Analysis of pesticides by LC-electrospray-MS with postcolumn removal of nonvolatile buffers

Compatibility Study of Peptide and Glycerol Using Chromatographic and Spectroscopic Techniques: Application to a Novel Antimicrobial Peptide Cbf-14 Gel

The interactions between active pharmaceutical ingredients (APIs) and excipients may lead to API degradation, thereby affecting the safety and efficacy of drug products. Cbf-14 is a synthetic peptide derived from Cathelicidin-BF, showing potential for bacterial and fungal infections. In order to assess impurities in Cbf-14 gel, we developed a two-dimensional liquid chromatography coupled with quadrupole/time-of-flight mass spectrometric method. A total of eleven peptide degradation impurities were identified and characterized. Furthermore, the compatibility tests were conducted to evaluate the interactions of Cbf-14 with glycerol and methylcellulose, respectively. The results revealed that the impurities originated from condensation reactions between Cbf-14 and aldehydes caused by glycerol degradation. Several aldehydes were employed to validate this hypothesis. The formation mechanisms were elucidated as Maillard reactions between primary amino groups of Cbf-14 and aldehydes derived from glycerol degradation. Additionally, the compatibility of Cbf-14 with glycerol from different sources and with varying storage times was investigated. Notably, the interaction products in the gel increased with extended storage time, even when fresh glycerol for injection was added. This study offers unique insights into the compatibility study of peptides and glycerol, contributing to the ongoing quality study of Cbf-14 gel. It also serves as a reference for the design of other peptide preparations and excipients selections.

Development and Validation of a Multiplexed Protein Quantitation Assay for the Determination of Three Recombinant Proteins in Soybean Tissues by Liquid Chromatography with Tandem Mass Spectrometry

Currently, traditional immunochemistry technologies such as enzyme-linked immunosorbent assays (ELISA) are the predominant analytical tool used to measure levels of recombinant proteins expressed in genetically engineered (GE) plants. Recent advances in agricultural biotechnology have created a need to develop methods capable of selectively detecting and quantifying multiple proteins in complex matrices because of increasing numbers of transgenic proteins being coexpressed or "stacked" to achieve tolerance to multiple herbicides or to provide multiple modes of action for insect control. A multiplexing analytical method utilizing liquid chromatography with tandem mass spectrometry (LC-MS/MS) has been developed and validated to quantify three herbicide-tolerant proteins in soybean tissues: aryloxyalkanoate dioxygenase (AAD-12), 5-enol-pyruvylshikimate-3-phosphate synthase (2mEPSPS), and phosphinothricin acetyltransferase (PAT). Results from the validation showed high recovery and precision over multiple analysts and laboratories. Results from this method were comparable to those obtained with ELISA with respect to protein quantitation, and the described method was demonstrated to be suitable for multiplex quantitation of transgenic proteins in GE crops.

Compliance analysis of phenylurea and related compounds in drinking water by liquid chromatography/electrospray ionization/mass spectrometry coupled with solid-phase extraction

A liquid chromatography/electrospray ionization/mass spectrometry method was reported for the compliance analysis of seven phenylurea compounds and two related herbicides (tebuthiuron and propanil) in drinking water. The volumes of the sample and final extract used in the method were 500 mL and 10 mL, respectively. The obtained method detection limits were less than 0.03 microg/L, and the mean recoveries were 74-128% with a relative standard deviation of 2.6-8.3% for all the studied compounds. The peak-to-peak signal-to-noise ratios ranged from 3.3 for cis-siduron to 34.2 for fluometuron. The accuracy and precision resulting from reagent and drinking water samples fortified at higher concentration levels were similar to these results. Several analytes were detected in the drinking water samples, including tebuthiuron at 0.5 microg/L, propanil at 0.7 microg/L, diuron at 0.1-2.1 microg/L, and linuron at 0.1-0.8 microg/L.

Simultaneous analysis of carbamate pesticides in tap and raw water by LC/ESI/MS

Ten carbamate pesticides including four suspected endocrine disruptors, methomyl, benomyl (carbendazim), aldicarb and carbaryl, were simultaneously analyzed by LC/ESI/MS. The influence of the matrix on the variation of the ion signal intensities of (M + H)+ and adduct ions was investigated. Although the intensities of three oxamyl ions changed depending on the matrix, the variation in the concentration calculation of oxamyl was reduced by using the sum total of the area value of two ions. The limits of the quantitation of ten pesticides without a concentration procedure were from 0.4 - 30 microg/l. The solid-phase recovery rates of ten pesticides spiked into tap water and raw water were in the range of 69-111%. Using this method, the concentrations of the pesticides in tap and raw water sampled at 14 monitoring points in Hyogo Prefecture were determined. Carbendazim in three raw water samples and carbofuran in one of these three samples were detected at low concentrations (less than 0.32 microg/l).

Preliminary investigation of the application of on-line membrane extraction of trifluoroacetic acid as an aid to improvement of negative ion electrospray mass spectrometry data

We have recently investigated the biodegradation of a number of acidic aromatic compounds that give excellent chromatography using trifluoroacetic acid (TFA) based HPLC methods. Unfortunately HPLC methods using TFA are not usually compatible with detection by negative ion mass spectrometry as TFA suppresses ionisation of the analyte during the electrospray process. We present a preliminary investigation of the use of an anion-exchange micro-membrane suppressor to remove TFA on-line post column with the aim of improvement of mass spectral data using an aromatic acid as an example, Thus LC-MS using a TFA based HPLC method with negative ion mass spectral detection is shown to be possible with good sensitivity.