Improvements in Deuterium Lamps Maximize HPLC ... - T.E.A.M.

Improvements in DeuteriumLamps Maximize HPLC SystemPerformance• Longer lamp life• Six- to ten-fold increase in sensitivity• A PerfectFit with the Agilent 1100Series HPLC lineBy Erich WagnerProduct Manager—HPLC ConsumablesThe Agilent 1100 Series HPLC as wellas the 1050 and 1090 systems arefound in analytical laboratoriesaround the globe, serving industriesthat depend on reliable and reproducibleresults—particularly at lowlevels of detection. However, mostanalysts do not realize that thedetector lamp they install can makea significant difference in their overallsystem performance.Lamp Improvements for the Agilent1100 Detectors Provide Long LifetimePlus Enhanced System Sensitivity—Lamp Life Extended by 50%The lifetime of detector lamps forthe Agilent 1100 HPLC instrumentis extended by applying a consistentand thick coating on the lamp cathode.Figure 1 shows the differencebetween a cathode in an improvedAgilent lamp versus a popular competitorlamp. The unique Agilentproprietary process forms a highdensity, uniform coating on the cathodewithout notable darkened areas.In contrast, there are observabledarkened areas along the Brand Xcathode. Darkened areas representbreaks in the cathode coating andcause shorter lamp lifetime. In fact,the new coating process increasesAgilent 1100 lamp lifetimes up to50%. In addition, improvements inthe cathode coating also result in amore consistent lamp-to-lamp voltageand therefore a more consistentFigure 1. A Consistent Coating on theAgilent Cathode Extends Lamp LifetimeDarkened areas along the Brand X cathoderepresent breaks in the cathode coating thatshorten lamp lifetime.Agilent CathodeBrand X Cathodelamp-to-lamp signal. These improvementsalso enhance the sensitivityof the Agilent 1100 instrument.The same cathode improvementsdescribed above have been appliedto the lamps for the Agilent 1090 and1050 Series Diode Array Detectors(DAD) and the 1050 MultipleWavelength Detector (MWD). Again,this proprietary coating processextends these lamp lifetimes by upto 50%.Increased Signal-to-Noise RatioMost commercially available deuteriumlamps are manufactured with a1.0 mm aperture. Agilent deuteriumlamps for the 1100 Series HPLC aredesigned with a much narroweraperture, which provides increasedlight intensity and decreased noise,translating into an appreciablyhigher signal-to-noise ratio. Theseimprovements in overall sensitivityare possible only if the apertureis aligned properly in the HPLCdetection system. Without properalignment, potential gains insensitivity cannot be realized.www.agilent.com/chem Separation Times Volume 16 Number 1 200317

