Analysis of Microcystins RR, LR and YR in Bottled, Tap and Surface Water by 2D LC/MS/MS
Oral Presentation
Prepared by J. Smith1, C. Mallet2
1 - Virginia Institute of Marine Science, 1375 Greate Road, Gloucester Point, VA, 23062, United States
2 - Workflow Integration Group, Waters Corporation, 34 Maple St, Milford, MA, 01757, United States
Contact Information: jlsmith@vims.edu; 804-684-7289
ABSTRACT
Anthropogenic eutrophication, or the accelerated introduction of excess nutrients to a water body, can lead to the production of harmful algal blooms (HABs) in freshwater systems. These blooms, i.e., dense aggregations of cyanobacterial cells, and their associated algal toxins deleteriously impact environmental health, public safety (e.g., drinking water), and recreational activities. The suite of algal toxins produced by cyanobacteria in freshwater systems (e.g., microcystins, cylindrospermopsins, saxitoxins, anatoxin-a) vary in their mode of toxicity, with different toxin groups possessing cytotoxic, hepatotoxic, neurotoxic, and/or carcinogenic attributes. Microcystin-LR, listed on EPA’s Chemical Contaminant List 3 (CCL 3), is the most common and toxic variant of microcystins, and the World Health Organization (WHO) set a guideline value of 1ppb for microcystin-LR in drinking water.
The extraction process was performed using a reversed-phase sorbent with a 3-cc SPE barrel using a sequential elution. From an acetonitrile stock solution, 15 µL of nodularin was added to the final extract as an internal standard. The concept of sequential micro-extraction was designed to capture the retention behavior of a target analyte in response to various extraction parameters (e.g., sorbent strength, elution polarity, solubility). As a result, optimized conditions can be selected to excise a region of interest during extraction. In this application, acetonitrile was chosen as the elution solvent, with a 10% organic incremental. As microcystins exhibit a zwitterionic structure, two sets of elution solutions were created to evaluate the elution profile (pH 3 and pH 10).
When the elution profile for the low pH and high pH are compared, microcystin-RR was eluted in a single fraction (20% acetonitrile) with low pH conditions, but can be seen in the 20% and 30% fractions (50/50) under high pH conditions. This elution behavior suggests that the acidic moieties of the structure show a stronger retention for the stationary phase. For microcystin-LR and -YR, elution occurred at 40% acetonitrile, under acidic conditions.
As to be expected with low-complexity samples, we achieved high recovery, 90-104%, for all three microcystins in the bottled water sample. The similarly elevated recoveries for tap and surface water samples, 75% to 85%, however, provide clear indication of the overall performance of the extraction protocol.
Oral Presentation
Prepared by J. Smith1, C. Mallet2
1 - Virginia Institute of Marine Science, 1375 Greate Road, Gloucester Point, VA, 23062, United States
2 - Workflow Integration Group, Waters Corporation, 34 Maple St, Milford, MA, 01757, United States
Contact Information: jlsmith@vims.edu; 804-684-7289
ABSTRACT
Anthropogenic eutrophication, or the accelerated introduction of excess nutrients to a water body, can lead to the production of harmful algal blooms (HABs) in freshwater systems. These blooms, i.e., dense aggregations of cyanobacterial cells, and their associated algal toxins deleteriously impact environmental health, public safety (e.g., drinking water), and recreational activities. The suite of algal toxins produced by cyanobacteria in freshwater systems (e.g., microcystins, cylindrospermopsins, saxitoxins, anatoxin-a) vary in their mode of toxicity, with different toxin groups possessing cytotoxic, hepatotoxic, neurotoxic, and/or carcinogenic attributes. Microcystin-LR, listed on EPA’s Chemical Contaminant List 3 (CCL 3), is the most common and toxic variant of microcystins, and the World Health Organization (WHO) set a guideline value of 1ppb for microcystin-LR in drinking water.
The extraction process was performed using a reversed-phase sorbent with a 3-cc SPE barrel using a sequential elution. From an acetonitrile stock solution, 15 µL of nodularin was added to the final extract as an internal standard. The concept of sequential micro-extraction was designed to capture the retention behavior of a target analyte in response to various extraction parameters (e.g., sorbent strength, elution polarity, solubility). As a result, optimized conditions can be selected to excise a region of interest during extraction. In this application, acetonitrile was chosen as the elution solvent, with a 10% organic incremental. As microcystins exhibit a zwitterionic structure, two sets of elution solutions were created to evaluate the elution profile (pH 3 and pH 10).
When the elution profile for the low pH and high pH are compared, microcystin-RR was eluted in a single fraction (20% acetonitrile) with low pH conditions, but can be seen in the 20% and 30% fractions (50/50) under high pH conditions. This elution behavior suggests that the acidic moieties of the structure show a stronger retention for the stationary phase. For microcystin-LR and -YR, elution occurred at 40% acetonitrile, under acidic conditions.
As to be expected with low-complexity samples, we achieved high recovery, 90-104%, for all three microcystins in the bottled water sample. The similarly elevated recoveries for tap and surface water samples, 75% to 85%, however, provide clear indication of the overall performance of the extraction protocol.
