Trace-Element Contamination--Findings of Study on the Cleaning of Sampler Caps, Nozzles, Bottles, and Bags for Trace-Element Work at the Part-Per-Billion Level




In Reply Refer To:                               February 19, 1993
Mail Stop 412


OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM 93.06

Subject:  Trace-Element Contamination--Findings of Study on the
          Cleaning of Sampler Caps, Nozzles, Bottles, and Bags 
          for Trace-Element Work at the Part-Per-Billion Level

                              SYNOPSIS

As part of the development of a new part-per-billion (ppb) 
protocol for collecting and processing samples for analysis of 
dissolved trace elements, the Office of Water Quality (OWQ) 
conducted a study on the effectiveness of cleaning plastic and 
Teflon 1/ D-77 sampler components (caps, nozzles, bottles, and 
bags) to reduce contamination.  Procedures for both laboratory and 
field cleaning were tested.  Nitric (HNO3) and hydrochloric (HCl) 
acids were compared for their effectiveness in cleaning, and tests 
were included to determine the amount of rinsing with deionized 
water (DIW) required to prevent carryover of nitrate, chloride, 
and methanol, or trace elements from methanol (a final methanol 
rinse is required on equipment when both trace elements and 
organics are collected).  To determine the success of the cleaning 
procedures, test results were compared to values of one-half the 
target reporting level (RL) specified for each trace element for 
the ppb procedure.  The major findings of the study were:

1.  DIW blanks processed through equipment in an "initial 
condition" (before any cleaning) contained trace elements above 
one-half the target RL.

2.  Dilute HNO3 and HCl solutions (approximately 5 percent by 
volume) were equally effective for cleaning both plastic and 
Teflon D-77 sampler caps, nozzles, bottles, and bags.

3.  Carryover of chloride and nitrate from the use of HCl and 
HNO3, respectively, was not evident for either the laboratory or 
field cleaning procedure.

4.  Both plastic and Teflon components are acceptable for trace-
element sampling because the laboratory cleaning procedure reduced 
trace-element contamination well below the target RLs.

5.  Both old and new plastic and Teflon components are acceptable 
because they were adequately cleaned by the laboratory procedure.
____________________
     1/ Any use of trade, product, or firm names is for descriptive 
purposes only and does not imply endorsement by the 
U.S. Government.

6.  The field cleaning procedure was effective in reducing trace-
element contamination for both plastic and Teflon sampler 
components to levels below one-half the target RLs for all 
constituents except beryllium (Be).  Based on the test results, 
the OWQ has revised the field cleaning procedure.

7.  Based on this study, in the D-77 bag sampler, Teflon bags are 
preferred and Reynolds Oven Bags are acceptable for use with the 
ppb protocol.

8.  A laboratory cleaning procedure for plastic and Teflon bags 
was effective except for manganese (Mn) and zinc (Zn).  Projects 
using bags should produce adequate equipment blanks to insure bag 
trace-element contamination is under control (less than one-half 
RLs).

                           INTRODUCTION

One of the key elements in developing a new ppb protocol for 
collecting and processing samples for dissolved trace elements is 
an adequate cleaning procedure.  Cleaning procedures for both 
laboratory and field cleaning of sampler caps, nozzles, bottles, 
and bags were developed.

In April 1992, the OWQ conducted a study on the effectiveness of 
newly developed laboratory and field procedures for cleaning 
plastic and Teflon sampler components used in D-77 samplers.  This 
memo describes the major findings of the study.

                            OBJECTIVES

The objectives of the study were to:

1.  Establish the efficacy of the proposed laboratory cleaning 
procedure (detergent scrubbing and soak, tap water rinse, dilute 
HCl soak, and copious DIW rinses) for precleaning those parts of 
surface-water samplers--for both plastic and Teflon components--
that come into direct contact with water-sediment samples.

2.  Determine if the laboratory cleaning procedure is effective 
for both new and old sampler components.

3.  Determine if HNO3 (a possible alternative cleaning agent) is 
better, equivalent, or worse than HCl (the cleaning agent selected 
for the procedure) for precleaning sampler components and bags.

4.  Determine the amount of DIW rinsing required to prevent 
carryover of chloride, nitrate, and methanol or trace elements 
from methanol.

5.  Establish the efficacy of the field cleaning procedure (dilute 
HCl rinses and copious DIW rinses) which is intended to be used 
between sampling sites to prevent trace-element carryover.

                         STUDY COMPONENTS

The study, designed by John Zogorski (OWQ), was conducted 
April 1-16, 1992, at the Central Region Branch of Regional 
Research facilities in Boulder, Colorado.  Kathy Fitzgerald (OWQ), 
Bob Boulger (Colo.), and Dave Johncox (Colo.) conducted the study, 
which consisted of the following components:

1.  Equipment blanks were collected from a series of plastic and 
Teflon bottles and bags (identified below) to assess their initial 
condition prior to cleaning.

