A LC-MS/MS method with electrospray ionization and atmospheric pressure chemical ionization source for analysis of pesticides in hemp

Background Pesticide testing for hemp has traditionally focused on techniques like QuEChERS with dSPE and SPE which demand time-consuming sample preparation, typically resulting in poor recovery rates for some pesticides, and requires the use of both LC-MS/MS and GC-MS/MS based instruments to cover the analysis for all regulated pesticides. In this study, we describe a streamlined approach for working with LC-MS/MS featuring a dual electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) sources using solvent extraction for faster and easier sample preparation and with 80–120% recovery for the analysis of all of 66 pesticides (regulated by California state in cannabis) with low detection limits in hemp. Methods A simple solvent extraction with acetonitrile was used to extract pesticides from hemp. A LC-MS/MS system with dual ESI and APCI source was used to determine sensitivity for the analysis of 66 pesticides in hemp matrix, 62 pesticides were analyzed using an 18-min LC-MS/MS method with an ESI source and the other 4 pesticides were measured using a 6-min LC-MS/MS method with an APCI source. Results The limit of quantitation (LOQ) of all 66 pesticides in hemp was in the range of 0.0025–0.1 μg/g which was well below the California state action limits of these analytes in cannabis products. A simple, fast, and cost-effective solvent extraction method was used for sample preparation to get good recovery in the range of 80–120% with RSD less than 20%. The unique ionization mechanism of chlorinated pesticides such as pentachloronitrobenzene using the LC-MS/MS system with an APCI source was elucidated. The proficiency test report generated with the LC-MS/MS method showed acceptable results for all of 66 pesticides in hemp with all of th z scores less than 2 with no false positives and negatives. The stability data collected over 5 days showed RSD less than 20% for 66 pesticides in hemp, and this demonstrated the robustness of the LC-MS/MS system used in this work. Conclusions A LC-MS/MS method with dual ESI and APCI sources was developed for the analysis of 66 pesticides in hemp. The recovery of all pesticides from a hemp matrix was in the acceptable range of 80–120% with RSD less than 20%.

Ionization of Volatile Organics and Nonvolatile Biomolecules Directly from a Titanium Slab for Mass Spectrometric Analysis

Atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) and electrospray ionization (ESI)-MS can cover the analysis of analytes from low to high polarities. Thus, an ion source that possesses these two ionization functions is useful. Atmospheric surface-assisted ionization (ASAI), which can be used to ionize polar and nonpolar analytes in vapor, liquid, and solid forms, was demonstrated in this study. The ionization of analytes through APCI or ESI was induced from the surface of a metal substrate such as a titanium slab. ASAI is a contactless approach operated at atmospheric pressure. No electric contacts nor any voltages were required to be applied on the metal substrate during ionization. When placing samples with high vapor pressure in condensed phase underneath a titanium slab close to the inlet of the mass spectrometer, analytes can be readily ionized and detected by the mass spectrometer. Furthermore, a sample droplet (~2 μL) containing high-polarity analytes, including polar organics and biomolecules, was ionized using the titanium slab. One titanium slab is sufficient to induce the ionization of analytes occurring in front of a mass spectrometer applied with a high voltage. Moreover, this ionization method can be used to detect high volatile or polar analytes through APCI-like or ESI-like processes, respectively.

A new LC-MS Method for the Determination of p-Chloroaniline and (S)-5-Chloro-α-(cyclopropylethynyl)-2- Amino-α- (trifluoromethyl) Benzene Methanol in Efavirenz Bulk Form

The main objective of the present research study is to develop and validate a sensitive, specific, accurate and precise LC-MS method for the determination of p-Chloroaniline and (S)-5-Chloro-α-(cyclopropylethynyl)-2- amino-α- (trifluoromethyl) benzene methanol in Efavirenz bulk form. The effective separation of p-Chloroaniline and (S)-5-Chloro-α-(cyclopropylethynyl)-2- amino-α- (trifluoromethyl) benzene methanol were achieved by using Hypersil BDS (C18, 100 x 4.6 mm, 3 µm) column and a solvent system of Buffer (0.1% Formic acid in water): Methanol (30:70 v/v) with a flow rate of 0.4 ml/min. The p-Chloroaniline and (S)-5-Chloro-α-(cyclopropylethynyl)-2- amino-α-(trifluoromethyl) benzene methanol were monitored on mass spectrometer coupled with atmospheric pressure chemical ionization, positive polarity mode and quadrapole mass analyzer. The Retention time of p-Chloroaniline, (S)-5-Chloro-α-(cyclopropylethynyl)-2- amino-α- (trifluoromethyl) benzene methanol and Efavirenz were found at 5.7min, 7.6min and 11.1min resepectively. The detection limit and quantification limit were observed at 0.25ppm and 0.75 ppm respectively for both p-Chloroaniline and (S)-5-Chloro-α-(cyclopropylethynyl)-2- amino-α-(trifluoromethyl) benzene methanol. Those analytes were linear in the concentration ranges from 0.75ppm to 3.75ppm and the percentage relative standard deviation of six replicates of same concentrations of both the analytes were less than 10%. Hence this method was effective in separation and determination of p-Chloroaniline and (S)-5-Chloro-α-(cyclopropylethynyl)-2- amino-α- (trifluoromethyl) benzene methanol in Efavirenz.