A longitudinal study of iodine excretion in normal pregnancy determined by inductively coupled plasma mass spectrometry

Abstract

We report here on a method for the determination of urine iodine by ICP-MS. The method proved to be fast, reliable and precise (within batch CVs v2.5%) and to have a low limit of detection (0.000 38 mmol L 21 ). Iodine was determined in a total of 379 urine samples from 86 healthy pregnant women who gave samples at intervals of 4 weeks from 16 weeks pregnancy to 10 weeks post-partum. Fifty-®ve control urine samples were analysed from age-matched non-pregnant females. Iodine excretion (mmol of iodine per mol of creatinine) increased signi®cantly from 28±40 weeks of pregnancy (pv0.05), returning to non-pregnant control levels by 10 weeks post-partum. This study con®rms the ability of our ICP-MS method to analyse large numbers of patient samples with the speed and performance acceptable for a routine assay.

Comparison of direct injection nebulizer and desolvating microconcentric nebulizer for analysis of chlorine-, bromine- and iodine-containing compounds by reversed phase HPLC with ICP-MS detection

“…In contrast to chlorine and bromine, the relative sensitivity for iodine increased with increasing amounts of methanol in the solvent at a flow rate of 50 ml min 21 . A similar effect was reported by Wind et al 8 This increase is due to a carbon enhancement effect, which is also known for other elements such as selenium.…”

“…The same general picture was seen in acetonitrile. When lowering the solvent flow rate to 25 ml min 21 , the influence on the sensitivity was less pronounced, which could be explained by a reduced organic solvent load of the plasma. Besides, the nebulizer performs best when the sample uptake rate is close to the natural self-aspiration rate, which for direct injection nebulizer used in this work has been determined to 10 ml min 21 .…”

“…The experiments were carried out on a PerkinElmer SCIEX Elan 6000 system equipped with platinum skimmer and sampler cones (PerkinElmer, Norwalk, CT, USA). The plasma and auxiliary argon flow rates were 14 and 1.2 l min 21 , respectively. The interfaces were a laboratory-made direct injection nebulizer 6 and an Aridus desolvating microconcentric nebulizer for ICP-MS (CETAC Technologies Inc., Nebraska, USA).…”

“…The interfaces were a laboratory-made direct injection nebulizer 6 and an Aridus desolvating microconcentric nebulizer for ICP-MS (CETAC Technologies Inc., Nebraska, USA). The direct injection nebulizer was operated with external argon supply at y0.2 l min 21 with an rf power of 1450 W. For the desolvating microconcentric nebulizer, a nebulizer gas flow of 0.9 l min 21 was used, and the rf power (700-1350 W) was optimised at varying sweep gas flow rates (2.0-3.2 l min 21 ). The temperatures of the Aridus fluoropolymer spray chamber and desolvating membrane were set at 70 uC and 160 uC respectively.…”

“…For chlorine and bromine, the relative sensitivity decreased with increasing amounts of methanol in the solvent at a flow rate of 50 ml min 21 . The same general picture was seen in acetonitrile.…”