Preparing Your Laboratory for USP Chapters <232>, <233> and <2322> and ICH Q3D A laboratory consumables buying guide

TECHNICAL GUIDE 90242

Introduction

The United States Pharmacopeia (USP) is in the process of implementing new guidelines for the determination of elemental impurities in drug-related products. The current guidelines are described in the USP General Chapter <231>, titled “Heavy Metals.” This chapter outlines a method for determining metal impurities in solutions based on a metal sulfi de precipitation reaction. The reaction produces a color change which is compared to a prepared lead standard. This method has been used for years; however, it suffers from a number of drawbacks related to sensitivity, selectivity, stability and reproducibility.

To address the shortcomings of the methodology outlined in Chapter <231>, three new chapters are being proposed to address elemental impurities in drug-related products and dietary supplements. Highlights from those chapters are as follows:

• Chapter <232> Elemental Impurities in Pharmaceutical Products – Limits Specifi es limits for elemental impurities in drug-related components and products. Fifteen elements are specifi ed with permissible daily exposure (PDE) limits, based on the known toxicological information and the drug’s administration route.

• Chapter <233> Elemental Impurities in Pharmaceutical Products – Procedures Outlines two suggested procedures using ICP-OES or ICP-MS instruments, following proper sample preparation. For those applications where ICP-OES or ICP-MS are not the most appropriate techniques, the chapter outlines a procedure to validate an alternative technique.

• Chapter <2232> Elemental Contaminants in Dietary SupplementsProvides maximum permissible limits for elemental impurities in nutraceuticals and supplements. This text refers to the methodology in Chapter <233> for analysis.

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The purpose of this document is to discuss proper laboratory practices with regard to sample handling and standard and sample preparation. The items listed here have been shown to be durable, accurate and free from contaminants. The information outlined here is meant to serve as a reference for selecting personal protection equipment, consumables, reagents and hardware to help prepare your laboratory for performing elemental analysis that is compliant with USP Chapter <233>. It is not meant to be a complete instruction guide for setting up your laboratory.

For more information on regulations and instrumentation for these methods please download this free Elemental Impurities in Pharmaceutical Products Primer.

Personal Protection EquipmentLaboratory CoatA proper safety coat should be worn when working in the laboratory. The coat should be long-sleeved and should properly cover your torso to protect your skin from chemical splashes. The coat should be small enough to prevent the sleeves from covering your hands and the coat from hanging loosely enough to be a hazard to your safety. Conversely, the coat should be large enough to allow comfortable movement. If you are working around open flames, always wear a laboratory coat made from non-flammable materials.

Recommended products:• United Scientific Supplies Lab Coats, button-front, size

medium (catalog #S04777)

• United Scientific Supplies Lab Coats, button-front, size large (catalog #S04778)

Protective EyewearIt’s important to wear eyewear that protects your eyes against chemical splashes. The eyewear itself should be chemical resistant and should be snug enough on your face to prevent liquids from coming into contact with your eyes. If you wear prescription glasses, you should still wear proper protective eyewear. Prescription glasses alone do not provide the sufficient level of safety for your eyes. Your protective eyewear should fit over your glasses with enough room to make snug contact with your face.

Recommended products:• Thermo Scientific™ Safety Choice™ Economy Chemical-

Resistant Goggles (catalog #19-181-502)

• Uvex™ Genesis X2™ Safety Glasses (catalog #17-377-419)

Safety GlovesLaboratory gloves should be worn to protect your skin when handling hazardous chemicals and reagents. Gloves also prevent oils and lotions from your hands from accidentally contaminating the standards and samples you are preparing. The gloves should be free from talcum powder, which will contaminate samples and the sample preparation area. Gloves should be tight enough to allow you to maintain your dexterity, yet loose enough to remain comfortable.

The gloves should be made from a material that is chemically resistant to the solvents that are being used in the laboratory. Nitrile is a good material for general laboratory use as it’s resistant to many acids, solvents and oils. It’s also a material that provides a clear indication of any tears or rips. If nitrile provides insufficient chemical resistance, gloves can be purchased of other materials such as Viton®, neoprene, butyl rubber and polyvinyl chloride (PVC). Latex gloves should not be worn in a laboratory. Aside from causing a reaction to those who are allergic, latex has a poor chemical resistance to many acids and organic solvents.

