Rigaku NIC MA-3000 Operating instructions

Troubleshooting FAQs
for
MA-3000
Ver 1.0
Copyright © 2023 Nippon Instruments Corporation. All rights reserved.

MA-3000 Troubleshooting FAQs
Leak Check Fails
Q: Leak Check (Check of flow path) fail
Situation Possible causes to be confirmed
①
、②、④
③、④、⑤、⑥、⑦
(i) NG is generated by any of the V1 to V3 checks.
⑧
、⑨
Possible causes:
①
Dirt in the inlet port
②
Missalignment of MFC
③
Damage to sample heating tube
④ Loose or damaged joints
⑤
Deterioration of O-ring (P22A), installation fail
⑥
V3 valve failure
⑦
Damaged Z-axis nut
⑧
Clogged sample heating tubes and outlet activated carbon filter
⑨
Damage to pressure regulator
①：Dirt in the inlet port
Recommended action:
a. Turn off MA-3000
b. confirm that the temperature at the inlet port has cooled,
c. check the inlet port and the O-ring.
d. If there is any dirt or foreign matter, wipe it off using paper with ethanol.
②：Misalignment of MFC
Recommended action:
For Old Type of MFC (Blue)
a. Check on the maintenance screen, visual check:
b. Remove the right side plate/cover of MA-3000
c. Adjust with the trimmer for origin adjustment (Picture 1) with no flow.
(i) Flow rate value does not drop from 0.01 to 0.02 L/min.
(ii) Flow rate value does not drop from 0.2 to 0.4 L/min.
Answer 1: If the leak check fails with NG, the following
situations are possible:
Answer 2 : If the plumbing check fails with NG, the
following causes is possible:
Picture 1
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MA-3000 Troubleshooting FAQs
For New Type of MFC (Silver)
a. Check on the maintenance screen, visual check
b. Remove the right side plate/cover of MA-3000
c. Press and hold small button (Picture 2) with no flow rate.
③：Damage to sample heating tube
Recommended action:
a.Visual check: life of sample heating tube,
c. Check for swelling signs or damage due to moisture absorption.
d. Replace a new sample heating tube if sample heating tube damage is found
④：Loose or damaged joints
Recommended action:
b. Check if there is any measurement of samples that could react with quartz such as fluorine
which shorten sample heating tube lifespan
a. Check by hand tightening: Turn it lightly in the loosening direction, and if it turns easily,
retightens it.
b. Tighten the different-diameter joints lightly by hand and then retighten about 1/2 turn with a
wrench.
c. Check by hand tightening: The screw idles when tightened and/or nut section is bent at an
angle, the screw section may be damaged. Replace a new one. (Picture 3)
Picture 2
Picture 3
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MA-3000 Troubleshooting FAQs
⑤
：Deterioration of O-ring (P22A), installation fail
Recommended action:
Check O-ring from the port side whether O-ring slipping off or broken.
⑥：V3 valve failure
Recommended action:
b. if the leak check passes, the Tygon tubemust be replaced.
⑦：Damaged Z-axis nut
Recommended action:
a. Take out Z-axis nut from Z-axis assembly and check if it is damaged.
b. If it is damaged, replace a new one.
⑧：Clogged sample heating tubes and outlet activated carbon filter
Recommended action:
a. Check by replacing parts.
Note: Periodic replacement (1-year replacement) of activated carbon filter is strongly recommended.
⑨：Damage to pressure regulator
Recommended action:
Note: Put back the Tygon tube after at least 5 seconds after conditioning starts. Otherwise the catalyst in
sample heating tube may shift
If the activated carbon filter is not replaced for a long period of time, it will cause in decrease of
mercury removal rate and hence, NG in the check of flow path.
Check the pressure regulator on the rear panel and replace it if the gauge exceeded maximum
value.
a. Check during leak check: Remove the right side plate/cover of MA-3000, start leak check, and
bend the Tygon tube as shown in Picture 4,
Picture 4
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MA-3000 Troubleshooting FAQs
Contamination
A: This situation is most likely due to severe contamination.
Depending on the frequency and concentration, please follow the steps below for repair.
