MELS500 Test 1

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Phases of testing

pre-analytical, analytical testing phase, post-analytical

pre-analytical testing phase

pre-testing, admin tasks

what does the pre-analytical phase consist of?

selecting appropriate test, obtaining and labelling specimen, providing timely transport to lab, registering receipt in lab, processing before testing

what does the analytical testing phase consist of?

testing the sample/running tests

what does the post-analytical testing phase consist of?

reporting of case to patients via clinicians

Types of fume hood

ducted, non-ducted, downflow/laminar, special

Ducted fume hood

wall or roof-controlled ducting to facilitate safe work environment

Non-ducted fume hood

filtration of air using activated charcoal

Downflow fume hood

working with fumes heavier than air

Laminar fume hood

has horizontal and vertical air flow for working with powders

Special fume hood

PCR work, genomics, molecular biology work, weight potent compounts and chemicals, radiation, highly corrosive material

Biohazard hood/cabinet

Enclosed, ventilated laboratory workspace for materials contaminated with pathogens requiring a defined biosafety level

Types of protection

Product protection, environmental protection, personnel protection

HEPA filter

protects environment by filtering air before it is exhausted

Class I biohazard hood

provides personnel and environmental protection, suitable for low to moderate risk, has hepa filter

Class II biohazard hood

provides personnel, environment and product protection, has 3 main features

Main features of class II biohazard hood

Front opening with maintained inward airflow, hepa filtered unidirectional airflow inside work area, hepa filtered exhaust air to the room

Class III biohazard hood

work with microbiological agents assigned to biosafety level 4, maximum protection ot user and environment

Class III applications

diseases that are emerging or near eradication, weighing and diluting chemical carcinogens

spectrometer use

measure wavelengths of light that has interacted with a sample

autoclaves

sterilisation at elevated temperature and pressure in relation to ambient

oven

drying, material testing, curing, heated storage

incubator

temperature-controlled environment to support growth of microbiological cultures

water baths

incubate samples at a constant temperature over a long period of time, heating flammable chemicals

light microscope

uses visible light and a system of lenses to generate magnified images

fluorescence filters

excitation filter, emission filter, dichroic beamsplitter

stereoscopic/dissecting microscope

low magnification using light reflected from surface of object

centrifuge

separate fluids/gases/liquids based on density for cell collection, organelle/virus/protein/nucleic acid purification

internal maintenance

housekeeping, validation, QC

external maintenance

service technician, service contracts

test tube

beaker

conical flask

volumetric flask

Chemical Hazard — Flammable

Chemical Hazard — Compressed Gas

Chemical Hazard — Corrosive

Chemical Hazard — Oxidising

Chemical Hazard — Harmful

Chemical Hazard — Harmful

Chemical Hazard — Toxic

Chemical Hazard — Explosive

Biological Hazard

Formula for volumes for reagent preparation

C1V1=C2V2

Define Molarity

Number of moles of solute per one litre of solution; A measure of concentration

Define Normality

Number of equivalents of solute per litre of solution

Molarity of needed solution (M)

Mass of Solute (g) x 1/Molar Mass (g/mol) x 1/Final Volume of Solution (L)

Mass of Solute (g)

Molarity (M) x Final Volume of Solution (L) x Molar Mass (g/mol)

Final Volume of Solution (L)

Mass of Solute (g) x 1/Molar Mass (g/mol) x 1/Molarity (M)

Saturated Solution

Solution containing maximum amount of a particular solute that will dissolve at that temp

Supersaturated Solution

Solution containing more solute than equilibrium conditions allow

Solute

Substance which is dissolved or has gone into solution; typically a solid

Solution

Uniform homogenous mixture of two or more substances; Individual substance may be present in varying amounts

Solvent

Substance which does the dissolving; typically liquid

Standard solution

Very precise solution used in quantitative analysis; 3-4 s.f.

Lab Math

Using calculations to analyse lab results; Any math skill or technique used in laboratory science

Why do we need lab math?

To understand principles of lab tech and experiments, calculate correct amounts of reagents used in sample testing, analyse results and troubleshoot problems

When do we use lab math?

Dilutions of samples or reagents, calculating concentrations, unit conversions, calculating volumes for reagent preparation, calculating analyte amounts or rates, quality control and SD, specimen volume calculations

How much water will you add to 20 mL of concentrated hydrochloric acid to make a 20% (v/v) HCl solution?

80mL water

How much sodium chloride (NaCl) in grams is needed to make up 5% (w/v) sodium chloride solution in 100 mL of distilled water?

5g NaCl

True or false? Always add water to acid, and not vice versa.

False

What does pH stand for?

Potential of hydrogen

Acid pH range

1 to just under 7

Base pH range

7 to 14; over 7

Exponential component use in laboratory settings?

To model phenomena exhibiting growth or decay at a rate proportional to their current value; e.g. bacteria growth

hecto

10²

kilo

10³

mega

10⁶

giga

10⁹

tera

10¹²

peta

10¹⁵

deca

10¹

deci

10^-1

centi

10^-2

milli

10^-3

micro

10^-6

nano

10^-9

pico

10^-12

femto

10^-15

Histology specimen

Body tissues

Microbiology specimen

Urine, faeces, bodily fluids

Haematology specimen

Blood

Transfusion science specimen

Blood

Immunology specimen

Blood, bodily fluids

Clinical chemistry specimen

Blood, bodily fluids

Specimen labelling

patient name, DOB, NHI#, date and time of collection, specimen type, test requested, clinical history and infectious status if known

Transport systems

lampson tubes, hand delivery, posting, sea, air, road

Specimen collection consideration

Aseptic precautions, anatomic sites/locations, timing, lab request form, transport media, correct specimen container, avoid contamination

Specimen criteria for rejection

Labelling errors, unsatisfactory specimens, insufficient quality, inappropriate container, contamination suspected, inappropriate transport or storage

Specimens must be…

good quality (adequate), sealed tightly and securely, not externally contaminated

Blood serum

liquid that remains after blood has clotted

Blood plasma

liquid that remains when clotting is prevented with addition of anticoagulant

Light blue top — Sodium citrate

coagulation tests

Red top — serum

therapeutic drug monitoring

Gold top — SST II

LFTs, iron, hormones

green top — heparin

lactate, ammonia, plasma K

Lavender top — EDTA

CBC, CD4

Pearlescent top — PPT

use as discard

Pink top — cross match

transfusion medicine

Grey top — fluoride oxalate

glucose, glucose tolerance