Poor qualitative analysis of Naled necessarily leads to incorrect quantitative analysis

This correspondence is in regards to a published article, titled “Prenatal Naled and Chlorpyrifos Exposure is Associated with Deficits in Infant Motor Function in a Cohort of Chinese Infants” Silver et al., Environ Int., 2017 Sep; 106:248–256. Upon careful review of this work we identified some significant issues in the mass spectral analysis of naled, specifically its identification and quantification. In this communication we address these issues and provide analytical data and rationale to support our criticism of the reported work. We collected mass spectral data for naled (analytical standard grade) under a variety of mass spectrometric conditions in an attempt to obtain a fragmentation pattern similar to what was reported in Silver et al., 2017. We however, could not reproduce a similar fragmentation pattern under any of the tested experimental conditions. Our results however were in excellent agreement with the National Institute of Standards and Technology (NIST) database, which is a very well established and widely accepted resource for such compounds. This leads us to conclude that naled was in all probability misidentified in the reported (Silver et al., 2017) study which consequently raises serious questions regarding the quantification of naled in the blood samples thus placing the whole statistical correlation of naled as a contributor to impairment of motor function in infants in question. •This correspondence is in regards to an article published in Environment International, Silver et al., 2017.•The identity of naled in Silver et al., 2017 cannot be substantiated:•Mass spectral peaks uniquely corresponding to naled fragments were not used for qualification and quantification of naled.•The peaks at m/z 109 → m/z 79 and m/z 145 → m/z 109 which were used to quantify naled, are not specific to naled.•Our results strongly suggest that Silver et al., 2017 misidentified naled, making the study conclusions questionable.