UHMC Water Quality Lab



Bring your fresh or sea water samples to the University of Hawai'i Maui College Water Quality Lab to measure: 
  • Inorganic nutrients: nitrate+nitrite, silicate, phosphate, and ammonia 
  • Organic nutrients: total nitrogen and phosphorus
  • Total suspended solids (TSS) 
  • Turbidity
  • Biological oxygen demand (BOD5)
  • Escherichia coli (E.coli)

Sample testing is available to all research organizations, industries, and any interested community members.

We accept samples Monday through Thursday 10am to 2pm on the University of Hawaii Maui College Campus, Ike Le'a Building Room 123. If Samples need to be dropped off or processed Friday through Sunday or outside of the M-Th standard hours, that must be arranged ahead of time and additional processing fees may apply. Please contact Crystal Henkel to arrange sample drop off day and times, email and at least one day prior is preferred (chenkel@hawaii.edu)If you are shipping your samples to the lab, please provide as much advanced notice as feasible to ensure proper collection and storage procedures. 
Please see table below for analyses cost and results turnaround times. 

Contact info: Crystal Henkel 
University of Hawaiʻi Maui College
310 W Kaʻahumanu Ave.
Ike Leʻa Building Rm 123
Kahului, HI 96732
Email: crystal.henkel@hawaii.edu
Lab Phone: 808-984-3682
Dr. Andrea Kealoha founded the UHMC Water Quality Laboratory in 2018. Her vision was to bring home many of the testing capabilities she had completed throughout her marine science career on Oahu and the mainland. Dr. Kealoha has moved on to become a Professor of Oceanography at UH Manoa. However she is still based on Maui and is deeply connected with Maui and the UHMC WQL. Crystal Henkel has taken over the position of WQL director and is working to further Andrea’s vision to expand water quality testing on island. Crystal is joined by Greg Masessa and Laura Martinez-Robles in the laboratory. They are prepared to help you with whatever your water quality needs are. If they cannot complete the work themselves they will connect you with someone that can and may be the best people to collect, preserve, and ship samples to other laboratories with expanded technologies. Please do not hesitate to reach out. We look forward to working with you!

Concerned about your water quality post fire, please check out this amazing organization UHMC WQL is supporting and promoting, they are doing great work.

Water Quality Lab Phone 808-984-3682
Crystal Henkel, chenkel@hawaii.edu
Greg Masessa, massesag@hawaii.edu
Laura Martinez-Robles, lauram7@hawaii.edu


SEAL AutoAnalyzer 3
The AA3 is a segmented flow autoanalyzer for colorimetric detection of dissolved nutrients. The instrument is composed of 5 channels, an autosampler, 2 digital colorimeters, 2 high precision pumps, and a fluorometer.

Nitrate and Nitrite - Nitrate is reduced to nitrite by a copper-cadmium reductor column. The nitrite reacts with sulfanilamide under acidic conditions to form a diazo compound, then couples with N-1-naphthylethylene diamine dihydrochloride to form a purple azo dye.

Phosphate - Following the method of Murphy and Riley, the procedure for the determination of ortho-phosphate is based on the colorimetric method in which a blue color is formed by the reaction of ortho-phosphate, molybdate ion and antimony ion followed by reduction with ascorbic acid at an pH<1.

Silicate - The determination of soluble silicates is based on the reduction of silico-molybdate in acidic solution to molybdenum blue by ascorbic acid. Oxalic acid is introduced to the sample stream before the addition of ascorbic acid to minimize interference from phosphates.

Ammonia - The sample is reacted with o-phthalaldehyde (OPA) at 75°C in the presence of borate buffer and sodium sulfite to form a fluorescent species proportional to the ammonia concentration. The fluorescence is measured at 460 nm following excitation at 370 nm.

Total dissolved nitrogen - Samples are first digested in an autoclave using a reagent composed of boric acid, potassium persulfate and sodium hydroxide, then run through the nitrate channel.

Total dissolved phosphorus - Samples are first digested in autoclave using a reagent composed of boric acid, potassium persulfate and sodium hydroxide, then run through the phosphate channel.

IDEXX Quanti-Tray 2000
The IDEXX Quanti-Tray/2000 is a semi-automated quantification method based on the Standard Methods Most Probably Number (MPN) model. After addition of the Colilert-18 ONPG-MUG substrate to the sample, the sample is then poured into a Quanti-Tray 2000 tray and sealed. The tray is incubated at 35º ± 0.5ºC for 18-22 hours to metabolize Colilert-18’s nutrient indicator ONPG/MUG and then checked for color change from clear to yellow (presence of total Coliforms) and bluish fluorescence (presence of E coli). Results are reported in terms of the Most Probably Number (MPN) of organisms present. This number is an estimate of the mean density of coliforms in the sample. The test can detect total coliforms and E. coli in water at 1CFU/100ml within 22 hours with as many as 2 million heterotrophic bacteria/100 ml present. The U.S. Environmental Protection Agency (EPA) has stated in writing that Quanti-Tray/2000 can be used for compliance testing.


Armstrong, F.A.J., Sterns, C.R. and Strickland, J.D.H., 1967 Deep Sea Res. 14, pp. 381-389.
"The measurement of upwelling and subsequent biological processes by means of the Technicon AutoAnalyzer and associated equipment."
Grasshoff, K., Technicon International Congress, June 1969.
Federal Water Pollution Control Administration Methods for Chemical Analysis of Water and Wastes, November 1969.
Methods of Seawater Analysis, K. Grasshoff et. al., Verlag Chemie, 2nd Edition, 1983.
J. Murphy and J.P. Riley, 1962. A modified single solution method for the determination of phosphate in natural waters. Analytica Chimica Acta 27:31-36.
L. Drummond and W. Maher, 1995. Re-examination of the optimum conditions for the analysis of phosphate. Analytical Chimica Acta 302: 69-74.
Methods of Seawater Analysis, K. Grasshoff, M. Ehrhardt, K. Kremling, second revised and extended edition, 1983
Fluorometric determination of ammonia in sea and estuarine waters by direct segmented flow analysis.
Kerouel, R, Aminot, A. Marine Chemistry Vol. 57, no. 3-4, pp. 265-275. Jul 1997.