2.  Equipment was cleaned using the laboratory procedure, and 
equipment blanks were collected after various levels of DIW 
rinsing to determine:

        (a) if both new and old equipment could be adequately
            cleaned,
        (b) if plastic and Teflon equipment could be adequately
            cleaned, and
        (c) the amount of DIW rinsing needed.

3.  Equipment was exposed to a solution containing a high trace-
element concentration and was subsequently recleaned using the 
laboratory procedure; equipment blanks were collected after 
various levels of DIW rinsing to determine the efficacy of the 
laboratory cleaning procedure.

4.  Equipment was exposed to a solution containing a high trace-
element concentration and was subsequently cleaned using the 
field procedure; equipment blanks were collected after various 
levels of DIW rinsing to determine the efficacy of the field 
cleaning procedure.

5.  Some of the equipment was cleaned with HCl and some with HNO3. 

                SAMPLER COMPONENTS AND BAGS EVALUATED

The following D-77 sampler components and bags were evaluated:

Plastic (polypropylene)    1 new (OWQ)
  components  
                           6 old (WA (2), CO, CA, KS (2))

Teflon components          1 new (KY)

                           5 old (NWQL 1/, CA, KY, MA, WA)

Small plastic bags         Glad brand                   2 bags

                           Reynolds Oven Bag            2 bags

Large plastic bags         Reynolds Oven Bag            2 bags

                             (from Charlie Demas)

                           Jensen Inert Tedlar          2 bags

Small Teflon bags          Corps of Engineers           2 bags

                             (Vicksburg, MS)

                           American Durafilm            2 bags

Large Teflon bags          American Durafilm            2 bags

                           Jensen Inert                 2 bags
______________________________________________________________
     1/NWQL = National Water Quality Laboratory.


Three-liter sampler bottles were shipped to the Colorado District 
from the Districts listed in column 2 above.  All bags, except for 
the oven bags from Charlie Demas, were purchased specifically for 
this study.  The Glad and Reynolds bags were purchased at local 
grocery stores.

                       CONSTITUENTS ANALYZED

Most trace elements were analyzed with inductively coupled plasma 
mass spectrometry by the Methods Research and Development Program, 
NWQL, with a detection level of 0.2 ug/L.  Constituents included 
aluminum (Al), arsenic (As), barium (Ba), beryllium (Be), cadmium 
(Cd), chromium (Cr), cobalt (Co), copper (Cu), lead (Pb), manganese 
(Mn), molybdenum (Mo), nickel (Ni), silver (Ag), thallium (Tl), 
thorium (Th), uranium (U), and zinc (Zn).  Five other elements 
including iron (Fe), lithium (Li), selenium (Se), strontium (Sr), 
and vanadium (V) were analyzed by the Inorganic Program, NWQL.  
Selected equipment blanks were also analyzed for major elements and 
nutrients at the NWQL.

                       DATA INTERPRETATION

To determine the efficacy of the two cleaning procedures, 
equipment blank results were compared to the levels representing 
one-half the respective target reporting levels specified for the 
new trace-element protocol.  These values were reported earlier in 
OWQ Technical Memorandum 92.12 and are given in table 1.

Table 1.--Reporting limits of selected elements for NASQAN, 1991,
          and the new part-per-billion (ppb) protocol
_________________________________________________________________
                                                 One-half target
                   1991             Target         reporting
                  NASQAN        reporting limit    limit for
             reporting limit 1/ for ppb protocol  ppb protocol 2/
Element           (ug/L)            (ug/L)           (ug/L)
_________________________________________________________________
  Al               10                10               5.0

  Ba                2                 2               1

  Be                0.5               0.5             0.25

  Cd                1                 1               0.5

  Co                3                 1               0.5

  Cr                1                 1               0.5

  Cu                1                 1               0.5

  Fe                3                 3               1.5

  Pb                1                 1               0.5

  Mn                1                 1               0.5

  Mo               10                 1               0.5

  Ni                1                 1               0.5

  Ag                1                 0.2             0.1

  Zn                3                 3               1.5
_________________________________________________________________
 1/For samples in which specific conductance < 2,000 uS/cm.
 2/Maximum limit set from all sources of contamination in the ppb 
  protocol.


The analytical data from this study are not presented in this 
memo, but are available for review.  Contact the Chief, Office of 
Water Quality, for additional information.

                          MAJOR FINDINGS

1. Many of the "initial condition" blanks (DIW blanks processed 
before any cleaning) contained trace-element concentrations in 
excess of one-half the target RL, especially Al, Cu, and Zn.  This 
finding supports the need for a rigorous cleaning, beyond rinsing 
only with DIW.

2. Dilute HNO3 and HCl solutions (approximately 5 percent by 
volume) were equally effective for cleaning both plastic and 
Teflon D-77 sampler caps, nozzles, bottles, and bags.

