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STANDARD OPERATING PROCEDURES

SOP: 1012

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DATE: 11/20/00

PREPARATION OF STANDARD SOLUTIONS

CONTENTS

1.0 SCOPE AND APPLICATION

2.0 METHOD SUMMARY

3.0 SAMPLE PRESERVATION, CONTAINERS, HANDLING AND STORAGE

4.0 INTERFERENCES AND POTENTIAL PROBLEMS

5.0 EQUIPMENT/APPARATUS

6.0 REAGENTS

7.

0 PROCEDURES

7.1 Documentation

7.1.1 Lot Number

7.1.2 Logbook

7.1.3

Standard Solution Bottle

7.2 Organic Standards

7.2.1 Standards for Volatile Analysis

7.2.2 Standards for Semi-volatile Analysis

7.2.3 Standards for Pesticide/PCB Analysis

7.3 Inorganic Standards

8.0 CALCULATIONS

9.0 QUALITY ASSURANCE/ QUALITY CONTROL

10.0 DATA VALIDATION

11.0 HEALTH AND SAFETY

12.0 REFERENCES

These sections affected by Revision 0.0

SUPERCEDES: SOP #1012; Revision 0.0; 11/20/00; U.S. EPA Contract EP-W-09-031

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PREPARATION OF STANDARD SOLUTIONS

1.0 SCOPE AND APPLICATION

The objective of this Standard Operating Procedure (SOP) is to define procedures for preparing standards

used in various analyses that are performed by SERAS laboratories. It also provides a uniform

documentation and tracking system. The procedures and requirements described in this SOP apply to all the standards prepared by SERAS analysts for all routine and non routine organic and inorganic analyses.

2.0 METHOD SUMMARY

Source standard materials or solutions will be purchased from commercial suppliers and then combined

and/or diluted by the analyst with solvent(s) or reagent(s) specified in the analytical methods. The

standards will be prepared at the concentrations specified in the associated analytical methods or SOPs.

An internal identification control number or SERAS lot number will be assigned to each source material

purchased from suppliers, stock standard solution, intermediate standard solution (if appropriate), surrogate

spike solution, matrix spike solution, instrument performance check standard solutions, and calibration

standard solutions. This number will be documented in the sample digestion log, sample extraction log,

and instrument run (analysis) log for each standard used in the data collection process.

3.0 SAMPLE PRESERVATION, CONTAINERS, HANDLING AND STORAGE

This section is not applicable to this SOP. Standard storage will be discussed in Section 9.0.

4.0 INTERFERENCES AND POTENTIAL PROBLEMS

Solvent, reagents, glassware, syringes, and other handling hardware may introduce artifacts and/or

interferences to standard solutions. Only high purity materials ($99%) should be used for preparing

standards. Solvents used to prepare pesticide/PCB and semi-volatile standards must be pesticide residue

analysis grade or equivalent; purge-and-trap grade solvent must be used to prepare volatile standards; trace

metal grade acids must be used for metals standards.

Soap residue on glassware may cause degradation of certain analytes. Aldrin, heptachlor, and most

organophosphorus pesticides in particular will degrade in this situation. All glassware and syringes must

be properly rinsed with designated solvents before use. It is recommended that only designated glassware

and syringes be used to prepare standards to avoid cross-contamination. Chromic acid may be useful to remove organic deposits from glassware; however, the glassware must be

thoroughly rinsed with deionized water to remove the last traces of chromium. This is especially important

if chromium is to be determined.

5.0 EQUIPMENT/APPARATUS

ƒ Class A volumetric pipettes (assorted sizes)

ƒ Class A volumetric flasks with ground-glass stoppers (assorted sizes) ƒ Microsyringes, gas-tight preferred (assorted sizes)

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PREPARATION OF STANDARD SOLUTIONS

ƒ High density polyethylene bottles (inorganic)

ƒ Teflon bottles (organics)

ƒ Amber glass bottles

ƒ 2, 10, 25, 50, 100-mL serum vials with crimp caps lined with Teflon

ƒ Analytical balance with accuracy of 0.001 g

6.0 REAGENTS

Deionized water, ASTM Type I or II (depending on application) Acetone, methylene chloride, and hexane; pesticide residue analysis grade or equivalent

Methanol; purge and trap grade10% nitric acid

Concentrated nitric acid, trace metal grade

Concentrated hydrochloric acid, trace metal grade

7.0 PROCEDURES

7.1 Documentation

7.1.1 Lot Number

ƒ All standards used for sample analyses must be traceable back to their sources whenever required. To achieve this objective, all standards (neat materials, concentrated standard solution purchased from commercial suppliers, stock standard solutions, calibration standard solutions, spike standard solutions, and instrument performance standard solutions) will be assigned a SERAS identification or lot number. ƒ The following scheme will be used to track standards prepared by all groups: ƒ Each lot number shall begin with a one or two letter code to identify the nature of the standard and be followed by date (in numerical expression) and a two- digit number. The date must be documented in the order of month, day, and year. The two-digit number begins with 01. ƒ The letter "S" will be used for all standards prepared for semi-volatile analysis. For example, S09150001 represents the first semi-volatile standard prepared on

September 15, 2000.

