The Evidence Guide provides advice on assessment and must be read in conjunction with the performance criteria, required skills and knowledge, range statement and the Assessment Guidelines for the Training Package.

Overview of assessment

Critical aspects for assessment and evidence required to demonstrate competency in this unit

Assessors should ensure that candidates can:

use balances and volumetric glassware

select and use primary and secondary standards

select and use indicators

perform quality assurance checks for solution performance

perform titrations using laboratory procedures with required accuracy and precision and within required timelines

calculate the concentration of the solution given the chemical reaction for the titration

recognise control results that are not within acceptable range

record results to enterprise standards

label and store solutions in accordance with enterprise procedures

interpret and follow enterprise SOPs

interpret and use safety information, such as that provided by MSDS and follow relevant safety procedures.

Context of and specific resources for assessment

This unit of competency is to be assessed in the workplace or simulated workplace environment.

This unit of competency may be assessed with:

relevant MSAL974000 series units of competency, and

relevant MSAL975000 series units of competency dealing with sampling, tests and measurements.

Resources may include:

standard laboratory equipped with appropriate volumetric equipment

laboratory reagents and equipment

SOPs and testing methods.

Method of assessment

The following assessment methods are suggested:

inspection and/or testing of solutions prepared by the candidate

review of records and workplace documentation completed by candidate

review of work outputs by the candidate over time to ensure accuracy, consistency and timeliness

feedback from peers and supervisors

observation of the candidate preparing, standardising and using a range of solutions

oral or written questioning.

In all cases, practical assessment should be supported by questions to assess underpinning knowledge and those aspects of competency which are difficult to assess directly.

Where applicable, reasonable adjustment must be made to work environments and training situations to accommodate ethnicity, age, gender, demographics and disability.

Access must be provided to appropriate learning and/or assessment support when required.

The language, literacy and numeracy demands of assessment should not be greater than those required to undertake the unit of competency in a work like environment.

This competency in practice

Industry representatives have provided the case studies below to illustrate the practical application of this unit of competency and to show its relevance in a workplace setting.

Manufacturing

A standard solution is used to determine the concentration of unknown solutions. The quality of these analyses is critically related to the accuracy with which the concentration of the standard solution is known. Therefore, laboratory technicians spend considerable effort to ensure that the materials and methods used for the preparation and standardisation will lead to a solution of accurately known concentration. For example, anhydrous sodium carbonate is often used to prepare solutions to determine the concentrations of acids. The sodium carbonate is heated at a suitable temperature to remove any trace of moisture and cooled in a dessicator. An appropriate quantity is dissolved in distilled water and made up to volume in a volumetric flask. This solution of known concentration is then titrated with acids of unknown concentration and the concentration of the acids determined.

Environmental

A laboratory technician was required to determine the total acidity of a water sample as part of a quality control program. The total acidity was measured by titrating the water sample with sodium hydroxide of known concentration using an appropriate indicator. The concentration of the sodium hydroxide was determined via a volumetric titration against a primary standard of potassium hydrogen phthalate.

The value of the total acidity was determined by multiplying the volume of sodium hydroxide used with a numerical 'factor' which had been determined by the laboratory supervisor in order to save time. The value of the 'factor' was displayed on the titration equipment. However, a new technical assistant did the full calculation and found that his/her result differed slightly from that obtained using the 'factor'. After discussion with the laboratory supervisor it was agreed that the error was in the 'factor' and the assumption that each new batch of sodium hydroxide prepared was exactly the same concentration as all previous batches. This was incorrect as the concentration of each batch differed slightly and its actual concentration was determined accurate, using the primary standard. The procedure was changed so that the full calculation was required for all tests.

