Clinical, Forensic & Toxicology
LC-MS/MS analysis of EtG and EtS is challenging due primarily to poor retention and resolution of EtG and EtS from matrix components. This article presents a foundation method that is useful for many samples and also demonstrates effective strategies for improving sensitivity and mitigating matrix effects.
Accurate analysis of amphetamines by LC-MS/MS can be achieved using chiral columns, but the analysis presented here provides a simpler, more cost-effective approach for high-throughput labs. Excellent separation of all enantiomers in urine was obtained in a fast, 7-min quantitative analysis on a Raptor C18 column with no interference from matrix components.
Simultaneous measurement of 58 antipsychotic and antidepressant drugs in human urine can be achieved with a simple sample preparation procedure and a fast 5.5-minute LC-MS/MS analysis on a Raptor Biphenyl column. This method provides accurate, high-throughput determinations and is suitable for both clinical and forensic monitoring.
A new LC-MS/MS method for methylmalonic acid (MMA) analysis was developed that provides complete chromatographic resolution from isobaric succinic acid in plasma samples. Excellent chromatographic results were obtained from the direct injection of a protein crash sample supernatant onto a Force C18 column, providing a much simpler sample preparation compared to typical methods.
The method established in this validation study provides accurate analysis of phosphatidylethanol (PEth) using a simple protein precipitation procedure and a fast 3.5 minute LC-MS/MS gradient run. Specific, sensitive analysis of PEth 16:0/18:1 in whole blood was obtained due to the unique selectivity and retention of the Raptor FluoroPhenyl column.
A rapid, robust method was established for the analysis of creatine and creatinine in human plasma and urine. An efficient separation was achieved in less than 1.5 min using a Raptor HILIC-Si column and a simple isocratic mobile phase.
Vitamin K1 and K2 analysis is typically complex and time-consuming because these lipophilic vitamins occur at low levels and are subject to matrix interference, particularly from phospholipids. The new method established here provides fast, accurate, and precise vitamin K levels in plasma using a simple phospholipid removal procedure and a sensitive 4-minute LC-MS/MS analysis on a Raptor Biphenyl column, making it suitable for high-throughput testing.
Accurate analysis of phosphatidylethanol (PEth) can be achieved with a simple protein precipitation procedure and a fast 3.5 minute LC-MS/MS gradient run. The method shown here utilizes a Raptor FluoroPhenyl column and provides a low-cost, high-throughput solution for labs monitoring PEth as a biomarker for alcohol consumption.
Quantitative analysis of bile acids in plasma is critical for diagnosing liver disease as well as assessing drug safety. Accurate reporting can be difficult because of analyte characteristics, matrix effects, and other factors. Here, we establish a rapid, robust, and selective LC-MS/MS method for the analysis of bile acids in human plasma using a Restek Raptor C18 column. One of the significant improvements over other reported methods was the baseline separation of all 17 bile acids in 6 minutes including three isomer groups.
This straightforward method for LC-MS/MS analysis of gamma-hydroxybutyrate (GHB) and its precursors gamma-butyrolactone and 1,4-butanediol provides simultaneous analysis of all target compounds in a fast, 5-min cycle time. Good low-level sensitivity was obtained, sufficient to measure low endogenous levels of GHB and identify exogenous drug consumption.
In general, LC-MS/MS analysis of urinary free cortisol and cortisone can provide better specificity than immunoassay-based methods. However, it is critical that the analytical column has the proper selectivity for chromatographically separating cortisol from isobaric matrix components. In the method presented here, complete separation of the target analytes and matrix interferences was obtained in a 3-minute analysis on a Raptor Biphenyl column.
Methylmalonic acid analysis is an important clinical test for diagnosing vitamin B12 deficiency as well as methylmalonic acidemia. Methods typically require extensive sample preparation, which involves significant time and expense. The LC-MS/MS method developed here offers a much simpler alternative, providing complete chromatographic resolution of isobaric analytes from the direct injection of a protein crash sample supernatant onto a Force C18 column.
Clinical diagnosis of pheochromocytoma and paraganglioma is often based on the analysis of catecholamines (epinephrine, norepinephrine, dopamine) and metanephrines (metanephrine, normetanephrine, 3-methoxytyramine) in urine. Analysis of these polar compounds using reversed-phase LC can be difficult due to limited chromatographic retention, which results in poor separation of the analytes from closely eluting matrix interferences. This method overcomes these problems by combining a simple solid phase extraction procedure with the consistent and accurate chromatographic performance of a Raptor Biphenyl column.
Highly sensitive analysis of metanephrines and in plasma is critical in the diagnosis and treatment of pheochromocytoma and paraganglioma. Here, a HILIC LC-MS/MS method was developed using a Raptor HILIC-Si column because this approach provides retention of all target compounds in highly organic mobile phases, thus providing the increased sensitivity needed to reach low detection limits. Data from linearity, accuracy, and precision testing demonstrate that accurate results are consistently obtained—even at trace levels—for these important clinical biomarkers.