ƒ The letter "V" will be used for all standards prepared for volatile analysis. For example, V10010010 represents the 10th volatile standard prepared on October

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1, 2000.

ƒ The letter "P" will be used for all standards prepared for pesticide/PCB analysis. For example, P11100015 represents the 15th pesticide standard prepared on

November 10, 2000.

ƒ A two letter code will be used for all standards prepared for metal analysis. The codes are as follows: MS - stock standard; MI - intermediate standard; MW - working standard; and MQ - QA/QC standard. For example, MQ05280002 represents the second metal QA/QC standard prepared on May 28, 2000. ƒ The letter "T" will be used for all standards prepared for tissue analysis by the Special Projects Group. The "T" will be followed by an "S", "V", or "P" to further represent semivolatiles, volatiles and pesticide/PCB standards, respectively. For example, TS10030002 represents the second semi-volatile tissue standard prepared on October 3, 2000. ƒ The lot number of each standard used for analysis must be entered in the standard preparation logbook, the label on the standard solution container, the sample digestion logbook, sample extraction logbook, and the instrument run (analysis) log. Due to multiple standards prepared for the pesticide/PCB and toxaphene analyses, a separate sheet documenting the standards used will be included in the data package.

7.1. Logbook

A standard preparation logbook must be used by each lab to document all information listed below.

Lot number assigned

Standard solution identification (such as BNA Cal Std) Compounds in the solution (refer to as Mix A, Mix B, etc) or affix the actual label in the logbook. Final concentration of each compound in the solution

Lot number of the source

NOTE: If source material was purchased from commercial vendor, enter the vendor's name, lot number, and catalog number. Maintain the certificate shipped with standard ampoule in a logbook, or three-ring binder.

Volume or weight of source(s) used

Solvent or reagent used

Volume of solvent or reagent used

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Date of preparation

Signature of person preparing the standard

Expiration date of the standard

Signature and date of peer review

Comments, if necessary

7.1.3 Standard Solution Bottle

The following information must be transcribed to a logbook tracking preparation of the standard solution:

Lot number

Standard identification

Concentrations of the standards

Solvent used

Expiration date

Initials of chemist

7.2 Organic Standards

7.2.1 Standards for Volatile Analysis

1. Log in all concentrated standard mixtures or individual standard(s) purchased from

commercial vendors by following the procedures described in Section 7.1. A SERAS lot number must be assigned to each mixture or individual standard received.

2. Determine the volumes of standard solutions to be prepared; calculate the dilution factor

by using the equation provided in Section 8.0.

3. Rinse all syringes and glassware with methanol to avoid cross-contamination. Make sure

to rinse the plunger and the needle of the syringe and the stopper of the volumetric flask.

4. Prepare the working 4-bromofluorobenzene (BFB) standard (50µg/mL) by the technique

described below. A stock solution of 4-BFB in a methanol solution may also be purchased from a commercial vendor and used as a stock solution. Fill the volumetric flask with methanol until it is approximately half full. Add the appropriate volume, precisely measured, of the stock BFB standard to the volumetric flask. Fill the flask with methanol so that the bottom of the solution meniscus lines up

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with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned to this working solution.

5. Prepare the working surrogate/internal standard mixture (250 µg/mL) by the technique

described below. A stock solution at 250 µg/mL of surrogates and internals standards may be purchased from a commercial vendor. Fill the volumetric flask with methanol until it is approximately half full. Add the appropriate volumes, precisely measured, of the concentrated surrogate standards and concentrated internal standards to the volumetric flask. Fill the flask with methanol so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned to this working solution.