Recommended products:

• Fisherbrand™ Powder-Free Nitrile Exam Gloves, latex-free, size small (catalog #19-130-1597B)

• Fisherbrand™ Powder-Free Nitrile Exam Gloves, latex-free, size large (catalog #19-130-1597D)

Sample Handling EquipmentLaminar Flow HoodAn enclosed preparation area with a hood is important for clean sample preparation. An ideal hood would have a laminar flow and a HEPA filter. The laminar (constant, unidirectional) flow can be either vertical or horizontal, depending on the hood design. A vertical flow hood directs air from the top of the hood cabinet down to the work surface and protects both the samples and the user. A horizontal flow hood directs air parallel to the work surface and provides protection to the samples or to the user (dependent on whether it is a positive or a negative pressure hood), but not both.

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Laminar flow hoods are designated as Class I, Class II and Class III, each providing a higher level of protection to the user and to the environment. Almost all samples being prepared for elemental impurity analysis under USP 232/233 guidelines can be safely handled and prepared in a Class I laminar flow hood.

Recommended products:• Hyperclean™ TruAir™ Ductless Fume Hoods, 19 inch

height interior (catalog #B1115361)

• Hyperclean™ TruAir™ Ductless Fume Hoods, 24 inch height interior (catalog #B1115483)

General GlasswareLaboratory preparation and handling equipment is important in ensuring that all standards and samples are measured, transferred, prepared and stored properly. While usually referred to as laboratory “glassware,” this equipment is often made from a material other than glass. Plastics and polymers provide chemical resistance that is superior to many glass products and they are shatter-resistant.

If hydrofluoric acid is used during any portion of the sample preparation process, glass equipment should not be used. At very low concentrations, hydrofluoric acid will react with the surface of the glass container and introduce contaminants from the glass (B, Na, Si, etc). At higher concentrations, hydrofluoric acid will react with and dissolve the glass container.

If mercury analysis is required, solutions should not be prepared in plastic prepware. Mercury is known for adhering to the surfaces of plastic material which will cause recovery, memory effect and cross-contamination issues with mercury-containing standards and samples.

All equipment used for preparation and handling should be properly cleaned and rinsed prior to each use. It is good practice to fill all sample handling and storage equipment with a dilute acid solution for storage.

Recommended products:Volumetric flasks• Corning™ Class A PMP Volumetric Flasks, 50 mL

(catalog #10-210-639)

• Corning™ Class A PMP Volumetric Flasks, 100 mL (catalog #10-210-640)

• Corning™ Class A PMP Volumetric Flasks, 250 mL (catalog #10-210-641)

• PYREX™ EZ Access™ Glass Class A Volumetric Flasks, 50 mL (catalog #08-549-12B)

• PYREX™ EZ Access™ Glass Class A Volumetric Flasks, 100 mL (catalog #10-462-873)

• PYREX™ EZ Access™ Glass Class A Volumetric Flasks, 250 mL (catalog #10-462-874)

Graduated cylinders• Nalgene™ Plastic Graduated Cylinder Variety Pack

(catalog #02-540-270)

• PYREX™ Glass Graduated Cylinder Assortment Pack (catalog #10-462-833)

Beakers• Fisherbrand™ Reusable Glass Beakers, 250 mL (catalog

#FB100250)

• Fisherbrand™ Re-usable Glass Beakers, 1000 mL (catalog #FB1001000)

• Thermo Scientific™ Nalgene™ Polypropylene Beakers, 250 mL (catalog #02-591-10D)

• Thermo Scientific™ Nalgene™ Polypropylene Beakers, 1000 mL (catalog #02-591-10G)

PipettesMany standard and sample preparation procedures require liquid dilution and the quality of the prepared solutions depends largely on the accuracy of the pipette/s used. Pipettes can have fixed or adjustable volumes and can be mechanical or digital. If a high precision pipette is required, Class A pipettes should be used; however, Class A pipettes are not typically available in volumes smaller than 0.5 mL.

