USGS-NWQL: O-2440-14: Pharmaceutical Compounds in Water by DAI and HPLC-MS/MS
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Official Method Name
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Human-Use Pharmaceuticals and Related Compounds in Filtered Water by Direct Aqueous Injection—High Performance Liquid Chromatography with Tandem Mass Spectrometry |
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Current Revision
| 2014 |
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Media
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WATER |
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Instrumentation
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Direct Aqueous Injection with High Performance Liquid Chromatography with Tandem Mass Spectrometry |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Brief Method Summary
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This method is suitable for determining 110 individual pharmaceuticals in filtered water at concentrations greater than 1 to 100 ng/L, depending on the specific pharmaceutical. All samples must be filtered prior to analysis. Using the procedure of Wilde and others (2004 with updates through 2009) for filtering samples at the time of sample collection removes much of the naturally occurring microbiota; this reduces the potential for degradation of pharmaceuticals during sample shipment. Samples are filtered in the field using 0.7-micro-meter (μm) pre-ashed glass-fiber filters, adding as much as 10 or 20 milliliters (mL) of sample to a 20- or 40-mL, respectively, amber glass vial with a Teflon-lined screw cap, and shipping the samples on ice to the laboratory by overnight express. Upon receipt, samples are stored refrigerated until analyzed. If a sample requires additional filtration upon request or after inspection, the sample is again passed through a 0.7-μm pre-ashed glass-fiber filter prior to analysis. For sample analysis, approximately 1 mL of the sample is withdrawn from the sample vial and placed into a 1.5-mL autosampler vial, and an aliquot of a mixture of isotope-dilution standard (IDS) pharmaceuticals is added to the vial. After thoroughly mixing the vials, environmental, laboratory QC, calibration, and other analytical samples are placed in the autosampler in a predetermined sequence. The report continues to explain the automated computer control sequence and various transitions in the analyis process. Because the responses of the individual pharmaceuticals of interest, the QC surrogate compounds, and the IDS compounds can be suppressed or enhanced by the sample matrix, results from several QC sample types are necessary to properly interpret the ambient environmental concentrations of pharmaceuticals in aqueous samples. See method report for full details. |
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Scope and Application
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All method analytes are determined without sample pre-concentration or isolation using direct injection of an aliquot of the filtered sample onto a high-performance liquid chromatograph/tandem mass spectrometer. Qualitative identification is by multiple-reaction monitoring tandem mass spectrometry. Nineteen deuterium- or carbon-13-labeled isotope-dilution standard (IDS) compounds are added to each sample just prior to analysis and are used for isotope-dilution quantitation. The 19 IDS compounds represent a range of pharmaceuticals and their associated physicochemical properties. For IDS compounds that are exact analogs to the native pharmaceutical or are structurally similar, the use of IDS quantitation automatically corrects the final concentration for any losses in the reported analyte concentration during analysis based on the absolute recovery of IDS compounds. For those compounds where an exact or structurally similar isotopic analog is not available, the IDS corrects for injection or other instrumental variations during analysis. The pharmaceutical IDS compounds also are quantified using a non-pharmaceutical IDS compound, and so the pharmaceutical IDS compounds are used as surrogates to monitor and compare method performance in environmental samples. |
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Applicable Concentration Range
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1-100 |
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Interferences
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A wide variety of additional compounds, dissolved organic carbon, and other organic and inorganic chemical matrix components are likely present in water samples. Their presence may result in potential interferences to the process of efficiently separating, accurately identifying, and quantifying the pharmaceuticals determined by this method. Further, this method is purposely designed for the determination of an array of pharmaceuticals that comprise a wide range of chemical characteristics and elemental and functional group compositions. Consequently, the potential is substantial for co-eluting interferences that may limit the qualitative identification of a pharmaceutical or may enhance or suppress the formation of a precursor ion during electrospray ionization. Careful attention to the results produced during instrumental analysis is necessary to ensure that matrix interferences do not compromise the determination of pharmaceuticals. Three aspects of matrix effects bear consideration: 1. interferences in the sample that degrade chromatographic performance and characteristics, such as peak shape and retention time, thereby decreasing the ability to separate and identify pharmaceuticals of interest chromatographically; 2. interferences persisting in the sample after chromatographic separation that alter ionization efficiency ofthe pharmaceutical of interest or compete for available charges during ESI, thereby altering the responses of pharmaceuticals of interest, which can result in apparent quantitative matrix enhancement or suppression; and 3. interferences persisting in the sample after chromatographic separation that produce a precursor-ion/product-ion transition that is the same as one of the two transitions used to identify the pharmaceutical of interest, thereby altering the MRM area ratios used for qualitative identification. |
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Quality Control Requirements
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QA/QC requirements include: 10.1. Surrogates 10.2. Laboratory Reagent Blank (LRB) Samples 10.3. Laboratory Reagent Spike (LRS) Samples 10.4. Continuing Calibration Verification (CCV) Samples 10.5. Continuing Calibration Blank (CCB) Samples 10.6. Limit of Quantitation (LOQ) Samples 10.7. Field Equipment Blank (FEB) Samples 10.8. Laboratory Matrix Spike (LMS) Samples 10.9. Isotope-Dilution Standard (IDS) Performance Criteria 10.10. Statistical Derivation of Quality-Control Limits 10.11. Secondary Data Review |
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Sample Handling
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All samples should be filtered and kept iced or refrigerated at 4oC from the time of collection until extraction. |
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Maximum Holding Time
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A sample holding-time study was conducted using filtered surface water fortified at 2,000 ng/L. Samples should be analyzed no later than 9 days from collection, preferably within 4 days, to ensure that sample results are minimally affected by degradation. |
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Relative Cost
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Greater than $400 |
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Sample Preparation Methods
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samples are collected and stored in 40-mL VOA vials until analysis |