Synthetic opioid drugs, such as fentanyl and sufentanil, have very high analgesic potency. Abuse of these prescription painkillers—along with a rapidly growing list of illicit analogues—is a significant public health problem. In this study, we developed a simple dilute-and-shoot method that provides a fast 3.5 minute analysis of fentanyl and related compounds (norfentanyl, acetyl fentanyl, alfentanil, butyryl fentanyl, carfentanil, remifentanil, and sufentanil) in human urine by LC-MS/MS using a Raptor Biphenyl column.
LC-MS/MS methods for folate deficiency biomarkers in plasma are complicated by the presence of matrix phospholipids and lysophospholipids. These interferences are problematic with reversed-phase LC because they can suppress response, reduce accuracy, and contaminate the MS source. Using a Raptor HILIC-Si column and the HILIC method shown here, folate deficiency biomarkers are completely separated from matrix interferences, allowing accurate determinations to be made in a fast, 5-minute analysis.
Methods for monitoring alcohol consumption biomarkers EtG and EtS are generally limited by poor retention and coelution with matrix interferences, as well as by long analysis times and short column lifetimes. The dilute-and-shoot EtG/EtS LC-MS/MS analysis developed here using the novel Raptor EtG/EtS column easily resolves EtG and EtS from matrix interferences, providing consistent, accurate results for high-throughput labs testing human urine samples for alcohol consumption.
Overcoming the Effects of Highly Organic Protein Precipitation Extracts on LC Peak Shape Using Direct Injection
Protein precipitation is frequently used to minimize matrix impact when analyzing biological samples. However, the effects of highly organic protein precipitation sample extracts on LC peak shape can negatively impact accurate quantification. Dilution or further sample preparation steps are often used to minimize these effects; however, here we show that direct injection of sample extracts is a viable option that can be used to prevent peak distortion, while avoiding the time and variability associated with additional sample preparation.
The success of organ transplant therapy depends in large part on the accurate and timely analysis of immunosuppressive drugs. In this study, we developed a fast, accurate method for cyclosporin A, tacrolimus, sirolimus, and everolimus in whole blood. The method pairs a single protein precipitation step with LC-MS/MS analysis using a Raptor Biphenyl column. A fast, 3-minute analysis time was obtained with no interference from matrix components. Excellent results were obtained for linearity, robustness, accuracy, and precision, demonstrating that the method is suitable for high-throughput therapeutic drug monitoring.
The analysis of total morphine is typically conducted by first subjecting urine samples to acid or enzymatic hydrolysis in order to cleave the glucuronide conjugates off of morphine’s primary metabolites [morphine-3β-D-glucuronide (M3G) and morphine-6β-D-glucuronide (M6G)] prior to analysis. With the glucuronide moiety removed, the resulting morphine molecule is much less polar and, therefore, more amenable to traditional reversed-phase chromatography than the metabolites are. However, both hydrolysis procedures cost an analyst time and result in sample variability due to incomplete hydrolysis or analyte conversion. By utilizing the retention characteristics of the Restek Force Biphenyl column, hydrolysis was not required and direct analysis of morphine, its M3G and M6G metabolites, and several related compounds using a simple “dilute-and-shoot” sample preparation was performed.
GC analysis of derivatized amphetamines and other drugs of abuse can be improved by using Rxi-5Sil MS columns. Robust and highly inert, these columns withstand harsh conditions, such as exposure to the derivatization reagents. High inertness and enhanced stability result in good peak shape and response, low phase bleed, and longer column lifetimes.
Analysis of Synthetic Cannabinoids and Metabolites: Adding New Compounds to an Existing LC-MS/MS Method
The analysis of synthetic cannabinoids and their metabolites can be a difficult and challenging task. Keeping up with the ever-growing list of synthetic cannabinoids that illicit drugmakers produce further complicates the analysis. As shown here, the retention and selectivity of the Raptor Biphenyl column allows new drugs to be added to an existing method, providing labs with an important vehicle for improving efficiency and productivity.
The C3 epimers of 25-hydroxyvitamin D have lower bioactivity than the primary metabolites and, unless they are chromatographically separated, can cause clinical vitamin D levels to be overestimated. Raptor FluoroPhenyl columns provide baseline resolution of all key compounds, and the method established here allows accurate quantification in a fast, 5-minute analysis time (7-minute total cycle time). This method is recommended for labs interested in reporting C3 epimer concentrations separately in order to obtain more accurate results for the clinical diagnosis of vitamin D status.
A Fast Dilute-And-Shoot Method for Simultaneous 5-Hydroxyindoleacetic Acid (5-HIAA), Vanillylmandelic Acid (VMA), and Homovanillic Acid (HVA) LC-MS/MS Analysis in Human Urine
Using Restek’s dilute-and-shoot method and a Raptor Biphenyl column, serotonin and catecholamine metabolites can be measured simultaneously in a quick 5-minute analysis. This method is applicable to clinical 5-HIAA, VMA, and HVA LC analysis in urine and provides the benefit of both fast analysis times and low-cost sample preparation procedures.
