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.

Laser desorption postionization mass spectrometry imaging of biological targets.

Laser desorption photoionization mass spectrometry (LDPI-MS) utilizes two separate light sources for desorption and photoionization of species from a solid surface. This technique has been applied to study a wide variety of molecular analytes in biological systems, but is not yet available in commercial instruments. For this reason, a generalized protocol is presented here for the use of LDPI-MS imaging to detect small molecules within intact biological samples.

Ion sources for mass spectrometric identification and imaging of molecular species.

Covering: 2013 The ability to transfer molecular species to the gas phase and ionize them is central to the study of natural products and other molecular species by mass spectrometry (MS). MS-based strategies in natural products have focused on a few established ion sources, such as electron impact and electrospray ionization. However, a variety of other ion sources are either currently in use to evaluate natural products or show significant future promise.

Differentiation of microbial species and strains in coculture biofilms by multivariate analysis of laser desorption postionization mass spectra.

7.87 to 10.5 eV vacuum ultraviolet (VUV) photon energies were used in laser desorption postionization mass spectrometry (LDPI-MS) to analyze biofilms comprised of binary cultures of interacting microorganisms.

Molecular imaging and depth profiling of biomaterials interfaces by femtosecond laser desorption postionization mass spectrometry.

Mass spectrometry (MS) imaging is increasingly being applied to probe the interfaces of biomaterials with invasive microbial biofilms, human tissue, or other biological materials. Laser desorption vacuum ultraviolet postionization with ∼75 fs, 800 nm laser pulses (fs-LDPI-MS) was used to collect MS images of a yeast-Escherichia coli co-culture biofilm. The method was also used to depth profile a three-dimensionally structured, multispecies biofilm.

Laser desorption VUV postionization MS imaging of a cocultured biofilm.

Laser desorption postionization mass spectrometry (LDPI-MS) imaging is demonstrated with a 10.5 eV photon energy source for analysis and imaging of small endogenous molecules within intact biofilms. Biofilm consortia comprised of a synthetic Escherichia coli K12 coculture engineered for syntrophic metabolite exchange are grown on membranes and then used to test LDPI-MS analysis and imaging.

Feasibility of depth profiling of animal tissue by ultrashort pulse laser ablation.

Experiments were performed to examine the feasibility of mass spectrometry (MS) depth profiling of animal tissue by ~75 fs, 800 nm laser pulses to expose underlying layers of tissue for subsequent MS analysis. Matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) was used to analyze phospholipids and proteins from both intact bovine eye lens tissue and tissue ablated by ultrashort laser pulses. Laser desorption postionization mass spectrometry (LDPI-MS) with 10.

Nanomole-scale protein solid-state NMR by breaking intrinsic 1HT1 boundaries.

We present an approach that accelerates protein solid-state NMR 5-20-fold using paramagnetic doping to condense data-collection time (to approximately 0.2 s per scan), overcoming a long-standing limitation on slow recycling owing to intrinsic (1)H T(1) longitudinal spin relaxation. Using low-power schemes under magic-angle spinning at 40 kHz, we obtained two-dimensional (13)C-(13)C and (13)C-(15)N solid-state NMR spectra for several to tens of nanomoles of beta-amyloid fibrils and ubiquitin in 1-2 d.