Method 1622 / 1623 / 1623.1 Quality Control Materials

The inaccuracy and imprecision of standard dilution methods for preparing low-level parasite stock suspensions are well-known. Since 1997, the WSLH Flow Cytometry laboratory has been preparing standards for testing and research laboratories whose work demands high-quality and precisely enumerated standards. The Laboratory’s Cryptosporidium and Giardia standards have been used as control samples for EPA methods 1622, 1623, and 1623.1, and for researchers developing and optimizing protozoon detection methods.

The WSLH is the sole source of live, flow cytometer-prepared standards approved for use with U.S. EPA methods 1622, 1623, and 1623.1 within the United States.


Cryptosporidium/Giardia Standards

Note: The table below lists the specifications for routinely prepared standards. Custom orders may include variations of those listed in the table above, typically at little or no additional cost.

Variations may include:

  • Organism concentration (one organism, 107/tube)
  • Tube type (low-volume PCR, 250 mL conical tubes)
  • Diluent composition
  • Final diluent volume
Isolates Cryptosporidium parvum (IOWA), Giardia lamblia (CH3) others available upon request
Diluent Reagent grade water (18 megaOhm) with 0.01% Tween 20
Volume 1 mL or 10 mL
Organism concentration 100, or 150-200
Relative SD of the mean Less than 2.5%
Expiry 6 weeks from preparation (Envirochek); 2 weeks from preparation (FiltaMax)
Storage 4º C
Price $320 (US) set of 10 tubes
Shipping $65

The lot specification sheet includes the mean and the relative standard deviation, isolate source and shed date, viability estimates based on propidium iodide exclusion, storage conditions, and expiration date.

Concentrated stock suspensions are assessed for general quality and intactness using DIC microscopy prior to use in standard preparations.

Initial and ongoing precision and accuracy measurements are used to verify the accuracy of the dose. The relative standard deviation of these measurements is less than 2.5%.

The Laboratory has an extensive QAQC program. Contact us at 608-224-6260 for more information.


Analyst Verification Slides

Analyst verification slides are a useful tool for evaluating the microscopy skills of a single or multiple microscopists and satisfying the analyst performance requirements outlined in methods 1622, 1623, and 1623.1.  The WSLH routinely prepares flow cytometer-enumerated, microscopist-verified analyst verification slides containing 40-200 fluorescently labeled Cryptosporidium and Giardia. Contact us at 608-224-6260 for more information.


Mock Proficiency Testing (PT) Samples

Mock PT samples are available for purchase for those laboratories that wish to evaluate their performance more than twice annually, or want to obtain materials for training or retraining laboratory personnel.  Contact us at 608-224-6260 for more information.


On Site Audit Package

This package consists of 2-50 mL blind samples, two vials of artificial matrix, and two IMS control samples. Additional samples may be required if your laboratory is seeking accreditation for more than one method version.

Note that analyst verification slides are also required for the on-site audit. Auditors will require one slide per analyst. Please contact the WSLH two weeks in advance of your audit to schedule receipt of your audit materials.