Accelerated air-assisted in-syringe extraction and needle spray ionization coupled with miniature mass spectrometry: A streamlined platform for rapid on-site analysis.

The present study reports on a streamlined analytical platform for rapid, straightforward, and on-site sample analysis using a miniature mass spectrometer with adequate tandem mass spectrometry (MS/MS) capability. An "all-in-one" workflow is developed combining accelerated air-assisted in-syringe extraction, sorbent-packed membrane clean-up, and needle spray ionization with an in-house built syringe assembly. A custom-made metal needle with a sharp, thin, and conical tip of micrometer-scale served as an integral component of the syringe assembly. This needle was capable of both aspirating a high-speed airflow for a highly efficient in-syringe extraction and performing stable electrospray for direct miniature mass spectrometry analysis. As a proof-of-concept demonstration, the developed protocol was implemented for the identification of 40 adulterated cosmetic ingredients and validated in terms of sensitivity, linearity, matrix effect, and recovery. A custom expandable mass spectral library was established in-house for smart suspect screening. Compound search and identification were conducted following a two-stage strategy using the full-scan MS and MS/MS data. The methodology demonstrates excellent potential for outside-the-laboratory chemical analysis by reducing the high time and labor costs associated with traditional sample preparation and chromatographic separation procedures, which would meet product quality and safety inspection requirements for on-site compliance check and regulatory enforcement at the testing sites such as supermarkets, department stores, wholesale markets, and roadside stalls.