Keywords: DPX, SPE, Pesticides, Fruits, Vegetables
Disposable Pipette Extraction (DPX) has been shown to be a rapid, efficient and reproducible method for performing solid-phase extraction (SPE) of pesticides from fruits and vegetables. DPX is a unique SPE method because the solid phase sorbent is contained inside a disposable pipette tip and is mixed with sample solutions. This mixing allows for the use of less solid phase sorbent material and results in faster extractions. Elution can be performed using small amounts of solvent, effectively providing a concentration step. Hence, solvent evaporation is not required for many applications such as pesticide analyses. Without the need for centrifugation or solvent evaporation, DPX methods can be readily automated and the resultant eluents directly injected into a gas or liquid chromatograph. The analyst is only required to initially process the samples to be analyzed and place the sample solutions into corresponding vials. The rest of the sample preparation can be automated, including the injection of the eluent into the analytical instrument. In this study, samples of fruits and vegetables (spiked with various pesticides) are blended with organic solvent, and the samples are then filtered and placed into sample vials. A GERSTEL MultiPurpose autosampler (MPS) is used to perform the DPX extractions and inject into the chromatographic instrument. Various types of fruits and vegetables are included in this study, and numerous pesticides are analyzed by this method including organophosphates, organochlorines, pyrethroids, and fungicides.
Keywords: Sample Preparation, DPX, Opiates, Automation
The analysis of opiates in blood and urine was accomplished using automated Disposable Pipette Extraction (DPX) followed by LC/MS analysis. The automated extractions were performed in about 5 minutes using a GERSTEL MultiPurpose Sampler (MPS). The eluents were subsequently dried and reconstituted in solvent and injected into a HPLC/MS/MS instrument. Recoveries ranged from 60 to 85% for the opiates in blood, and recoveries ranged from 78 to 85% for the opiates in hydrolyzed urine. The %RSDs were lower than 6% for all analytes.
Keywords: DPX, LC/MS/MS, Sample Preparation, Lab Automation
This study focuses on the automated extraction of small sample volumes coupled to LC/MS/MS in order to provide high throughput analysis of an extended list of benzodiazepines. Using a GERSTEL MPS autosampler, DPX extractions of a variety of biological matrices were performed, using a mixed-mode cation exchange (DPX-CX) sorbent. The resulting eluents from the automated DPX extractions were then introduced into an Agilent 6410 LC/MS/MS instrument. Coupling DPX to LC/MS/MS provides rapid, just-in-time sample preparation for high throughput analysis. Data show the use of an Agilent 6410 LC/MS/MS instrument to be a highly sensitive procedure for the analysis of benzodiazepines with limits of quantitation of 0.5 ng/mL, and good linearity. The DPX extraction removes potential matrix interferences and ion suppression, and high sensitivity is therefore achieved.
Keywords: DPX, LC-MS/MS, Sample Preparation, Laboratory Automation
This study focuses on the automated extraction of small sample volumes combined with LC-MS/MS analysis providing high throughput analysis of common pain management drugs. Using a GERSTEL MultiPurpose Sampler (MPS), DPX extractions of hydrolyzed urine were performed, using a reversed phase sorbent with a proprietary salt additive (DPX-RP-S). The resulting eluents from the automated DPX extractions were introduced into an Agilent 6460 LC-MS/MS instrument.
Keywords: DPX, Solid Phase Extraction, Mycotoxins, Aflatoxin B1, LC/MS/MS
The extraction of Aflatoxin B1 residues from contaminated corn samples using disposable pipette extraction (DPX) is described. DPX is a solid-phase extraction (SPE) technique that is based on loosely contained sorbent inside a pipette tip fitted with a screen. This device provides faster extraction because only minimal conditioning steps are needed. A weak anion exchange sorbent (DPX-WAX) was found to provide selective extraction of Aflatoxin B1 from a crop sample. Recovery of the analyte of interest was 81 % with a relative standard deviation of 8 %.
Keywords: DPX, LC-MS/MS, Sample Preparation, High Throughput Laboratory Automation
This study focuses on the automated extraction of small volumes of urine samples (< 500 uL) using disposable pipette extraction (DPX) for the comprehensive screening for pain management drugs by LC-MS/MS. Using a GERSTEL MPS autosampler, DPX extractions of hydrolyzed urine were performed, using a reversed phase (DPX-RP-S) sorbent. The resulting eluents from the DPX extractions were automatically diluted and injected into an Agilent® Technologies LC-MS/MS system. Sample preparation was performed just-in-time enabling high throughput screenings, averaging a cycle time of 7 min/sample. Validation results show that the automated DPX-LC-MS/MS screening method provides adequate sensitivity for over 65 analytes and internal standards. Lower limits of quantitation (LLOQ) ranged between 0.5 – 50 ng/mL and % RSDs were below 10% in most cases.