6. Prepare the volatile (VOA) working standard mixtures and matrix spike standard

mixtures by combining the appropriate number of concentrated standard mixtures for the complete VOA list. The working standard and the matrix spike must be prepared from two independent sources of material. NOTE: If sources from two independent manufacturers are not available, two different lots from the same manufacturer may be used. A custom VOC mixture at a 250 µg/mL concentration in methanol (i.e. Accustandard Inc., catalog # 5-4821) may be used for the preparation of working standards. A matrix spike mixture solution (i.e. Supelco Inc., catalog #4-8399) may be used for the preparation of the matrix spike. Fill the volumetric flask with methanol until it is approximately half full. Add the appropriate volumes, precisely measured, of the concentrated standard mixtures with syringes and add them to the volumetric flask. Fill the flask with methanol so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned to this working solution. These solutions will be used for calibration and matrix spike purposes. Each working calibration standard is not assigned a SERAS lot number since these standards are prepared fresh before use.

7.2.2 Standards for Semi-volatile Analysis

1. Log in all concentrated standard mixtures or individual standards purchased

from commercial vendors by following the procedures described in Section 7.1. A SERAS lot number must be assigned to each type of mixture and/or individual standard.

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2. Determine the volumes of standard solutions to be prepared; calculate the

dilution factor by using the equation provided in Section 8.0.

3. Rinse syringes and volumetric flasks with methylene chloride to avoid cross-

contamination. Take care to rinse the plunger and the needle of the syringe and the stopper of the volumetric flask.

4. Prepare the decafluorotriphenylphosphine (DFTPP) working standard using the

technique described below or purchase from a commercial vendor. Fill the volumetric flask with methylene chloride until it is approximately half full. Add the appropriate volume, precisely measured, of the concentrated DFTPP to the volumetric flask. Fill the flask with methylene chloride so that the bottom of the solution meniscus of the solution lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber glass bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned.

5. Prepare the surrogate spike working solution by using the technique described

below or purchase from a commercial vendor. Fill the volumetric flask with acetone until it is approximately half full. Add the appropriate volume, precisely measured, of the base neutral and acid extractable concentrated standard mixtures into the volumetric flask. Fill the flask with acetone so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution into a clean amber glass bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned.

6. Follow step 5 to prepare the matrix spike working solution. A source

independent of calibration is used to prepare the matrix spike.

7. A semi-volatile (BNA) stock standard solution (including surrogates) of 160

µg/mL will be prepared from concentrated standard mixtures purchased from commercial vendors. Alternatively, a 160 µg/mL base neutral and a 160 µg/mL acid extractable standard may be purchased from a commercial vendor and combined. Transfer the solution to a clean amber glass bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned.

8. Make various dilutions from the 160 µg/mL BNA standard to prepare the

calibration standards. Each concentration level must be assigned a SERAS lot number. All documentation procedures described in Section 7.1 must be followed.

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7.2.3 Standards for Pesticide/PCB Analysis

1. Log in all concentrated standard mixtures or individual standards purchased

from vendors by following the procedures described in Section 7.1. A SERAS lot number must be assigned to each type of mixture and/or individual standard. These concentrated standard solutions will be used as stock solutions to prepare working standard solutions.

2. Determine the volumes of standard solutions to be prepared; calculate the

dilution factor by using the equation provided in Section 8.0.

3. Rinse syringes and volumetric flasks with acetone followed by hexane to avoid

cross contamination. Take care to rinse the plunger and the needle of the syringe and the stopper of the volumetric flask.

4. Prepare surrogate spike working solution by following the technique described

below. Fill the volumetric flask with acetone until it is approximately one-third full. Add the appropriate volume of the concentrated stock standard purchased from the commercial vendor into the volumetric flask. Fill the flask with acetone so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber glass bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned.

5. Follow step 4 to prepare matrix spike working solution using a separate source

from that used for calibration.

6. Prepare pesticide calibration standards by making various dilutions of the

concentrated stock solutions purchased from commercial vendors. Fill the volumetric flask with hexane until it is approximately one-third full. Add the appropriate volumes, precisely measured, of the concentrated pesticide standard mixture, alpha-chlordane standard, gamma-chlordane standard, and surrogate standard mixture purchased from the commercial vendor to the volumetric flask. Fill the flask with hexane so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber glass bottle; label the bottle with information described in Section

7.1. A SERAS lot number must be assigned to each concentration level

prepared.

7. Prepare toxaphene calibration standards by making various dilutions of the

concentrated stock solution purchased from the commercial vendors. Fill the volumetric flask with hexane until it is approximately one-third full.

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Add the appropriate volumes, precisely measured, of the concentrated toxaphene standard and surrogate standard purchased from the commercial vendor to the volumetric flask. Fill the flask with hexane so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber glass bottle; label the bottle with the information described in Section 7.1. A SERAS lot number must be assigned to each concentration level prepared.

