USEPA Validation Study Report for Hach Method 10267, TNTplus 

810/811TM Total Organic Carbon

Spectrophotometric Measurement of Total Organic Carbon in Drinking 

Water

Submitted by:

Hach Company

5600 Lindbergh Drive

Loveland Colorado 80538

Cary Jackson 

and

Luke Johnson

December 2015
Hach Company Validation Study Report

Measurement of TOC in Water and Wastewater, Method 10267

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Background

Purpose of Study

The purpose of this study is to evaluate the proposed Hach Company Measurement of Total 

Organic Carbon (TOC) in Water and Wastewater, Method 10267 against USEPA Reference TOC

Method SM5310-TOC C for approval and use in USEPA regulatory water compliance and 

reporting programs.

Method Summary

Hach Method 10267 TNTplus TOC chemistry follows persulfate digestion to oxidize TOC to 

carbon dioxide (CO2). The generated CO2 passes through a gas-permeable membrane into a 

liquid color indicator solution. The CO2 liberated from reaction with persulfate digestion is 

measured spectrophotometrically. Inorganic carbon (IC) is removed from the sample prior to 

digestion by acidification and agitation. Carbon dioxide produced during this sample 

pretreatment process is liberated by mechanical dispersion. 

Method Justification

The EPA Reference Method SM 5310-C for the measurement of TO is slow and requires costly

instrumentation. A simple, more efficient and lower cost analytical method is desirable. The 

proposed method uses pre-packaged chemistries in test vials and simple spectrophotometry, 

completes a batch of 30 samples in 2 hours, and can analyze samples containing solids.

Scope of Method

Method 10267 is applicable for use in drinking water, surface, and municipal and industrial 

wastewaters. 

Study Design and Objectives

The design and objectives of this validation study are detailed in the Validation Study Plan0F

1

appended to this report.

Study Implementation

Study Sponsor

The organizational sponsor responsible for managing this study is Hach Company.

 1 Hach Validation Study Plan, January 2015
Hach Company Validation Study Report

Measurement of TOC in Water and Wastewater, Method 10267

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Study Participants

The participants, laboratories, and test matrices were selected from geographically diverse 

regions of the United States and are listed in the following table.

Treated Drinking 

Water Matrix 

Facility

Laboratory Source of Treated 

Test Water

Loveland, Colorado Hach Company Surface Water

Iowa City, Iowa University of Iowa and Test America-Cedar Falls Surface Water

Parker, Colorado Parker Water Ground Water

Sample Collection and Distribution

Matrix samples for this validation study were collected, preserved, and stored per SM 5310-C 

protocols.

Analysis Description

The description of the type and number of analyses are described in the Validation Study Plan 

appended to this report.

Data Reporting and Validation

Data Collection, Laboratory Submission, and Validation

For each laboratory performing analyses, results from each test measurement were read from a 

DR3900 spectrophotometer with built-in calibration and manually transferred to an electronic 

spread sheet. Each laboratory then submitted the electronic spread sheet to the Hach Study 

Director for review and statistical evaluation. 

Results

Summary results of the validation study are listed in Tables 1-5. Initial demonstration of 

capability is demonstrated by accuracy (bias) and precision data which are generated 

throughout the calibration range in several matrices. These data were collected at the Hach 

laboratory and are included in Table 1. The quantitation range and method reporting limits for 

this method are 1.0 – 25.0 mg/L TOC.
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Measurement of TOC in Water and Wastewater, Method 10267

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Table 1 – Initial Demonstration of Capability for Hach Method 10267

Parameter Concentration 

(mg/L)

Average Percent Recovery by Matrix

LIS 250 mg/L CO3

250 mg/L 

CaCO3

Method Blank 0 0.2 0.6 0.5

Average Percent Bias by Matrix

LIS 250 mg/L CO3

250 mg/L 

CaCO3

Accuracy (bias) 

2.0/3.0 4.7 7.1 7.7

10.0 1.6 0.4 3.0

25.0 0.2 1.2 0.5

Percent Relative Standard Deviation by Matrix

LIS 250 mg/L CO3

250 mg/L 

CaCO3

Precision 

2.0/3.0 8.8 0.6 3.0

10.0 2.8 0.4 0.3

25.0 1.8 0.8 1.2

Average Percent Bias by Matrix

Loveland DW Brighton DW Keokuk DW

Matrix Spike Accuracy 

(bias)