Keywords: DPX, LC/MS/MS, Sample Preparation, High Throughput Laboratory Automation
This study focuses on the rapid cleanup of urine samples (< 500 uL) using disposable pipette extraction (DPX) for high throughput LC/MS/MS screening of buprenorphine (Bup) and main active metabolite norbuprenorphine (Nbup). Using a GERSTEL MultiPurpose autosampler (MPS), DPX extractions of hydrolyzed urine were performed, and analysis results were directly compared to results obtained using the "dilute-and-shoot" (D&S) approach for the same samples. The automated DPX cleanup process significantly reduced matrix effects without compromising the required minimum reportable limits (MRLs), whereas when using the D&S approach, samples had to be diluted by up to a factor 100 to remove such effects, which directly affected the ability to determine Bup and Nbup at the MRLs. Moreover, the addition of valve switching control from MAESTRO software further increased the throughput potential of the solution. The resulting eluents from the automated DPX extractions were injected into an Agilent 6460 LC/MS/MS instrument configured with 2 LC pumps (gradient and re-generative) allowing rapid, just-in-time sample preparation for high throughput screening, averaging a cycle time of 4 min/sample.
Keywords: Doping, Equine Urine, Automated Sample Preparation, Disposable Pipette Extraction, Triple Quadrapole Mass Spectrometry, Gas Chromatography
This application note describes a fully automated method for the determination of selected doping compounds in equine urine. A GERSTEL MultiPurpose autosampler (MPS) with Disposable Pipette Extraction (DPX) option is employed for extraction and cleanup. After gas chromatographic separation the analytes are detected by a triple-quadrupole mass spectrometer (QqQ-MS). The method is rugged, provides an excellent cleanup of the complex sample matrix and shows very good limits of detection, from below 0.1 to just under 10 ng/mL, when compared to labor intensive manual manual SPE methods.
Keywords: DPX, LC/MS/MS, Sample Preparation, High Throughput Laboratory Automation
This work demonstrates the use of disposable pipette extraction (DPX) as a fast and automated sample preparation technique for the determination of barbiturates and 11-nor-9-carboxy- 9-THC (COOH-THC) in urine. Using a GERSTEL MultiPurpose autosampler (MPS) with DPX option coupled to an Agilent 6460 LC/MS/MS instrument, 8 barbiturates and COOH-THC were extracted and their concentrations determined. The resulting average cycle time of 7 min/sample, including just-in-time sample preparation, enabled high throughput screening. Validation results show that the automated DPX-LC/MS/MS screening method provides adequate sensitivity for all analytes and corresponding internal standards that were monitored. Lower limits of quantitation (LLOQ) were found to be 100 ng/mL for the barbiturates and 10 ng/mL for COOH-THC and % CVs were below 10 % in most cases.
Keywords: DPX, LC/MS/MS, Sample Preparation, Drugs of Abuse, High Throughput Lab Automation
This application demonstrates the use of Disposable Pipette Extraction (DPX) for rapid, automated sample preparation of urine samples for comprehensive LC/MS/MS screening. The combination of automated sample cleanup and introduction with mass spectrometric detection using a Scheduled MRM™ (AB SCIEX) algorithm and fast MS/MS spectral acquisition allowed high confidence compound identification based on mass spectral library matching. The automated workflow enabled monitoring of large panels of analytes (100+ drugs); detecting and quantifying these compounds in a single run. The new automated DPX-LC/MS/MS workflow provides rapid extractions, high recoveries, and minimized matrix interferences with complete automation capabilities towards high throughput chromatographic analysis.
Keywords: Pesticide Residue Monitoring, QuEChERS, LC/MS/MS, Sample Preparation, DPX, Lab Automation
In this report, we describe an automated sample preparation and analysis workflow for the screening of pesticides residues in different food matrices (fruits, vegetables and spices) by LC/MS/MS. The automated cleanup of the QuEChERS extracts methodology was performed using disposable pipette extraction (DPX). Analytical methodology for confirming the presence of a variety of pesticides in various food samples was developed using a GERSTEL MultiPurpose Sampler (MPS), a combined autosampler and liquid handling robot, interfaced to an AB SCIEX QTRAP® 4500 LC/MS/MS System.
Keywords: Mycotoxins, LC/MS/MS, Sample Preparation, Lab Automation, Food Safety
In this report, we describe a completely automated sample preparation work multi-mycotoxin residues in different food matrices (corn, wheat) by LC/MS/MS. The extraction and cleanup was performed using a GERSTEL MultiPurpose Sampler (MPS) followed by LC/MS/MS determination using an AB SCIEX QTRAP® 4500. The automated sample preparation work flow involved centrifugation, dispersive solid phase extraction (dSPE) and evaporative concentration, providing extraction efficiencies greater than 70 % with RSDs less than 15 % for most analytes. The LC/MS/MS method was developed for screening for a panel of 14 mycotoxins (aflatoxins, trichotecenes and fuminosins) using the Scheduled MRM™ algorithm in combination with fast polarity switching, achieving excellent linearity (R2 values of 0.98 or greater) , average accuracies greater than 88 % and limits of quantitation lower than the action levels established by the EC and FDA.
Keywords: Sample Preparation, LC/MS/MS, High Throughput Laboratory Automation, DPX, Urine, Glucuronides
A major mechanism of the metabolism of many pain management drugs involves conjugation of the analyte with glucuronic acid. To ensure accurate results when drugs are determined from urine matrices, the analytes must be deconjugated which is typically performed by hydrolysis using enzymes such as beta-glucuronidase. Typical hydrolysis procedures involve long incubation periods and specified temperatures and have traditionally been performed manually. This study shows how a typical enzymatic hydrolysis procedure can be easily automated using a GERSTEL MultiPurpose Sampler (MPS), combining an automated extraction and clean-up procedure with introduction to the LC/MS/MS, in order to provide high throughput analysis of common pain management drugs.