An evaluation of M interference correction approaches associated with As and Se in ICP-MS using a multi-day dataset along with ICP-MS/MS/HR-ICP-MS based analysis and hierarchical modeling as a means of assessing bias in fortified drinking waters and single component matrices.

Three mass oriented rare earth element (REE) M correction approaches (fixed factor, a dual internal standard, and an in-sample) are evaluated for use in an ICP-MS environmental method update. The multi-variant-based evaluation includes analyzing the same 19 REE-fortified matrices on eight different days over a two-month period using two instrument tunes. These REE-fortified matrices were also analyzed using HR-ICP-MS and ICP-MS/MS to estimate the reference value for use in the principal component analysis (PCA) and hierarchical modeling evaluation.

Analytical considerations associated with implementing M correction factors to address false positives on As and Se within U.S. EPA method 200.8.

Rare earth elements (REE) can produce M ions in ICP-MS and Nd, Sm, and Gd can produce false positives on As and Se. Alternative instrumental tuning conditions, that utilize lower He flows within the collision cell, reduce these false positives by a factor of 2 (to 0.8 ppb As and 19 ppb Se in solutions containing 50 ppb Nd and Gd) with comparable OCl reduction (<100 ppt false V in 0.

Development of an analytical scheme for the determination of pyrethroid pesticides in composite diet samples.

Analysis of an individual's total daily food intake may be used to determine aggregate dietary ingestion of given compounds. However, the resulting composite sample represents a complex mixture, and measurement of such can often prove to be difficult. In this work, an analytical scheme was developed for the determination of 12 select pyrethroid pesticides in dietary samples.

A gradient anion exchange chromatographic method for the speciation of arsenic in lobster tissue extracts.

A gradient anion exchange chromatographic technique was developed for the separation of arsenobetaine (AsB), arsenocholine (AsC), arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) in one chromatographic run. This technique used low residue ammonium carbonate buffer and the inductively coupled plasma-mass spectrometry (ICP-MS) chromatograms showed little baseline drift. Gradient elution improved peak shape and peak separation.

Pesticides and their metabolites in the homes and urine of farmworker children living in the Salinas Valley, CA.

In support of planning efforts for the National Children's Study, we conducted a study to test field methods for characterizing pesticide exposures to 20 farmworker children aged 5-27 months old living in the Salinas Valley of Monterey County, California. We tested methods for collecting house dust, indoor and outdoor air, dislodgeable residues from surfaces and toys, residues on clothing (sock and union suits), food, as well as spot and overnight diaper urine samples. We measured 29 common agricultural and home use pesticides in multiple exposure media samples.

Comparison of extraction procedures for the determination of arsenic and other elements in lobster tissue by inductively coupled plasma mass spectrometry.

A variety of extraction procedures were evaluated for the extraction of arsenic and other analytes from lobster tissue samples using inductively coupled plasma mass spectrometry (ICP-MS) detection. Soxhlet, room temperature mixing, sonication, microwave assisted, supercritical carbon dioxide and subcritical water extractions were evaluated for a variety of solvent systems and optimum conditions determined using a partially defatted Lobster Hepatopancreas marine certified reference material, TORT-2 (National Research Council of Canada). The solubility trends and solvents into which the analytes extracted gave an indication as to the polar/non-polar nature of the compounds present.