detectachem seekere · 2018-07-05 · detectachem llc. proprietary – not for distribution...

DetectaChem LLC. PROPRIETARY – NOT FOR DISTRIBUTION


DetectaChem SEEKERe

ASTM Testing & Evaluation Report R1

DetectaChem LLC.

4100 Greenbriar Dr. Suite 180

Stafford, TX 77477

April 5, 2017

MRIGlobal Project No. 311449-01-001

FOR:


MRIGlobal-ISR\311449-01-001_R1 ii


Preface

Mr. Evan Durnal wrote this report with Ms. Elsy Naveo. Technical questions regarding this

report should be directed to Mr. Durnal at 816-326-5466. Contractual questions concerning this

report should be directed to Matthew Cates, Contract Management Section, at 816-326-5888.

MRIGlobal prepared this report for DetectaChem under Contract No. 311449.

MRIGlobal

Mr. Evan Durnal M.S.

Senior Chemist

ISR Division

Approved:

Dr. Joe Clement

Section Manager

Advanced Technologies

April 5, 2017


MRIGlobal-ISR\311449-01-001_R1 iii


Contents

Preface............................................................................................................................................. ii

Executive Summary .........................................................................................................................1

Section 1. Introduction ....................................................................................................................2

1.1 Objectives ..............................................................................................................4

Section 2. Technical Approach .......................................................................................................4

2.1 Operational Characteristics ...................................................................................4

2.2 Material Identification ...........................................................................................4

Section 3. Results ............................................................................................................................5

3.1 Operational Characteristics ...................................................................................5

Section 4. ASTM Testing .............................................................................................................10

4.1 Method Overview ................................................................................................10

4.2 Sample & Standard Preparation ..........................................................................11

Section 5. Quality Assurance (QA) and Quality Control (QC) ....................................................13

Section 6. Results & Conclusions .................................................................................................14

Figures

Figure 1. SEEKERe .......................................................................................................................2

Figure 2. SEEKERe Features ........................................................................................................5

Figure 3. SEEKERe Home Screen ................................................................................................6

Figure 4. SEEKERe Test Card ......................................................................................................6

Figure 5. SEEKERe System Check Screen ...................................................................................7

Figure 6. Sample Card Crushing ...................................................................................................7

Figure 7. SEEKERe Analysis Screen ............................................................................................7

Figure 8. Positive (left) and Negative (right) Result Screens ........................................................8

Figure 9. Micro USB Communications Port .................................................................................9

Figure 10. LOD Scoring Criteria from ASTM E2520-15 .............................................................11

Figure 11. Product Scoring Matrix from ASTM E2520-15 ..........................................................11

Figure 12. ASTM E2520-15 Score Results ...................................................................................15

Tables

Table 1. SEEKERe Instrument Specifications .............................................................................3

Table 2. Materials for Single Compound Testing ........................................................................4

Table 3. Initial Standard Preparation Form ................................................................................12

Table 4. Subsequent Standard Preparations ...............................................................................12

Table 5. Data Quality Objectives ...............................................................................................13

Table 6. Range Finding and Final Replicate Trial Summary ....................................................14

Table 7. Calculated LOD90 Values ...........................................................................................15


MRIGlobal-PDRM\311449-01-001_R1 1


Executive Summary

The SEEKERe is a compact, handheld explosives detector manufactured by DetectaChem. The

instrument is ruggedized to MIL-810-G and IP-66 standards for survivability and exclusion of

dust and water. Measuring 2.6 in. x 4.5 in. x 1.4 in and weighing 0.4 lbs., the SEEKERe is one of

the smallest powered explosives detection units on the market.

MRIGlobal performed an evaluation of the SEEKERe for ease of use and the ability to identify

unknown explosive related materials. The SEEKERe instrument features large, physical joystick

that is easily manipulated wearing common personal protective equipment and a brightly backlit

display screen that is easily viewable in high-and low-light conditions. The on-board software is

straightforward and features illustrated screens to guide the non-expert user through the data

acquisition process.

The detection performance of the SEEKERe instrument was also evaluated by analyzing a

variety of single compounds as outlined in ASTM E2520-15. MRIGlobal performed nearly

900 tests of record through the duration of testing. The results of the ASTM scoring system are

presented below.

