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:

prepare working solutions in compliance with relevant standards, appropriate procedures and/or enterprise requirements

follow OHS procedures to safely use laboratory chemicals glassware and equipment

make up working solutions according enterprise procedures

check existing stocks of solutions as being fit for purpose.

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:

MSL922001A Record and present data

MSL943002A Participate in laboratory/field workplace safety.

Resources may include:

standard laboratory equipped with appropriate equipment and reagents

SOPs and testing methods

access to appropriate containers and storage facilities.

Method of assessment

The following assessment methods are suggested:

inspection of solutions prepared, labelled and stored by the candidate

review of solution records and workplace documentation completed by the candidate

feedback from peers and supervisors

observation of the candidate preparing working 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 show its relevance in a workplace setting.

Manufacturing

When starting materials used for the manufacture of common household materials are in transit from the supplier to the manufacturer, they may degrade if subjected to conditions, such as heat, moisture, light and oxygen. Even when the supplier ships quality materials to the manufacturing plant, the materials may be sub-standard when they arrive. Quality control tests are designed to test starting materials to ensure they are within specification. For example, aspirin forms salicylic acid when stored under adverse conditions. Laboratory assistants prepare and monitor the quality of solutions, such as ferric chloride solution, which gives an intense violet colour when added to salicylic acid but gives no colour with aspirin. Absence of the violet colouration indicates that breakdown of the aspirin hasn't occurred.

Biomedical

A laboratory assistant made up 1 litre of buffer solution using buffer tablets and a 1 litre volumetric flask as specified in the method. To ensure the solution was suitable for use the assistant measured the pH and found it was within acceptable range. The assistant then appropriately labelled a storage vessel and stored the buffer according to requirements. By following enterprise procedures the shelf life of the buffer was maximised.

Environmental

An environmental laboratory is contracted to determine the acidity of water samples taken from local lakes and streams. A laboratory assistant is required to make up small batches of 0.01M sodium hydroxide and to determine its concentration by titrating it against a standard solution of potassium acid phthalate using phenolphthalein indicator. This procedure is carried out monthly to ensure that the concentration of the sodium hydroxide solution is accurately known. Alternatively, the laboratory assistant may be required to prepare and standardise a fresh batch of sodium hydroxide on a monthly basis. In this case, he/she must understand the underpinning knowledge of basic acid/base theory, potential problems of interferences (such as slow absorption of carbon dioxide by sodium hydroxide solution) so as to ensure that the concentrations of workup solutions are accurately known. He/she must also be skilled in calculating and performing dilution when required to prepare such low concentrations (0.01M) of working solutions.

Required skills

Required skills include:

using appropriate materials, equipment and procedures to prepare solutions

following appropriate occupational health and safety (OHS), and hygiene procedures, if appropriate

using all equipment safely and efficiently

using enterprise procedures to calculate concentrations

identifying solutions not fit for use

using titrations to determine the concentration of solutions

labelling, storing and disposing of solutions appropriately

recording and presenting data appropriately

Required knowledge

Required knowledge includes:

relevant biological, chemical, food and laboratory terminology

principles of metrology

the international system of units (SI)

concentration terms, such as % w/w, % w/v, % v/v, ppm (mg/L) and molarity

basic theory of acids, bases, salts, buffers and neutralisation

enterprise procedures for preparing solutions

calculations required to prepare specified amounts of solutions of specified concentration

appropriate OHS procedure for preparing, handling and disposal of solutions

use of material safety data sheets (MSDS)

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 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

standard operating procedures (SOPs)

Concepts of metrology

Concepts of metrology may include:

that all measurements are estimates

measurements belong to a population of measurements of the measured parameters

repeatability

precision

accuracy

significant figures

sources of error

uncertainty

traceability

Typical test solutions

Typical test solutions may include:

solutions required for diagnostic/analytical and limit tests in food and chemical laboratories, such as sulphates, chlorides and heavy metals

solutions, such as stains for standard diagnostic/analytical procedures in biomedical/environmental laboratories, such as cell staining, fixation of cells and tissues, suspension of cells and titrimetric indicators

solutions required for laboratory maintenance and disinfection, such as 70% ethanol and hypochlorite

Laboratory equipment

Laboratory equipment may include:

pH meters

balances

magnetic stirrers, water baths and hot plates

measuring cylinders, beakers, conical flasks, volumetric flasks, pipettes and burettes

filter papers and funnels

fume cupboards

Hazards

Hazards may include:

corrosive chemicals, such as acids and alkalis

sources of heat, such as burners

sharps and broken glassware

spillages

Safety precautions

Safety precautions may include:

use of MSDS

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

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 decontamination of equipment and work areas

Monitoring quality of solutions

Monitoring quality of solutions may include:

noting turbidity to exclude absorption of moisture

noting deposits to exclude microbial contamination or chemical degradation

noting crystals to exclude evaporation

conducting titrations to check concentration

noting colour changes indicating a pH shift with solutions containing indicators

checking expiry dates on solution containers

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