Determination of perchlorate in infant formula by isotope dilution ion chromatography/tandem mass spectrometry

Abstract

A sensitive and selective isotope dilution ion chromatography/tandem mass spectrometry (ID IC-MS/MS) method was developed and validated for the determination of perchlorate in infant formula. The perchlorate was extracted from infant formula by using 20 ml of methanol and 5 ml of 1% acetic acid. All samples were spiked with 18O4 isotope-labelled perchlorate internal standard prior to extraction. After purification on a graphitised carbon solid-phase extraction column, the extracts were injected into an ion chromatography system equipped with an Ionpac AS20 column for separation of perchlorate from other anions. The presence of perchlorate in samples was quantified by isotope dilution mass spectrometry. Analysis of both perchlorate and its isotope-labelled internal standard was carried out on a Waters Quattro Ultima triple quadrupole mass spectrometer operating in a multiple reaction monitoring (MRM) negative ionisation mode. The method was validated for linearity and range, accuracy, precision, sensitivity, and matrix effects. The limit of quantification (LOQ) was 0.4 μg 1−1 for liquid infant formula and 0.95 μg kg−1 for powdered infant formula. The recovery ranged from 94% to 110% with an average of 98%. This method was used to analyse 39 infant formula, and perchlorate concentrations ranging from <LOQ to 13.5 μg 1−1.

Placental transfer of and infantile exposure to perchlorate

“…The median concentrations of perchlorate in infant formula samples collected in China were in the same range as those recently reported in other studies from the U.S. (1.50 ng mL À1 ), Canada (1.27 ng mL À1 ) and Korea (6.78 ng g À1 ) (Lee et al, 2012;Wang et al, 2011) (Fig. 1), but were higher than those reported in Japan (0.59 ng mL À1 ) (Asami et al, 2013).…”

“…1. To our knowledge, nearly all previously studies on perchlorate in the breast milk, infant formula and urine of infants were from the U.S. (Borjan et al, 2011;Dasgupta et al, 2008;Kirk et al, 2007Kirk et al, , 2012Kirk et al, , 2005Leung et al, 2012;Leung et al, 2009;Pearce et al, 2007;Valentin-Blasini et al, 2011), but several studies reported perchlorate concentrations in infant formula from Canada (Wang et al, 2011), Korea (Her et al, 2010;Lee et al, 2012) and Japan (Asami et al, 2013). The urinary concentrations of perchlorate that were detected among all infants from Nanchang, China were up to 20 (range: 2e20) fold higher than those of American infants (Fig.…”

Determination of Perchlorate in Bottled Water from Italy

“…The presence of common anions had no significant negative impact on perchlorate recoveries, which were in a range of 94%-108%. Monitoring the 37 Cl and 35 Cl transitions by MS/MS improved the specificity of the method. The LOQ of the method was calculated to be 5 ng/L and was adequate to collect useful data on perchlorate levels in drinking water samples.…”

“…These data show that quantification can be performed with good linearity and sensitivity. The measured isotopic ratio of 35 Cl to 37 Cl varies from 2.7 to 3.4. When ESI is used for quantitative analysis, the effect of ionization suppression or enhancement must be considered.…”

“…As the collision energy is increased to 40 eV, the complexity of the spectrum is increased (Figure 3b Cl transition was monitored to provide additional confirmation of the presence of perchlorate. The measured isotopic ratio of 35 Cl to 37 Cl is derived from the natural abundance of chlorine isotopes. Figure 4 shows the MRM chromatograms for analysis of a 100 ng/L perchlorate standard.…”