Summary Result Figure – ETD Scoring Matrix

Overall, the SEEKERe system performed well without a single system malfunction nor any

downtime attributable to instrument operation. The system had a 0% false positive rate over 337

blank and background trials. The batteries lasted just under eight hours when used non-stop, and

the system did not require any non-routine cleaning, maintenance, or repairs. The system is very

easy to use, with easily interpreted results, and satisfies all criteria set forth in ASTM E2520-15.




Section 1. Introduction

There are a wide variety of handheld explosive detectors available on the market today. These

products are designed for down-range field use and typically include reference libraries or single

colorimetric methods to assist with unknown material identification. The SEEKERe is a

ruggedized handheld explosives and narcotics analyzer designed for field use and features on-

board software to perform in-field materials identification. A full listing of instrument

specifications can be found in Table 1.

In February 2017, DetectaChem tasked MRIGlobal to evaluate the SEEKERe system. The

instrument was evaluated by two operators for ease of use, including time required to acquire a

result, ease of use when wearing various PPE, and intuitiveness of the on-board software.

Instrument performance was evaluated by analyzing a variety of compounds of different

chemical classes and recording the ability of the instrument to successfully identify the

compound class using the on-board identification feature. The ease of use and materials

identification performance of the SEEKERe instrument was evaluated in accordance with ASTM

E2550-15 Standard Practice for Measuring and Scoring Performance of Trace Explosive

Chemical Detectors.

Figure 1. SEEKERe

1.1 Objectives

The objectives of the task were as follows:

Challenge the SEEKERe explosive detection system with eight (8) target compounds and

a single background material via ASTM E2520-15

Determine LOD90 values for eight (8) total compounds representative of eight explosive

classes

Determine the Effective Sampling Rate as defined by ASTM E2520-15

Determine the ETD Score as defined by ASTM E2520-15




Table 1. SEEKERe Instrument Specifications

Specification Value

Technology Readiness Level (TRL) 9

Market Entry Date 2015

User Feedback Sources IHEODTD, NSWC Crane, USAF, Federal Reserve, MRIGlobal

Physical Parameters

Dimensions 2.6 x 4.5 x 1.4 in. ( 68 x 116 x 37 mm)

Weight .43 lbs. ( .197kg)

Power Requirements Lithium ion battery, AC 100 - 240v

Noise Produced 0db

Logistical Parameters

Transportability Handheld

Durability MIL STD - 810G, IP66, rugged

Operating Conditions -10F to 140F

Consumables Detection cards (swab method)

Solvents/Reagents Yes

Calibration Schedule No user calibration required

Suggested Routine Maintenance Clean/wipe as needed. Non-scheduled

Available Accessories Battery charger, GPS dongle, international power adapters, carrying case, external storage, printer.

Data Analysis Support Equipment N/A

Data File Type/Format pdf report, csv data file

Communications Interface Micro USB, GPS dongle

Expected Operational Life 5 years

Shelf Life 24 months for detection cards

Unit Cost Contact DetectaChem

Maintenance Cost N/A

Operational Parameters

Tested for Explosives MDK and EDK: Nitroaromatics, Nitramines , Nitrate Esters, Inorganic Nitrates, Chlorates, Peroxides, Perchlorates plus Combinations and

Derivatives

Tested for Narcotics MDK & DDK: Methamphetamine, MDMA, Ketamine, Cocaine, THC, LSD, Opiates, Heroin, others

Number of Library Entries N/A

Customize for New Targets No

Sample Introduction Solid; Liquid

Sensitivity/Detection Limits ng

Known Interferents/Inhibitors Not specified

False Positive Rates <2%

Start-up Time (From cold start to sample ready)

30 seconds

Response Time (sample application to output)

10-59 seconds

Total Run Time variable, max of 90 seconds

Alarm Capability Audible, visible

Software Control Yes

Training, Shipping, and Other Information

Operator Skills Required Non-technical Background

Training Available Yes

Manuals Available Yes

Reachback Service Not specified

Warranties 1 year at no charge; Up to 5 additional years available to purchase

ITAR Export Regulations No

IATA Shipping Restrictions Not specified

Approved Vendors Not specified




Section 2. Technical Approach

The SEEKERe was evaluated in accordance with the ASTM E2520-15. The evaluation focused

on two major areas: operational characteristics and detection capabilities.