Low 0.7 2.4 0.1

Mid 1.6 9.8 1.9

High 0.6 4.0 3.6

Percent Relative Standard Deviation by Matrix

Loveland DW Brighton DW Keokuk DW

Matrix Spike Precision

Low 5.2 7.6 3.9

Mid 1.6 1.0 1.4

High 1.2 0.1 0.8
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Measurement of TOC in Water and Wastewater, Method 10267

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 Table 2 – Loveland Colorado Tap Water Performance Results 

Method 

Detection 

Limit (mg/L)

Method 

Detection 

Limit (mg/L)

Low Ionic Strength 

Reagent Water

0.17 0.28

High Ionic Strength 

Reagent Water 0.09 0.29

Average 

Percent (%) 

Recovery

Percent Bias Standard 

Deviation

Average 

Percent (%) 

Recovery

Percent Bias Standard 

Deviation

Low Ionic Strength 

Reagent Water 102 2 1.0 102 2 0.16

High Ionic Strength 

Reagent 105 5 5.1 104 4 1.2

Average 

Percent (%) 

Recovery

Relative 

Percent 

Difference

Average 

Percent (%) 

Recovery

Relative 

Percent 

Difference

99.4 3.8 101 0.3

Matrix Spike Analysis Matrix Spike Analysis

Matrix

Standard Method 5310-C Hach Method 10267

Initial Precision and Recovery Initial Precision and Recovery

Loveland Treated 

Tap Water
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Measurement of TOC in Water and Wastewater, Method 10267

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Table 3 – Iowa City Drinking Water Plant Summary Results 

Method 

Detection 

Limit (mg/L)

Method 

Detection 

Limit (mg/L)

Low Ionic Strength 

Reagent Water

0.06 0.65

High Ionic Strength 

Reagent Water 0.07 0.39

Average 

Percent (%) 

Recovery

Percent Bias Standard 

Deviation

Average 

Percent (%) 

Recovery

Percent Bias Standard 

Deviation

Low Ionic Strength 

Reagent Water 101 1 0.33 105 5 2.4

High Ionic Strength 

Reagent 105 5 0.48 107 7 1.0

Average 

Percent (%) 

Recovery

Relative 

Percent 

Difference

Average 

Percent (%) 

Recovery

Relative 

Percent 

Difference

104 0.6 97.9 2.7

Initial Precision and Recovery

Iowa City Treated 

Tap Water

Matrix Spike Analysis Matrix Spike Analysis

Matrix

Standard Method 5310-C Hach Method 10267

Initial Precision and Recovery
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Measurement of TOC in Water and Wastewater, Method 10267

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Table 4 – Parker Colorado Drinking Water Plant Summary Results

Development of QC Acceptance Criteria

Quality control acceptance criteria for method detection limit (MDL), initial precision and 

recovery (IPR), and matrix spike recovery are described in Table 5. Calibration verification is 

demonstrated through the accuracy (bias) data. These criteria are based on intra-laboratory 

data. 

Method 

Detection 

Limit (mg/L)

Method 

Detection 

Limit (mg/L)

Low Ionic Strength 

Reagent Water

0.04 0.11

High Ionic Strength 

Reagent Water 0.24 0.23

Average 

Percent (%) 

Recovery

Percent Bias Standard 

Deviation

Average 

Percent (%) 

Recovery

Percent Bias Standard 

Deviation

Low Ionic Strength 

Reagent Water 101 1 0.00 103 3 1.1

High Ionic Strength 

Reagent 101 1 0.08 104 4 0.68

Average 

Percent (%) 

Recovery

Relative 

Percent 

Difference

Average 

Percent (%) 

Recovery

Relative 

Percent 

Difference

101 0.0 99.8 1.1

Matrix

Loveland Treated 

Tap Water

Matrix Spike Analysis Matrix Spike Analysis

Standard Method 5310-C Hach Method 10267

Initial Precision and Recovery Initial Precision and Recovery
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Table 5 – Quality Control Performance Criteria for Hach Method 10267

