A machine learning approach for early prediction of gestational diabetes mellitus using elemental contents in fingernails.

The aim of this pilot study was to predict the risk of gestational diabetes mellitus (GDM) by the elemental content in fingernails and urine with machine learning analysis. Sixty seven pregnant women (34 control and 33 GDM patient) were included. Fingernails and urine were collected in the first and second trimesters, respectively. The concentrations of elements were determined by inductively coupled plasma-mass spectrometry. Logistic regression model was applied to estimate the adjusted odd ratios and 95% confidence intervals. The predictive performances of multiple machine learning algorithms were evaluated, and an ensemble model was built to predict the risk for GDM based on the elemental contents in the fingernails. Beryllium, selenium, tin and copper were positively associated with the risk of GDM while nickel and mercury showed opposite result. The trained ensemble model showed larger area under curve (AUC) of receiver operating characteristic curve (0.81) using fingernail Ni, Cu and Se concentrations. The model was validated by external data set with AUC = 0.71. In summary, the results of the present study highlight the potential of fingernails, as an alternative sample, together with machine learning in human biomonitoring studies.

Suppression of spectral interference in dual-elemental analysis of single particles using triple quadrupole ICP-MS.

Single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS) was used in the analysis of single particles/cells. Although quadrupole mass analyzers are widely used, the long settling time restricts measurement to single elements in individual particles. Recently, dual-elemental analysis has successfully been developed with the assistance of oxygen gas in the collision cell. This simple approach greatly expands the capability of quadrupole-based ICP-MS. In this study, we adopted bandpass mode in the first quadrupole (Q1) to improve the limit of detection of single particles against spectral interference. A model was developed to explain the rationale behind the selection of quadrupole voltages. The quadrupole voltages were optimized systematically so that the mass bandwidth of Q1 allowed the transmission of two target analytes while the interference species were rejected. As a result, the signal from the polyatomic interference was reduced by 98% with no significant change in the analyte signal. The bandpass mode was further applied to accurately determine the isotope ratio of 109Ag/107Ag in 80-nm Ag nanoparticles, as well as the Ag content in AgSn alloy particles, under the polyatomic interference of 91Zr16O originating from dissolved ions and particles. This technique was further applied to the determination of two Yb isotopes in algal cells with interference from Gd. Results indicate that this approach has great potential for assessing single particles and biological cells in the presence of severe interference from imaging agents, drugs, or biological fluids.

Dual-elemental analysis of single particles using quadrupole-based inductively coupled plasma-mass spectrometry.

Single-particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) is used for elemental analysis of single particles and biological cells. Time-of-flight (TOF) mass analyzers are widely used for multiple element analysis of individual particles. Owing to the sequential nature of the mass analyzer, quadrupole-based ICP-MS generally gives poor analytical performance when more than one element are being monitored. In this study, we present the first accurate and precise dual-mass measurement of individual particles using quadrupole-based ICP-MS, with the assistance of oxygen collision gas. Simultaneous measurement of the intensity of 107Ag and 109Ag of Ag nanoparticles (AgNP) showed particle recovery of 100% and Pearson correlation coefficient of 0.97, indicating proper sampling of all particles in the ICP. This technique gives good measurement precision (RSD <8%) and high accuracy in size measurement (error <3%). This technique was further applied to determine the elemental content and isotope ratios of particles and to study cell viability after Cisplatin staining. The results are comparable to that of existing TOF and multi-collector ICP-MS, indicating that quadrupole-based ICP-MS can be a cost-effective alternative for simultaneous measurement of two isotopes. Acquisition with longer integration time and shorter settling time is also proposed to further improve the sensitivity and number of isotopes monitored. This study will potentially open up more possibilities of using quadrupole based ICP-MS in biomedical research as quantification of multi-elements in single cells is far more informative. Other possible applications include classification of cancer subtypes according to the abundance of several biomarkers, as well as elemental bio-imaging of transcripts and proteins in tissues by laser ablation.

Double-Viewing-Position Single-Particle Inductively Coupled Plasma-Atomic Emission Spectrometry for the Selection of ICP Sampling Position in SP-ICP Measurements.

Double-viewing-position single-particle inductively coupled plasma-atomic emission spectrometry (DVP-SP-ICP-AES) measures emission intensity at two ICP vertical positions simultaneously using a single photomultiplier tube. A particle travelling up the ICP gives two consecutive temporal emission peaks. The Yb II 328.937-nm emission intensity of the two peaks for single Yb2O3 particles of diameter of 200 - 2000 nm are plotted against each other in a correlation plot. The correlation is poor when the gas temperature at the lower observation position is approximately the boiling point of the particles. Poor particle vaporization at the center of the central channel occurs because the gas temperature is 400 K lower than the temperature at the rim. The correlation is improved by shifting the observation positions up or using helium-argon mixed carrier gas to increase the gas temperature. Gas temperature is an important parameter for precise single particle-ICP measurements. DVP-SP-ICP-AES can be used to identify poor particle vaporization without the need of temperature measurement.