2.1 Operational Characteristics

Throughout the course of testing, ease of use was evaluated by noting the following attributes:

Startup time, time to acquire a result, extract data (spectrum and search/match report) from the

instrument. Users evaluated the menus and controls while performing these actions to compare

ease of use. Factors such as intuitive controls, manual dexterity while wearing different PPE,

need for one or two hands, ability to operate in a chemical fume hood were all documented.

2.2 Material Identification

The chemicals listed in Table 2 challenged the SEEKERe ability to identify chemicals of interest

as outlined in ASTM E2520-15. A single compound representative of each of the eight energetic

classes was tested.

Table 2. Materials for Single Compound Testing

No. Category Explosive Class Chemical CASRN

1

Explosive

Nitramine RDX 121-82-4

2 Nitro-ester PETN 78-11-5

3 Nitro-aromatic TNT 118-96-7

4 Nitrosamine Nitrosomorpholine 59-89-2

5 Peroxide TATP 17088-37-8

6 Inorganic Nitrate Ammonium Nitrate 6484-52-2

7 (Per)chlorate Potassium Chlorate 3811-04-9

8 Smokeless Powder Nitroglycerin 55-63-0

9 Background Challenge Material

Domestic Dust SRM 2585 House and

Hotel Dust --




Section 3. Results

3.1 Operational Characteristics

Physical Attributes, Specifications, and Ease of Use

The SEEKERe is a hand-held, powered colorimetric device that uses the color change associated

with test reagents and a photo sensor to identify explosives based on chemical class. The

instrument measures 2.6 in. x 4.5 in. x 1.4 in., weighs 0.43 lbs., and is ruggedized to MIL-STD-

810G and IP66 standards.

Figure 2. SEEKERe Features

The user interacts with the SEEKERe through a joystick mounted below the display screen. The

joystick is well designed and easy to use while wearing protective equipment such as nitrile or

butyl gloves. The display screen is easy to read from a variety of angles and is designed for

visibility in direct sunlight conditions. Virtually all display features are user-adjustable via the

setup menu. The SEEKERe is equipped with an integrated mechanical sample press to facilitate

sample card crushing. The SEEKERe on-board software is simple and easy to use and is geared

toward the non-expert user with illustrated guides for each step of the measurement process. On-

board measurement parameter adjustment is limited, but advanced users can access methods,

perform advanced data analysis, and other advanced features. The SEEKERe comes pre-loaded

with a vendor library containing over 30 explosives and narcotics. The unit do not have the

ability to accept custom user libraries. On-board searching is performed automatically following

data acquisition and utilizes a matching algorithm.

All operations performed during the SEEKERe evaluation were done with the operator wearing

standard laboratory personal protective equipment (PPE) including laboratory coat, nitrile

gloves, and laboratory eyewear. The physical buttons were very easy to use even when wearing

gloves and the bright backlight of the display ensure that the screen will remain visible when

operating the instrument in bright light conditions. All operators remarked that the instrument

was easy to use when fully equipped with PPE.




Performing an Analysis

After powering the instrument on and allowing the software to initialize, the user is presented

with the home screen of the SEEKERe, shown in Figure 3. A sample measurement is initiated by

using the physical button on the right side to select green highlighted option. The measurement

process begins with an illustrated screen instructing the user to scan the barcode of the test card

(Figure 3), followed by instructing the user to insert and crush the test card. If the system

identifies the barcode has already been analyzed it will not allow the user to proceed.

Figure 3. SEEKERe Home Screen

Figure 4. SEEKERe Test Card

After the system performs a system check (cleanliness test), it prompts the user to crush the

single use card as shown in Figures 5 and 6. User should hold the unit in a vertical (upright)

position for the duration of the analysis. The unit will stand on end on level surfaces without

support. Figure 7 is the running test screen; the top indicates what type of card is being analyzed.

The countdown timer allows the user to see the remaining analysis time and the plot displays the

color response over test time.




Figure 5. SEEKERe System Check Screen

Figure 6. Sample Card Crushing

Figure 7. SEEKERe Analysis Screen

Once data acquisition has completed, the system automatically initiates a search of the

experimental data against the loaded reference. The best match results are displayed in list

format and assigned a linear bar graph (full bar representing the best match) describing the

similarity between the experimental and reference identification. An example result list is

displayed below in Figure 8.