The calibration of each pipette should be checked periodically and should be re-calibrated as often as is necessary.

Recommended products:• Finnpipette™ F1 Variable Volume Single Channel

Pipette, 1-10 µL (catalog #4641040N)

• Finnpipette™ F1 Variable Volume Single Channel Pipette, 10-100 µL (catalog #4641070N)

• Finnpipette™ F1 Variable Volume Single Channel Pipette, 100-1000 µL (catalog #4641100N)

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• Fisherbrand™ Reusable Class A Volumetric Pipets, 0.5 mL (catalog #13-650-2A)

• Fisherbrand™ Reusable Class A Volumetric Pipets, 1.0 mL (catalog #13-650-3B)

• Fisherbrand Bulbs for Large Pipets, (catalog #03-448-28)

Pipette TipsPipette tips are required to properly use fixed and adjustable volume pipettes. Each tip should only be used once to avoid cross contamination between solutions. If Class A volumetric pipettes are being used, syringe bulbs are used instead of pipette tips.

Recommended Products:• Thermo Scientific™ Finntip™ Flex™ Pipette Tips, 10 µL

maximum volume (catalog #14-387-208)

• Thermo Scientific™ Finntip™ Flex™ Pipette Tips, 200 µL maximum volume (catalog #14-387-200)

• Thermo Scientific™ Finntip™ Flex™ Pipette Tips, 1000 µL maximum volume (catalog #14-387-84)

Acids and ReagentsClean WaterWater is used for many purposes in the laboratory – cleaning and rinsing glassware, dissolutions, and dilutions. If the water contains particles, impurities and/or excessive levels of salts, all blanks, standards and samples that are prepared with it are at risk for contamination. The purity of water is usually measured by its resistance or conductivity in the presence of an electric current. If purity is being measured by its resistance, the resistivity should be at least 18 MΩ∙cm. If purity is being measured by its conductivity, it should have a conductivity no higher than 0.1 µS/cm.

Recommended products:• Thermo Scientific™ Barnstead™ E-Pure™ Ultrapure

Water Purification System, 4 module-system (catalog #09-050-255)

• Thermo Scientific™ Barnstead™ Smart2Pure™ Water Purification System, compact, benchtop system, 3 L/hr flow rate (catalog #10-451-045)

AcidsA variety of acids will be used for proper sample preparation, handling and storage. Low purity acids will contain measurable concentrations of elemental contaminants. For that reason, ultrapure acids should be used at all times. High purity acids are available for purchase; however, acids can be further distilled (also known as sub-boiling) to increase their purity. If all laboratory analyses are being performed on an AA or an ICP-OES instrument, the purity of the acid can be slightly lower (TraceMetal™ Grade) than if an ICP-MS is being used for analysis. Acids of slightly lower purity are less expensive.

Nitric acid and hydrochloric acid will likely be the two acids predominantly used for sample preparation and storage. For drug-related products where Si-containing components must be dissolved and stabilized, hydrofluoric acid may need to be used.

NOTE: If hydrofluoric acid is used in the laboratory, proper safety precautions should be employed, all personnel should be trained in its proper handling and use, and calcium-containing treatments should be made available.

Recommended products:• Nitric Acid (Optima™), Fisher Chemical, 1 L bottle

(catalog #A467-1)

• Nitric Acid (TraceMetal Grade), Fisher Chemical, 2.5 L bottle (catalog #A509P212)

• Hydrochloric Acid (Optima™), Fisher Chemical, 1 L bottle (catalog #A466-1)

• Hydrochloric Acid (TraceMetal Grade), Fisher Chemical, 2.5 L bottle (catalog #A508-P212)

• Hydrofluoric Acid (Optima™), Fisher Chemical, 1 L bottle (catalog #A463-1)

• Sulfuric Acid (Optima™), Fisher Chemical, 1 L bottle (catalog #A468-1)

• Phosphoric Acid, 85% (Certified ACS), Fisher Chemical, 1 L bottle (catalog #A242-1)

NOTE: Due to the hazardous nature and product restrictions associated with these acids, the Fisher Scientific Customer Service department should be contacted for assistance (1-800-766-7000 or CS.WebEmail@thermofisher.com)

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StandardsHigh quality stock standards are vital to the creation of accurate, high quality calibration standards. Stock standards should be NIST traceable and should have certification papers that specify the identity and concentrations of any impurities present. There are a number of vendors who produce accurate and consistent standards, three of which are listed below.