8. Prepare polychlorinated biphenyl (PCB) calibration standards by making various

dilutions of the concentrated stock solution purchased from the commercial vendors. Fill the volumetric flask with hexane until it is approximately one-third full. Add the appropriate volumes, precisely measured, of the concentrated PCB standard and surrogate standard purchased from the commercial vendor to the volumetric flask. Fill the flask with hexane so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber glass bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned to each concentration level prepared.

9. Prepare the resolution check standard by diluting the concentrated stock solution

purchased from commercial vendors. Fill the volumetric flask with hexane until it is approximately one-third full. Add the appropriate volume, precisely measured, of the concentrated stock standard purchased from the commercial vendor to the volumetric flask. Fill the flask with hexane so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber glass bottle; label the bottle with information described in Section 7.1. A SERAS lot number must be assigned.

10. Prepare the performance evaluation check standard by diluting the concentrated

stock solution purchased from the commercial vendors. Fill the volumetric flask with hexane until it is approximately one-third full. Add the appropriate volume, precisely measured, of the concentrated standard purchased from the commercial vendor to the volumetric flask. Fill the flask with hexane so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. Transfer the solution to a clean amber glass bottle; label the bottle with

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information described in Section 7.1. A SERAS lot number must be assigned.

11. Transfer the remaining stock standard solutions to vials lined with Teflon. Store

in the refrigerator.

7.3 Inorganic Standards

1. Log in all concentrated standard solutions or individual element standards purchased

from commercial vendors by following the procedures described in Section 7.1. A SERAS lot number must be assigned to each type of mixture and/or individual element standard. These concentrated standard solutions will be used as stock solutions to prepare intermediate solutions.

2. Determine the volumes of standard solutions to be prepared; calculate the dilution factor

by using the equation provided in Section 8.0.

3. Rinse volumetric flasks and pipettes with 10% nitric acid, followed by deionized water.

4. Intermediate Standard Solutions

Fill approximately one-tenth of the volumetric flask with deionized water; add an appropriate volume of concentrated nitric acid to produce 5% HNO3 at final volume; add the appropriate volume of the concentrated stock solution. Fill the flask with deionized water so that the bottom of the solution meniscus lines up with the mark on the neck of the flask. Stopper the volumetric flask and invert three times to mix well. NOTE: Use the appropriate volumes of concentrated nitric and hydrochloric acids for mixed-acid standards. Transfer standard solutions to high density polyethylene bottles; label the bottle with the information described in Section 7.1. Assign a SERAS lot number to each stock or intermediate solution.

5. Secondary Standard Solutions

The secondary standard solution will be prepared from the intermediate standard solution for AA analysis. Follow the procedure described in step 4. Assign a SERAS lot number for each concentration level prepared.

6. Working Standard Solutions

For furnace AA analysis, the working standard solution will be automatically prepared by the instrument during analysis by serially diluting the secondary standard solution. For flame AA or ICP analysis, the working standard solutions are prepared from the intermediate standard by the analyst following the technique described in step 4. All working standard solutions are only prepared when needed in very small quantities. To ensure the traceability of standards used for all sample analyses, the following

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information must be documented on the instrument printouts or calibration log sheets: the source lot number and the preparation date of the working standards. The signature of the chemist who prepared the working standard solution for AA or ICP analysis must also be documented.

7. Quality Control Standard (QCS)

Concentrated QCS will be purchased from commercial vendors. The preparation procedures specified by the vendor will be followed. A SERAS lot number must be assigned to the working QCS. All documentation requirements described in Section 7.1 must be followed at all times.

8.0 CALCULATIONS

The following equation can be used to prepare diluted standard solutions.

C 1 V 1 = C 2 V 2

where, C1 = concentration of analyte in the stock or intermediate standard solution to be diluted V1 = volume of stock or intermediate standard to be used C2 = final concentration of the standard solution to be prepared V2 = total volume of the standard solution to be prepared EXAMPLE: If 10 mL (V2) of a 2-µg/mL (C2) standard will be prepared from a 20-µg/mL (C1) stock or intermediate standard, the volume of the stock or intermediate standard to be withdrawn can be calculated by using the above equation:

20 µg/mL (C1) x V1 = 2 µg/mL (C2) x 10 mL (V2)

V1 = (2 µg/mL x 10 mL)/20 µg/mL = 1 mL

To prepare the 2-µg/mL solution, 1 mL of the 20-µg/mL standard will be added into a 10-mL volumetric

flask which contains approximately one-third of the proper solvent or reagent. The proper solvent or

reagent will be added to the mark and mixed well.

9.0 QUALITY ASSURANCE/QUALITY CONTROL

1. All standards must be documented in the standard logbook with information specified in Section

7.1.

2. Peer review must be conducted on every entry in the logbook for correctness in content and

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