“The Big Pain”: Development of Pain-Free Methods for Analyzing 231 Multiclass Drugs and Metabolites by LC-MS/MS
As the demand for testing of pain management drugs increases, many laboratories are turning to LC-MS/MS for its increased speed, sensitivity, and specificity. The methods shown here use a Raptor Biphenyl column because it provides fast, accurate analysis of 231 drugs and drug metabolites.
Rapid and Accurate LC-MS/MS Analysis of Nicotine and Related Compounds in Urine Using Raptor Biphenyl LC Columns and MS-Friendly Mobile Phases
A rapid, accurate, and reproducible method was developed for high-throughput testing of nicotine, cotinine, trans-3'-hydroxycotinine, nornicotine, norcotinine, and anabasine in urine. Data show that a fast and highly efficient analysis of these basic compounds can be achieved with the Raptor Biphenyl column using standard, low pH, reversed-phase LC-MS mobile phases which are compatible with a variety of LC-MS instrumentation.
Rxi-5Sil MS columns produce excellent results for a number of forensic applications. The versatile selectivity separates a wide variety of compounds, which lets you keep analyzing samples instead of changing columns between methods. (PDF - 0kB)
Raptor LC columns combine the speed of superficially porous particles (i.e., SPP or “core-shell”) with the resolution of highly selective USLC technology. Featuring Restek's most popular LC stationary phase, the rugged Raptor Biphenyl is extremely useful for fast separations in bioanalytical testing applications like drug and metabolite analyses, especially those that require a mass spectrometer (MS). (PDF - 6071kB)
When we engineered our superficially porous particle (SPP or "core-shell") Raptor LC columns, we developed the bonding chemistries that are best suited to both the SPP construction and our highly selective USLC phases. But we didn't stop here. Take a closer look at a new species as we dissect the upgraded hardware and new, proprietary packing techniques behind Raptor LC columns and Raptor EXP guard columns. (PDF - 1725kB)
Rtx-BAC Plus 1 and Rtx-BAC Plus 2 columns provide definitive data in a fast, 2-minute analysis, so you can be certain of your results, maximize sample throughput, and get accurate, reliable results quickly, which is is critical for labs analyzing blood alcohol concentration (BAC). (PDF - 5471kB)
Rtx-BAC Plus 1 and Rtx-BAC Plus 2 columns provide definitive data in a fast, 2-minute analysis, so you can be certain of your results, maximize sample throughput, and get accurate, reliable results quickly, which is is critical for analyzing blood alcohol concentration (BAC). (PDF - 963kB)
Column selectivity has the most significant influence on chromatographic peak separation, or resolution, so choosing the right column can greatly speed up HPLC and UHPLC method development. In this article, we discuss column choice and identify a set of just 4 stationary phasesRestek’s USLC column setthat encompasses the widest range of reversed phase selectivity available today.
4.5 Minute Analysis of Benzodiazepines in Urine and Whole Blood Using LC/MS/MS and an Ultra Biphenyl Column
Sample throughput for benzodiazepines in urine and whole blood can be increased by adopting this dilute-and-shoot LC/MS/MS method which uses an Ultra Biphenyl HPLC column. Partial validation data are presented in this application note.
Fast Screening of Recalled Tylenol for Tribromoanisole and Related Adulterants Using QuEChERS and GC-TOFMS
Screening methods for consumer product adulteration cases, such as the recent Tylenol recall, can benefit from fast QuEChERS-based sample preparation and sensitive, full mass-range GC/TOF-MS.
An Rxi-5ms column will resolve acidic/neutral or free basic drugs under one set of conditions. There is no interference from column bleed not even at 330°C. This is one of the first published applications for our new family of Rxi columns.
New Rxi-5Sil MS columns produce consistent results for amphetamine—even after 400 injections of derivatizing reagent—resulting in less time and money spent on column maintenance and replacement.
The headspace (HS) analysis of gamma-hydroxybutyrate (GHB) described here reduces contamination and eliminates time-consuming derivatization. Confirmation testing using an Rtx-5MS column, provides definitive results in less than 7 minutes.
The headspace (HS) analysis of gamma-hydroxybutyrate (GHB) described here reduces contamination and eliminates time-consuming derivatization. Confirmation testing using an Rtx-5MS column, provides definitive results in less than 7 minutes. (PDF - 0kB)
GC/MS analysis of urinary steroid hormones is a demanding application, and the Rxi-1ms column meets the requirements for low bleed and inertness better than any column we have tested. We analyzed a variety of derivatized steroid sex hormones in less than 25 minutes, with excellent resolution and symmetric peaks. At 300°C or above, bleed from the Rxi-1ms column was negligible.
Basic drugs can interact with active sites on the surface of the inlet liner, reducing responses. The combination of a base-deactivated liner and a base-deactivated Rtx-5Amine column ensures the greatest responses in analyses for these compounds.
Thermal desorption is used extensively for forensic science. This 16-page publication from Markes International Ltd. presents several key applications including drugs, arson accelerants, trace explosives, shotgun propellant, and inks. (PDF - 0kB)