The multi-element standards listed below contain the elements identified in USP <232> at appropriate ratios. The advantage to using standards like these is that they can be converted to working standards after a simple dilution. If additional standards are required, or if standards are required for interference troubleshooting or internal standardization, high purity single-element standards can be purchased from the same vendors.

It is recommended to have small, disposable cups or beakers on-hand into which a small amount of each stock standard can be poured into. This prevents any object from being placed directly into any of the standards bottles and reduces the likelihood of any of the stock standards from becoming contaminated.

Recommended products:Inorganic Ventures• USP 232 Drug Substance and Excipients, 125 mL

(catalog #IV-STOCK-60-125ML)

• USP 232 Oral Elemental Impurities, 125 mL (catalog #IV-STOCK-40-125ML)

• USP 232 Parenteral Elemental Impurities, 125 mL (catalog #IV-STOCK-41-125ML)

• USP 232 Precious Metals Elemental Impurities, 125 mL (catalog #IV-STOCK-38-125ML)

SPEX CertiPrep• USP Oral Elemental Impurities A in 5% HNO3, 125 mL

(catalog #USP-TXM2)

• USP Precious Metal Impurities B (with Os) in 15% HCl, 125 mL (catalog #USP-TXM3)

• USP Precious Metal Impurities B (without Os) in 15% HCl, 125 mL (catalog #USP-TXM4)

• USP Oral/Parenteral Elemental Impurities C in 5% HNO3, 125 mL (catalog #USP-TXM5)

High Purity Standards• USP 232-1 Oral Elemental Impurities Standard in 7%

HNO3 (SKU: USP232-1)

• USP 232-2 Oral/Parenteral Elemental Impurities Standard in 7% HNO3 (SKU: USP232-2)

• USP 232-3A Precious Metal Impurities Standard 3A in 15% HCl (SKU: USP232-3A)

• USP 232-3B Precious Metal Impurities Standard 3B in 15% HCl (SKU: USP232-3B)

• USP 232-4 Parenteral Elemental Impurities in 7% HNO3 (SKU: USP232-4)

Sample PreparationTop-Loading BalanceA good quality analytical balance (accurate to 3 places past the decimal point) should be used when standards and samples are prepared by weight. A top-loading balance should have an enclosure to prevent drafts from affecting the measured weight. The balance should be calibrated according to the manufacturer’s recommendations and the calibration should be checked frequently. A grounding strap should be worn when using the balance to ensure static electricity effects do not interfere with the weight measurements.

If standards and samples are not going to be weighed directly into a sample preparation vessel (microwave vessel, beaker, volumetric flask, etc), disposable weighing paper or weighing boats should be used.

Recommended products:• Mettler Toledo™ NewClassic ME Precision Balance, max

capacity 420 g (catalog #01-912-406)

• Fisherbrand™ Low-Nitrogen Weighing Paper, 3 x 3 in. (catalog #09-898-12A)

Microwave Sample PreparationAccording to USP 233 methodology samples that are not directly soluble in aqueous or organic solvents must use a closed vessel acid digestion technique in order to provide a total metal extraction. Microwave digestion provides a means to prepare the samples reproducibly and without loss of volatile elements. A single method can be used for the majority of pharmaceutical samples. Information about the temperatures achieved in the digestion can be easily verified for quality assurance.

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CEM offers two platforms for microwave digestion• Discover® SP-D™, the most popular option, is

an automated sequential system which provides unattended operation

• MARS 6™ is a batch digestion system for laboratories preparing more than 50 samples per day

Discover SP-D Automated Microwave Digestion SystemThe Discover SP-D Microwave Digestion System includes a 24 place autosampler and utilizes a simple to use quartz vial with a snap on cap. The system comes standard with its own fume cabinet freeing up hood space and features full control and reporting of each sample.

