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Published byCarmella Fisher Modified over 9 years ago
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pH and ICP Techniques Clemson
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pH quality control checks Scoop 2 checks One blank Double scoop 6 samples Tag set with lab number, check, and blank positions
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Quality control row Two QC check samples Two samples at beginning, middle, and end of set Cross Check electrodes #1 and #2 231
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End of run verification Check both QC check values at beginning and within set Check all double scooped samples at beginning, middle, and end of set Buffer run - checks Buffer run - blank (1:1, water:buffer) ck
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Maintenance Friday ◦clean out electrode filling solution ◦fill with water Ultrasonic cleaner Store in buffer pH 7 for the weekend
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Maintenance – cont. Monday ◦Take water out of electrode ◦Refill with KCl filling solution Verify flow of KCl through filter Refresh buffer solutions Electrode (from Fisher) ◦Accumet rugged bulb pH combination electrode ◦13-620-183A
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pH Check values Check B data since April 1, 2010 115 continuous reads over a 2.5 month period Rinse pH 7.0 NAPT value 5.15 Lab average 5.15 stdev 0.036
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ICP quality control checks Two checks within the set One blank
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Sample entry Probe – Leeman Labs ◦Phone: 603-886-8400 ◦Part number 902-00017 Check all tubing for cleanliness and kinks Change pump winding tube when needed Adjust pump winding clamp - look for smooth flow as sample travels though tube
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Nebulizer gas flow Aspirate yttrium stock solution Look for the tip of the red bullet Adjust nebulizer gas flow rate TJA ARCOS
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Nebulizer and spray chamber Keep clean ◦Take apart to rinse out nebulizer and spray chamber parts TJA – use cleaning wire ARCOS ◦SeaSpray Nebulizer ◦Twister Spray Chamber ◦Cross Flow TJA ARCOS
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Torch ARCOS – clean as needed – salt buildup TJA – clean ~once a year TJA ARCOS
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Setting the flush time ARCOS - Crossflow Transient scan – run standard Check to see when the peak intensities stabilize Clemson – 35 second total flush ◦25 seconds at 60 rpm ◦10 seconds at 30 rpm 25 seconds Time (seconds) using pump speed of 60 rpm P K
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Transient scan on ARCOS 18 seconds 25 seconds Crossflow spray chamber Twister spray chamber
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Transient scan going to rinse ARCOS - Crossflow Options for changing flush time ◦Spray chamber ◦Tubing length ◦Pump speed ◦Sample loop Ca – 100 ppm Na – 50 ppm P – 100 ppm K – 100 ppm 45 seconds Time in seconds using pump speed of 60 rpm 25 seconds
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Setting the flush time - TJA Run time scan Check time for stability Clemson soil method ◦pump speed 200 rpm ◦flush time 30 seconds Ca - 40 seconds Pump speed 175 rpm
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Line selection – ARCOS Look at several recommended lines Clemson - Ca line – 317.933 for soil Ca – 396.847 Saturated signal Ca – 315.887
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Method development - ARCOS Set peak position Select clean area for background subtraction Look for uncontaminated blank Cu – 324.754 blank Peak position Blank correction
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Instrument profile and data verification Run profile when needed On the AROCS - check intensity of P158.599 line If significant UV intensity drop – clean window and/or lens to optics Check new standard against old Read reference sample at start, mid point, and end of run Verify 2 check samples and blank within set
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