manufacturer:       Varian      

model:                   SpectrAA 300

annotation:           Dokumente engl.

Instrument Parameters

LAMP POSITION                     SpectrAA-400 (automatic turret) 1 through 8.

SpectrAA-300 (manual turret) 1 through 4.

These parameters will not appear on the screen if you selected FLAME EMISSION as the instrument mode on the method page. Lamp current will be locked at 0.

lf a coded lamp for the selected element is already in the turret, the LAMP POSITION will be automatically entered.

If there is no coded lamp in the turret and this page is entered from the METHOD page, the LAMP POSITION entry will default to #1 and status message LAMP NOT RECOGNIZED will be displayed. If this page is entered from any page other than METHOD, the LAMP POSITION data will remain at its previously entered value.

If you are using uncoded lamps, it is recommended that you keep a note of the lamp positions used for each element.

When a manual turret is being used, you must enter the correct lamp position number for uncoded lamps even though the turret must be manually set to the required position. The system uses the lamp position number to apply the selected lamp current to the appropriate lamp.

LAMP CURRENT                    0 — 20 (mA)

SLIT WIDTH                            0.1, 0.2, 0.5, 1.0 (nm)

You cannot use a slit width of 0.1 nm with reduced slit height

SLIT HEIGHT                           Use the HOME key to select normal or reduced.

If you inadvertently select reduced height with 0.1 nm slit width, error message E 79 will be displayed on the screen.

WAVELENGTH                       180.0 to 900.0 & 0.0 (nm)

When you originally develop a method, the system will automatically select the most sensitive absorption line. You may, of course, change this wavelength if you want to use a less sensitive line.

Note particularly that when using flame emission, the wavelength automatically selected will still be the most sensitive absorption line and this may not be the required emission wavelength. See Section Eleven for a list of recommended emission wavelengths.

FLAME                                     Use the HOME key to select:

air-acetylene

nitrous oxide-acetylene

air only.

SAMPLE                                  Use the HOME key to select::

INTRODUCTION                     manual

auto normal

auto micro

MANUAL sample introduction means 'hand-held" samples. If you want to operate the sample changer by `manual control', you must select one of the auto modes.

AUTO NORMAL is the standard method of using the sample changer for fully automated analysis, or you may operate the sample changer by 'manual control:

AUTO MICRO enables you to use the microsampling technique for automatic determinations on very small volumes of sample. Analytical measurements are male in either the peak height or peak area mode. For this technique, you may use the optionally available microsampling carousel with appropriate microsample vials.

DELAY TIME                            0 to 100 in 1 s increments

NOT applicable in AUTO MICRO mode.

When AUTO NORMAL is being used, this is the time in seconds which elapses between the probe reaching the fully down position and the start of the actual measurement. For MANUAL sampling, it is the time which elapses between pressing READ and the start of the actual measurement. This delay allows the flame to stabilize before the actual reading is taken. For most applications the flame will be stable about 10 seconds after the start of aspiration.

For vapor generation analyses with the VGA-76, the delay period required is generally about 40 seconds; for mercury it is about 45 seconds (refer also to the VGA-76 Operation Manual).

The delay time applies to all measurement modes. Note that if replicate measurements are being taken in the Integration mode the delay is applied before the first replicate only (in peak height or peak area I-nodes the delay will occur before each replicate).

MEASUREMENT TIME          This is the period over which the measurement will be integrated before the Jesuit is displayed. You may use any period between 1 and 500 seconds in 0.1 second increments. A period of 3 seconds will provide adequate readout precision for most analyses; generally you are unlikely to require more than 10 seconds.

For the microsampling mode ALWAYS observe the following criteria:

(i) The MEASUREMENT TIME must always be longer that the DIP TIME (SAMPLE CHANGER page).

(ii) Never use a MEASUREMENT TIME of less than 4 seconds.

(iii) A MEASUREMENT TIME of 6 seconds will generally be adequate for most analyses.

PRECISION                            These parameters will only appear on the screen if you selected

DEFAULT TIME                       PROMT as the measurement mode when compiling the method page.

This measurement mode allows you to select the precision that you would like to achieve. You may 'request" any precision between 0.1 and 99.9%.

The default time allows you to place a sensible limit on the time over which the system attempts to achieve the specified precision. lf the specified precision cannot be achieved during this time, the progressive calculation of the precision optimized measurement will be automatically terminated and the precision displayed will be that obtained in the time allowed.

REPLICATES                          This is the number of separate analytical results that you require from the blank, every standard, sample and

reslope solution. You may select any number of replicates between 1 and 40. The number of replicate measurements required will generally be governed by the degree of statistical confidence required for your analyses.

NOT required when using the PROMT mode.

The system will display each replicate measurement together with the RSD (%) for the series. Note, however, that the analytical results displayed are 'rounded values, whereas the system uses actual values to compute the RSD. Consequently, there may be an APPARENT anomaly between the series of replicates and the RSD. For example, the values for three replicate measurements may be displayed as 0.142, 0.142, 0.142 with an RSD of 0.3%. This is NOT a calculation error within the system, it is a consequence of the displayed values being `rounded" while the actual values are used for computation.

BACKGROUND                      Use the HOME key to select:

CORRECTION                       background corrector on

background corrector off

background only

The background corrector options will not appear if you selected LAMP EMISSION or FLAME EMISSION as the instrument mode on the methods page.

EXPANSION FACTOR           1 to 100

This parameter will only appear on the screen if you have selected SCALE EXPANSION as the calibration mode when compiling the method page.