Future Plans at the National Institute of Standards and Technology for Hemp Quality 

Assurance Program and Reference Materials

Walter B. Wilson, Charles A. Barber, Melissa M. Phillips, Catherine A. Rimmer, and Laura J. Wood

Chemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA

NIST is developing a Hemp QAP to help improve hemp measurements for testing laboratories and product manufacturers, while supporting the

development of new hemp and hemp-derived RMs. The initial Hemp Quality Assurance Program (QAP) exercises will focus on the analysis of the highly

targeted analytes within the hemp community. Hemp QAP participants will receive information regarding the accuracy and precision of their results, as

well as concordance within the community. Detailed study reports and certificates of completion will be provided for participants, and workshops and

webinars will be held to discuss results as well as methodological advancements in the area of hemp measurements.

Similarly, NIST has recently established the Health Assessment Measurements Quality Assurance Program (HAMQAP) to identify, understand, and

address community-wide measurement challenges for other botanical materials. This program helps to improve measurement accuracy by providing an

opportunity for laboratories to assess their in-house measurement performance and to demonstrate an effort to comply with applicable regulations.

Standardization programs, proficiency testing, interlaboratory comparisons, and participation in QAPs, in conjunction with the use of reference materials

(RMs), are all essential in order to improve the comparability and precision of data over time. The breakdown of participants for the first set of HAMQAP

exercises are shown in Figure 1, which may be a good indicator of the participants for a Hemp QAP.

A potential lifecycle for the initial Hemp QAP exercise is illustrated in Figure 2. Once the overall measurement performance within the hemp community

has been explored for a plant material, accuracy and precision can be improved through use of RMs, which can be used to validate methods, establish

traceability, provide quality control when producing in-house RM, or produce scientific data that can be referred readily to a common base. Hemp QAP

will help support the development of characterized RMs that are value assigned for chemical composition, by incorporation of candidate RMs into the

studies. NIST has previously produced numerous RMs for chemical composition of foods, dietary supplements, and botanical authenticity, by

incorporating these materials into QAPs. The initial exercises of a Hemp QAP and RM development will focus on several targeted analyte groups

discussed in detail below for a dried plant material. These materials will also be screen for total yeast, mold, and microbiological contaminants.

1. Developing New Capabilities for Hemp at NIST

Δ9-THC, THCA, Total THC, and Moisture

Hemp was legalized with the passage of the 2018 Farm Bill by removing it from the Schedule 1

controlled substance list making it possible for all analytical laboratories ability to do hemp

research with no DEA license requirements. The bill also defined hemp by the Δ9-THC

concentration of not more than 0.3 % on a dry weight basis. However, THCA is the primary

component of THC in the cannabis plant, which can be converted into Δ9-THC through

decarboxylation as shown in Figure 3.

A typical packaging label for cannabis will show the percentage of Δ9-THC, THCA, and total

THC. The reported values could be significantly different when determining the “potency” of a

cannabis material. Total THC is not calculated through the addition of THC and THCA values

because Δ9-THC has a smaller molecular weight than THCA and conversion of THCA to Δ9-THC

is not always 100 % efficient. The best way to calculate the theoretical maximum percent dry

weight value for the total THC is below.

NIST plans for all RM or QAP materials (plant, extracts, or finished products) shipped from NIST

will not only have a Δ9-THC concentration ≤ 0.3 %, but a total THC value ≤ 0.3 %. These

samples no matter the target analytes of analysis will be accompanied with some form of

documentation summarizing the mass fraction, uncertainties with 95 % confidence, and

analytical procedure for measuring total THC. Since the true value for total THC will lie within the

assigned uncertainty, the upper confidence limit for total THC will be ≤ 0.3 %.

Moisture measurements will play a critical role in assigning values on a dry-mass basis.

Currently moisture measurements depend on the requirement of the state. All QAP and RM

dried plant materials will have moisture measurements using standard approaches employed at

NIST (i.e. oven drying, desiccator drying, and/or Karl Fischer).

• September • July 

• January • May

Call for 

Participants

Sample 

Distribution 

Results 

Due

Release 

Preliminary 

Data Tables

Final Report

Workshop

Figure 2: Potential Hemp QAP exercise lifecycle over 12 months.

Third Party Laboratories (34 %) Industry Laboratories (32 %)

Government Laboratories (19 %)

Academic Laboratories (10 %)

Non-Profit R&D Centers (4 %)

• evaluate new findings

Standards Manufacturers (1 %)

Figure 1: HAMQAP participants breakdown for the first set of exercises.

Total THC = (0.877 x % THCA) + % THC

THCA

Δ9-THC

200 

oC

Figure 3: Conversion THC into Δ9-THC.

