Microflow Liquid Chromatography Coupled to Mass Spectrometry—An Approach to Significantly Increase Sensitivity, Decrease Matrix Effects, and Reduce Organic Solvent Usage in Pesticide Residue Analysis

Abstract

This manuscript reports a new pesticide residue analysis method employing a microflow-liquid chromatography system coupled to a triple quadrupole mass spectrometer (microflow-LC-ESI-QqQ-MS). This uses an electrospray ionization source with a narrow tip emitter to generate smaller droplets. A validation study was undertaken to establish performance characteristics for this new approach on 90 pesticide residues, including their degradation products, in three commodities (tomato, pepper, and orange). The significant benefits of the microflow-LC-MS/MS-based method were a high sensitivity gain and a notable reduction in matrix effects delivered by a dilution of the sample (up to 30-fold); this is as a result of competition reduction between the matrix compounds and analytes for charge during ionization. Overall robustness and a capability to withstand long analytical runs using the microflow-LC-MS system have been demonstrated (for 100 consecutive injections without any maintenance being required). Quality controls based on the results of internal standards added at the samples' extraction, dilution, and injection steps were also satisfactory. The LOQ values were mostly 5 μg kg(-1) for almost all pesticide residues. Other benefits were a substantial reduction in solvent usage and waste disposal as well as a decrease in the run-time. The method was successfully applied in the routine analysis of 50 fruit and vegetable samples labeled as organically produced.

A Critical Review of Bottom-Up Proteomics: The Good, the Bad, and the Future of This Field

“…One important requirement that gets increasingly supported by the literature is the fact that the current column hardware is no longer adequate to maintain the very high efficiencies and small peak volumes produced by the high-quality particles (continually smaller) and high-quality packing procedures. The proteomics field has also been utilizing very slow microflow rates in order to increase sensitivity, which cuts down on buffer costs, but also increases analysis time [113].…”

High-Temperature Liquid Chromatography and the Hyphenation with Mass Spectrometry Using High-Pressure Electrospray Ionization

“…Although ow splitters can be used to divert the extra eluent to waste, it would be economical and more sensitive to employ µL/min ow rate for the whole LC and ESI system to reduce the sample and solvent consumption and matrix e ects. 64,65) Technically, low ow rate HTLC can be coupled to micro or nanoESI via a ow restrictor but the back pressure generated by restrictor depends on the viscosity and varies with the liquid ow rate. Under the ow regime of several tens or several µL/min and with the reduced viscosity at high temperature, the pressure drop across the restrictor may be insu cient for elevated temperature (>120°C) operation.…”

Quantitative mass spectrometry methods for pharmaceutical analysis

“…Several reviews give an overview of the advances made in both column sizes and LC modules [87,93,109,110]. The major advantage of miniaturized LC set-ups is the enhanced sensitivity due to higher efficiencies, lower flow rates and minimized void volumes, which will have a positive influence on the ionization efficiency and the peak shapes [111]. Additionally, the run time and solvent consumption are reduced which results in more environmental friendly and economic analysis.…”