ISO 15839:2003 水質—水用のオンラインセンサー/分析装置—仕様と性能テスト | ページ 5

3.1

accepted reference value

[SOURCE:Adapted from ISO 5725-1:1994]

3.2

accuracy

closeness of agreement between a measured value and the accepted reference value

Note 1 to entry: The term accuracy, when applied to a set of measured values, involves a combination of random components and a common systematic error or bias component.

[SOURCE:Adapted from ISO 5725-1:1994]

3.3

analytical chain

set of instruments and actions covering all the steps involved in determining a reference value in a field test, including sampling, fractioning, conditioning, storage and transportation of the sample to the laboratory for analysis

3.4

availability

percentage of the full measurement period during which the measurement chain is available for making measurements

Note 1 to entry: The full measurement period is the period which includes all specified automatic or manual maintenance operations at least once

3.5

bias

consistent deviation of the measured value from an accepted reference value

Note 1 to entry: Bias is the total systematic error as contrasted to random error. There may be one or more systematic error components contributing to the bias. A larger systematic difference from the accepted reference value is reflected by a larger bias value.

[SOURCE:Adapted from ISO 5725-1:1994]

3.6

blank solution

solution, free of determinand, to which the on-line sensor/analysing equipment is exposed in the same way as calibration or sample solutions

Note 1 to entry: The value of the measurement is known as the “blank value”.

3.7

calibration solution

solution containing a substance or mixture of substances giving a defined value of the determinand and used for calibration of the on-line sensor/analysing equipment

3.8

calibration procedure

set of operations that establishes, under specified conditions, the relationship between the amount or quantity of calibrant and the response indicated by the on-line sensor/analysing equipment

3.9

coefficient of variation

ratio of the standard deviation of the on-line sensor/analysing equipment to the mean of the working range of the equipment

[SOURCE:Adapted from ISO 8466-1:1990]

3.10

day-to-day repeatability

precision under day-to-day repeatability conditions

3.11

day-to-day repeatability conditions

conditions whereby independent test results are obtained with the same method on identical test items in the same laboratory by the same operator using the same equipment and reagents over several days

3.12

delay time

time interval between the instant when the on-line sensor/analysing equipment is subjected to an abrupt change in determinand value and the instant when the readings pass (and remain beyond) 10 % of the difference between the initial and final value of the abrupt change

Note 1 to entry: For on-line sensor/analysing equipment with a sample-handling system the delay time frequently depends on the time needed to convey the sample from the sampling point to the analyser inlet.

3.13

determinand

property/substance that is required to be measured and to be reflected by/present in a calibration solution

3.14

fall time

difference between the response time and the delay time when the abrupt change in determinand value is negative

3.15

interference

undesired output signal caused by a property(ies)/substance(s) other than the one being measured

[SOURCE:ASTM D 3864-96]

3.16

interferent

component of the sample, excluding the determinand, that affects the output signal

3.17

limit of detection

LOD

lowest value, significantly greater than zero, of a determinand that can be detected

3.18

limit of quantification

LOQ

lowest value of a determinand that can be determined with an acceptable level of accuracy and precision

3.19

linearity

condition in which measurements made on calibration solutions having determinand values spanning the stated range of the on-line sensor/analysing equipment have a straight-line relationship with the calibration solution determinand values

3.20

long-term drift

slope of the regression line derived from a series of differences between reference and measurement values obtained during field testing, expressed as a percentage of the working range over a 24 h period

3.21

lowest detectable change

LDC

smallest significantly measurable difference between two measurements

3.22

period between maintenance operations

time between successive maintenance operations on the measurement chain

Note 1 to entry: The shortest period between maintenance operations will typically be of the order of a few hours (between two automatic rinse operations). The longest period between maintenance operations will typically be of the order of a few months (between services).

3.23

measurement

mean value of at least 10 consecutive readings

3.24

measurement chain

set of instruments and actions that covers all the steps involved in measuring a determinand, including the on-line sensor/analysing equipment, sampling and pretreatment, transportation and storage of the sample

3.25

memory effect

temporary or permanent dependence of readings on one or several previous values of the determinand

[SOURCE:Adapted from ISO 6879:1995]

3.26

on-line sensor

analysing equipment

automatic measurement device which continuously (or at a given frequency) gives an output signal proportional to the value of one or more determinands in a solution which it measures (see Annex B)

3.27

performance characteristics

set of parameters describing the performance of the on-line sensor/analysing equipment and measurement chain

3.28

precision

the closeness of agreement between independent measured values obtained under stipulated conditions

Note 1 to entry: Precision depends only on the distribution of random errors and does not relate to the true value or the specified value.

Note 2 to entry: The measure of precision is usually expressed in terms of imprecision and computed as a standard deviation of the test results. Less precision is reflected by a larger standard deviation.

[SOURCE:Adapted from ISO 5725-1:1994]

3.29

reading

manual or automatic registration of the on-line sensor/analysing equipment response

Note 1 to entry: Readings are taken with a frequency which depends on the dynamics of the on-line sensor/analysing equipment (i.e. on the response time — see 3.33 and 5.1.2).

3.30

reference material

substance, or mixture of substances, the composition of which is known within specified limits, and one or more of the properties of which is sufficiently well established, over a stated period of time, to be used for the calibration of an instrument or the assessment of a measurement method

3.31

repeatability

precision under repeatability conditions

[SOURCE:ISO 5725-1:1994]

3.32

repeatability conditions

conditions where independent test results are obtained with the same method on identical test items in the same laboratory by the same operator using the same equipment and reagents within short intervals of time (e.g. one day)

[SOURCE:Adapted from ISO 5725-1:1994]

3.33

response time

time interval between the instant when the on-line sensor/analysing equipment is subjected to an abrupt change in determinand value and the instant when the readings cross the limits of (and remain inside) a band defined by 90 % and 110 % of the difference between the initial and final value of the abrupt change (see 5.2.1)

Note 1 to entry: In laboratory testing, the response time of the on-line sensor/analysing equipment is measured. In field testing, it is the whole measurement chain which is tested.

3.34

rise time

difference between the response time and the delay time when the abrupt change in determinand value is positive

3.35

ruggedness

on-line sensor/analysing equipment stability when the equipment is subjected to different environmental conditions which could possibly affect its performance

Note 1 to entry: Ruggedness also describes the behaviour of the equipment in the hands of different operators who will inevitably introduce small variations in operations such as calibration and maintenance which may or may not have a significant influence on performance.

3.36

selectivity

extent to which the on-line sensor/analysing equipment can determine a particular determinand in a complex mixture without interference from the other components in the mixture

Note 1 to entry: On-line sensor/analysing equipment which is perfectly selective for a determinand is said to be specific.

3.37

short-term drift

slope of the regression line derived from a series of measurements carried out on the same calibration solution during laboratory testing, and expressed as a percentage of the measurement range over a 24 h period

3.38

signal

conveyor of information about one or more determinands

Note 1 to entry: An input signal is a signal applied to the on-line sensor/analysing equipment. An output signal is a signal delivered by the equipment.

3.39

stated range

range covered by the on-line sensor/analysing equipment as stated by the manufacturer/supplier

3.40

test procedure

series of measurements performed to determine the value of a performance characteristic

3.41

test bench

test facilities which are necessary to test on-line sensor/analysing equipment or a complete measurement chain

3.42

up-time

percentage of a full measurement period during which the measurement chain is actually measuring during field testing

3.43

working range

range between the lowest and highest determinand value for which tests to determine precision and bias have been carried out