Data Analysis/Discussion

MDL Results

The MDL results for each of the three facilities ranged from 0.04 mg/L to 0.17 mg/L (low ionic 

strength matrix) for the EPA Reference Method SM 5310-C and 0.11 mg/L to 0.65 mg/L (low 

ionic strength matrix) for the Hach Method 10267. The high ionic strength matrix MDL results 

ranged from 0.07 mg/L to 0.24 mg/L for the EPA Reference Method SM 5310-C and 0.23 mg/L 

to 0.39 mg/L for the Hach Method 10267. The pooled MDL results for EPA Reference Method 

SM 5310-C were determined to be 0.09 mg/L for low ionic strength matrix water and 0.12 mg/L 

for high ionic strength matrix water. The pooled MDL results for the Hach Method 10267 were 

determined to be 0.33 mg/L for low ionic strength matrix water and 0.25 mg/ for high ionic 

strength matrix water. 

Initial Precision and Recovery Results

Low Ionic Strength 

Reagent Water

High Ionic Strength 

Reagent Water

Initial Precision and 

Recovery Analysis

Average 

Percent (%) 

Recovery

Percent 

Bias

Lower Limit 

of % 

Recovery

Upper Limit 

of % 

Recovery

95% 

Precision of 

Recovery

Average 

Percent (%) 

Recovery

Percent 

Bias

Lower Limit 

of % 

Recovery

Upper Limit 

of % 

Recovery

95% 

Precision of 

Recovery

Low Ionic Strength 

Reagent Water

101 1 98.3 104 0.01 103 3 97.5 109 0.03

High Ionic Strength 

Reagent

104 4 94.1 113 0.06 105 5 99.4 111 0.02

Average 

Percent (%) 

Recovery

Percent 

Bias

Lower Limit 

of % 

Recovery

Upper Limit 

of % 

Recovery

95% 

Precision of 

Recovery

Average 

Percent (%) 

Recovery

Percent 

Bias

Lower Limit 

of % 

Recovery

Upper Limit 

of % 

Recovery

95% 

Precision of 

Recovery

101 1 94.4 108 0.07 99.5 1 94.3 105 0.06

Matrix

Standard Method 5310-C Hach Method 10267

Initial Precision and Recovery (IPR) Initial Precision and Recovery (IPR)

Drinking Water 

Matrix Analysis

Matrix Spike Recovery Matrix Spike Recovery

Method Detection Limit 

(MDL) mg/L

0.09

0.12

Method Detection Limit 

(MDL) mg/L

0.33

0.25
Hach Company Validation Study Report

Measurement of TOC in Water and Wastewater, Method 10267

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The IPR average recovery results for low ionic strength matrix water for each of the three 

facilities ranged from 101% to 103% for EPA Reference Method SM 5310-C and 102% to 105% 

mg/L for Hach Method 10267. The IPR average recovery results for high ionic strength matrix 

water ranged from 101% to 107% for EPA Reference Method SM 5310-C and104% to 107% for 

the Hach Method 10267. The pooled low ionic strength matrix recovery results for EPA 

Reference Method SM 5310-C ranged from 98.3% to 104% with a 95% precision of 0.01and 

97.5% to 109% with a 95% precision of 0.03 for Hach Method 10267. The pooled high ionic 

strength matrix recovery results for the EPA Reference Method SM 5310-C ranged from 94.1% 

to 113% with a 95% precision of 0.06 and 99.4% to 111% with a 95% precision of 0.02 for Hach 

method 10267.

Matrix Spike Results

The average matrix spike recovery results of the three facilities ranged from 99.4% to 104% for 

EPA Reference Method SM 5310-C and 97.9% to 101% for Hach method 10267. The relative 

percent difference for matrix spike recoveries ranged from 0.0 to 3.8 for EPA reference method 

SM 5310-C and 0.3 to 3.3 for Hach method 10267. The pooled matrix spike results of recovery 

ranged from 94.4% to 108% for EPA Reference Method SM 5310-C and 94.3% to105% for Hach 

Method 10267. The 95% Precision of Recovery results for the EPA Reference Method 5310-C 

and Hach Method 10267 were determined to be 0.07 and 0.06 respectively.

Conclusion

A validation study was conducted to compare the performance of Hach Method 10267 for the 

measurement of TOC in water to that of the EPA Reference Method SM 5310-C. The results of 

the study indicate that Hach Method 10267 is equally effective to that of the EPA Reference 

Method SM 5310-C for Safe Drinking Water Act monitoring and compliance reporting 

programs.