Discover SP-D System Recommended for USP 232 • Discover SP-D 80

• 24 place autosampler

• Fume cabinet

• 21 CFR Part 11 compliant software and control package

• 12 Quarts Vessels

• 100 vessel caps (part #925344)

• Installation and 1/2-day training for laboratory staff

• IQ/OQ/PQ - performed by factory trained service experts

• Service Plan - all CustomerCare Plus® plans include NIST traceable calibrations, an annual calibration visit, and multiple other options

MARS 6 Batch Microwave Digestion SystemThe MARS 6 is perfect for labs needing high sample throughput of similar samples because it can process all samples simultaneously.

Discover SP-D Features• Test any variety of samples from tablets to emulsions

to capsules individually which allows you to select a different method for each sample.

• Each method is preloaded. Just select and run.

• Digest and cool sample in less than 10 minutes.

• Most samples use an acid mixture of 9 mL HNO3 and 1 mL HCl.

• Set up your entire day at once or add on samples as they arrive.

• 21 CFR Part 11 Compliant software

• NIST calibrated temperature sensor

• Includes IQ/OQ/PQ

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MARS 6 Features• Run vitamins and dietary supplements in a single batch.

• Most applications use an acid mixture of 9 mL HNO3 and 1 mL HCl.

• Faster testing with wireless temperature monitoring with iWave technology.

• Pre-installed methods, using One Touch Technology™.

• Can be operated with 21 CFR Part 11 compliant on board touch screen or with optional remote tablet based iLink control.

• Includes IQ/OQ/PQ

MARS 6 System Recommended for USP • MARS 6 with iWave™ (part #927524)

• iPrep Starter Set

• 1/2 Day Install and Training for laboratory staff

• IQ/OQ/PQ - performed by factory trained service experts

• iLink Premium (optional) Remote control and monitoring system

• Service Plan - all CustomerCare Plus® plans include NIST traceable calibrations, an annual calibration visit, and multiple other options

Instrument ConsumablesIf elemental analysis is being performed with an ICP-OES or an ICP-MS, there are several items that will consistently come into contact with sample solutions and will require replacement on a recurring basis. A few of those consumable items are listed here.

Pump TubingRegardless of the elemental analysis instrument being used, solutions must be delivered into the instrument at a constant flow rate. While some applications allow for free aspiration of solutions into the nebulizer, the majority of standard and sample solutions will be pumped into the instrument via a peristaltic or syringe pump.

If solutions are being introduced via peristaltic pump, suitable pump tubing is required. The tubing will have either 2 or 3 stops, depending on the size of the pump, and should be made from a material that is chemically resistant to the solution being pumped through it. For most aqueous applications, PVC tubing is sufficient; however, organic solvents require the use of solvent resistant PVC tubing (typically tinted yellow and referred to as SolventFlex tubing). In some cases, the solvent may be reactive enough that special synthetic rubber (Viton™) or thermoplastic (Santoprene™) tubing may be required.

Regardless of the manner in which solution is introduced, all excess solution must be actively pumped from the instrument’s spray chamber. In addition to selecting the proper number of stops and tubing material (as described above), drain tubing must be selected with a larger inside diameter than that being used for pumping solution into the introduction system. Selecting a larger inside diameter will ensure that more solution is drained from the sample introduction system than is introduced.

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Recommended products:

Matrix Function Stops Description and Catalog #Aqueous Sample Uptake 2 Tygon™ orange/white (0.64 mm I.D.) 2-stop pump tubing, 6/pk (catalog

#NC9608336)

Aqueous Drain 2 Tygon™ white/white (1.02 mm I.D.) 2-stop pump tubing, 6/pk, (catalog #NC9608337)

Aqueous Sample Uptake 3 Tygon™ orange/white (0.64 mm I.D.) 3-stop pump tubing, 6/pk (catalog #NC0710800)

Aqueous Drain 3 Tygon™ white/white (1.02 mm I.D.) 3-stop pump tubing, 6/pk (catalog #NC0710801)

