Keywords: LC Fraction Collection
Multidimensional capillary gas chromatography, and, in its ultimate form, comprehensive GC, result in the highest obtainable peak capacity and overall resolution. The combination of GC techniques is however restricted to the analysis of volatile (GC amenable) compounds and the separation mechanism is mostly based on volatility (boiling point separation). High molecular weight compounds or very polar compounds cannot be analyzed or will contaminate the analytical system. The potentials of multidimensional HPLC, in this respect, are much larger and very specific separations based on hydrophobicity, polarity, ion strength, molecular size or affinity can be obtained. HPLC, on the other hand, cannot offer the same peak capacity and overall resolution as GC. HPLC and GC are thus quite complementary to each other and therefore the on-line combination of the two techniques is very interesting. Recently on-line HPLC-GC equipment became commercially available. In this paper, a new automated and modular system based on a flow cell and large volume PTV injection is presented.
Keywords: Membrane Extraction, Triazines, VOCs, Large Volume Injection, LVI
Typically membrane-assisted solvent extraction (MASE) is carried out off-line in a vial, from which the organic extract is transferred to a sample vial followed by large-volume injection (LVI). In this study the extraction device for the membrane-assisted solvent extraction was modified for use with a conventional 20 mL headspace vial. For this purpose a tube of nonporous polypropylene membrane was sealed at one end to produce a membrane pouch, which could be inserted into the vial with the aid of a stainless steel adapter. 15 mL of the aqueous sample and 500 μL of solvent was used for the extraction procedure. A GERSTEL MultiPurpose autosampler (MPS) was used to place the solvent in the membrane pouch, followed by extraction in a heated agitator. After extraction, the MPS performed LVI directly from the extraction vial.
Keywords: Membrane Extraction, Waste Water
A procedure to analyze several semi-polar, nitrogen-containing compounds in untreated industrial waste water by means of membrane extraction is described. The selected analytes cover a broad range of volatility and can be extracted with either chlororform or diisopropyl ether. Recoveries are 40 – 110% for test solutions containing approximately 250 μg/L.
Keywords: Automation, Sample Preparation, Filtration, Weighing, SPE, Saponification, Esterification
A robotic X-Y-Z coordinate autosampler commonly used for sample introduction in GC or HPLC can be used to perform a wide variety of sample preparation techniques using a single instrument and controlling software. The MAESTRO software enables control of an expanded list of sample preparation techniques such as derivatization, addition of an internal standard, saponification, esterification, analytical weighing, filtration, and solid phase extraction. In addition to ease of use and intuitive windows-based setup, the software includes tools to automate and optimize timing parameters ensuring efficient sequence creation and maximum sample throughput. The sampler can be configured as part of a GC or LC system or can be configured as a benchtop workstation.
In this paper, we discuss various sample preparation techniques available when using the robotic autosampler in conjunction with the MAESTRO software. Examples of automating techniques such as solid phase extraction, Twister solvent back extraction for HPLC, and steps such as sample weighing are shown.
Keywords: Biodiesel, Automation, ASTM D6584-07
Biodiesel is defined as mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats which conform to ASTM D6751 specifications for use in diesel engines. Biodiesel is produced from the fat or oil by transesterification. Glycerin is an unwanted byproduct of the reaction and must be removed from the final product. ASTM Method D6584-07 measures the amount of residual free and bonded (mono-, di-, and triglycerides) glycerin in the biodiesel fuel. Standard and sample preparation, which requires a derivatization step, can be laborious and time consuming. Using the GERSTEL MPS Dual Rail PrepStation and MAESTRO control software, the entire method, including standards and sample preparation, derivatization, dilution, and analysis can be fully automated. This paper shows the details of the automation.
Keywords: QuEChERS, LC/MS/MS, Sample Preparation, Lab Automation
QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation methods were developed to help monitor pesticides in a range of food samples . These methods are quite labor intensive, however, since they include several manual steps, such as shaking, centrifugation, and dispersive SPE. If dispersive SPE clean up of QuEChERS type extracts could be automated, laboratory productivity for monitoring pesticide residues in food could be improved significantly. In the work presented here, an automated dispersive SPE clean-up method for QuEChERS extracts was developed and combined with LC/MS/MS analysis of the cleaned extracts. Extracts were prepared with commercially available kits from Agilent Technologies. Automation was achieved using a GERSTEL MPS XL PrepStation configured with an Anatune CF-100 centrifuge. Analytical methodology for confirming the presence of a variety of pesticides in a range food samples was developed using an Agilent G6460A Triple Quadrupole Mass Spectrometer. The sensitivity and selectivity of LC/MS/MS enable sufficiently low limits of determination to meet acceptance criteria for reporting the maximum residue levels (MRLs) that are established by regulatory agencies. The ability to automate the dispersive SPE clean-up of QuEChERS extracts combined with introduction of the cleaned extract directly to the LC/MS/MS system results in improved laboratory productivity by streamlining the complete analytical process.
