usp 735 as an alternative to usp 233 for elemental impurity analysis in pharmaceutical products

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USP <735> as an Alternative to USP <233> for Elemental Impurity Analysis in Pharmaceutical Products

Justin Masone, Dan Davis;Shimadzu Scientific Instruments, Columbia, MD

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What is the USP?

United States Pharmacopeial Convention

Non-profit organization that sets the standards for the identity, strength, quality, and purity of medicines, food ingredients, and dietary supplements.

USP drug standards are enforced in the US by the FDA

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Current Regulations

USP <231>: HEAVY METALS is the current chapter regarding elemental impurities.

It is based on precipitation of the metal sulfide in a sample and compares the intensity to a lead standard.

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New Regulations: Why?

RTI has described <231> as a “non-specific colorimetric test with low sensitivity requiring significant quantities of the tested material.” 1

Prone to error

Requires skilled analyst to interpret the color correctly

USP <231> omission will become official on January 1, 2018

1 https://www.rti.org/pubs/aaps2013-harrington-poster.pdf

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New Regulations

Chapter <232>:

Chapter <233>:

Chapter <735>:

January 1, 2018

Elemental Impurities - Limits

Elemental Impurities - Procedures

X-Ray Fluorescence Spectrometry

May 1, 2015

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USP <231>

Metals Included:

Pb, Hg, As, Cd, Sb, Sn, Bi, Ag, Cu, Mo [10]

Three Different Procedures:

Method I: for substances that yield clear, colorless, preparations

Method II: for substances that do not yield clear, colorless preparations under Method I, or interfere with the precipitation of metals buy sulfide ion, or for fixed and volatile oils (Method II does not recover Hg)

Method III: wet-digestion method used when neither I nor II can be used

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USP <231> Shopping List

H2SO4

Pb(NO3)2

NH4C2H3O2

HCl

HNO3

NH4OH

CH3COOH

Drug Sample

Grams of sample = 2/(1000*L); where L is the Metals Limit (in %)

200 mg (Cu) 13.3 g (As)

C2H5NS

C3H8O3

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USP <231> Determination

“Filter…into a 50-mL color-comparison tube…view downward over a white surface: the color of the solution from the Test Preparation is not darker than that of the solution from the Standard Preparation, and the color of the solution from the Monitor Preparation is equal to or darker than that of the solution from the Standard Preparation.”

1870

1 http://en.wikipedia.org/wiki/Colorimetry_(chemical_method)

1

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USP <232> Elemental Impurities: Limits

<232> specifies limits for the amounts of elemental impurities (“EI”) in drug products

EI includes catalysts and environmental contaminants that may be present in drug substances, excipients, or drug products.

When EI are known to be present, have been added, or have the potential for introduction, compliance to the levels in <232> is required

If manufacturers can demonstrate the absence of EI, further testing is not needed

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When testing is done to demonstrate compliance, the “Big Four” must be included as a minimum (As, Cd, Pb, Hg).

<232> limits do not apply to excipients or drug substances (except where specified).

<232> limits do not apply to products intended only for veterinary use and conventional vaccines.

<232> limits do not apply to dietary supplements and their ingredients (addressed in <2232> Elemental Contaminants in Dietary Supplements).


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Toxicity limits are defined as maximum permissible daily exposure (PDE). These differ between routes of exposure, such as:

Oral (incl. mucosal and topical)Parenteral InhalationalLarge-volume parenteral (LVP, 100 mL)

PDE values are in μg/dayBased on an “average” 50 kg (110 lbs) person

LVP for injection volume >100 mLMust be controlled through the individual components used to

manufacture the drug product (Summation Option)


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Element [15] Oral PDE (μg/day)Parenteral PDE

(μg/day)Inhalational PDE

(μg/day)LVP Compondent

Limit (μg/g)Cadmium 25 2.5 1.5 0.25Lead 5 5 5 0.5Inorganic arsenic 1.5 1.5 1.5 0.15Inorganic mercury 15 1.5 1.5 0.15Iridium 100 10 1.5 1.0Osmium 100 10 1.5 1.0Palladium 100 10 1.5 1.0Platinum 100 10 1.5 1.0Rhodium 100 10 1.5 1.0Ruthenium 100 10 1.5 1.0Chromium -- -- 25 --Molybdenum 100 10 10 1.0Nickel 500 50 1.5 5.0Vanadium 100 10 30 1.0Copper 1000 100 100 10


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<233> describes two analytical procedures for the evaluation of the levels of EI:

ICP-OES ICP-MS

<233> also allows for an equivalent alternative technique, and describes certain acceptance criteria.

