Paper Spray Ionization: Applications and Perspectives

Paper spray ionization has grown to become one of the most successful ambient ionization methods within the past decade. Requiring little to no sample preparation and being remarkably simple to construct, this technique has seen application in a wide number of fields. This review approaches the mechanism of how paper spray works, and seeks to better classify what it is and is not in a rapidly expanding field of ambient techniques. Additionally, many applications of the technique in clinical, forensic, environmental, and reaction monitoring regimes are explored. Finally, perspectives towards the future of how paper spray could be utilized will be expanded upon, including unexplored substrates and possibilities for the 'omics space

Genetic and Biochemical Studies of Phosphatase Activity of PhoR

In Escherichia coli, PhoR is the histidine kinase of the phosphate regulon. It has been postulated that PhoR may function as a phospho-PhoB phosphatase. Experiments with four precise phoR deletion mutants supported this hypothesis and suggested that this activity resides within the histidine phosphorylation domain. This biochemical activity was confirmed by using a separately expressed histidine phosphorylation domain

Pressure-Sensitive Adhesive Combined with Paper Spray Mass Spectrometry for Low-Cost Collection and Analysis of Drug Residues

Illicit drug use causes over half a million deaths worldwide every year. Drugs of abuse are commonly smuggled through customs and border checkpoints and, increasingly, through parcel delivery services. Improved methods for detection of trace drug residues from surfaces are needed. Such methods should be robust, fieldable, sensitive, and capable of detecting a wide range of drugs. In this work, commercially produced paper with a pressure-sensitive adhesive coating was utilized for the collection and analysis of trace drug residues by paper spray mass spectrometry (MS). This modified substrate was used to combine sample collection of drug residues from surfaces with rapid detection using a single paper spray ticket. The all-in-one ticket was used to probe different surfaces commonly encountered in forensic work including clothing, cardboard, glass, concrete, asphalt, and aluminum. A total of 10 drugs (acetyl fentanyl, fentanyl, clonazolam, cocaine, heroin, ketamine, methamphetamine, methylone, U-47700, and XLR-11) were evaluated and found to be detectable in the picogram range using a benchtop mass spectrometer and in the low nanogram range using a portable ion trap MS. The novel approach demonstrates a simple yet effective sampling strategy, allowing for rapid identification from difficult surfaces via paper spray mass spectrometry