Figure 8. Positive (left) and Negative (right) Result Screens

The SEEKERe will categorize a positive result into five groups:

Group 1 – Nitro-aromatics (TNT, TNB, DNT, DNB, and Tetryl)

Group 2 – Nitrate Esters and Nitramines (HMX, RDX, PETN, NG, EGDN, Pyrodex,

Triple 7, Gunpowder/Smokeless Powder, Semtex)

Group 3 – Inorganic Nitrates (Ammonium Nitrate, Urea Nitrate, KNO3)

Group 4 – Chlorates (Sodium Chlorate, Potassium Chlorate)

Group 5 – Peroxides (TATP and HMTD)

The user can utilize the joystick to scroll to a desired match result, and then press down or the

select button to bring up the color chart of the observed trace. The user can also initiate a

chemical wiki feature that provides basic information on the specific compounds within a group

including chemical structure, physical appearance, common uses, stability, and hazard

information. The chemical wiki is an extremely useful feature for users unfamiliar with explosive

classes.

Viewing Previous Results

From the Home screen, the user can select the Results button to bring up a list of previously

collected sample results, organized chronologically by acquisition. Selecting a file will display

the full test data, including the test details (name, date, duration, and cleanliness), identification

results, color chart, and export option. Alternatively, the user can search for the results for a

specific test card by performing a Barcode Search and scanning the previously analyzed card.

Each individual sample scan is saved automatically as associated with a barcode to avoid

confusion.




Data Transfer

The SEEKERe can accomplish data transfer operations using WIFI, BLUETOOTH, or USB

transfer. The wireless transfer features of the SEEKERe were not evaluated. All data transfer

operations were accomplished using a USB drive to transfer files between the SEEKERe and a

PC. The communications port is located on the top of the instrument as shown in Figure 9.

Figure 9. Micro USB Communications Port

Users can export raw data files, full test reports, and summary reports. The reports create pre-

formatted and easy to interpret results that can be used for graphic generation or overall result

trends. No additional analysis are required or useful to the field user once data has been

transferred from the SEEKERe to a PC. The time to export varies with the amount of data to be

transferred and is typically done in less than a minute. No data manipulation or interpretation

was done using external software. Exported data can be securely and permanently archived, and

used by the instrument manufacturer to diagnose operational issues remotely.




Section 4. ASTM Testing

4.1 Method Overview

As stated by ASTM –

This practice may be used for measuring, scoring, and improving the overall performance of

detectors that alarm on traces of explosives on swabs. These explosive trace detectors (ETDs)

may be based on, but are not limited to, chemical detection technologies such as ion mobility

spectrometry (IMS) and mass spectrometry (MS). Technologies that use thermodynamic or

optical detection are not specifically addressed, but may be adapted into future versions of this

practice.

This practice considers instrumental (post-sampling) trace detection performance, involving

specific chemical analytes across eight types of explosive formulations in the presence of a

standard background challenge material. This practice adapts Test Method E2677 for the

evaluation of limit of detection, a combined metric of measurement sensitivity and repeatability,

which requires ETDs to have numerical responses.

This practice considers the effective detection throughput of an ETD by factoring in the sampling

rate, interrogated swab area, and estimated maintenance requirements during a typical eight-

hour shift. This practice does not require, but places extra value on, the specific identification of

targeted compounds and explosive formulations.

This practice requires the use of a single set of ETD operational settings for calculating a system

test score based on the factors described in 1.2, 1.3, and 1.4. A minimum acceptable score is

derived from criteria established in Practice E2520-07.

Generally speaking, the method provides guidance on the initial range-finding of test levels for

each test analyte, the requirement for blank and background contamination replicates, and the

required results for a given detection level. The low-level replicates are collected at a mass on

swab resulting in a positive detection in ten or fewer trials out of twelve. The high-level

replicates are collected at a mass on swab resulting in a positive detection in eleven or more trials

out of twelve. The time taken to collect 25 blank samples is used to calculate an effective

sampling rate, which is based on the number of swabs expected to be run in an 8-hour workday.