①
Repeat "Purge" measurement
②
Wash joints
③
If there is no improvement after the steps
①
and
②
④
If there is no improvement after the step
③
①：Repeat "Purge" measurement
a. Prepare several sample boats with 200 µl of water and
b. Repeat the measurement by alternating water and purge measurement in the sample tab.
c. This will gradually remove the mercury residue and decrease the blank.
d. Check the blank again after repeating several measurements.
②：Wash joints
a. Wash joints and cells (refer to instruction manual).
b. Perform
①
again after assembling the cleaned parts.
③：If there is no improvement after the operations in ① and ②
b. After that, perform step
①
④：If there is no improvement after the operation ③
Q: What should I do if a cell dark error occurs after sample measurements?
If mercury remains in the cell or in the tubing, it will later wriggle out and cause cell dark.
Recommended action:
When this happens, perform purge sufficiently and repeatedly. If contamination persists, parts
may need to be replaced.
Q: After measurement of sample with high mercury concentration, the blanks do not go
down. What should I do?
a. Replace the "boat handling poker," "sample heating tube," and "collector tube" according to
the instruction manual.
a. Other parts (solenoid valves, gas-liquid separation pipes, feed ports, and piping for each
section) and activated carbon filters need to be replaced.
b. If there is no improvement after performing the operations described in
②
-
④
, please
contact NIC for further assistance.
A: Cell dark error is most likely triggered by system contamination due to excessive amount of
mercury released from sample after thermal decomposition.
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MA-3000 Troubleshooting FAQs
Q:Sensitivity is low, what should I do?
Phenomena of low sensitivity includes:
1. Poor recovery of check standards
2. Poor recovery of CRM/SRM measurement
A: Below are possible causes:
Standards Solution related:
①Deterioration of standard solutions or standards preparation errors
Sample Nature related/Application issue:
②Decreased sensitivity due to sample nature
Consumables and hardwares/parts related:
③
Lifespan of sample heating tube/combustion tube
④Contamination of tubing, joints
⑤Accumulated dirt on sample boat
External factors:
⑥Affected by environment
Recommended action:
Possible Cause ②：Decreased sensitivity due to sample nature
Recommended action:
Possible Cause
①
：Deterioration of standard solutions or standards preparation
errors
- For heating method, prepare a standard solution using 100 ppm of L-cysteine solution in the
diluent.
- For reducing vaporization, prepare a standard solution using 10 ppm of L-cysteine solution
in the diluent.
Some sample types (such as sample contains high level of halogen, sulphur or oil) may
cause decreased sensitivity of the instrument after sample measurement. For samples with
poor reproducibility, measure the standard solution after the measurement to confirm.
If a decrease in sensitivity is occurring, it is necessary to change the measurement method,
reduce the sample volume, use an additive, or otherwise change the measurement technique.
Low Sensitivity
Mercury standard solutions are unstable, it can be easily adsorbed onto the glassware
surface or volatilized causing lost of mercury analyte.
a. To avoid mercury memory effect on the glassware, all glasswares used in the preparation
of mercury standard solutions should be thoroughly washed with 10% nitric acid.
b. We also recommend the use of L-cysteine solution in the diluent to provide better retention
of mercury.
Note: Please consult NIC for application advice if sample gives poor reproducibility or causes poor
sensitivity after measurement.
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MA-3000 Troubleshooting FAQs
Possible Cause
③
：Lifespan of sample heating tube
Recommended action:
a. If the number of measurements is more than 2000 times, please replace it.
Possible Cause ④：Contamination of tubing, joints
Recommended action:
Tubing will need to be replaced, fittings cleaned, etc.
Possible Cause ⑤：Accumulated dirt on sample boat
In the case where:
Recommended action:
⑥：Affected by evironment
Instrument is located in a room/environment consists of some interfering compounds
Recommended action:
Never use/operate instruments in rooms consists of halogenated reagents such as
organochlorine solvents or potassium iodide.
・If the tubing is contaminated, or if the gold in the collection tube section is blown into the
piping at the latter stage, a decrease in sensitivity may occur.