Keywords: Dispersive Solid Phase Extraction, Automation, QuEChERS, Pesticides
This paper describes an automated dispersive SPE (dSPE) cleanup method for QuEChERS extracts that is performed with commercially available kits from Agilent® Technologies. Extraction and clean-up is performed using a micro-scale version of this method and automation is achieved using a GERSTEL MPS autosampler equipped with an Anatune CF-100 centrifuge. The clean-up process is followed by automated injection of the cleaned extract to a GC/MS system using the GERSTEL Automated TDU-liner EXchange (ATEX) technique. The sensitivity and selectivity of GC/MS combined with the described injection technique, results in method detection limits that meet acceptance criteria for reporting maximum residue levels (MRLs) as established by regulatory agencies. The ability to automate the dSPE clean-up of QuEChERS extracts and to couple extraction and clean-up directly to GC/MS analysis, results in the improved laboratory productivity by streamlining the complete analytical process.
Keywords: Automated Evaporation, mVap, SPE, DPX
Having to reach ever lower limits of detection is a daily challange in modern laboratories. In order to succeed in obtaining sufficiently sensitive analysis methods, sample preparation techniques such as Solid Phase Extraction (SPE) or Liquid-Liquid Extraction are often used as concentration steps. The concentration factor achieved in these cases depends on the amount of solvent used for analyte elution from the SPE cartridge or for liquid extraction. Following the extraction step, further concentration of analytes can be achieved by reducing the amount of solvent left in the extract. This is typically achieved by evaporation. Such a concentration step can contribute significantly to improved limits of detection for the overall analytical method. For the evaporative concentration step, commercially available rotary evaporators as well as custom solutions are widely used. These are mainly stand-alone systems for manual operation. The GERSTEL MultiPosition Evaporation Station (mVAP) in combination with the GERSTEL MultiPurpose Sampler (MPS) now offers fully automated concentration of sample extracts. The system enables complete automation of all sample preparation steps including introduction to an a LC or GC system. The evaporation is controlled by controlling the applied vacuum leading to reproducible results independent of the solvent used. The user can also benefit from a real increase in laboratory efficiency, since batches of samples can be processed automatically overnight. In this Application Note we demonstrate the performance of the mVAP and compare the results with those obtained using a commercially available evaporation system based on nitrogen flow.
Keywords: Solid Phase Extraction, SPE, LC/MS/MS, Sample Analysis, Laboratory Automation
Acrylamide is thought to be produced during the roasting process associated with coffee production. Acrylamide has been labeled as a probable human carcinogen. Due to the use of roasted coffee beans in making coffee and the high consumption of coffee world-wide, brewed coffee could be a source of daily exposure to acrylamide. Acrylamide determination has been shown to be challenging due to presence of co-extractives in the final extract. Manual solid phase extraction followed by LC-MS/MS analysis has been reported as a successful method for the determination of acrylamide from brewed coffee samples. However, performing solid phase extraction manually can be tedious and time consuming and there is increasing demand for automation of these methods. In this study, we show that a manual SPE method used for the determination of acrylamide in brewed coffee can be converted to an autosampler compatible cartridge format and automated using a robotic autosampler controlled by user-friendly software. Calibration standards prepared in freshly brewed green coffee (un-roasted) resulted in a linear calibration curve (r2=0.99) from 1 ng/mL to 500 ng/mL. Precision of the automated SPE-LC/MS/MS method was calculated as CV = 1.7 %.
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: Automation, Total Fat, Trans Fat, Saturated Fat, Food, Gas Chromatography, Microwave, Saponification, FAMEs
Determination of total fat, saturated fat, monounsaturated fat and trans fat content in food samples is necessary for complying with applicable food labeling requirements. A typical procedure for saponification of the sample involves refluxing with sodium methoxide in methanol, followed by a second reflux with boron trifluoride in order to esterify the free fatty acids. Prior to injection into the gas chromatograph, the fatty acid methyl esters (FAMEs) must be extracted from the reaction mix and the extract must be dried. The reflux times are typically an hour. After the sample is prepared, the round bottomed flask and condenser must be cleaned. This process is laborious and time consuming, which limits sample throughput. A combined autosampler and liquid handling robot, which is commonly used for a wide variety of sample preparation techniques can be interfaced directly to a CEM Discover SP-D microwave unit. In this way, a single integrated system under MAESTRO software control can perform saponification of fats in combination with further sample preparation steps and finally introduction to a GC or HPLC system.
Keywords: GC/MS, Lab Automation, Sample Preparation, Polymers and Plastics, Toys, Toy Safety, Child Care Articles
The US Consumer Product Safety Commission’s (CPSC) Test Method CPSC-CH-C1001-09.3 , is used by testing laboratories for the determination of phthalate content in children’s toys and child care articles covered by the standard set forth in the Consumer Product Safety Improvement Act Section 108. The CPSC determined that an appropriate combination of methods of extraction and analysis is sufficient to determine the concentration of the six regulated phthalates in most consumer products. The general manual approach is to dissolve the sample completely in tetrahydrofuran, precipitate any PVC polymer with hexane, filter and then dilute the solution with cyclohexane, and analyze by Gas Chromatography-Mass Spectrometry (GC/MS). A combined autosampler and sample preparation robot commonly used for sample introduction in GC or HPLC can be used to perform a wide variety of sample preparation techniques using a single instrument set-up and associated control software. Among the autosampler capabilities controlled by MAESTRO software are filtration and centrifugation, both of which can be used to clean up polymer extracts for further analysis. The autosampler can be configured as part of a GC or LC system or can be used independently as bench top workstation. In this work, we demonstrate automated extraction of phthalates in consumer products based on CPSC method CPSC-CH-C1001-09.3 directly combined with GC/MS analysis of the extract. The entire extraction and analysis process is streamlined and helps reduce or eliminate exposure of laboratory personnel to potentially hazardous materials.