Observed detection results are entered into an online LOD90 calculator provided by NIST

(http://pubapps.nist.gov/loda). An LOD score is derived from the resultant value and used in a

larger calculation of the overall system score.

The figures below present the LOD score associated with a given mass on swab, and scoring

sheet used to determine the overall score.

http://pubapps.nist.gov/loda




Figure 10. LOD Scoring Criteria from ASTM E2520-15

Figure 11. Product Scoring Matrix from ASTM E2520-15

4.2 Sample & Standard Preparation

Sample preparation methods are documented and finalized in an approved laboratory notebook

and are available on request.

Background Contamination Material

A standard solution of BCM (background contamination material (SRM-2585)) was prepared per

ASTM E2520-15. 400mg of reference material was weighed using a calibrated balance (Mettler

Toledo, XS105 DR MRI# Y-11203) valid from 12.3mg to 120g. Actual mass recorded, and

directly added to a 100mL volumetric flask. The solution was brought to final volume using B&J

HPLC grade Isopropanol, inverted 10 times to mix, and transferred to a 100mL amber glass

bottle for storage. The preparation results in a 4 mg/mL background suspension. Standard

solutions of the target were purchased and/or prepared in chromatographic-grade solvent

(MeOH, ACN, or H2O).

Target Analyte Solutions

The target solutions were delivered onto the substrate after it had been spiked with the BCM and

the solvent allowed to evaporate for 5 minutes prior to analyte spiking. Drying time for targets

varied considerably, TNT and RDX samples were allowed to dry for 1 minute and PETN

samples for 3 minutes. While TATP, Nitroglycerin, and Nitrosomorpholine samples were tested

without drying time. Since Ammonium Nitrate and Sodium Chlorate were dissolved in water,

these samples were allowed to evaporate for 10 and 15 minutes, respectively. All BCM and

target solution delivery was performed with a calibrated Eppendorf pipette (1-10µL).




Certified reference standards of TATP1, Nitroglycerin2, PETN2, RDX2, and TNT2 were

commercially procured from 1) Accustandard, and 2) Sigma Aldrich. Initial solutions were

prepared allowing for 1-5µL spike volumes to achieve target mass-on-swab values as shown in

Table 3.

Table 3. Initial Standard Preparation Form

MRIGlobal prepared solutions of Ammonium Nitrate and Potassium Chlorate (originally Sodium

Chlorate) from neat materials using an identical type of dilution scheme to achieve the

appropriate stock solution concentration as indicated above. Ammonium Nitrate and Potassium

Chlorate did not dissolve in acetone or acetonitrile at the target spike solution concentration.

Ammonium Nitrate and Potassium Chlorate solutions were made in methanol and originally

tested but not pursued. Nitrosomorpholine was originally procured as a neat material but a

certified reference material became available shortly after testing started, it was purchased and

used for the remainder of R-salt testing. Dilution of the nitrosomorpholine standard was not

required.

Following the initial range-finding trials, the preparation of numerous additional solutions was

required. Table 4 below summarizes all solutions that were prepared. A total of 22 solutions

were prepared and tested for the effort.

Table 4. Subsequent Standard Preparations

Analyte Solution(s) Prepared

Nitroglycerin in ACN 16 µg/mL; 40 µg/mL; 100 µg/mL

PETN in ACN 80 µg/mL; 250 µg/mL

RDX in ACN 20 µg/mL; 50 µg/mL

TNT in ACN 20 µg/mL; 50 µg/mL

TATP in ACN 1.5 mg/mL

Ammonium nitrate in H2O 2.53 mg/mL; 7.54 mg/mL; 7.73 mg/mL

Ammonium nitrate in MeOH 2.60 mg/mL

Nitrosomorpholine in ACN 3.07 mg/mL; 7.72 mg/mL

Sodium chlorate in H2O 2.53 mg/mL; 6.27 mg/mL

Sodium chlorate in MeOH 2.60 mg/mL

Potassium Chlorate in H2O 2.54 mg/mL; 21.0 mg/mL; 62.5 mg/mL; 62.7 mg/mL

Potassium Chlorate in MeOH 2.60 mg/mL

Chemical

Conc. of

Stock

(mg/mL)

Stock

Solution ID

Stock

Exp. Date

Vol.