- there is no separation of boats used for mercury standard solution and sample
measurements;
- and after measurement, these sample boats are only heat treated without washing for a
long period of time,
In rare cases, reducing substances may accumulate within the sample boat which decreases
instrument sensitivity over time.
Soak and wash the sample boats in 1% nitric acid for 8 hours or more may improve the
situation.
If usage of sample heating tube has exceeded its lifespan (typically 2000 times), the internal
catalyst will no longer be able to remove interfering components effectively, and thus it
affects the system's sensitivity, optimum performance cannot be achieved.
b. If the number of measurements is less than 2000 times, repeat the purge and 200 μl of
water for 5 sets of measurements to see if the sensitivity recovers.
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MA-3000 Troubleshooting FAQs
Troubleshooting in Optional Attachment - SCRD
Q: Sensitivity error occurs with optional units (SC-3+RD-3, SC5+RD5).
A: Below are the possible causes of poor sensitivity:
① Flow rates are decreasing.
② There is leak.
③ Sample tube is contaminated.
①：Flow rates are decreasing.
・Replace the air pump tube if the replacement frequency (1 year) is exceeded.
・Visually inspect the air pump rotor and replace it if it is shaved or dented (Picture).
・Visually check the membrane filter and replace it if it has water droplets on it.
②：There is leak.
b. If MA-3000 standalone passes leak check, setup the configulation back to SC/RD.
d. If the bubbling is weaker than usual (less bubbles observed), check ① again.
③：Sample tube is contaminated.
a. Dispose of the measurement effluent in the sample tube.
Remark:
- Always perform alkaline rinsing of the sample container after each measurement.
- If you do not have an ultrasonic cleaner, soak the container overnight and scrub it with a brush.
- If alkaline detergent is not available, a 0.1M sodium hydroxide solution will also work.
④ Problems specific to reducing vaporization (blanks, standard solution, pretreatment, etc.)
- Do not mix measurement effluent with heavy metal solutions or other liquids that may
contain mercury.
b. After rinsing with water, place in a container with alkaline detergent solution and
ultrasonically clean for 30 minutes.
- If SnCl 2 remains in the sample container, it will react with mercury and volatilize while waiting for
measurement.
a. From System→Setup, set SC/RD to None (NONE) and confirm that the MA-3 alone
passes the leak check.
c. Fill the sample tube with about 5 mL of water and perform the measurement to confirm
bubbling.
- This step is important to eliminate the contamination issue because alkaline detergent solution can
remove SnCl2 effectively.
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MA-3000 Troubleshooting FAQs
d. After further rinsing with water, rinse with distilled water.
e. Dry and store to prevent dust, etc. from entering.
Please check the FAQs for the reduction vaporizer (RA-4500).
The standard solution may deteriorate, the L-cysteine concentration may be wrong, the
sensitivity may decrease during pretreatment, or the blank may rise during pretreatment.
c. Next, rinse well with water and ultrasonically clean in the same way with nitric acid (1+10)
for 30 minutes.
Remark: If cleaning detergent or nitric acid is used repeatedly, it may be contaminated. Please
replace it with a new one periodically.
- If you use a dryer after washing, please refrain from using it once as there is a possibility of
contamination during drying.
Remark: Sample tube that are opaque or have noticeable scratches will be difficult to clean. Replace
it with a new one.
④
：Problems specific to reducing vaporization (blanks, standard solution,
pretreatment, etc.)
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MA-3000 Troubleshooting FAQs
Troubleshooting in Optional Attachment - RH-MA3
Q:Sensitivity error occurs in the optional unit (RH-MA3).
A: Below are the possible causes :
①
Flow rates are decreasing.
②
There is leak.
③
Tube is contaminated.
④
Collector tube is degraded.
① Flow rates are decreasing.
b. Replace the air pump tube if the replacement frequency (1 year) is exceeded.
c. Visually inspect the air pump rotor and replace it if it is shaved or dented.
② There is leak.
a. Drain the buffer solution completely.
b. Tighten the roller clamps x2 if they are loose. If the silicone tube is damaged, replace it.
d. Setup configulation back to RH-MA3
g. After checking, slowly remove your finger from the collector tube.
