this review is devoted to an analysis of the gas-phase uni- and bimolecular reactivity of Ni(+) and Ni(2+) complexes.

Gas-phase ion chemistry in organometallic systems

This review essentially deals with positive ion/molecule reactions occurring in gas-phase organometallic systems, and encompasses a period of time of approximately 7 years, going from 1997 to early 2004. Following the example of the excellent review by Eller & Schwarz (1991; Chem Rev 91:1121-1177), in the first part, results of reaction of naked ions are presented by grouping them according to the neutral substrate, while in the second part, ligated ions are grouped according to the different ligands. Whenever possible, comparison among similar studies is attempted, and general trends of reactivities are evidenced.