Stock

Added

(µL)

√

when

added

Final

Vol.

(mL)

Target

Spike

Solution

(µg/mL)

Conc.

Spiking

Soln.

(µg/mL)

Spike

Vol.

(µL)

Initial

Target

Mass on

Card (µg)

Actual

Mass on

Card

with

Spike

(µg)

Nitroglycerin 1.00 -- Oct. 2020 500 o 5 100 100 5.00 0.50 0.50

PETN 1.00 -- Dec. 2020 400 o 5 80 80 2.00 0.15 0.16

RDX 1.00 -- Dec. 2019 250 o 5 50 50 2.00 0.10 0.10

TNT 1.00 -- Oct. 2020 250 o 5 50 50 2.00 0.10 0.10

TATP 10.00 -- Jun. 2017 750 o 5 1500 1500 3.00 5.00 4.50

Ammonium Nitrate 2.50 14019-1-1 Feb. 2018 -- o -- 2500 2500 2.00 5.00 5.00

Nitrosomorpholine 3.00 14019-1-2 Feb. 2018 -- o -- 3000 3000 5.00 15.0 15.0

Sodium Chlorate 2.50 14019-1-3 Feb. 2018 -- o -- 2500 2500 2.00 5.00 5.00




Section 5. Quality Assurance (QA) and Quality Control (QC)

All work for this effort met the requirements specified in the MRIGlobal Corporate Quality

Manual and its related policy and procedures. This plan was developed to meet the requirements

of ISO 9001:2008. The operations of MRIGlobal’s evaluation programs (as well as all of

MRIGlobal) are certified to ISO 9001:2008 standards, with the most recent re-certification in

August 2015. The testing included the following quality assurance/control measures:

1. Each target chemical used on this project has a current Certificate of Analysis verifying

its purity.

2. Use of test matrix approved by the client.

3. Blank BCM samples (25) were analyzed at the start of the testing phase per ASTM

requirements.

4. All test trials included negative control samples used to monitor system cleanliness each

day. These control samples include the following:

5. Solvent Method Blank: A volume of solvent equal to the volume of target solution used

was spiked onto substrate(s) and allowed to evaporate in the same manner as samples.

The card is analyzed by the SEEKERe system to verify a non-detection at the start of

each testing day and/or for each solvent.

6. Card Method Blank: A blank, fresh out of container card. The card is analyzed by the

SEEKERe system to verify a non-detection at the start of each testing day and/or for each

solvent.

Table 5 summarizes the data quality objectives for test system acceptance and data validation;

corrective actions are also listed. No corrective actions were required for the duration of testing.

The units did not require additional cleaning, nor did any blank sample result in a false positive.

Table 5. Data Quality Objectives

QC Analysis Frequency Data Quality

Objective Outcome

Method Blank Once per solvent Non-detection 0% False positive rate over 337 Trials

Card Blank Between Each Sample Non-detection 0% False positive rate over 337 Trials




Section 6. Results & Conclusions

Single compound identification consisted of eight compounds representing each of eight

chemical classes. Range finding for each compound started at levels at or above the

manufacturer stated LOD. Data files collected using the SEEKERe instrument were transferred

to a PC and provided to the manufacturer. 875 trials were performed and documented during

single compound identification and ASTM testing. Table 5 summarizes the results of single

compound identification testing. Complete trial logs are provided as an appendix.

Table 6. Range Finding and Final Replicate Trial Summary

Analyte Range Finding Summary (Hits/Trials)

Nitrosomorpholine in MeOH

0/2 at 15µg; 1/4 at 22.5µg; 3/4 at 25µg

Nitroglycerin in ACN 0/2 at 0.032 µg; 2/3 at 0.048 µg; 1/3 at 0.056 µg; 3/3 at 0.064 µg; 6/6 at 0.08

µg; 4/4 at 0.2µg; 2/2 at 0.5µg;

PETN in ACN 0/2 at 0.16µg; 1/3 at 0.32µg; 4/4 at

0.4µg

RDX in ACN 0/2 at 0.04 µg; 1/2 at 0.06 µg; 2/4 at 0.08

µg; 5/5 at 0.1µg

TNT in ACN 1/3 at 0.04 µg; 2/2 at 0.06 µg; 3/4 at 0.08

µg; 5/5 at 0.1µg;