Note:
Please be careful not to remove your finger from the collector tube too abruptly.
It may cause the gold component or quartz wool in collector tube to shift.
③：Tube is contaminated.
b. If gold or dirt from the collection tube adheres to the downstream,
④：Collector tube is degraded.
Recommended Action:
The collection tube is a consumable item, and periodic replacement is recommended.
a. Fill the wash bottle with distilled water, perform the measurement, and check for bubbling.
a. Contamination of the MA-3000 V4 valve and RH-MA3 tubing may result in poor data.
Please replace them periodically (about once/year).
- Clean the wash bottle, dehumidifying bottle, and fittings using 1+10 nitric acid and ultrasonic
cleaning for 30 minutes or soaking for at least 8 hours.
- If cleaning of parts does not restore the system, replace the above parts (air rinse bottle,
dehumidification bottle, and fittings) and piping tubes with new ones.
If the quartz wool at the rear of the collection tube is discolored, or if the collector is not fixed
in place and has shifted, mercury leaks during sampling and gold may jump to the latter stage,
resulting in reduced sensitivity.
c. From System→Setup, set SC/RD to None (NONE) and confirm that the MA-3 alone passes
the leak check.
e. With the buffer solution completely drained, connect the collection tube and start
measurement, then press down the inlet of the collection tube with your finger.
f. If air can be removed from the silicone tube at the bottom of the air wash bottle, there is no
leak.
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MA-3000 Troubleshooting FAQs
Q: Which method should I use for sample with unknown composition?
A: It is dangerous to decompose a lot of a sample which composition is unknown.
Recommended action:
a. Always start with a small amount (a few mg or so) of sample.
c. If it does give good and reasonable reproducibility, increase sample size slightly.
Typical Challenging Sample Matrices
The following are some examples of the most frequently asked questions.
① Samples with high oil content
② Samples with high halogen content
③ Samples with high salt content
④ Samples with high sulphur content
⑤ I got the measurement results, but I don't know if the values are correct.
⑥ Sensitivity decreased after sample measurement.
①
：Samples with high oil content
- their tendency to boil/react vigorously under high heat (low flash point) or,
- contain high levels of inorganic mercury
Recommended action:
Please contact NIC for application/method discussion
Methods for Unknown Sample
b. Check the recovery of check standards and standard addition to see if it gives good
reproducbibility.
Some oil-based samples require methods optimization and measurement know-how because
most of them are difficult samples due to
Copyright (C) 2023 NIC. All rights reserved.

MA-3000 Troubleshooting FAQs
②
：Samples with high halogen content
Recommended action:
- May require use of Additives.
Please contact NIC for application/method discussion.
Note:
1 Usage of Appendix K sample heating requires nitrogen carrier gas.
2 Regeneration of the Appendix K sample heating tube is necessary.
③
：Sample with high salt content
Recommended action:
a. Always start with a small amount (a few mg or so)
b. Please consult NIC for application/method discussion.
④
: Sample with high sulphur content
Sample with high sulphur content might affect system sensitivity.
Recommended action:
b. May require use of Additive B during sample measurement.
c. Please consult NIC for application/method discussion
⑤
：I got the measurement results, but I don't know if the values are correct.
Recommended action:
b. Confirm measurement result by performing standard addition recovery tests, etc.
⑥
：Sensitivity decreased after sample measurement.
- Presence of interfering compounds or,
- incomplete combustion or,
- the method is not appropriate, or,
- the sample volume is too large, or,
- additives are required, or,
- combination of the above factors
Recommended action:
Please contact NIC for application/method discussion
a. Always perform check standards, CRM and standard addition after such sample
measurement to ensure system sensitivity remains.
a. Check the sensitivity after sample measurement by measuring check standards, CRM after
the measurement
Samples that decrease in sensitivity after sample measurement may indicate factors below:
- For measurement of samples containing halogen, attach a sample heating tube (Appendix
K) (Code: S1106-0621-01).
Sample with high salt content may leave traces of salt deposited onto the quartz of sample
heating tube. Under a long period of high heat exposure, the sample heating tube will crack.
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