Component Profiling in Agricultural Applications Using an Adjustable Acupuncture Needle for Sheath-Flow Probe Electrospray Ionization/Mass Spectrometry

Abstract

In previous work, probe electrospray ionization/mass spectrometry (PESI/MS) and sheath-flow probe electrospray ionization/mass spectrometry (sfPESI/MS) were reported for the rapid and minimally invasive analysis of food. In this work, a modified version of sfPESI will be reported. The sample surface was pricked with an acupuncture needle inserted in the sfPESI probe that protruded from the terminus of the tip by 5 mm. The invasion depth of the needle into the sample was ∼1 mm. After sampling, the needle was retracted into the solvent-preloaded capillary with a protrusion length of 0.1−0.2 mm from the tip. A mass spectrum of the sample captured on the needle was obtained by applying a high voltage to the needle. This method could be applicable to profiling analyses of plants with the epicuticular wax covering on the surfaces that are difficult to analyze by sf-PESI. The on-site mass spectrometric analysis for a growing apricot in the field was performed to monitor the developing stage of the fruit.

Point Analysis of Foods by Sheath-Flow Probe Electrospray Ionization/Mass Spectrometry (sfPESI/MS) Coupled with a Touch Sensor

“…The observed trend is in agreement with the previous work. , Darbyshire and Henry suggested that the concentration change is due to hydrolysis of fructans to free fructose which achieves osmotic adjustment as the base cells expand during bulbing of the onion. In addition, Hex may be functioning in protecting the plant against water deficit as an osmoregulator . To our surprise, the mass spectrum showed a drastic change with #7 → #8.…”

“…It should be kept in mind that the surface sampling methods such as sfPESI, LESA, , DESI, nanoDESI, SPESI, and Single-probeMS give information mainly on the surface components but not necessarily on the bulk components. For the analysis of components underneath the surface (i.e., bulk analysis), dPESI and ad-sfPESI are more preferable than the surface sampling methods.…”

“…The great merit of the discontinuous sampling/electrospray is that the suppression effect was largely moderated in PESI because of the occurrence of sequential and exhaustive electrospray . As modified versions of PESI, sheath-flow PESI (sfPESI), − dipping PESI (dPESI), and adjustable sfPESI (ad-sfPESI) were developed. In sfPESI, an acupuncture needle was inserted into a fine plastic capillary with a protrusion of 0.1–0.2 mm out of the tip.…”

Investigating distributions and changes of alkaloids in living Catharanthus roseus under low‐phosphorus stress using wooden‐tip electrospray ionisation mass spectrometry

“…More recently, the use of solid substrate for sample delivery and direct electrospray ionisation (ESI) has attracted a lot of attention 18 . Particularly, wooden tip and other probes/needles allow in vivo sampling of living plants for subsequent direct ESI‐MS analysis of raw samples 19–21 . Wooden‐tip ESI‐MS has been successfully demonstrated as an effective, simple, and rapid method for direct analysis of raw samples.…”

Sheath-flow probe electrospray ionization (sfPESI) mass spectrometry for the rapid forensic analysis of human body fluids

“…27 However as PESI is only applicable to liquid samples, sheath-ow PESI (sfPESI) was later developed to enable the analysis of non-liquid samples. 28,29 Sheath-ow PESI is a modication of the PESI technique in which the needle is contained within a solvent-lled gel-loading tip with a slight protrusion (0.1 mm) of the needle from the base. When the probe touches the sample surface, the convex liquid at the base of the probe wets the sample and enables analyte extraction from the surface.…”