TATP in ACN 0/1 at 3µg; 0/1 at 4.5µg; 0/3 at 6.0µg;

1/5 at 7.5µg; 1/3 at 15µg

Ammonium Nitrate in H2O

0/2 at 5µg; 1/3 at 8.75µg; 4/4 at 12.5µg; 4/6 at 15.4µg

Potassium Chlorate in H2O

0/25 at 12.5µg; 2/4 at 57.75µg; 2/5 at 63.0µg; 0/1 at 63.0 µg; 2/2 at 73.5 µg;

3/3 at 84 µg

As can be seen in Table 6, the SEEKERe instrument performed as expected (within a factor of

two) or better than expected for six of the eight explosive classes. The unit seems to have trouble

reliably detecting chlorates at the expected levels, and minimal trouble detecting Nitrates at

expected levels. The SEEKERe instrument demonstrated excellent performance (0% false-

positive identifications) for the 337 blank and background contaminated samples. The testing did

however, result in a 33% false negative rate for samples at or above the manufacturer stated

LOD (98/295). The system trials produced a 100% correct identification rate, as no erroneous

groups were identified out of the 258 positive test cases.

The first primary object of testing was to determine the LOD90 value for each target compound

per ASTM E2520-15. The results of the 25 blank BCM samples, 12 low replicates, and 12 high

replicates for each analyte were entered into the NIST online LOD90A calculator. Table 7 shows

the resultant values in µg on swab. The system performed extremely well (<10ug LOD) for all

but Nitrate and Chlorate based compounds, with chlorates having the highest calculated LOD at

~35ug. All calculated values should be considered trace detections, as the representative amounts

for all classes are barely visible or not at all visible to the human eye.




Table 7. Calculated LOD90 Values

Analyte LOD90 Score

Corresponding Mass

RDX 3 <0.1µg

PETN 2 <1.0µg

TNT 3 <0.1µg

Nitrosomorpholine 1 <10µg

TATP 1 <10µg

Nitroglycerin 3 <0.1µg

Ammonium Nitrate 1 <100µg

Potassium Chlorate 1 <100µg

The second primary objective was to determine the Explosives Trace Detector (ETD) score of

the SEEKERe unit as defined by ASTM E2520-15. Base on the calculations required by the

method, the SEEKERe passes the minimum score threshold and exceeds the standards set forth

in ASTM E2520-15. Figure 12 provides all derived values and ultimate score of the SEEKERe

system.

Figure 12. ASTM E2520-15 Score Results

The third and primary objective of the testing was to determine the Effective Sampling Rate

(ESR) of the SEEKERe units as also defined by ASTM E2520-15. The effective sampling rate is

a number that estimates the number of samples processed per minute during an average eight-

hour shift. The calculation includes considerations for calibrations, clear-down, tune, and

otherwise maintain the system. A rate of greater than one sample per minute is very good. The

SEEKERe system tests, based on over 875 trials conducted over a three-week period produced

an ESR of 1.22 samples per minute.

Overall, the SEEKERe system was a pleasure to work with. Not a single system malfunction

occurred, nor was any downtime attributable to instrument operation. The batteries lasted just

shy of eight hours when used non-stop, and the system did not require any non-routine cleaning,

maintenance, or repairs. The system is very easy to use, with easily interpreted results, and

satisfies all criteria set forth in ASTM E2520-15.

A Effective Area (cm2) 2.40

φ1 (min) 1.05

φ2 (min) 30

R (samples/min) 0.55

t (min) 45.8

Metric RDX PETN TNT Nitrosomorpholine TATP Nitroglycerin Ammonium Nitrate Potassium Chlorate

S 2 2 2 2 2 2 2 2

LOD90A 3 2 3 1 1 3 1 1

ESR 1.22 1.22 1.22 1.22 1.22 1.22 1.22 1.22

SSR 9.05 9.40 9.05 10.0 10.0 9.05 10.0 10.0

SSR* ESR 11.1 11.5 11.1 12.2 12.2 11.1 12.2 12.2

Test Score Σ

Minimum Passing Test Score Σ

93.7

80

detectachem seekere · 2018-07-05 · detectachem llc. proprietary – not for distribution...

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