Detection of Anatoxins in Human Urine by Liquid Chromatography Triple Quadrupole Mass Spectrometry and ELISA.

Harmful cyanobacterial blooms are becoming more common and persistent around the world. When in bloom, various cyanobacterial strains can produce anatoxins in high concentrations, which, unlike other cyanobacterial toxins, may be present in clear water. Potential human and animal exposures to anatoxins occur mainly through unintentional ingestion of contaminated algal mats and water. To address this public health threat, we developed and validated an LC-MS/MS method to detect anatoxins in human urine to confirm exposures. Pooled urine was fortified with anatoxin-a and dihydroanatoxin at concentrations from 10.0 to 500 ng/mL to create calibrators and quality control samples. Samples were diluted with isotopically labeled anatoxin and solvent prior to LC-MS/MS analysis. This method can accurately quantitate anatoxin-a with inter- and intraday accuracies ranging from 98.5 to 103% and relative standard deviations < 15%, which is within analytical guidelines for mass spectrometry methods. Additionally, this method qualitatively detects a common degradation product of anatoxin, dihydroanatoxin, above 10 ng/mL. We also evaluated a commercial anatoxin-a ELISA kit for potential diagnostic use; however, numerous false positives were detected from unexposed individual human urine samples. In conclusion, we have developed a method to detect anatoxins precisely and accurately in urine samples, addressing a public health area of concern, which can be applied to future exposure events.

Use of Diagnostic Ions for the Detection of Fentanyl Analogs in Human Matrices by LC-QTOF.

To combat the ongoing opioid epidemic, our laboratory has developed and evaluated an approach to detect fentanyl analogs in urine and plasma by screening LC-QTOF MS/MS spectra for ions that are diagnostic of the core fentanyl structure. MS/MS data from a training set of 142 fentanyl analogs were used to select the four product ions and six neutral losses that together provided the most complete coverage (97.2%) of the training set compounds. Furthermore, using the diagnostic ion screen against a set of 49 fentanyl analogs not in the training set resulted in 95.9% coverage of those compounds. With this approach, lower reportable limits for fentanyl and a subset of fentanyl-related compounds range from 0.25 to 2.5 ng/mL in urine and 0.5 to 5.0 ng/mL in plasma. This innovative processing method was applied to evaluate simulated exposure samples of remifentanil and carfentanil in water and their metabolites remifentanil acid and norcarfentanil in urine. This flexible approach enables a way to detect emerging fentanyl analogs in clinical samples.

Application of the fentanyl analog screening kit toward the identification of emerging synthetic opioids in human plasma and urine by LC-QTOF.

Human exposures to fentanyl analogs, which significantly contribute to the ongoing U.S. opioid overdose epidemic, can be confirmed through the analysis of clinical samples. Our laboratory has developed and evaluated a qualitative approach coupling liquid chromatography and quadrupole time-of-flight mass spectrometry (LC-QTOF) to address novel fentanyl analogs and related compounds using untargeted, data-dependent acquisition. Compound identification was accomplished by searching against a locally-established mass spectral library of 174 fentanyl analogs and metabolites. Currently, our library can identify 150 fentanyl-related compounds from the Fentanyl Analog Screening (FAS) Kit), plus an additional 25 fentanyl-related compounds from individual purchases. Plasma and urine samples fortified with fentanyl-related compounds were assessed to confirm the capabilities and intended use of this LC-QTOF method. For fentanyl, 8 fentanyl-related compounds and naloxone, lower reportable limits (LRL100), defined as the lowest concentration with 100 % true positive rate (n = 12) within clinical samples, were evaluated and range from 0.5 ng/mL to 5.0 ng/mL for urine and 0.25 ng/mL to 2.5 ng/mL in plasma. The application of this high resolution mass spectrometry (HRMS) method enables the real-time detection of known and emerging synthetic opioids present in clinical samples.

Quantitation of saxitoxin in human urine using immunocapture extraction and LC-MS.

AIM: An immunomagnetic capture protocol for use with LC-MS was developed for the quantitation of saxitoxin (STX) in human urine. MATERIALS & METHODS: This method uses monoclonal antibodies coupled to magnetic beads. STX was certified reference material grade from National Research Council, Canada. Analysis was carried out using LC-MS. RESULTS: With an extraction efficiency of 80%, accuracy and precision of 93.0-100.2% and 5.3-12.6%, respectively, and a dynamic range of 1.00-100 ng/ml, the method is well suited to quantify STX exposures based on previously reported cases. CONCLUSION: Compared with our previously published protocols, this method has improved selectivity, a fivefold increase in sensitivity and uses only a third of the sample volume. This method can diagnose future toxin exposures and may complement the shellfish monitoring programs worldwide.

Detection of human exposure to saxitoxin and neosaxitoxin in urine by online-solid phase extraction-liquid chromatography-tandem mass spectrometry.

Saxitoxin (STX) and neosaxitoxin (NEO) are potent neurotoxins that cause paralytic shellfish poisoning (PSP). PSP typically occurs through the ingestion of bivalve shellfish that have consumed toxin producing dinoflagellates. Due to initial presentation of symptoms being nonspecific, a clinical measurement is needed to confirm exposure to these toxins. Our group has developed an online solid phase extraction hydrophilic interaction liquid chromatography (HILIC) method for the analysis of STX and NEO in human urine with tandem mass spectrometry. A unique feature of this online method is the incorporation of a new synthetic (15)N4-STX labeled internal standard used for quantitation. Manual sample preparation time was reduced by approximately 70% for 98 urine samples as compared to a previously reported method. The lowest reportable limit for STX was improved from 5.0 ng/mL to 1.01 ng/mL and from 10.0 ng/mL to 2.62 ng/mL for NEO. Three analysts validated the method with 20 calibration curves total over 30 days with precision and accuracy within ±15% for all QCs. This new online method rapidly identifies STX and NEO exposure with improved sensitivity, which can facilitate the work of public health authorities to confirm the cases of PSP, complementing the many shellfish monitoring programs worldwide.

Comparison of two automated solid phase extractions for the detection of ten fentanyl analogs and metabolites in human urine using liquid chromatography tandem mass spectrometry.

Two types of automated solid phase extraction (SPE) were assessed for the determination of human exposure to fentanyls in urine. High sensitivity is required to detect these compounds following exposure because of the low dose required for therapeutic effect and the rapid clearance from the body for these compounds. To achieve this sensitivity, two acceptable methods for the detection of human exposure to seven fentanyl analogs and three metabolites were developed using either off-line 96-well plate SPE or on-line SPE. Each system offers different advantages: off-line 96-well plate SPE allows for high throughput analysis of many samples, which is needed for large sample numbers, while on-line SPE removes almost all analyst manipulation of the samples, minimizing the analyst time needed for sample preparation. Both sample preparations were coupled with reversed phase liquid chromatography and isotope dilution tandem mass spectrometry (LC-MS/MS) for analyte detection. For both methods, the resulting precision was within 15%, the accuracy within 25%, and the sensitivity was comparable with the limits of detection ranging from 0.002ng/mL to 0.041ng/mL. Additionally, matrix effects were substantially decreased from previous reports for both extraction protocols. The results of this comparison showed that both methods were acceptable for the detection of exposures to fentanyl analogs and metabolites in urine.