Ingo Christ

For obvious reasons, pesticide levels in food need to be carefully controlled. Traditionally, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC)-MS have been two of the most popular techniques for identifying and quantifying pesticides in food, but due to the often complex chemical nature of food products, low levels of pesticides can be challenging to analyze with these single quadrupole instruments. Interference from the sample matrix (which can distort… Mehr anzeigen

For obvious reasons, pesticide levels in food need to be carefully controlled. Traditionally, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC)-MS have been two of the most popular techniques for identifying and quantifying pesticides in food, but due to the often complex chemical nature of food products, low levels of pesticides can be challenging to analyze with these single quadrupole instruments. Interference from the sample matrix (which can distort chromatographic peak shapes or peak areas) often makes it difficult to perform reliable measurements of the chromatographic data of analytes. This matrix-interference problem has largely been solved by the introduction of MS/MS in GC-MS/MS and LC-MS/MS systems. Using two quadrupoles in tandem with a quadrupole collision cell in-between (hence the name “triple quadrupole”), adds a very high degree of specificity by eliminating the effects of matrices. Therefore, the benefit of triple quadrupole mass spectrometric detection is most pronounced for samples with very complex matrices. In this study, a QuEChERS method, followed by thermal desorption and GC-MS/MS with an Evolution-upgraded Agilent GC-MS, were used to analyze 89 types of pesticides in one GC run. The samples were red currant pulp and mushroom, both spiked with 5 µg/kg of various pesticides, including aldrin, dieldrin, propaconazol, chlorthal-dimethyl, pentachloraniline, pirimiphos-methyl, tebuconazol and others.

The objective of this study was to obtain reliable chromatographic data in a single run for 89 different pesticides in a complex food matrix at a trace concentration of 5 µg/kg using a QuEChERS sample preparation, followed by Thermal Desorption and GC-MS/MS separation and detection. Analyte peaks should have a well-defined, approximately Gaussian shape. Weniger anzeigen

Autosamplers have improved the productivity of HPLC systems by allowing them to work for 24 hours per day. The system described in this article further improves HPLC system productivity by enhancing the efficiency of the HPLC sample process. It combines filtration and storage into one simple device that can be integrated with the autosampler. Preparing an analytical sample for injection into HPLC equipment can involve several steps. Figure 1 shows the typical protocol for sample preparation to… Mehr anzeigen

Autosamplers have improved the productivity of HPLC systems by allowing them to work for 24 hours per day. The system described in this article further improves HPLC system productivity by enhancing the efficiency of the HPLC sample process. It combines filtration and storage into one simple device that can be integrated with the autosampler. Preparing an analytical sample for injection into HPLC equipment can involve several steps. Figure 1 shows the typical protocol for sample preparation to remove protein precipitates prior to HPLC analysis. Sample preparation protocols tend to be tedious when large numbers of samples need to be analyzed. For example, an individual in a laboratory using the above protein precipitation protocol must follow six different steps before readying the sample for injection into HPLC. When
sample preparation is done manually, an operator can prepare about 50 samples in one working day. Weniger anzeigen

Headspace sampling for gas chromatographic (GC) analysis has
many advantages, the most important of which is the elimination of many interferences from the sample matrix. In addition to the standard methods for headspace sampling, the technique of solidphase microextraction (SPME) has found wide acceptance because it is simple and inexpensive. More recently, single-drop
microextraction (SDME) has been evaluated as an alternative to SPME. In this straightforward technique, a microdrop… Mehr anzeigen

Headspace sampling for gas chromatographic (GC) analysis has
many advantages, the most important of which is the elimination of many interferences from the sample matrix. In addition to the standard methods for headspace sampling, the technique of solidphase microextraction (SPME) has found wide acceptance because it is simple and inexpensive. More recently, single-drop
microextraction (SDME) has been evaluated as an alternative to SPME. In this straightforward technique, a microdrop of
solvent is suspended from the tip of a conventional microsyringe and then is immersed in a sample solution in which it is immiscible or suspended in the headspace above the sample. Weniger anzeigen

Keywords: SPME, Multidimensional GC (heartcutting), GCx GC, Ethylcarbamate

Keywords: Heart cutting multidemensional GC, SPME, Twin PAL