Improvements in Deuterium LampsContinued from page 17Through innovative design and constructionsteps, Agilent DAD andMWD longlife deuterium lamps arealigned precisely during the manufacturingprocess. A computercontrols positions and permanentlysecures the glass bulb of the lampinto the aluminum mounting-ring,thereby creating a pre-alignedproduct for the Agilent 1100 HPLCinstrument. The PerfectFit finalproduct is not only optimized forperformance, but the lamp is easierto handle during both installationand removal.Shine-Through Deuterium Lamps forHigh-Intensity UV-Vis WavelengthsShine-Through Deuterium lamps forthe Agilent 1100 are constructedso that essentially two lamps—oneultraviolet and the other visible—areplaced in series, providing a highintensity broad-spectrum operatingrange of 200 to 800 nm.A Ten-Fold Increase in SensitivityThe overall increase in sensitivitygained when selecting an AgilentShine-Through Deuterium lamp withan Agilent 1100 could be as high astenfold. This is demonstrated inFigure 2, which compares a separationof lysozyme using an AgilentShine-Through Deuterium lamp withthe same separation conductedusing a deuterium lamp not made toAgilent specifications. Whether operatingin the ultraviolet region at 214nm or at 280 nm, the differences arestriking. Both lamps easily detect themain component at approximately13.2 minutes, but only the Agilentlamp on this absorbance scale clearlydetects the low-level impuritiesFigure 2. Lamp Selection Impacts Chromatographic Performance–Separation ofLysozyme and its ImpuritiesImpurity peaks at retention times greater than 16 minutes are clearly present when the instrumentis configured with the Agilent lamp.mAU200150100500-50mAU200150100500-50mAU1512.5107.552.50-2.5mAU1512.5107.552.50-2.5Agilent Shine-ThroughDeuterium Lamp at 214 nm0 2.5 5 7.5 10 12.5 15 17.5 20 min(Time)Non-Agilent Lamp at 214 nm0 2.5 5 7.5 10 12.5 15 17.5 20 min(Time)Agilent Shine-ThroughDeuterium Lamp at 280 nm0 2.5 5 7.5 10 12.5 15 17.5 20 minNon-Agilent Lamp at 280 nm(Time)Clear detectionof low-levelimpurity peaksPoor impurityidentificationClear detectionof low-levelimpurity peaksPoor impurityidentification0 2.5 5 7.5 10 12.5 15 17.5 20 min(Time)13.1513.1713.1513.1718.5718.9218.5718.9220.7120.71O R D E RG U I D EInstrument/Detector Lamp Type Part Number1100 Series DAD/MWD Shine-Through Deuterium 2140-05901100 Series DAD/MWD Long-Life, Shine-Through Deuterium 5181-15301090 Series Diode Array Detector (DAD) Deuterium 79883-600021050 Series Diode Array Detector Deuterium 79883-600021050 Series Multiple Wavelength Deuterium 79883-60002Detector (MWD)18 Separation Times Volume 16 Number 1 2003 www.agilent.com/chem

Improvements in Deuterium LampsContinued from page 18having retention times between16 and 20 minutes in this sample.Expanding the absorbance scale forthis peptide separation at 214 nmclearly shows that the Agilent lampprovides a six- to ten-fold highersignal-to-noise ratio than the non-Agilent lamp (see Figure 3). Byproviding higher sensitivity, Agilentlamps can extend detection capabilitiesand improve quantification attrace levels—for more than 2,000hours of use.Performance TestsWe also tested four lamps, each froma different manufacturer, for alignmenttolerance and noise followingthe ASTM protocol. The followingtable summarizes the results of thesetests. None of the four lamps testedwere correctly aligned for theAgilent 1100 instrument; all hadalignment tolerances greater than100% and noise levels were high—upto 20 times higher than Agilent specificationsfor the wavelengths listedthe table.PerfectFit Agilent LampsAgilent deuterium lamps are differentand better because they arespecifically designed to last longerand to provide enhanced sensitivitywhen using the Agilent 1100 as wellas the 1090 and 1050 Series HPLCline.Figure 3. Agilent Lamps Are Optimized to Maximize Sensitivity–Separationof Lysozyme and its Impurities (expanded scale) at 214 nmPerfectFit Agilent lamps, with increased signal-to-noise, provide increased sensitivity,precision, and accuracy at low levels.mAU605550454035mAU605550454035Agilent Lamp at 214 nm116.5816 17 18 19 20 min(Time)Non-Agilent Lamp at 214 nm116.58Peak 1 S/N = 150Peak 2 S/N = 400Peak 3 S/N = 300Peak 1 S/N = 15Peak 2 S/N = 50Peak 3 S/N = 5016 17 18 19 20 min(Time)For More InformationVisit www.agilent.com/chemand click “Library” then enterpublication 5980-2372E inthe keyword field and click“Search.” Or ask your localAgilent sales representativefor additional information.Improved S/Nensures detectionof all impuritiesNo impuritydetected218.57218.5718.92320.71320.7120.9420.94Performance Tests Find Competitor Lamp Performance Outside SpecificationsAll of these non-Agilent lamps were outside noise level and alignment specifications (>100%).Non-Agilent Lamp Alignment Tolerance (%) ASTM Noise in mAU measured at:Measurement x-dir y-dir z-dir 254 nm 750 nm 254 nm 750 nm 254 nmAgilent Specifications 100% 100% 100%