3. Carryover of chloride and nitrate from the use of HCl and HNO3, 
respectively, was not evident for either the laboratory or field 
cleaning procedure.

4. The laboratory cleaning procedure (detergent scrubbing and 
soak, tap water rinse, dilute HCl soak, and copious DIW rinses) 
was effective in reducing trace-element contamination to levels 
well below one-half the target RLs for both plastic and Teflon 
sampler components.  Therefore, either plastic or Teflon 
components can be used with the D-77 sampler for trace-element 
sampling at the ppb level.

5. Both new and old plastic and Teflon D-77 components were 
adequately cleaned by the laboratory cleaning procedure.  
Therefore, both new and old components may be used with the new 
ppb protocol.

6. The field cleaning procedure (dilute HCl rinses and copious DIW 
rinses) was effective in reducing trace-element contamination for 
both plastic and Teflon sampler components to levels below one-
half the target RLs for all constituents except Be.  Blanks from 
both the plastic and Teflon components were found to contain Be at 
levels slightly above one-half the target RL (0.25 ug/L).  Low-
level hits of Cu were also consistently found for both plastic and 
Teflon components; however, detected levels were consistently 
below one-half of the target RL (0.5 ug/L).  Based on the test 
results, the OWQ has revised the field cleaning procedure.

7. The following types of bags were evaluated:  Teflon (Jensen 
Inert and American Durafilm), and plastic (Glad and Reynolds Oven 
brands).  After a futile attempt to detergent wash Glad plastic 
bags and Reynolds oven bags, the study team decided that this step 
should be eliminated from the laboratory cleaning procedure (it is 
possible to wash the thicker Teflon bags).  Laboratory cleaning of 
plastic and Teflon bags thus consisted of an acid (HCl) soak and 
copious DIW rinses.  Because plastic and oven bags are 
inexpensive, they can be disposed of after use, which eliminates 
the need for field cleaning.  The field cleaning procedure was 
effectively used on the Teflon bags.  One of the plastic Glad bags 
developed holes during the laboratory cleaning and rinsing 
process; because oven bags are sturdier, they are the preferred 
choice for non-Teflon bags.  Based on this study, for use in D-77 
bag samplers, Teflon bags are preferred, Reynolds Oven Bags are 
acceptable, and the other tested bags are unacceptable for use 
with the ppb protocol.

8. The laboratory cleaning procedure for plastic and Teflon bags 
was effective in consistently reducing trace-element contamination 
to levels below one-half of the target RLs for all constituents 
except manganese (Mn) and zinc (Zn).  Two of the 10 equipment 
blanks for plastic bags contained Mn above one-half the target RL 

(0.50 ug/L) (small plastic bag = 0.61 ug/L; large plastic bag = 
0.50 ug/L).  One of the 21 equipment blanks for plastic and Teflon 
bags contained Zn above one-half the target RL (1.50 ug/L) (small 
Teflon bag = 1.50 ug/L), although approximately 50 percent of all 
blanks contained detectable levels of Zn.  Based on these results, 
acid soaking with copious DIW rinses is effective for cleaning 
plastic and Teflon bags for all constituents except possibly Mn 
and Zn.  Projects that choose to use plastic and Teflon bags 
should incorporate more than the normal percentage of equipment 
blanks into their quality control plan to determine if 
contamination from the sampler bag actually occurs.

                              SUMMARY

Previous studies have shown that the D-77 and DH-81 samplers are 
the least contaminating samplers for dissolved trace-element 
sample collection.  This study was conducted to test the 
effectiveness of procedures for cleaning the plastic and Teflon 
components of these samplers.  Only 3-liter D-77 bottles were 
tested, but the results should apply to any size bottle made of 
the same materials.

The study showed that (a) cleaning beyond DIW rinsing is 
necessary, (b) the laboratory cleaning procedure is effective for 
ppb-level work for both plastic and Teflon, and for both new and 
old equipment, (c) the field cleaning procedure is not completely 
effective and needed to be modified, (d) plastic bags can be 
cleaned with acid (HCl) soaks and DIW rinsing prior to use, but 
should be disposed of after use, and (e) Teflon bags can be 
cleaned and reused.

Art Horowitz will be conducting training sessions in each of the 
Regions on the new cleaning procedures beginning in April 1993.  
Following training, side-by-side comparisons of the new and old 
procedures will be done in at least one District in each Region.  
The results will be evaluated, modifications will be made if 
necessary, and additional training will then be completed.  Full 
implementation of the ppb sampling procedure is scheduled for 
October 1993.




                                 David A. Rickert
                                 Chief, Office of Water Quality

This memorandum refers to Office of Water Quality Technical 
Memorandum 92.12.

Key Words:  Contamination, samplers, trace element

Distribution:  A, B, S, FO, PO