<233> Elemental Impurities: Procedures

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Sample Preparation

Forms of sample prep include:

Neat (unsolvated)

Direct aqueous solution (sample dissolved in aqueous solvent)

Direct organic solution (sample dissolved in organic solvent)• May requires sample introduction system for organics or

additional gases (for example, mixed Ar/O2)

Indirect solution (digestion)• Requires microwave digester


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Sample Analysis

Calibration:• Matrix-matched blank• Low standard (0.5J)• High standard (2J)

Sample batch

Blank

SST (High standard)Criteria for pass: ± 20%


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Alternate Procedure Validation

DetectabilityStandard solution

• At concentration J

Spike Sample 1

• Analysis sample spiked at J

• Acceptance criteria: ± 15%

Spike Sample 2

• Analysis sample spiked at 0.8J

• Acceptance criteria: I < Spike Sample

1

<233> Elemental Impurities

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Precision (Repeatability)

6 analysis samples Independent samples spiked at J

Acceptance criteria RSD ≤ 20%



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Accuracy

Spike Samples Spike samples at concentrations ranging from 50%-150% of J

Acceptance Criteria 70%-150% for the mean of three replicate preparations at

each concentration



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USP <735> X-Ray Fluorescence Spectrometry

Chapter <735> describes XRF, and it is not limited to <232> Elemental Impurities

What is XRF?

Can it satisfy <232> limits?

How does it compare to ICP or ICP-MS?

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First, some clarification…

X-Ray Fluorescence Spectrometry

Energy-Dispersive XRF

(EDXRF)

Wavelength-Dispersive XRF(WDXRF)

USP <735> X-Ray Fluorescence Spectrometry

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What is ED-XRF?

Energy-Dispersive X-Ray Fluorescence

Energy-dispersive: Ability to discern the energies of x-rays

X-Ray: Form of energy; source of ionizing radiation

Fluorescence: Phenomenon of absorbing energy (short λ) and subsequently emitting energy (longer λ)

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What are X-Rays?

X-rays are a kind of electromagnetic energy.

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How Do X-Rays Interact with Matter?When X-rays strike matter, some of them are absorbed and some pass through.

The degree of absorption and penetration depend on the elemental composition, density, and thickness of matter.

A consequence of absorption is that secondary X-rays are generated, which are characteristic of that matter.

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How Do X-Rays Interact with Atoms?

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- -

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++-

-

-

-

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-Irradiating

X-ray

Ejected Electron

Fluorescent X-ray

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EDX Spectrum

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How Does an EDX Work?

EDX is a type of spectrophotometer. It contains:

X-ray tube

Filters

Collimator

C-MOS camera

Detector (SDD)

Sample

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Auto-sampler

12-position auto-sampler

Designed to fit standard XRF cups

Can run a different method for each position

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Analytical Range

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USP <735> Shimadzu White Paper

Report to the pharmaceutical elemental analysis method using the EDX-7000

1. Purpose:Evaluation of calibration curve and

sensitivity of metal element in solution and cellulose using EDX-7000

2. Measurement Condition:The apparatus used for the

measurement is EDX-7000.The measurement condition is shown

in Table 1.

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3. Sample Preparation:Elements to be measured are Cr, Ni, As, Ru, Pd and Pt.The sample was prepared by using diluted AAS standard solutions as

shown below in Table 2.

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4. Experimental Condition:The experimental conditions of each element are shown

in Table 3.

5. Result:5.1 Calibration Curve Evaluation

A 6.0 mL solution and 2.0 g pressed cellulose powder were used for creating calibration curves of each element. The “RMS” and “Correlation” were evaluated for reliability of the calibration curves. The calibration curves for the solution and cellulose of each element are given in below Figures 1 – 12.

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RSD

6.37%

1.39%

2.53%

1.47%

6.18%

3.02%

5.2 Measurement Result at Repeatability Test:Tables 6 and 7 demonstrate the 10-time repeatability using a solution and

cellulosesample to calculate the average and standard deviation. The sample was used5.0 ppm for Cr, As, Ru, Pd, Pt, and 30 ppm for Ni.

RSD

5.56%

2.99%

1.21%

4.55%

11.57%

2.61%

Solution

Cellulose

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USP <735> Shimadzu White Paper5.3 Lower Limit of Detection Evaluation:

Tables 8 and 9 demonstrate the lower limit of detection for solution and cellulose sample from the 10 times repeatability of the blank sample. The lower limit of detection is defined as three times value of the standard deviation obtained from the repeat measurement of blank samples.

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5.4 Small Mass Sample Measurement:100 mg of a cellulose sample was put into the sample cup the

calibration curves and LLDs were evaluated determined and evaluated.

5.4.1 Calibration Curve Evaluation:100 mg of cellulose powder was used for creating calibration

curves of each element using the conditions in Table 10. The “RMS” and “Correlation” were evaluated for reliability of calibration curve.

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5.4.2 Low Limit of Detection EvaluationTable 12 demonstrates the lower limit of detection for a cellulose

sample from the 10-time repeatability of the blank. The lower limit of detection is defined as three times value of the standard deviation obtained from the repeat measurement of blank samples.

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USP <233> or USP <735>?

Which is the optimal technique?

vs.

XRF ICP

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USP <233> or USP <735>?

Application

What are the detection limits? What concentration ranges are expected? (Dynamic range) How much accuracy and precision are required? How many samples and at what frequency? (Sample throughput) How much time spent on sample prep? Is there a limited amount of sample available? Will matrix interferences have a major impact on analysis?

Installation

What is the size of the instrument? How much lab space is required? How clean must the lab/sample prep area be?

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USP <233> or USP <735>?

User

How easy is the instrument to use? What training is required?

Financial

What is the cost of the instrument? What is the cost to run the instrument? What is the cost of a specialized laboratory? What is the cost to have a dedicated expert(s) to run the instrument?

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USP <233> or USP <735>?

Application

What are the detection limits?

ICP and ICP/MS will have better LODs than EDX. However, this is not of a concern for USP. ICP/ICP-MS involves sample digestion, which results in ~500-fold dilution of the sample.

EDX requires minimal sample prep, if any at all, and this will not result in any dilution. EDX meets the limits presented in <232>.

What concentration ranges are expected? (Dynamic range)

Multiple dilutions will need to be performed for ICP/ICP-MS. EDX range is <1 ppm – 100%.

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USP <233> or USP <735>?

How much accuracy and precision are required?

Not a concern; ICP/ICP-MS/EDX all meet USP requirements

How many samples and at what frequency? (Sample throughput)

ICP/ICP-MS have greater capacity for sample throughput (3 minute analysis; 240-position auto-sampler vs. 12-sample turret for EDX).

This may not be that important for many customers, and sample prep may limit the number of samples per batch for ICP/ICP-MS.

Will matrix interferences have a major impact on analysis?

Interferences with EDX are well-known and easily accounted for (all software based; post-run). ICP would require a skilled analyst and extra solutions.

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USP <233> or USP <735>?

How much time spent on sample prep?

EDX has the obvious advantage. Sample prep is minimal (pressing sample into a pellet) to none.

ICP and ICP-MS sample prep could include digestion, multiple dilutions (aqueous or organic solvents), etc.

This is also an indirect cost of ownership for an ICP-MS—the more samples you have to prep, the more time is spent paying a highly-trained analyst to do benchwork chemistry—time that could be spend analyzing other samples (think contract lab).

Is there a limited amount of sample available?

This could be a concern for ICP/ICP-MS (multiple digestions and dilutions to get samples into working range of instrument). EDX can meet criteria for <232> using only 0.1 g of sample.

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USP <233> or USP <735>?

Installation

What is the size of the instrument?

45 kg (99 lbs)450 mm x 590 mm x 360 mm

210 kg (462 lbs)1300 mm x 660 mm x 720 mm

vs.

vs.

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USP <233> or USP <735>?

How clean must the lab / sample prep area be?

EDX is measuring ppm-level, so cleanroom is not necessary.

ICP-MS will require a VERY clean lab and VERY clean prep room.

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USP <233> or USP <735>?

User

How easy is the instrument to use? What training is required?

EDX is the simplest of all elemental analysis techniques.

It can be set up and optimized during installation, only requiring the analyst to place a sample in the chamber and press start.

ICP-MS is the most complex of all elemental analysis techniques. It requires a skilled analyst and lengthy training.

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USP <233> or USP <735>?

Financial

What is the cost of the instrument?

EDX: <$75,000. No special accessories required for USP. If anything, a pellet press could be used ($10,000-$15,000). Total cost is less than $100,000.

ICP-MS: $200,000. Microwave digester ($75,000). Temperature-controlled spray chamber ($10,000). Total cost is nearing $300,000.

What is the cost of a specialized laboratory?

Not required for EDX. Required for ICP-MS ($50K? $100K?).

ICP/ICP-MS requires ventilation.

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USP <233> or USP <735>?

What is the cost to have a dedicated expert(s) to run the instrument?

Major concern for ICP-MS

What is the cost to run the instrument?

EDX: No consumables. 120V, 2A ($950 over 10 years, including PC)

ICP (~14,450/year)Gases (liquid argon)Electric ($750/year)Consumables (Sample introduction accessories, sample and

skimmer cones, etc.)

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USP <233> or USP <735>?

What is the cost to run the instrument?

EDX cost/sample over 10 years, including:• Main body• X-ray tube (2 replacements)• Inverter• Detector• Electric

• For 100 analyses: $0.15/sample• For 1200 analyses: $1.85/sample

ICP-MS cost/sample over 10 years:• Industry estimate of RUNNING COST (not including main body

and accessories) is $0.71/sample.• $2.25/sample including cost of instrumentation

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USP <233> or USP <735>?

Pros Cons• Minimal to no sample

prep• Cost of the unit• Cost of ownership• No gases• No exhaust• 120V vs 220V• Minimal bench space• No sample waste• Skilled analyst not

required• Interferences well-

understood and easily accounted for

EDX vs. ICP/ICP-MS

• Limited number of samples (12 vs 240)

• But remember…for ICP/ICP-MS you will need to pay someone to prep the 240 samples first.

• LODs (but not a concern for USP)

Bottom-line: Cheaper, simpler, more efficient

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Thank You

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usp 735 as an alternative to usp 233 for elemental impurity analysis in pharmaceutical products

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