Organic Sample Uptake 2 Solvent Flex 2-stop pump tubing, 6/pk (catalog #NC0902511)

Organic Drain 2 Solvent Flex 2-stop pump tubing, 6/pk (catalog #NC0902512)

Organic Sample Uptake 3 Solvent Flex 3-stop pump tubing, 6/pk (catalog #NC1061987)

Organic Drain 3 Solvent Flex 3-stop pump tubing, 6/pk (catalog #NC1061986)

Internal Standard AdditionInternal standards are used for dynamic correction to account for physical differences between standard and sample matrices. These differences can affect the generation and transport of the sample aerosol and, if left uncorrected, can produce errors during data collection.

An internal standard can be added in one of three ways:1. Manual addition (usually via pipette) to every blank,

standard and sample

2. Manual addition to the diluent being used to prepare all blanks, standards and samples

3. On-line addition via mixing tee or mixing Y

The recommended delivery method is via on-line addition with a proper mixing kit, similar to that illustrated below. This method ensures the most consistent and accurate internal standard delivery and minimizes the opportunity for introducing contaminants or errors. It should be noted that the entire internal standard kit is not generally considered to be a consumable item. The mixing tee and mixing coil would need to be replaced if they were damaged or became irreversibly blocked; however, replacing those components is a rare necessity. Only the pump tubing would need to be replaced on a consistent basis.

Orange/White Sample Tubing Orange/Blue Sample Tubing

Peri Pump

Sample Bottle of Internal standard

Mixing coil

Internal Standard is mixed at a 1 to 5

ratio with Sample

©2017 Thermo Fisher Scientific Inc. All rights reserved. Viton is a trademark of The Chemours Company FC, LLC. Santoprene is a trademark of Norton Company. Santoprene is a trademark of Exxon Mobile Corporation. Discover, SP-D, Mars, CustomerCare Plus, One Touch Technology and iWave are trademarks or service marks of CEM Corporation. Falcon, Corning and Pyrex are trademarks of Corning Corporation. All other trademarks are the property of Thermo Fisher Scientific. This information is presented as an example of the capabilities of Thermo Fisher Scientific products. It is not intended to encourage use of these products in any manner that might infringe the intellectual property rights of others. Specifications, terms and pricing are subject to change. Not all products are available in all countries. Please consult your local sales representative for details. TG90242-EN 0217S

Find out more at thermofisher.com

Recommended products:• On-line internal standard kit for the Thermo Scientific™

iCAP™ 7200 (part #842312051551)

• On-line internal standard kit for the Thermo Scientific™

iCAP™ 7400/7600 (part #842312052651)

• On-line internal standard kit for the Thermo Scientific™

iCAP™ RQ (part #1324690)

Many instruments are operated with autosamplers for ease and convenience. Autosampler racks require sample tubes to contain each solution. To minimize the opportunity for cross contamination, sample tubes should be properly cleaned or disposed of after every use. Sample tubes, particularly the caps, can be a significant source of contamination so if they are being reused, they should be monitored to ensure they don’t introduce contaminants.

Sample tubes are available in a variety of materials such as polystyrene, polypropylene and polyvinylchloride. They can be purchased in a range of shapes (conical, flat-bottom, round bottom) and sizes (8 mL, 15 mL, 30 mL, 50 mL, etc) to accommodate different autosampler rack styles. Two commonly used products are listed.

Recommended products:• Falcon™ 50 mL Conical Centrifuge Tubes (catalog

#14-432-22)

• Falcon™ 15 mL Conical Centrifuge Tubes (catalog #14-959-53A)

Additional Resources• Elemental Impurities in Pharmaceutical Products Primer

• Thermo Fisher Scientific - Elemental Impurities Storefront www.thermofisher.com/usp232

• Thermo Fisher Scientific - Elemental Impurities Learning Center

• Official USP Website: http://www.usp.org

• The latest versions of USP Chapters <232> and <233>

• ICH Q3D Guideline for Elemental Impurities

• USP Blog Site: qualitymatters.usp.org