Keywords: Opiates, Opioids, Cocaine, Solid Phase Extraction, SPE, Automation, GC/MS
Analyzing blood serum for opioids, cocaine and metabolites is a routine task in forensic laboratories. The most commonly used methods involve several manual or partly-automated sample preparation steps such as protein precipitation, solid phase extraction, evaporation and derivatization followed by GC/MS or LC/MS determination. In this study a comprehensively automated method is compared with a validated, partly-automated routine method. Following manual protein precipitation, the automated method relies on a MultiPurpose Sampler (MPS) to perform all remaining sample preparation steps. These include solid phase extraction (SPE), evaporation of the eluate, derivatization and introduction to the GC/MS. Quantitative analysis of close to 170 serum samples, as well as more than 50 samples of other matrices like urine, different tissues and heart blood, was performed using both methods. Cocaine, benzoylecgonine, methadone, morphine, codeine, 6-monoacetylmorphine, dihydrocodeine and 7-aminofl unitrazepam were determined quantitatively and the methods were found to produce equivalent analytical results even near the limits of quantification
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: Glyphosate, LC/MS/MS, Sample Preparation, Lab Automation, Food Safety
Glyphosate and glufosinate are widely used herbicides and, thus, there is an interest in the reliable and sensitive determination of glyphosate in water and food. These pesticides are difficult to extract and analyze because of their high polarity. In this report, we describe an automated work flow for the FMOC derivatization, sample cleanup, and LC/MS/MS analysis using a GERSTEL MultiPurpose Sampler (MPS XL) configured with an online solid phase extraction (SPEXOS) module coupled to an AB SCIEX QTRAP® 4500 system for the identification and quantitation of glyphosate, its major metabolite AMPA, and glufosinate in water and food samples. The online SPE-LC/MS/MS method allowed detection and quantitation of all target pesticides in matrix samples at 10 μg/kg concentration levels with excellent reproducibility and values well within the ±20 % range.
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.
Keywords: THC, THC-OH, THC-COOH, Serum, Solid Phase Extraction, SPE, Automation, GC/MS
This note presents a fully automated analysis system for the determination of THC and its metabolites in blood serum. Automation is based on the GERSTEL MultiPurpose Sampler (MPS) equipped for solid phase extraction and a module for automated eluate evaporation (GERSTEL mVAP). A validated, semi-automated analysis method used for routine analysis was transferred and automated using the described system. Improvements were realized such as a reduction of sample volume and the use of a smaller SPE cartridge format. The method was validated according to Society for Toxicology and Forensic Chemistry (GTFCh) guidelines. Limits of quantification below 1 ng/mL for THC and THC-OH, extraction efficiencies between 70 and 93% and RSDs between 3 and 10% were achieved.The SPE system performs sample preparation in parallel with the chromatographic run, enabling the GC/MS system to operate at maximum capacity.
Keywords: Urine Hydrolysis, β-Glucuronidase, LC/MS/MS
In this report, a completely automated, 96 well plate format “Prep-and-Shoot” workflow including enzymatic hydrolysis, dilution and injection is described. A GERSTEL MultiPurpose autosampler (MPS) coupled to an AB SCIEX QTRAP® 4500 LC/MS/MS system was used for a fast enzymatic hydrolysis process (15 minutes), dilution and injection of urine samples. The procedure was applied to the analysis of multiple drug classes (e.g., opiates, opioids, benzodiazepines, muscle relaxants, hallucinogens) in urine. This automated workflow employed an ultra-pure β-Glucuronidase enzyme yielding hydrolysis efficiencies of glucuronide conjugates above 80 % for the analytes tested. The methodology developed allowed the reproducible injection and analysis of over 960 samples on the same analytical column, with % RSDs ≤ 10 %. Moreover, the combined automation of urine hydrolysis, injection and analysis allowed the system to process more than 200 samples in a day.
Keywords: Automation, Chromatography, Sample Handling, Automation, Sample Preparation
The primary function of an autosampler for a chromatographic instrument is to provide unattended operation and thereby increase instrument utilization and improve sample throughput in the lab. A second important benefit of autosampler use is the improved reproducibility of analytical results compared to manual injections. Automation of sample preparation steps would have similar benefits in improving sampling reproducibility. This paper describes a software solution to control a common autosampler for HPLC or GC (MPS, GERSTEL) that provides flexible sample preparation capability without purchasing expensive laboratory robots. The following example applications illustrate the flexibility of this software for custom method generation: