5 Why tools for Root cause analysis in pharmaceuticals

Originating in the manufacturing industry, the “5 Whys” analysis technique has found effective adaptation and application in various fields, including pharmaceuticals. It involves asking “why” multiple times (typically five) to dig deeper into the root causes of a problem. In the context of pharmaceuticals, the 5Whys tool can help identify the underlying causes of quality issues, compliance violations, safety concerns, and other problems.

How to use 5 why analysis in finding root cause:

1.Define the Problem: Start by clearly defining the problem you want to investigate. This could be a product defect, a deviation from regulatory standards, or any other issue.

2. Ask “Why?” for the Problem: Ask why the problem occurred. This is your initial question, and you should answer it based on available information. For example, if the problem is a batch of contaminated medication, the first “why” might be: “Why did contamination occur in the batch??”

3. Repeat the Question: Once you have an answer to the first “why,” ask “why” again based on the answer to the previous question. Continue this process for at least five iterations or until you reach a point where the root cause becomes evident. Each “why” should probe deeper into the causes behind the previous answer.

4. Document the Responses: Record the answers to each “why” question. This documentation is crucial for analysis and future reference.

5. Identify the Root Cause: By the time you reach the fifth “why,” you should ideally have identified the root cause of the problem. The root cause is the fundamental issue that, when addressed, will prevent the problem from recurring.

Example of 5 why technique in pharmaceutical industry:

Problem: Batch of Medication Failed Quality Control

5 why Analysis example
  1. Why did contamination occur in the batch? (Answer: Due to a problem with the manufacturing process)
  2. Why did the manufacturing process have a problem? (Answer: Lack of maintenance led to equipment malfunction)
  3. Why did the team neglect equipment maintenance? (Answer: Maintenance schedule not clearly defined)
  4. Why was the maintenance schedule not defined? (Answer: Lack of proper documentation and oversight)
  5. Why was there a lack of documentation and oversight? (Answer: Insufficient training and resources allocated)

In this example, the root cause of the contaminated batch is the lack of training and resources allocated for equipment maintenance and oversight. By addressing this root cause, the pharmaceutical company can prevent similar issues in the future.

The 5 Whys tool is valuable in pharmaceuticals because, firstly, it promotes a systematic approach to problem-solving, helps identify underlying causes, and ultimately supports the improvement of product quality and compliance with regulatory standards.

Root cause Analysis


Evaporative Light Scattering Detector(ELSD)

ELSD stands for Evaporative Light Scattering Detector. It serves as a type of analytical instrument in chromatography for detecting and quantifying non-volatile compounds lacking a natural chromophore or fluorophore. It proves especially valuable when analyzing compounds that UV, fluorescence, or conductivity detectors, commonly used in chromatography, cannot detect.

How ELSD Works:

  1. Evaporation: ELSD operates by evaporating the mobile phase (solvent) from the column effluent, leaving behind the solute particles.
  2. Light Scattering: After evaporating the solvent, a nebulizer or nebulizing gas disperses the solute particles into a gas stream. These solute particles then pass through a region where they encounter a beam of light (usually a laser or an LED).
  3. Scattering Detection: When the solute particles encounter the light beam, they scatter the light in all directions. The scattered light is collected at a specific angle. Typically 90 degrees, to minimize the interference from the direct beam of light. This scattered light is then measured and used to quantify the amount of solute in the sample.

Applications of ELSD:

  1. Analyzing Non-Volatile Compounds: ELSD is particularly useful for analyzing compounds that are non-volatile or have low volatility. These include lipids, steroids, certain pharmaceuticals, and natural products. Since ELSD detects particles rather than molecules, it is less dependent on the chemical nature of the analyte, making it versatile for a wide range of compounds.
  2. High-Performance Liquid Chromatography (HPLC): “Researchers often use ELSD in conjunction with HPLC, a powerful separation technique. To detect and quantify compounds in complex mixtures.” It is especially valuable when analyzing samples with a broad range of compound classes or when the sample matrix interferes with other detection methods.
  3. Food and Beverage Analysis: Employed to quantify lipids, fatty acids, and other non-volatile components.” in Food and Beverage Analysis. This is crucial for quality control and nutritional labelling.
  4. Pharmaceutical Research: Used in pharmaceutical research for the analysis of drug compounds, especially those that lack chromophores or fluorophores. Used to determine the purity of pharmaceutical products.
  5. Environmental Analysis: Applied in environmental monitoring to detect and quantify various non-volatile environmental contaminants, such as pesticides and herbicides.
  6. Natural Product Chemistry: Used in natural product chemistry to analyze complex mixtures of plant extracts, essential oils, and other natural products.

In summary, Evaporative Light Scattering Detector (ELSD) is a versatile analytical tool for the detection and quantification of non-volatile compounds in various fields. Including pharmaceuticals, food science, environmental monitoring, and natural product chemistry, where other detection methods may be less suitable.

Refractive Index Detector (RID)

A Refractive Index Detector (RID), also known as a Refractometer or Refractive Index Detector, is a detection device commonly used in High-Performance Liquid Chromatography (HPLC) and other liquid chromatography techniques. RIDs operate based on the principle of measuring changes in the refractive index of a sample as it elutes from the chromatographic column. Here are its key features, applications, and limitations:

Key Features of Refractive Index Detector (RID):

Key Features of Refractive Index Detector (RID):

  1. Universal Detection: RIDs are considered universal detectors because they can detect virtually all compounds that pass through the detector cell. This is because changes in the refractive index are a general property of all compounds, regardless of their chemical structure or UV absorption properties.
  2. Non-Destructive: RIDs are non-destructive detectors, meaning they do not require sample derivatization or destruction of the analytes, making them suitable for analyzing a wide range of compounds, including biomolecules.
  3. High Sensitivity: RIDs are highly sensitive detectors capable of detecting compounds in the nanogram to picogram range, depending on the specific instrument and sample concentration.
  4. Linear Response: RIDs typically provide a linear response over a wide range of analyte concentrations, making them valuable for both quantitative and qualitative analysis.

Applications of Refractive Index Detector (RID):

  1. Polymer Analysis: RIDs are commonly used in the analysis of polymers, such as determining molecular weight distributions and monitoring polymerization reactions.
  2. Carbohydrate Analysis: RIDs are widely employed in the analysis of carbohydrates, including sugars and polysaccharides, in food, pharmaceutical, and biochemistry applications.
  3. Pharmaceutical Analysis: RIDs are useful for quantifying and characterizing drug compounds, including those that may not have strong UV absorbance.
  4. Food and Beverage Analysis: RIDs are applied in food and beverage analysis to measure sugar content, identify and quantify additives, and determine the concentration of various components.
  5. Environmental Analysis: RIDs are used to detect and quantify environmental contaminants, such as organic compounds in water and wastewater samples.
  6. Quality Control: RIDs are utilized in quality control laboratories to ensure the purity and consistency of products in industries like pharmaceuticals, chemicals, and food manufacturing.

Limitations of Refractive Index Detector (RID):

  1. Lack of Compound Specificity: RIDs do not provide compound-specific information, making it challenging to identify individual components in a complex mixture. Additional detectors, such as UV detectors or mass spectrometers, may be needed for compound identification.
  2. Lower Sensitivity Compared to Some Detectors: While RIDs are highly sensitive, they may not be as sensitive as some other detectors, such as mass spectrometers, making them less suitable for trace-level analysis.
  3. Limited Selectivity: RIDs detect changes in refractive index, which can be influenced by solvent changes or changes in temperature. This lack of selectivity can be a limitation in some applications.
  4. Sample Solvent Compatibility: Compatibility with the sample solvent is crucial for RIDs, as certain solvents may cause baseline drift or other issues.

Summary: Overall, Refractive Index Detectors are valuable tools in liquid chromatography, particularly for applications where compound-specific information is not necessary, and high sensitivity is required for a wide range of analytes. They find common use in polymer, carbohydrate, and pharmaceutical analysis, among others.

Fluorescence Detectors(FLD)

Fluorescence Detector (FLD) is a specialized analytical instrument used to detect and quantify fluorescent compounds in various samples. It operates on the principle of fluorescence, a process where molecules absorb light at one wavelength and then re-emit it at a longer wavelength. Here are the applications and uses of fluorescence detectors:

Applications of Fluorescence Detectors:

  1. Analytical Chemistry: Fluorescence detectors are extensively used in analytical chemistry for the quantification and identification of various compounds. They are highly sensitive and selective, making them suitable for a wide range of applications.
  2. Pharmaceutical Analysis: In the pharmaceutical industry, fluorescence detectors are crucial for analyzing drug compounds, including pharmaceuticals, metabolites, and impurities. They are used in quality control and formulation studies.
  3. Environmental Monitoring: Fluorescence detectors are employed to detect and measure pollutants, such as polycyclic aromatic hydrocarbons (PAHs), heavy metals, and organic contaminants in water, soil, and air samples.
  4. Biomedical Research: In biological and biomedical research, fluorescence detectors play a vital role in studying cellular processes, protein interactions, DNA sequencing, and gene expression. Fluorescent labels are often used to tag biomolecules for detection.
  5. Clinical Diagnostics: Fluorescence detectors are used in clinical laboratories for assays, immunoassays, and tests that rely on fluorescent labels. They are valuable tools for diagnosing diseases and monitoring biomarkers in patient samples.
  6. Food and Beverage Analysis: Fluorescence detectors are utilized in the food industry to detect and quantify contaminants, additives, vitamins, and other compounds. They are crucial for quality control and safety assessments.
  7. Drug Discovery: Fluorescence detectors are employed in high-throughput screening (HTS) assays to identify potential drug candidates and evaluate their interactions with specific targets, including receptors and enzymes.
  8. Environmental Fluorescence Sensors: Fluorescence detectors can be integrated into environmental sensors to continuously monitor specific analytes or parameters, such as pH, oxygen levels, and pollutant concentrations in natural water bodies.
  9. Material Science: Fluorescence detectors help researchers investigate the properties and characteristics of materials, such as polymers, nanoparticles, and quantum dots, through fluorescence spectroscopy.
  10. Forensic Science: In forensic laboratories, fluorescence detectors are used for the analysis of various substances, including drugs, explosives, and bodily fluids. They can help identify trace amounts of these substances in crime scene investigations.

Limitations of Fluorescence Detectors:

  1. Limited to Fluorescent Compounds: Fluorescence detectors can only detect compounds that exhibit fluorescence. Not all substances are naturally fluorescent, which restricts their applicability.
  2. Background Interference: Fluorescence detectors may be susceptible to background fluorescence, which can affect the accuracy of measurements. Proper sample preparation and background correction techniques are necessary to mitigate this issue.
  3. Instrument Complexity: These detectors can be complex and require specialized knowledge to operate and maintain effectively.


Despite their limitations, fluorescence detectors are indispensable tools in many scientific and industrial fields, offering high sensitivity, selectivity, and versatility for a wide range of applications. Researchers and analysts often choose fluorescence detection when working with fluorescent compounds or when requiring high sensitivity in their analyses.

Diode Array Detector

Diode Array Detector (DAD), also known as a UV-Visible Detector, is a type of detector commonly used in analytical chemistry techniques like High-Performance Liquid Chromatography (HPLC) and other forms of liquid chromatography. It differs from a single-wavelength UV detector in that it can simultaneously measure absorbance at multiple wavelengths across the UV-Visible spectrum. Here are its applications and limitations:

Applications of Diode Array Detector (DAD):

Quantitative Analysis: DADs are widely used for quantitative analysis in HPLC. They allow for the measurement of absorbance at multiple wavelengths, which is especially useful when analytes have different absorption maxima at different wavelengths. This versatility improves accuracy in quantification.

  1. Qualitative Analysis: DADs are valuable for identifying compounds in a mixture. The ability to collect UV-Vis spectra for each peak in a chromatogram helps differentiate between different compounds with similar retention times based on their unique spectra.
  2. Peak Purity Analysis: DADs are used to assess the purity of chromatographic peaks. Deviations in the UV-Vis spectra can indicate the presence of impurities or other compounds in a sample.
  3. Method Development: During method development, DADs are employed to evaluate the spectral characteristics of analytes. Researchers can choose the most appropriate detection wavelength for optimal sensitivity and selectivity.
  4. Stability Studies: DADs are useful for monitoring changes in the UV-Vis spectra of compounds over time. This is critical in stability studies for pharmaceuticals and other compounds to identify degradation products and assess stability.
  5. Chiral Separations: DADs can help confirm the identity of separated enantiomers in chiral chromatography by examining their UV-Vis spectra.
  6. Natural Product Analysis: DADs are commonly used in the analysis of natural products, such as herbal extracts, to identify and quantify various compounds in complex mixtures.

Limitations of Diode Array Detector (DAD):

  1. Cost: DADs are more expensive than single-wavelength detectors, which may make them less accessible for some laboratories.
  2. Complexity: DADs are more complex instruments, which may require additional maintenance and expertise to operate and maintain.
  3. Limited Wavelength Range: DADs typically cover a limited UV-Vis wavelength range (e.g., 190 to 800 nm), which may not be suitable for some specialized applications requiring extreme UV or near-IR detection.
  4. Resolution: The resolution of DADs may not be as high as that of other detectors, such as mass spectrometers, which limits their ability to separate closely eluting peaks with overlapping spectra.
  5. Sensitivity: In some cases, DADs may have lower sensitivity compared to other detectors, which can be a limitation when analyzing trace-level compounds.

Despite these limitations, DADs are powerful tools in analytical chemistry and are widely used for their ability to provide spectral information for both qualitative and quantitative analysis, making them essential in various research, pharmaceutical, and quality control laboratories. Researchers often choose the detector based on their specific analytical needs and budget constraints.

UV VIS Detector and it’s application

A UV-Vis (Ultraviolet-Visible) detector is a common analytical instrument used in chemistry and biochemistry to measure the absorbance of ultraviolet and visible light by a sample.

Principle and Component of UV-Vis

Here are some key points about UV-Vis detectors and their applications:

  1. Principle of Operation: UV-Vis detectors operate based on the principle that molecules absorb light at specific wavelengths. By measuring the amount of light absorbed by a sample at different wavelengths, you can obtain information about its chemical composition.
  2. Components: A typical UV-Vis detector consists of a light source that emits UV and visible light, a sample cell, a monochromator to select specific wavelengths, and a photodetector to measure the intensity of transmitted or absorbed light.

Application of UV-Vis

  1. UV-Vis Spectra: The resulting UV-Vis spectrum provides information about the electronic transitions within molecules. Peaks or bands in the spectrum correspond to specific transitions, aiding in compound identification.
  2. Quantitative Analysis: Widely used for quantitative analysis of substances such as nucleic acids, proteins, and various chemical compounds. The concentration of a substance can be determined by measuring the absorbance at a known wavelength using Beer’s Law.
  3. Qualitative Analysis: UV-Vis spectroscopy is used for identifying substances based on their absorption spectra. Each compound has a unique spectrum, allowing for qualitative analysis and identification.
  4. Chemical Kinetics: UV-Vis detectors are valuable for studying reaction kinetics by monitoring changes in absorbance over time. This is useful in chemical reaction rate studies.
  5. Quality Control: Industries like pharmaceuticals and food use UV-Vis detectors to ensure product quality. They can detect impurities, concentrations, and verify the consistency of products.
  6. Environmental Analysis: In environmental monitoring to detect and quantify pollutants, such as heavy metals, organic compounds, in water or air samples.
  7. Life Sciences: In biology and biochemistry, UV-Vis detectors are used for DNA and RNA quantification, protein analysis, and enzyme kinetics studies.
  8. Material Science: UV-Vis spectroscopy can be applied to characterize and study the electronic properties of materials, including semiconductors and nanoparticles.

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Limitations: UV-Vis spectroscopy is limited to compounds that absorb UV or visible light. It may not be suitable for substances that do not absorb in this range. Additionally, it cannot provide structural information about a compound.

In summary, UV-Vis detectors play a crucial role in various scientific and industrial applications, allowing for both quantitative and qualitative analysis of substances based on their absorption of UV and visible light.

Different Types of HPLC Detectors

High-performance liquid chromatography (HPLC) detectors are essential components of HPLC systems that help identify and quantify analytes in a sample as they elute from the chromatographic column. There are various types of HPLC detectors, each with its own strengths and limitations. Here are some common types of HPLC detectors:

  1. UV-Visible (UV-Vis) Detector:
    • UV-Vis detectors are one of the most commonly used detectors in HPLC.
    • They measure the absorbance of light at specific wavelengths as it passes through the sample.
    • These detectors are suitable for compounds that absorb UV or visible light.
  2. Diode Array Detector (DAD):
    • DADs are an advanced version of UV-Vis detectors.
    • DADs can collect absorbance data across a range of wavelengths simultaneously, allowing for spectral analysis.
    • DADs are useful for peak purity assessment and identification of co-eluting compounds.
  3. Fluorescence Detector:
    • Fluorescence detectors measure the fluorescence emitted by certain compounds when they are excited by UV or visible light.
    • They are highly sensitive and selective, making them suitable for compounds that fluoresce.
    • Fluorescence detection is often used in pharmaceutical and environmental analyses.
  4. Refractive Index Detector (RID):
    • RIDs measure changes in the refractive index of a sample as it passes through the detector.
    • They are non-destructive and can be used for compounds that lack UV-Vis absorbance or fluorescence.
    • RIDs are commonly used in sugar and polymer analysis.
  5. Conductivity Detector:
    • Conductivity detectors measure changes in the electrical conductivity of a solution as ions elute from the column.
    • They are often used for the analysis of ionic or charged compounds, such as ions, acids, and bases.
    • Conductivity detectors are frequently employed in ion chromatography.
  6. Mass Spectrometry Detector (MS):
    • MS detectors can provide highly specific identification and quantification of compounds based on their mass-to-charge ratios.
    • They are versatile and suitable for a wide range of analytes, including small molecules and large biomolecules.
    • Common MS detectors in HPLC include quadrupole, time-of-flight (TOF), and ion trap mass spectrometers.
  7. Evaporative Light Scattering Detector (ELSD):
    • ELSD detectors measure the scattered light from aerosolized analyte particles.
    • They are suitable for compounds with low UV-Vis absorption and low volatility.
    • ELSD is commonly used for analysis of lipid and polymer analysis.
  8. Electrochemical Detector:
    • Electrochemical detectors measure the current produced by redox reactions of analytes at an electrode.
    • They are highly sensitive and selective for electroactive compounds like neurotransmitters, drugs, and pesticides.
  9. Pulsed Amperometric Detector (PAD):
    • PAD is a kind of electrochemical detector used for carbohydrates, sugars and other electroactive compounds.
    • They provide excellent sensitivity and selectivity for carbohydrates.

The choice of detector in HPLC depends on the specific analytical requirements, the nature of the analytes, and the sensitivity needed for detection. Many HPLC systems allow for the use of multiple detectors in series to provide complementary information about the analytes in a sample.

Hausner’s Ratio

Hausner’s ratio, also known as the Carr’s compressibility index, is a measure used in the pharmaceutical industry to assess the flowability and compressibility of powders and granular materials. It is a simple way to predict how well a powder will flow and how easily it can be compressed into tablets or other solid dosage forms.

Hausner’s ratio is calculated using the following formula:

Hausner’s Ratio = (Bulk Density / Tapped Density)


Bulk Density: The bulk density of a powder is the ratio of the mass of the powder to its bulk volume. It is typically measured by pouring the powder into a graduated cylinder and recording the volume it occupies.

Tapped Density: The tapped density of a powder is the ratio of the mass of the powder to its tapped volume. Tapped density is determined by mechanically tapping the container holding the powder until there is no further volume reduction.

The Hausner’s ratio provides an indication of the flowability of the powder. Generally, lower values of Hausner’s ratio indicate better flow properties. Here is a rough interpretation of Hausner’s ratios:

 Flowability Scale 
Compressibility IndexFlow CharacterHausner Ratio
<10Excellent1.00 – 1.11
11 – 15Good1.12 – 1.18
16 – 20Fair1.19 – 1.25
21 – 25Passable1.26 – 1.34
26 – 31Poor1.35 – 1.45
32 – 37Very Poor1.46 – 1.59
>38Very Very Poor>1.60

Flowability Scale

Pharmaceutical manufacturers use Hausner’s ratio and related flowability measurements to optimize the formulation and processing of powders for tablet production and other dosage forms. Powders with poor flow properties may require modifications to their composition or processing conditions to improve flowability and ensure consistent tablet quality.

Also read: Angle of repose

Angle of repose

The angle of repose is an important concept in pharmaceuticals and various other industries. It refers to the maximum angle at which a pile of granular or powdered material will remain stable without collapsing.

Application and Importance:

In pharmaceuticals, the angle of repose has several key applications and importance:

  • Powder Flowability: The angle of repose is a critical parameter for assessing the flow properties of pharmaceutical powders. Powders with a steep angle of repose may flow poorly, leading to problems in manufacturing processes such as blending, tablet compression, and capsule filling. Pharmaceutical companies need powders to flow smoothly and consistently to ensure accurate dosing and product quality.
    • Uniform Dosage: In the production of solid dosage forms like tablets or capsules, it’s essential that the pharmaceutical powder is distributed evenly to ensure each dose contains the correct amount of active ingredient. Powders with a high angle of repose may segregate during processing, leading to inconsistent dosing.
    • Quality Control: Monitoring and controlling the angle of repose can be part of quality control processes in pharmaceutical manufacturing. It helps identify and rectify issues related to powder flow that could impact the quality and uniformity of the final product.
    • Formulation Development: During the formulation of pharmaceutical products, understanding the angle of repose can guide the selection of excipients and processing conditions. Formulators aim to achieve an ideal angle of repose for their powder blends to optimize product quality.
    • Troubleshooting: If pharmaceutical powders exhibit poor flow properties, understanding the angle of repose can help troubleshoot production issues. By modifying particle size, shape, or using flow-enhancing agents, manufacturers can improve powder flow and prevent production bottlenecks.
    • Regulatory Compliance: Regulatory agencies often require pharmaceutical companies to demonstrate that their products meet certain quality standards, including uniformity of dosage. Controlling and documenting the angle of repose can be part of meeting these regulatory requirements.

In summary, the angle of repose plays a crucial role in pharmaceutical manufacturing by influencing powder flowability, which directly impacts the quality, consistency, and efficiency of the production process. Pharmaceutical companies must carefully consider and control this parameter to ensure the safe and effective manufacture of pharmaceutical products.

Also read: Hausner’s Ratio

Best Books for Health and Fitness

ICH Guidelines

The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) provides guidelines to ensure the quality, safety, and efficacy of pharmaceutical products. These guidelines cover various aspects of drug development and regulation, including:

Q1: Stability Testing of New Drug Substances and Products
Q2: Validation of Analytical Procedures
Q3: Impurities in New Drug Substances
Q4: Pharmacopoeias
Q5: Quality of Biotechnological Products
Q6: Specifications: Test Procedures and Acceptance Criteria for New Drug Substances and New Drug Products
Q7: Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients
Q8: Pharmaceutical Development
Q9: Quality Risk Management
Q10: Pharmaceutical Quality System
Q11: Development and Manufacture of Drug Substances (Chemical Entities and Biotechnological/Biological Entities)
Q12: Technical and Regulatory Considerations for Pharmaceutical Product Lifecycle Management.

Q13: Continuous Manufacturing of Drug Substances and Drug Products

These guidelines help ensure that pharmaceutical products meet international standards and can be marketed globally. Always refer to the latest versions and regional regulatory requirements for specific guidance.

For more details on ICH guidelines refer to the link below


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