title: Modifications to United States Environmental Protection Agency methods 1622 and 1623 for detection of Cryptosporidium oocysts and Giardia cysts in water.
abstract: Collaborative and in-house laboratory trials were conducted to evaluate Cryptosporidium oocyst and Giardia cyst recoveries from source and finished-water samples by utilizing the Filta-Max system and U.S. Environmental Protection Agency (EPA) methods 1622 and 1623. Collaborative trials with the Filta-Max system were conducted in accordance with manufacturer protocols for sample collection and processing. The mean oocyst recovery from seeded, filtered tap water was 48.4% +/- 11.8%, while the mean cyst recovery was 57.1% +/- 10.9%. Recovery percentages from raw source water samples ranged from 19.5 to 54.5% for oocysts and from 46.7 to 70.0% for cysts. When modifications were made in the elution and concentration steps to streamline the Filta-Max procedure, the mean percentages of recovery from filtered tap water were 40.2% +/- 16.3% for oocysts and 49.4% +/- 12.3% for cysts by the modified procedures, while matrix spike oocyst recovery percentages ranged from 2.1 to 36.5% and cyst recovery percentages ranged from 22.7 to 68.3%. Blinded matrix spike samples were analyzed quarterly as part of voluntary participation in the U.S. EPA protozoan performance evaluation program. A total of 15 blind samples were analyzed by using the Filta-Max system. The mean oocyst recovery percentages was 50.2% +/- 13.8%, while the mean cyst recovery percentages was 41.2% +/- 9.9%. As part of the quality assurance objectives of methods 1622 and 1623, reagent water samples were seeded with a predetermined number of Cryptosporidium oocysts and Giardia cysts. Mean recovery percentages of 45.4% +/- 11.1% and 61.3% +/- 3.8% were obtained for Cryptosporidium oocysts and Giardia cysts, respectively. These studies demonstrated that the Filta-Max system meets the acceptance criteria described in U.S. EPA methods 1622 and 1623.
authors.affiliation: Clancy Environmental Consultants, Inc., St. Albans, Vermont 05478, USA.
authors.forename: Randi M
authors.initials: RM
authors.lastname: McCuin
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Clancy
mesh_terms: D000818:Animals; D003458:Cryptosporidium / Q000254:growth & development / Q000302:isolation & purification*; D005374:Filtration; D005872:Giardia / Q000254:growth & development / Q000302:isolation & purification*; D007753:Laboratories; D033661:Oocysts / Q000302:isolation & purification*; D015203:Reproducibility of Results; D014481:United States; D014484:United States Environmental Protection Agency / Q000592:standards; D014867:Water / Q000469:parasitology*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
chemical_list: D014867:Water