Required skills

Required skills include:

interpreting and following enterprise standard operating procedures (SOPs)

determining equivalence points using indicators and graphical methods

using calculation methods, including appropriate units, uncertainties, balancing equations, the concentration of the solution given the chemical reaction for the titration

using apparatus and reagents to prepare standard solutions such as balances and volumetric glassware

selecting and using primary and secondary standards and indicators

performingquality assurance checks for solution performance

performing titrations

recognising control results that are not within acceptable range

interpreting and using safety information, such as that provided by material safety data sheets (MSDS) and follow relevant safety procedures

Required knowledge

Required knowledge includes:

solution terminology, chemistry of acids, bases, buffers, redox reactions and complexiometric reactions

concepts of metrology

grades of glassware, reagents and their use

reactions used for standardisation and desirable characteristics

enterprise communication and reporting procedures

occupational health and safety (OHS) procedures, including those for using corrosive materials

relevant health, safety and environment requirements

The range statement relates to the unit of competency as a whole. It allows for different work environments and situations that may affect performance. Bold italicised wording, if used in the performance criteria, is detailed below. Essential operating conditions that may be present with training and assessment (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) may also be included.

Codes of practice

Where reference is made to industry codes of practice, and/or Australian/international standards, it is expected the latest version will be used

Standards, codes, procedures and/or enterprise requirements

Standards, codes, procedures and/or enterprise requirements may include:

Australian and international standards, such as:

AS 2163-2000 Laboratory glassware - Measuring cylinders

AS 2165-1996 Laboratory glassware - Burettes AS 2162.1-1996 Verification and use of volumetric apparatus - General - Volumetric glassware

AS ISO 1000-1998 The international system of units (SI) and its application

AS/NZS ISO 9000 Set:2008 Quality management systems set

AS ISO 17025-2005 General requirements for the competence of testing and calibration laboratories

AS/NZS 2243 Set:2006 Safety in laboratories set

Australian code of good manufacturing practice for medicinal products (GMP)

calibration and maintenance schedules

enterprise recording and reporting procedures

equipment manuals

equipment startup, operation and shutdown procedures

MSDS and safety procedures

material, production and product specifications

national measurement regulations and guidelines

principles of good laboratory practice (GLP)

production and laboratory schedules

quality manuals

SOPs

waste minimisation and safe disposal procedures

Solutions

Solutions may include but are not limited to:

solutions of strong/weak acids and bases

oxidising/reducing agents

solutions used for complexometric or precipitation titrations

stains for cells and tissues, enzymes, buffers and antibodies

diluents for maintaining isotonicity

organic solutions and histological fixatives

Apparatus and reagents to prepare standard solutions

Apparatus and reagents to prepare standard solutions may include:

balances

pipettes, burettes, volumetric glassware and weighing bottles

dessicators and filtering media

ovens and muffle furnaces

solutions, indicators and primary and secondary standards

auto titrators, pH meters and other related meters and electrodes for determining equivalence points, top pan and analytical balances

magnetic stirrers and heaters, and water baths

Checking useability of solutions

Checking useability of solutions may include:

examining stained samples for correct staining reactions

performing pH checks

confirming enzyme activity

checking red cell suspensions for haemolysis

ferric chloride for phenolic solutions

isotonicity for saline

Hazards

Hazards may include:

chemicals, such as strong acids and bases, and stains

sharps and broken glassware

burners, hot plates, ovens and furnaces

Safe work practices

Safe work practices may include:

use of MSDS

use of personal protective equipment, such as gloves, safety glasses, goggles, faceguards, coveralls and gowns

use of biohazard containers, laminar flow cabinets and fume hoods

correct labelling of reagents and hazardous materials

handling and storing hazardous materials and equipment in accordance with labels, MSDS, manufacturer's instructions, and enterprise procedures and regulations

regular cleaning and/or decontaminating of equipment and work areas

Occupational health and safety (OHS) and environmental management requirements

OHS and environmental management requirements

all operations must comply with enterprise OHS and environmental management requirements, which may be imposed through state/territory or federal legislation - these requirements must not be compromised at any time

all operations assume the potentially hazardous nature of samples and require standard precautions to be applied

where relevant, users should access and apply current industry understanding of infection control issued by the National Health and Medical Research Council (NHMRC) and State and Territory Departments of Health