Additional Natural and Synthetic Cannabinoids

AOAC currently has a working group developing a Standard Method Performance

Requirements (SMPR) document for the quantitation of cannabinoids in hemp plant

materials. The proposed SMPR includes the requirement of measuring CBD, CBDA,

and CBN in addition to Δ9-THC and THCA. Nine additional cannabinoids are included as

desirable (CBC, CBCA, CBDVA, CBG, CBGA, CBDV, Δ8-THC, THCV, THCVA), which

would allow for any separation method to provide a chromatographic profile of the

cannabinoids in any hemp or hemp-derived product.

Preliminary studies have been conducted at NIST looking at the different retention

characteristics for the 14 cannabinoids listed in the proposed SMPR as shown in Figure

4. The cannabinoids were separated using a C18 column with the dimensions of 150 mm

x 4.6 mm; 3 μm average particle diameter. The separation conditions included a 1.0

mL/min flowrate, 15 oC column temperature, and isocratic elution at 75 % acetonitrile or

79 % methanol (both in 0.1 % formic acid) and water mobile phases. Significant

retention difference were observed for multiple cannabinoids.

Synthetic cannabinoids are a concern moving forward as the market grows and

changes. Development of generic LC-MS/MS or GC-MS methods for identifying them in

real samples would be useful for the industry and addition of their mass spectra to the

NIST database.

5 15 25 35 45

2 28 54 80 106

Time (min)

220 nm

254 nm

Time (min)

Figure 4: RPLC-UV chromatogram of 15 

cannabinoid reference standards.

75 % ACN

79 % MeOH

CBC

THCA-A

CBC-A

THCV-A

CBN

CBDV-A

CBDV

CBD-A

THCV

CBD

Δ9-THC

CBG-A

CBG

CBN-A

Δ8-THC

Δ9

-THC

CBC

Δ8

-THC

THCV

CBN

-A

CBG-A

THCV

CBD-A

CBDV

CBDV-A

CBD

CBG

CBN-A THCA-A CBC-A

2. NIST Capabilities to be Extended for Contaminants in Hemp

Available materials include grains, meats, and processed foods

SRM 3232 Kelp PowderSRM 3246 Ginkgo LeavesSRM 3247 Ginkgo ExtractSRM 3248 Ginkgo TabletsSRM 3262 St. John’s WortSRM 3398 Ginger Rhizome

As X X X X X

Cd X X X X X

Hg X X X X X X

Pb X X X X X

NIST Botanical Supplement SRMs 

with Heavy Metal Values

NIST Food SRMs for Heavy Metal Contamination

Figure 5: Some NIST SRMs providing heavy metals values.

Mycotoxins

NIST has developed a new SRM that can be used to identify

mycotoxins in corn products that allow analytical scientists to

make reliable measurements for these poisonous compounds

that are produced by mold.

Mycotoxins are naturally occurring and often form when grains

and cereals are stored in areas of high humidity or in rye and

wheat crop fields, which can cause economic losses for farmers

and food producers if left undetected and allowed to spread.

The assigned mass fraction values are summarized in Figure 6

through measurements made at NIST, FDA, and an

interlaboratory study. NIST plans to apply the same analytical

approaches developed for the corn measurements to dried

hemp plant material at ppb levels.

Pesticide Residues

Hemp and marijuana samples obtained from retail shops or dispensaries may be contaminated with

pesticides used to eliminate or prevent infestations. Currently, there aren’t any federal regulations on

pesticide use for cannabis and the laws vary widely from state to state. Pesticides are introduced either

by the growers, through contaminated soil, and/or airborne chemical spread from other farms.

NIST has recently started developing analytical methods for measuring pesticides in a variety of plant

and food materials. Research has focused on the determination of glyphosate in organic and nonorganic oat cereals as illustrated in Figure 7. Low levels of glyphosate were measured in the organic

materials.

Multiple screening methods have been developed at NIST to identifying 207 pesticides through the

combination of QuEChERS and LC-MS/MS analysis of honey oats cereal, kale, apple sauce, and

frozen fruits. This same approach will be utilized for future pesticide analysis of hemp QAP or RM plant

materials.

Incurred Blank

Figure 6: Mass fraction value comparisons for mycotoxins in corn (SRM 1565).

Figure 7: Glyphosate 

comparisons in oat 

cereals.

Toxic Heavy Metals

Heavy metals are one of the most highly targeted contaminants in

cannabis materials. Commonly the key metals of importance

include cadmium (Cd), arsenic (As), lead (Pb), and mercury (Hg),

which fall into the FDA class 1 category. These metals are

considered highly toxic because the human body is unable to

remove these metals efficiently after exposure. NIST currently has

a large number of SRMs with assigned values for these toxic

metals as illustrated in Figure 5.

The FDA recommends these four elements be evaluated during

the risk assessment for all forms of food and supplements;

however, the literature is lacking direct studies on health effects of

toxic metals in hemp. NIST is looking to expand past these four

metals to also include five additional heavy metals recommend by

the FDA in tobacco products: beryllium, chromium, cobalt, nickel,

and selenium.